CUNY Advanced Science Research Center
85 St Nicholas Terrace,
New York, NY 10031
June 23rd and 24th 2016
1. A carbon nanotube optical reporter maps endolysosomal lipid flux
Prakrit V. Jena*, Daniel Roxbury, Thomas V. Galassi, Leila Akkari, Christopher P. Horoszko, Januka Budhathoki-Uprety, Nina H. Pipalia, Abigail S. Haka, Jackson D. Harvey, Jeetain Mittal, Frederick R. Maxfield, Johanna Joyce, Daniel A. Heller
Dept. of Molecular Pharmacology Memorial Sloan Kettering Cancer Center
Lipid accumulation within the lumen of endolysosomal vesicles is observed in various pathologies including atherosclerosis, liver disease, neurological disorders, lysosomal storage disorders, and cancer. Current methods cannot measure lipid flux specifically within the lysosomal lumen of live cells. We developed an optical reporter, composed of a photoluminescent carbon nanotube of a single chirality, which responds to lipid accumulation via modulation of the nanotube's optical bandgap. The reporter localizes exclusively to the lysosomal lumen where the emission wavelength can be spatially resolved to generate quantitative maps of lipid content. Measurements of patient-derived Niemann-Pick type C fibroblasts identified lipid accumulation and phenotypic reversal of this lysosomal storage disease. Single-cell kinetics of low-density lipoprotein uptake within macrophages revealed accumulation rates that differed among cells by an order of magnitude. The reporter discerned sub-cellular differences in lipid content, illuminating significant intracellular heterogeneity among lysosomes of differentiating bone marrow-derived monocytes. This carbon nanotube-based reporter confers a new capability for the investigation of lipid-linked diseases.
2. ECM Stiffness Regulates Differentiation of Myelinating Glia
Mateusz Urbanski*; Lyle Kingsbury; Daniel Moussouros; Imran Kassim; Saraf Mehjabeen; Navid Paknejad; Carmen Melendez-Vasquez
Dept. of Biological Sciences, Hunter College
Studies from our laboratory have shown that inhibition of non-muscle myosin II (NMII) activity enhances oligodendrocyte (OL) myelination and impairs it in Schwann cells (SC). Other studies demonstrated NMII involvement in mechanotransduction, the cellular response to the elastic properties of the extracellular matrix (ECM). To evaluate whether NMII mediated mechanotransduction of ECM elastic properties plays a role in regulating glial cell differentiation, we have grown primary glial cultures on synthetic ECM-like matrices of variable elasticity. We found that for OL, stiffer matrices increase NMII activity while inhibiting morphological maturation and differentiation, while SC grown on stiffer matrices adopt a less complex morphology with fewer actin-based protrusions. However, SC differentiation is not affected by matrix stiffness alone, but is potentiated on rigid matrices with high laminin concentration mimicking a mature basal lamina. This indicates that myelinating glial cell differentiation is mechanosensitive, and is modulated by basal lamina composition in SC. These findings are strengthened by recent work from our laboratory which confirms that both CNS and PNS tissue can exhibit significant changes in ECM stiffness in the course of demyelinating injury as well as during normal development. Using atomic force microscopy (AFM) measurements, we show that chronically demyelinated CNS tissue is significantly stiffer than healthy controls, while in the PNS sciatic nerves steadily increase in stiffness during the first week of development as the resident SC deposit increasing amounts of basal lamina.
3. Organizing Organic Semiconductors in 3D DNA Arrays
Xiao Wang*, Martin Kristiansen, Carina Hernandez, Ruojie Sha, James W. Canary and Nadrian C. Seeman
Dept. of Chemistry, New York University
One of the ultimate goals of structural DNA nanotechnology is organizing nanoelectronics into 3D arrays and eventually constructing biochip computers by this 'bottom-up' strategy. The DNA tensegrity triangle is a robust motif used to assemble single molecules into 3D macroscopic crystals. We show the possibilities of this versatile strategy by attaching a semiconductor to every unit cell of a crystal. In this study, a polyaniline (PANI) octamer was covalently placed between two different DNA sequences on its ends. This molecule was incorporated into an asymmetric covalently fused DNA double tensegrity triangle motif; the DNA sequences flanking the PANI were paired by Watson-Crick base pairing with extensions on each of the two triangles. The complete double triangle unit, including the PANI portion was then allowed to self-assemble into a 3D crystal. The PANI molecule within the crystal single unit can act as two different kinds of 'switch'. The conversion between pernigraniline and leucoemeraldine states makes it a redox 'switch'. Moreover, emeraldine PANI molecules in the crystal can be doped by protons to form a conductive emeraldine salt state under relatively mild conditions (pH 5). These changes are visualized by color changes in the crystals. The ease of switching between the emeraldine and emeraldine salt states of the PANI molecule suggests that it could act as an electronic switch inside the crystal.
4. A novel 3D in vitro model for metastasis elucidates the contribution of basement membrane in cancer dissemination
Asja Guzman*, Catherine Ruiqi Zhang, Yen Nguyen, Laura J. Kaufman
Dept. of Chemistry, Columbia University
While metastasis is the most lethal aspect of cancer, reliable methods for early prediction and therapy of metastatic disease are still lacking, partly due to the scarcity of physiologically relevant in vitro models that would recapitulate the cellular processes in complex 3D environments. Metastatic disease in cancers of epithelial origin starts with tumor cells breaching the basement membrane (BM) that surrounds the primary tumor, before invading into the collagen I-rich environment of soft tissues. To address cellular events both during BM breaching and the subsequent invasion we developed a novel, biochemically well-defined and optically accessible 3D in vitro model. This new method allows generation of multicellular aggregates surrounded by a BM which can be embedded into versatile 3D matrices for extended culture and monitoring. Importantly, the BM in this model is assembled from exogenously added components bound and polymerized in a cell-mediated process resulting in a cell-bound BM of tunable composition and thickness. Using 3D immunocytochemistry and multicolor confocal microscopy we demonstrated that the BM layer fully prevents dissemination of non-malignant cells, while cancer cells are able to breach it and invade into the surrounding collagen, thus recreating a hallmark of the metastatic disease. Furthermore we showed that changes in BM thickness are sufficient to induce a switch from individual to multicellular invasion, thus recapitulating another fundamental feature of the metastatic process in vivo. Importantly, using this model we demonstrated that matrix-degrading enzymes (MMPs) are crucial during BM breaching but not during the subsequent dissemination in the collagen matrix, thus offering an explanation why pharmacological MMP inhibitors failed in clinical studies of late stage cancer treatment. In short, our newly developed in vitro model of metastasis allows to address 3D cancer cell invasion not only as a function of a particular primary tumor, but as a function of its heterogeneous environment and the different stages of invasion. As such, this model offers an exciting new tool for dissecting basic mechanisms of metastasis and developing new therapeutic approaches in a physiologically relevant, yet inexpensive and highly tunable in vitro setting
5. Developing a Dissociative Nanocontainer for Peptide Drug Delivery
Patrick Kelly*, Prachi Anand, Sujoy Manir, Mande Holford
Dept. of Biochemistry, CUNY Graduate Center, Hunter College
Small peptides, because of their potency, selectivity, and general lack of side effects, represent one of the current frontiers of pharmacological research. They are especially promising for the treatment of neurological disorders and pain. However, small peptides generally cannot cross the blood-brain barrier (BBB). The lack of an effective system for the transport and delivery of these agents in vivo is a primary obstacle to their therapeutic application. This project modifies the viral capsid of P22 bacteriophage to serve as a tunable nanocontainer for the packaging and controlled release of neuropeptides derived from the venom of marine snails. Recent results in the Holford group have demonstrated that venom peptides can be effectively expressed in the interior of the P22 capsid and translocated across a BBB model using cell-penetrating peptide, HIV-Tat, conjugated to the capsid exterior. Releasing the cargo peptide at the target site remains a challenge, as disassembly must proceed under physiological conditions, i.e., at moderate pH in an aqueous environment. In this work a Ring Opening Metathesis Polymerization (ROMP) is applied to trigger the release of cargo peptide. ROMP is a polymerization reaction driven by the release of ring strain in an olefin substrate (norbornene) in the presence of a ruthenium catalyst. Our hypothesis is that ROMP will disrupt the capsid architecture by linking together norbornene moieties conjugated to the capsid exterior. Preliminary findings are presented to characterize the triggered release of cargo peptides from P22 capsid using a catalyst driven ROMP reaction.
6. Development of Injectable Cellulosic Hydrogels for Soft Tissue Replacement
Steven B. Nicoll*
Dept. of Biomedical Engineering, The City College of New York
There are several indications for the use of permanent fillers for volumetric augmentation, including the correction of localized tissue atrophy and deficits due to trauma, tumor resections, infectious processes (i.e., HIV infection), and congenital craniofacial anomalies. In addition, injury and degeneration of specialized connective tissues, such as those found in the intervertebral disc of the spinal column, require surgical intervention to restore function. Tissue engineering strategies may provide novel replacement therapies for such damaged or diseased soft tissues. However, there remains a need for biomaterials that are effective, biocompatible, renewable, and inexpensive. Potential candidates include derivatives of the plant polysaccharide, cellulose, which may be chemically modified to create injectable, in situ gelling materials with tunable properties tailored for specific clinical applications. These hydrogels may be used alone or in combination with mesenchymal stem cells to engineer viable tissue analogs. This seminar will focus on the design of these cellulosic materials, considering multiple factors such as anatomical site and FDA regulatory pathways, to guide the research and development process toward eventual clinical translation.
7. Designer Peptide Nanomaterials
Gary Scott*,a Rein V. Ulijna,b and Tell Tuttlea
a WestCHEM Department of Pure and Applied Chemistry, University of Strathclyde, Glasgow; b Advanced Science Research Center, City University of New York, New York
Peptide self assembly has attracted much interest from the food, cosmetic and biomedical industries due to their ability for form large supramolecular networks capable of forming a range of different nanostructures. Coarse grain molecular dynamics  allows examination of all potential targets, with the most exciting cases closely examined further. A selected number of targets are then further examined and analysed experimentally to give validation.
Using design rules that we have derived from computational methods,  we have been able to experimentally validate a number of different nanostructures. As a range of different nanostructures were obtained, identifying the assembly of these structures at oil and water interface were explored to give rise to new emulsifiers.  In addition, we have shown how the addition of small dipeptides into a known tripeptide gelator affects the fiber integrity.
 Marrink, S-J et al, J. Phys. Chem., 2007, 11, 7812-7824.  Frederix, P.W.J.M et al, Nat. Chem., 2015, 7, 30-37.  Scott, G.G et al, Adv. Mat., 2016, 28, 1381-1386.
8. Liquid Phase Synthesis and Self-Assembly of Polypeptides on Interfaces
Matthew B. Kubilius*, Raymond S. Tu
Dept. of Chemical Engineering, City College of New York
Low-cost synthesis of periodically-sequenced polypeptides is rarely achieved using modern peptide synthesis techniques. The liquid-phase synthesis alternative is challenging in part because of polydispersity increases of high molecular weight polypeptide samples. To overcome this, we designed synthetic amino acid dimers that are both amphipathic and water-soluble. When polymerized, these repeat sequences give rise to a peptide with alternating hydrophilic/hydrophobic side groups, and are thus engineered to develop a periodicity conducive to the formation of β-sheets. We then lower polydispersity in the growing polypeptide chains by modifying the kinetics of growth through transport-limited chain elongation. Our experiments show that in the absence of a micellular interface, standard bulk-phase condensation polymerization occurs. The amphipathic character of the peptide chain increases with molecular weight, yielding a polypeptide that increasingly partitions into assemblies, interfaces, and surfactant micelles with increasing extent of polymerization. This partitioning, during chain growth, serves to narrow the polydispersity of our periodically-sequenced polypeptide. We quantify polypeptide sizes and assemblies using multi-angle light scattering and mass spectrometry and define the evolving sheet-like secondary structure using circular dichroism. Our results show that the peptides grown in the presence of micelles show significantly enhanced self-assembly and a narrowed polydispersity index. From this, we conclude that the transport-limited chain elongation polymerization method shows great promise in the manufacture of low-cost, interfacially assembling polypeptides. Finally, the purified polypeptides were compressed on a Langmuir-Blodgett trough, yielding surface pressure data characterizing the β-sheets on the air water interface and imaged using Brewster angle microscopy.
9. Designer Gels for Cell Culture
Elia Lopez-Bernardo*, Eleanore Irvine, David Lightbody and Rein Ulijn
Biogelx Limited is a biomaterials company that designs tuneable peptide hydrogels, offering artificial tissue environments to cell biologists for a range of cell culture applications.
The hydrogels are highly tuneable, cell-matched biomaterials, capable of revolutionizing the way cell biologists control and manipulate cell behavior in the laboratory. This is of direct relevance to fundamental cell research, including the study of stem cells and disease models within academic and medical labs. However, the major commercial significance this has is the dramatic impact on the development of cell-based assays and drug discovery/toxicology platforms within large pharmaceutical companies, representing a rapidly growing global market with revenues of over $5 billion per annum.
Biogelx offers a range of hydrogel platforms that are three dimensional (3D), 99% water and have the same nanoscale matrix structure as human tissue. This gives control back to the cell biologist, as the gels can be tuned to meet the needs of any given cell type.
This poster showcases the underlying chemistry of Biogelx's peptide hydrogels, highlighting the range of chemical and mechanical modifications that can be implemented within the gels, in order to address a wide range of cell based applications. Some examples of academic and industrial collaborative work shall also be presented, include how the gel tuneable properties, can be use to influence the differentiation pathway of stem cells.
10. Spatio-temporal control of biocatalytic self-assembly by enzyme immobilization on magnetic nanoparticles
M. P. Conte *, J. Sahoo and R.V. Ulijn
Dept. of Pure and Applied Chemistry, University of Strathclyde
Combining (bio-)catalysis and molecular self-assembly provides an effective approach for developing smart biomaterials, allowing to integrate the processes of biological systems with the formation of hierarchical nanostructures. Enzymes proved to be effective to control the self-assembly of aromatic peptide amphiphiles and to develop complex next-generation nanomaterials. This approach can allow for a highly controlled process in which the assembly is localized in the vicinity of the enzyme. In this study, the possibility to trigger the localized self-assembly of peptide amphiphiles exploiting immobilized enzymes is investigated. The enzymes are immobilized on magnetic nanoparticles and the electron microscopy images show that the self-assembly initiates from the nanoparticle-enzyme conjugate. This approach provides a new means to achieve spatio-temporal control of self-assembly.
11. Synthesis of chlorin conjugates for Bio-medical applications
N V S Dinesh K Bhupathiraju, William Perea, Chu Huong, Junior Gonzales, Man Yuen,* Nancy L. Greenbaum and Charles Michael Drain
Dept of. Chemistry, Hunter College
Porhyrinoids such as porphyrins, phthalocyanines and chlorins serve as good theranostic agents in biomedical applications. Among these porphyrinoids, chlorins have a good balance between singlet oxygen quantum yields for photodynamic therapy (PDT) and fluorescence quantum yield for diagnosis of different diseases (theranostics). Chlorins have one double bond less than porphyrins and a strong red absorption around 650 nm. Chlorins were studied previously as an antiviral and antibacterial agents in addition to cytotoxic agents for cancer. Here we present the synthesis of chlorin possessing polyethylene glycol (O-PEG) with a carboxylate linker followed by the conjugation to three different molecules lysozyme enzyme, single strand DNA and bovine serum albumin (BSA).
12. Photo-physical characterization of porphyrin conjugates
Naxhije Berisha*, Bibi Begum, N. V. S. Dinesh K. Bhupathiraju, Christopher Farley, Charles M Drain
Dept. of Chemistry and Biochemistry, Hunter College
Porphyrins are aromatic heterocyclic organic compounds with interesting photo-physical properties. Due to the aromaticity of the macrocycle, these compounds tend to absorb intensely in the visible light region. This makes them practical for applications in diagnostic tracking and alternative therapies such as photo-dynamic therapy (PDT). The latter application works by taking advantage of production of reactive oxygen species (ROS) to trigger an apoptotic pathway in cells. However, organic dyes are limited in their effectiveness because of their low solubility and low up-take in cells. Most dyes are conjugated with groups that impart water solubility or increase cell-uptake or selectivity for a particular cell line. The goal of this project was to characterize and test the efficiency of an array of porphyrin-conjugates, utilizing either tannic acid or hyaluronic acid as targeting vectors. Tannic acid and hyaluronic acid contain many carboxylic acid and alcohol groups which are available for linking more than one photosensitizer. This makes it possible to direct multiple photo-active molecules into cells of interest. Photo-physical characterization of conjugates includes UV-vis spectroscopy, steady state-fluorescence spectroscopy and fluorescence lifetimes. Generation of ROS was measured using an indirect fluorometric determination of the reaction between singlet oxygen (an important ROS) and a commercially available sensor, Singlet Oxygen Sensor Green, SOSG. We also studied the cell uptake of these conjugates by fluorescence microscopy imaging.
13. Engineering Lipoproteoplexes for Gene and Drug Delivery
Raymond Chen*,a, Samuel Berensa, Joseph A. Frezzoa, Jin Kim Montclare, Ph.Da,b.
a Department of Chemical and Biomolecular Engineering, NYU Tandon School of Engineering, Brooklyn, NY; b Department of Chemistry, NYU, New York, NY
With many advances in treatment options for malignancies comes the fundamental issue of safe, efficient, and effective delivery of the payload to target cells. This eventually leads to a bottleneck for treatment options on the clinical side. We sought to design delivery vehicles that could efficiently contain therapeutic molecules with triggered release of the payload once the vehicle crosses the membrane of a cell. We employ a mutant of the naturally-occurring Cartilage Oligomeric Matrix Protein coiled-coil (COMPcc), called COMP Supercharged Protein (CSP), in which we selectively mutate several arginine residues while retaining COMPcc's form and function to create a highly positively charged variant. CSP will be used for the simultaneous delivery of small interfering RNA (siRNA) and the small drug molecule doxorubicin (dox). The custom siRNA used is a silencer for the housekeeping gene GAPDH. We will also employ the use of the transfection reagent Lipofectamine TM 2000 for the formation of the final lipoproteoplex. CSP acts to complex with and condense the siRNA, encapsulate the dox without covalent modification, and release the entire payload once within the cellular membrane. Here, we target the progression of the metastatic breast cancer cell line MCF-7. We have also designed an alternate lipoproteoplex delivery vehicle which includes our engineered protein CSP and a liposome formation consisting of N-[1-(2,3-Dioleoyloxy)propyl]-N,N,N-trimethylammonium methyl-sulfate (DOTAP): 3α,7α,12α-Trihydroxy-5β-cholan-24-oic acid sodium salt (Sodium Cholate). DOTAP is a known liposomal transfection reagent and sodium cholate has been used in conjunction with DOTAP to create uniform liposomal vesicles with suitable surface charge and distribution for transfection. These lipoproteoplexes complexed with a custom DNA will be used by our collaborators at Ceradini Lab to improve diabetic wound healing.
14. Chirality Meditated by &pi'-&pi Stacking in Functional Supramolecular Filaments
Myungshim Kang*,†, Pengcheng Zhang^, Honggang Cui^, Sharon M. Loverde
Department of Chemistry, College of Staten Island, The City University of New York, 2800 Victory Boulevard, Staten Island, New York, 10314, United States; ‡Ph.D. Program in Chemistry, The Graduate Center of the City University of New York, New York, NY, 10016; ~Ph.D. Program in Biochemistry, The Graduate Center of the City University of New York, New York, NY, 10016; |Ph.D. Program in Physics, The Graduate Center of the City University of New York, New York, NY, 10016;^Department of Chemical and Biomolecular Engineering and Institute for NanoBioTechnology, The Johns Hopkins University, 3400 North Charles Street, Baltimore, Maryland, 21218, United States.
While a great diversity of peptide-based supramolecular filaments have been reported, the impact of an auxiliary segment on the chiral assembly of peptides remains poorly understood, particularly for those involving strong, associative interactions. Herein we report on the formation of chiral filaments by the self-assembly of a peptide-drug conjugate containing a tau peptide and an aromatic drug camptothecin (CPT) in a computational study. We find that the chirality of the filament is initially mediated by the π-&pi stacking between CPTs, as well as the well-expected intermolecular hydrogen bonding between peptide segments. Our molecular simulations show that π-π stacking of CPTs governs the early stages of the self-assembly process, while the hydrogen bonding network rearranges in a relatively later stage, acting in concert with the π-&pi interactions, to define the eventual morphology of the filament. Our results also show the possible presence of water within the core of the CPT filament, in sharp contrast to the typical core-shell structures formed by peptide amphiphiles containing linear hydrocarbons. These results provide new insights for understanding and designing the functional supramolecular assemblies of peptide conjugates with aromatic segments.
15. Dipyridamole Delivery by Engineered Protein as an Alternative to Recombinant Bone Morphogenetic Treatment of Bone Fracture
Albert S. Agustinus*, Liming Yin, Nicole L. Schnabel, Lukasz Witek, Paulo Coelho, and Jin K. Montclare
Dept. of Chemical and Biomolecular Engineering, NYU Tandon School of Engineering
In the United States, it has been estimated that more than 1.5 million individuals experience bone fracture caused by diseases. Bone morphogenetic protein (BMP-2) has been employed in current clinical setting as a treatment besides autologous and cadaveric graft. However, it has been recently discovered that BMP-2 leads to several adverse effects. Stimulation of adenosine A2A receptor (ADORA2A) has been reported to exhibit significant reduction in bone pitting and porosity, which motivates the development of stimuli as alternative treatments. Dipyridamole has been observed to indirectly stimulate ADORA2A and has shown promising in vivo and in vitro results on par with conventional treatment of BMP-2. Nevertheless, injection on a daily basis is required due to rapid clearance of dipyridamole. Here, we proposed the coiled-coil domain of cartilage oligomeric matrix protein (COMPcc) as a carrier to deliver dipyridamole. COMPcc when self-assembled into homopentamer bears a hydrophobic cavity, that can effectively binds to a variety of hydrophobic molecules. In this study, we did binding studies of COMPcc to dipyridamole via circular dichroism, fluorescence microscopy and size exclusion chromatography and tried to assess the binding capacity in order to further optimize the formulation for the treatment.
16. Ovarian Cancer Biomarker Detection by Single-Walled Carbon Nanotube Optical Bandgap Modulation
Ryan M. Williams*, Christopher Lee, Rachel Leicher Thomas Galassi, Maria Sirenko, Janki Shah, Jackson Harvey, Douglas Levine, Daniel A. Heller
Dept. of Molecular Pharmacology, Memorial Sloan Kettering Cancer Center
Ovarian cancer is the fifth-leading cause of cancer-related deaths among females in the United States. Over 22,000 new cases will be diagnosed and 14,000 deaths will result from this disease in 2016. Diagnosis after metastasis occurs in 61% of patients, higher than any other form of cancer. Late detection hinders prognosis, though 91% five-year survival rates are seen with earlier detection. Detection of ovarian cancer in high-risk populations, monitoring patient response to treatment, and disease relapse is necessary to increase survival rates.
The unique optical properties of single-walled carbon nanotubes (SWCNT) confer ideal sensing properties for biological applications. SWCNT near-infrared photoluminescence exhibits photostability, penetration through biological media, and environmental sensitivity. Nanotube emission can undergo modulation of the optical bandgap, causing a shift in emission wavelength. These characteristics allow for consistent rapid and long-term analyte detection and quantification in complex ex vivo and in vivo environments.
We have used these characteristics of SWCNT to develop a sensor for an ovarian cancer protein biomarker. This sensor exhibits rapid, sensitive, and specific detection and quantification of the biomarker in complex in vitro, ex vivo, and in vivo environments. We have used this sensor to detect and quantify the protein biomarker in patient serum and ascites and mice with ovarian cancer. Future work will further monitor the longitudinal progression of ovarian tumors in vivo towards clinical translation. We expect this optical biomarker sensor to aid in early ovarian cancer detection, thereby reducing patient burden and mortality.
17. Determining conformation of engineered protein fibers
Che Fu Liu*, Lindsay K. Hill, Teeba Jihad, Sumayya Vawda, and Jin Kim Montclare, PhD
Dept. of Department of Chemical and Biomolecular Engineering, New York University Tandon School of Engineering
Because of their biocompatibility, proteins have become appealing drug delivery vehicles. Development of these therapeutics, however, relies on assessment of protein secondary structure and conformational characteristics to ensure suitable engineering for drug delivery. The N-terminus of the Cartilage Oligomeric Matrix Protein, COMPcc, is a pentameric coiled-coil motif. Our group has engineered this domain to create the protein Q, which maintains patches of positive and negative surface charges, allowing for lateral nanofiber assembly. Upon binding to the small molecule, curcumin, the protein Q further assembles into microfibers. Both circular dichroism (CD) spectroscopy and attenuated total reflectance-Fourier transform infrared spectroscopy (ATR-FTIR) are employed to characterize the secondary structure of Q protein assemblies. We have found that ATR-FTIR and CD provide drastically different results and hypothesize that FTIR has improved accuracy given the that protein Q assembles into solid fibers. Using FTIR, we evaluate structural changes upon drug binding to ensure the maintenance of the coiled-coil structure which is optimal for drug delivery.
18. Non-Destructive Detection of Metabolites Using Single Walled Carbon Nanotubes
Thomas V. Galassi*, Prakrit V. Jena, Daniel Roxbury, Janki Shah, Daniel Heller
Dept. of Physiology, Biophysics, and Systems Biology, Weill Cornell Medicine
The transport, storage and degradation of macromolecules in cells represent tightly regulated processes that are vital to cellular function. Cells and organisms that are unable to regulate these processes will exhibit deleterious phenotypes such as impaired nervous system or liver function. Developing treatments for such disorders is challenging, due in part to a lack of methods for quantifying specific metabolites within live cells and animals. As such, this work aims to develop a tool with the ability to non-invasively detect cellular metabolites in live cells and animals. To achieve this goal, an optical reporter was engineered using single walled carbon nanotubes (SWCNTs). Semiconducting SWCNTs exhibit properties that make them ideal materials for the engineering of optical probes. These include fluorescence in the near infrared region of the spectrum which is modulated by the local environment, a lack of photo bleaching, and a large Stokes shift. In this work, we developed an optical reporter capable of detecting cellular metabolites and demonstrated its use in live cells. Future work will focus on applying this reporter to study the pathologies of various diseases in vitro and in vivo.
19. Effects of Substituting Solvent-Exposed Phenylalanines on the Stability and Function of Phosphotriesterase
Roni Barak Ventura*, Andrew Olsen, Ching-Yao Yang, Liming Yin, Leif Halvorsen, Prof. Richard Bonneau and Prof. Jin Kim Montclare
Dept. of Chemical and Biomolecular Engineering, NYU Tandon School of Engineering
Organophosphates (OP) comprise a class of neurotoxins known to interfere with the activity of acetylcholinesterase. The widespread misuse of OP-based pesticides is accountable for 200,000 fatalities annually. Phosphotriesterase (PTE), a catalytic bioscavenger that naturally occurs in the soil bacteria Pseudomonas diminuta, is capable of detoxifying OPs. Although being the most efficient of available OP-hydrolases, PTE's poor stability limits its practical use. Therefore, we sought to create a more stable and soluble PTE structure. Eight solvent-exposed phenylalanine residues were identified for mutagenesis and evaluated using Rosetta, a computational software developed to predict macromolecular interactions. The stability and activity of mutated PTEs have been further characterized through circular dichroism spectroscopy, differential scanning calorimetry, and kinetic assays. Here, we demonstrate the stability and activity of the variants.
20. Fabrication of Tri-block Protein Polymer Hydrogels
Yao Wang*, Andrew Olsen, Joseph Frezzo, Jin Montclare
Dept. of Chemical and Biomolecular Engineering, NYU Tendon
Our lab has generated a tri-block protein polymer, CEC, that consists of two self-assembling domains (SADs): a coiled-coil domain of the cartilage oligomeric matrix protein (C) and the elastin-like polypeptide motif domain (E). Inspired by nature, we aim to develop biological mimics that exert chemomechanical control leading to our current research of fabricating biological protein hydrogel materials. Free-standing hydrogels have been generated from CEC conjugated to a photo-activatable diazirine group (CEC-DAz) followed by UV-mediated crosslinking. The diazirine crosslinker concentration, conjugation efficiency, optimal UV exposure time and the amount of CEC and CEC-DAz retained on unmodified glass surfaces post UV-exposure has been experimentally determined. Characterization of the secondary structure and the percentage of different secondary structures of CEC and CEC-DAz has been analyzed using circular dichroism (CD) spectroscopy and Fourier Transform Infrared Spectroscopy (FTIR).
21. Sub-Cellular Localization of Photoluminescent Single-Walled Carbon Nanotubes in Human Cancer Cells
Januka Budhathoki-Uprety,† Rachel E. Langenbacher,‡ Prakrit V. Jena,† Daniel Roxbury,† and Daniel A. Heller*,†,‡
†Memorial Sloan Kettering Cancer Center, New York, New York 10065, United States ‡Weill Cornell Medical College, New York, New York 10065, United States
Since the onset and progression of cancer and many other diseases involve dysregulation of certain sub-cellular compartments, accurate visualization of events using probes localized in sub-cellular organelles would facilitate the understanding of disease processes. Molecular probes based on single-walled carbon nanotubes (SWCNTs) are ideal for imaging and molecular sensing with spatio-temporal resolution due to their non-bleaching photoluminescence in the near infrared region-the optical regime where interference is minimal from absorption and scattering of light in biological specimens. Achieving specificity in sub-cellular localization of nanoscale optical probes is often challenging but can be mediated by surface chemistry. We cloaked SWCNTs in polycarbodiimide polymers to suspend them in aqueous environments and to integrate biocompatible functionalities. The polymers preserved nanotube photoluminescence while promoting their localization in sub-cellular spaces of cultured human cancer cells without cytotoxicity.
22. 4D Biomanufacturing
Carlos Carbonell* and Prof. Adam Braunschweig
Department of Chemistry, University of Miami
Controlling the organization of biomaterials on surfaces with nanometer resolution is of paramount importance for fundamental biological, physical, and medical studies, and for the development of optical and electronic devices. State of the art technologies for constructing materials composed of delicate organic and biologically active matter are based primarily upon ink-jet printing, pin-printing, whereas conventional photolithography presents is expensive and destructive. By marrying massively parallel scanning-probe based nanolithography approaches, specifically polymer-pen lithography (PPL) and beam-pen lithography (BPL), with the development of new surface organic chemistry, we have developed new approaches for preparing glycan arrays, functionalizing graphene, and creating brush polymer arrays. By combining massively parallel scanning probe nanolithography, microfluidics, and brush polymer chemistry, we have recently achieved 4D organic micromanufacturing, where the four dimensions are the 3 Cartesian coordinates (x,y,z) and the fourth is the chemical composition of each spot in an array. This novel materials manufacturing approach could pave the way towards materials with the chemical and topological complexity common to biological interfaces.
23. Responsive emulsifiers achieved by enzyme-triggered self-assembly of simplistic short peptides
Inês Moreira,*,b Tell Tuttle,a Rein Ulijna,b
aWestCHEM Department of Pure and Applied Chemistry, University of Strathclyde, Glasgow; bAdvanced Science Research Center, City University of New York, New York.
In this work, the biocatalytic self-assembly of natural short peptide amphiphiles is used in aqueous/organic mixtures to create on-demand emulsifiers. Aromatic peptide amphiphiles have been extensively studied due to their ability to self-assemble into nanostructures through non-covalent interactions, forming self-supporting gels. An alkaline phosphatase was demonstrated to transform phosphorylated precursors into self-assembling short peptide amphiphiles in aqueous systems, providing a route to trigger self-assembly of nanofibrous networks and hydrogels. When in biphasic organic/aqueous systems, these networks form preferentially at the droplets' interface, which is shown by different microscopy and spectroscopy techniques. The advantages of self-assembled network formation at interfaces are then combined with enzymatic triggering to achieve responsive emulsifiers, enabling interfacial control under constant and physiological conditions.
In particular, the phosphatase-mediated conversion of a phosphorylated peptide amphiphile presenting a modest surfactant-type behaviour to the corresponding dephosphorylated gelator, which forms a stable, permanent interfacial network, is described. This gives rise to the possibility of on-demand activation of emulsifying ability, producing switchable emulsions that may be activated by enzyme addition, even after storage of the biphasic mixture for several weeks.
Alkaline phosphatase is shown to be active in an organic/aqueous medium, in the same extent as it is in aqueous buffer, and also when added to the demulsified mixture at different time points. In addition, the concentration of alkaline phosphatase has been shown to play a key role over the self-assembling process, making it possible to control the desired strength of hydrogel formed and/or emulsion stability. Experimental (Fluorescence and FTIR spectroscopy) and computational techniques (Molecular Dynamics) are combined to show that the self-assembly process of aromatic peptide amphiphiles occurs through aromatic interactions and hydrogen bonding to generate a nanostructured network at the aqueous/organic interface. The stability of the emulsions and the possibility of on-demand activating the emulsifying ability provide a promising tool for different processes in the cosmetics and food industries when emulsions are desired only during a specific stage of a process.
 I. P. Moreira, I. R. Sasselli, D. A. Cannon, M. Hughes, D. A. Lamprou, T. Tuttle and R. V. Ulijn, Soft Matter, 2016, 12, 2623-2631.  S. Bai, C. Pappas, S. Debnath, P. W. J. M. Frederix, J. Leckie, S. Fleming and R. V. Ulijn, ACS nano, 2014, 8, 7005-7013.  G. G. Scott, P. J. McKnight, T. Tuttle and R. V. Ulijn, Advanced Materials, 2016, 28, 1381-1386.
24. Examining the Sub-Cellular Localization of Single-Walled Carbon Nanotubes
Rachel E Langenbacher*, Januka Budhathoki-Uprety, Daniel Roxbury, Prakrit Vaibhav Jenab and Daniel A Heller
Graduate School, Weill Cornell
Single-walled carbon nanotubes have a number of properties of interest for their development as sensors and molecular probes for use in biological media. They are inherently fluorescent in the near-infrared 'tissue transparent window' and do not photobleach. Multiple, optically distinct nanotube species can be used for extensive multiplexing in a single sample. To preserve these desirable qualities while solubilizing and functionalizing the hydrophobic nanotube, we have developed non-covalent wrappings consisting of helical polycarbodiimide polymers. The polymers can be modulated to control internalization and sub-cellular localization. Assessing the localization of carbon nanotubes is of the utmost importance for their further development in biological applications.
25. Dynamic Peptide Libraries for Discovery of Supramolecular Nanomaterials
Charalampos G. Pappas* and Rein V. Ulijn
The tremendous functionality of living systems is based on sequence-specific polymers and it is increasingly clear that much simpler oligomers, such as peptides, are suitable building blocks for supramolecular nanomaterials with myriad applications. However, the design and selection of self-assembling sequences is challenging due to the vast combinatorial space available. We demonstrate a methodology that enables the peptide sequence space to be searched for self-assembling structures. In this approach, unprotected homo- and hetero dipeptides including aromatic, aliphatic, polar and charged amino acids are subjected to continuous enzymatic condensation, hydrolysis and sequence exchange to create a dynamic combinatorial peptide library. The free energy change associated with the assembly process itself giving rise to selective amplification of self-assembling candidates. By changing the environmental conditions during the selection process, different sequences and consequent nanoscale morphologies are selected. Thus, dynamic peptide libraries enable directed discovery of peptide nanomaterials under user-defined conditions.
26. Single-Walled Carbon Nanotubes for the Quantification of Biomarkers in Biofluids
Jackson Harvey*, Hanan Baker, Xinghuo Li, Prakrit Jena, and Daniel Heller
Dept. of Pharmacology, MSKCC
As optical sensors, single-walled carbon nanotubes (SWCNTs) have properties that make them ideally suited for detection of biologically important analytes. Carbon nanotubes exhibit bandgap fluorescence which does not photobleach or blink, and their fluorescent properties can be modulated by changes in their immediate environment. Tissue transparent emission, biocompatibility, and versatile modes of optical response make SWCNTs uniquely valuable optical biosensors. Using these properties, we have rationally designed SWCNT-based sensors for enhanced quantification of biomarkers in biofluids for diagnostic applications and for the study of fundamental biological processes.
27. Mechanostimulation Promotes Nuclear and Epigenetic Changes in Oligodendrocytes
M. Hernandez, J. Patzig*, S.R. Mayoral, K.D. Costa, J.R. Chan and P. Casaccia
Icahn Medical Institute at Mount Sinai
Oligodendrocyte progenitors respond to biophysical or mechanical signals, and it has been reported that mechanostimulation modulates cell proliferation, migration, and differentiation. Here we report the effect of three mechanical stimuli on mouse oligodendrocyte progenitor differentiation and identify the molecular components of the linker of nucleoskeleton and cytoskeleton (LINC) complex (i.e., SYNE1) as transducers of mechanical signals to the nucleus, where they modulate the deposition of repressive histone marks and heterochromatin formation. The expression levels of LINC components increased during progenitor differentiation and silencing the Syne1 gene resulted in aberrant histone marks deposition, chromatin reorganization and impaired myelination. We conclude that spatial constraints, via the actin cytoskeleton and LINC complex, mediate nuclear changes in oligodendrocyte progenitors that favor a default pathway of differentiation.