Research

Introduction

Research in the Deming lab is focused on synthesis, processing, characterization and evaluation of biomimetic materials based on polypeptides. These materials are being studied since they can be prepared from renewable resources, can be biocompatible and biodegradable, and possess unique self-assembling properties. The Deming lab develops new synthetic materials with properties that rival the complexity found in biological systems. Our emphasis is on development of new synthetic methodologies as well as the use of biological precedents and strategies for the design of new materials. Our lab continues to take on significant new challenges in the exploration of applications of our materials for interaction with biological systems and for medicine, as well as development of new economical and scalable preparative routes to more complex and functional polypeptide architectures.

NCA Monomer Preparation and Polymerization

The building blocks of synthetic polypeptides. NCAs can often be prepared in large scale (grams to kilograms) in a single step from amino acids.
Cheng, J.; Deming, T. J. Top. Curr. Chem., 2012, 310, 1 – 26.

Polypeptide Synthesis via Catalysis

Our catalysis chemistry allows allows living polymerization of NCAs with significant rate enhancement over conventional initiators.
Deming, T. J.; Curtin, S. A. J. Am. Chem. Soc., 2000, 122, 5710-5717.
Curtin, S. A. and Deming, T. J. J. Am. Chem. Soc., 1999, 121, 7427-7428.
Deming, T. J. Macromolecules, 1999, 32, 4500-4502.
Deming, T. J. J. Am. Chem. Soc., 1998, 120, 4240-4241.
Deming, T. J. Nature, 1997, 390, 386-389.

Multidomain Block Copolypeptide Self Assembly

This methodology allows the synthesis of well defined block copolypeptides through sequential additions of different monomers to the growing chains. Our lab has pioneered the self-assembly of amphiphilic block copolypeptides in water into a variety of structures with tunable properties.
Deming, T. J. WIREs Nanomed. Nanobiotechnol., 2014, 6, 283-297.
Hanson, J. A.; Chang, C. B.; Graves, S. M.; Li, Z.; Mason, T. G.; Deming, T. J. Nature, 2008, 455, 85-89.
Holowka, E. P.; Sun, V. Z.; Kamei, D. T.; Deming, T. J. Nature Materials, 2007, 6, 52–57.
Bellomo, E.; Wyrsta, M. D.; Pakstis, L.; Pochan, D. J.; Deming, T. J. Nature Materials, 2004, 3, 244-248.
Nowak, A. P.; Breedveld, V.; Pakstis, L.; Ozbas, B.; Pine, D. J.;Pochan, D.; Deming, T. J. Nature, 2002, 417, 424-428.
Cha, J. N.; Stucky, G. D.; Morse, D. E.; Deming, T. J. Nature, 2000, 403, 289-292.

Introducing Biological Functionality into Polypeptides

Synthesis of Functionalized NCAs

The use of functionalized NCAs allows direct incorporation of biologically relevant functional groups in precise locations in chains, but may require multiple synthetic steps and tedious purification.
Perlin, P.; Gharakhanian, E. G.; Deming, T. J. Chem. Commun., 2018, 54, 6196 - 6199.
Deming, T. J. Chem. Rev. 2016, 116, 786–808.
Yakovlev, I.; Deming, T. J. J. Amer. Chem. Soc., 2015, 137, 4078-4081.
Yakovlev, I.; Deming, T. J. ACS Macro Lett., 2014, 3, 378-381.
Rhodes, A. J.; Deming, T. J. ACS Macro Lett., 2013, 2, 351-354.
Rhodes, A. J.; Deming, T. J. J. Amer. Chem. Soc., 2012, 134, 19463-19467.
Kramer, J. R.; Deming, T. J. J. Amer. Chem. Soc., 2012, 134, 4112-4115.
Kramer, J. R.; Deming, T. J. J. Amer. Chem. Soc., 2010, 132, 15068–15071.
Kramer, J. R.; Deming, T. J. Biomacromolecules, 2010, 11, 3668 - 3672.

PEGylated NCAs

Glycosylated NCAs

Post-Polymerization Functionalization via Methionine Modification

Our methodology utilizes methionine NCA, derived from the natural amino acid and readily prepared and polymerized without need of protecting groups. High yield, efficient modification of thioether groups after polymer formation provides a scalable route to highly functional, and biologically relevant polypeptides.
Deming, T. J. Bioconjugate Chem., 2017, 28, 691−700.
Petitdemange, R.; Garanger, E.; Bataille, L.; Dieryck, W.; Bathany, K.; Garbay, B.; Deming, T. J.; Lecommandoux, S. Biomacromolecules, 2017, 18, 544-550.
Gharakhanian, E. G.; Deming, T. J. Chem. Commun., 2016, 52, 5336-5339.
Kramer, J. R.; Petitdemange, R.; Bataille, L.; Bathany, K.; Wirotius, A.-L.; Garbay, B.; Deming, T. J.; Garanger, E.; Lecommandoux, S. ACS Macro Lett., 2015, 4, 1283-1286.
Gharakhanian, E. G.; Deming, T. J. Biomacromolecules, 2015, 16, 1802-1806.
Rodriguez,A. R.; Kramer, J. R.; Deming, T. J. Biomacromolecules, 2013, 14, 3610-3614.
Kramer, J. R.; Deming, T. J. Chem. Commun., 2013, 49, 5144 - 5146.
Kramer, J. R.; Deming, T. J. Biomacromolecules, 2012, 13, 1719-1723.

Methionine Oxidation

Methionine Alkylation and Demethylation

Polypeptides with Switchable Chain Conformations

Our lab has discovered that functional polypeptides based on poly(homocysteine) backbones can undergo reversible switching between alpha-helical and disordered conformations via mild, and reversible chemical modifications under biologically relevant conditions.
Kramer, J. R.; Deming, T. J. J. Amer. Chem. Soc., 2014, 136, 5547–5550.
Kramer, J. R.; Deming, T. J. J. Amer. Chem. Soc., 2012, 134, 4112-4115.

Thermoresponsive Polypeptides

Using methionine alkylation and demethylation methodology, we prepared a series of oligoethylene glycol functionalized poly(homocysteine) derivatives, all from the same parent poly(methionine) sample. These polymers undergo reversible temperature dependent solubility transitions (lower critical solution temperature behavior) in aqueous media. These and related polypeptides are being developed for use in stimuli responsive block copolypeptide assemblies.
Gharakhanian, E. G.; Deming, T. J. J. Phys. Chem. B, 2016, 120, 6096-6101.
Kramer, J. R.; Deming, T. J. J. Amer. Chem. Soc., 2014, 136, 5547–5550.

Diblock Copolypeptide Hydrogels (DCH) for Central Nervous System Repair In collaboration with the lab of Prof. Michael Sofroniew (Neurobiology Dept, UCLA), were are developing polypeptide hydrogels for study of biology and neural repair in central nervous system (CNS) tissues. Synthetic DCH have been designed with tunable physical properties (stiffness, porosity, chemical functionality), and can be degraded in vivo. We have shown that many DCH formulations form hydrogel deposits and are well tolerated in healthy mouse forebrain tissue. DCH are being developed to encapsulate and release both hydrophilic (e.g. protein) and hydrophobic (e.g. small molecule active agent) cargos within CNS tissues. We are also developing DCH formulations to encapsulate neural progenitor stem cells (NPSCs) to allow cell grafting within CNS tissues, and to provide biomimetic scaffolds for encapsulated cells. Recent efforts have focused on study and development of DCH formulations to facilitate neural repair after spinal cord injury.
Anderson, M. A.; O’Shea, T. M.; Burda, J. E.; Ao, Y.; Barlatey, S. L.; Bernstein, A. M.; Kim, J. H.; James, N. D.; Rogers, A.; Kato, B.; Wollenberg, A. L.; Kawaguchi, R.; Coppola, G.; Wang, C.; Deming, T. J.; He, Z.; Courtine, G.; Sofroniew, M. V. Nature, 2018, 561, 369-400.
Anderson, M. A.; Burda, J. E.; Ren, Y.; Ao, Y.; O’Shea, T. M.; Kawaguchi, R.; Coppola, G.; Khakh, B. S.; Deming, T. J.; Sofroniew, M. V. Nature, 2016, 532, 195-200.
Yang, C-Y.; Song, B.; Ao, Y.; Nowak, A. P.; Abelowitz, R. B.; Korsak, R. A.; Havton, L. A.; Deming, T. J.; Sofroniew, M. V. Biomaterials, 2009, 30, 2881-2898.

Encapsulation of Hydrophobic Molecules within DCH

The hydrophobic domains of DCH are able to dissolve small hydrophobic molecules. These can be small molecule drugs or signalling molecules.

Zhang, S.; Anderson, M. A.; Ao, Y.; Khakh, B. S.; Deming, T. J.; Sofroniew, M. V. Biomaterials, 2014, 35, 1989-2000.

Tuning of Cargo Loading Capacity and Release Rate

Variation of hydrophobic segments in DCH allows adjustment of loading capacity and release rate

Encapsulation and Release of Growth Factors (proteins) in DCH

Release of nerve growth factor (NGF) from a DCH depot in healthy mouse forebrain shows biological effects on cholinergic neurons (ChAT) in vivo, where they respond to NGF by increasing in size. DCH provide prolonged release of NGF compared to injection of NGF in saline.
Song, B.; Song, J.; Zhang, S.; Anderson, M. A.; Ao, Y.; Yang, C-Y.; Deming, T. J.; Sofroniew, M. V. Biomaterials, 2012, 33, 9105-9116.

Encapsulation and Release of Small Molecules in DCH

Release of Tamoxifen from a DCH depot in the lesion core of a spinal cord injury model in mouse shows biological effects on scar forming astrocytes. In the astrocytes (also identified using GFAP), Tamoxifen activates reporter gene expression of green fluorescent protein (GFP) in transgenic mice.
Zhang, S.; Anderson, M. A.; Ao, Y.; Khakh, B. S.; Deming, T. J.; Sofroniew, M. V. Biomaterials, 2014, 35, 1989-2000.

Non-Ionic DCH for Cell Grafting

To improve cell compatibility, non-ionic DCH were developed. In the initial design, oligoethylene glycol functionalized polypeptide segments were used to replace cationic lysine segments found in original DCH. These DCH were able to support encapsulated NPSCs, which could then be grafted into CNS tissue with high viability and integration with host tissue.
Zhang, S.; Alvarez, D. J.; Sofroniew, M. V.; Deming, T. J. Biomacromolecules, 2015, 16, 1331-1340.
Anderson, M. A.; Zhao, Z.; Ao, Y.; Cheng, Y.; Sun, Y.; Deming, T. J.; Sofroniew, M. V. ACS Biomater. Sci. Eng., 2015, 1, 705-717.

Poly(Methionine Sulfoxide) based Non-Ionic DCH

As we continue to develop and optimize our DCH formulations, we have switched from unnatural oligoethylene glycol based hydrophilic segments in non-ionic DCH to use of natural poly(methionine sulfoxide) segments (DCH_MO). The sulfoxide functionality in these hydrogels possesses non-fouling properties (similar to PEG), but gives DCH that are degradable and resorbable, in addition to being less expensive and easier to synthesize. DCH_MO is currently being used for a variety of NPSC grafting studies in mice.
Wollenberg, A. L.; O’Shea, T. M.; Kim, J. H.; Czechanski,A.; Reinholdt, L. G.; Sofroniew, M. V.; Deming, T. J. Biomaterials, 2018, 178, 527-545.

Polyion Complex DCH (DCH_PIC)

Another recent development has been the design of DCH that can assemble via polyion complexation as opposed to hydrophobic interactions. By taking advantage of the ability of enantiomerically pure poly(lysine) and poly(glutamate) segments to form beta-sheet structured polyion complexes, we were able to form DCH that retain the functionality of DCH_MO, but are assembled via stronger electrostatic and H-bonding interactions. The result is DCH_PIC that are significantly more resistant to dissolution compared to DCH_MO, and can be prepared with much greater stiffness as two-component formulations while retaining cell and tissue compatibility.
Sun, Y.; Wollenberg, A. L.; O’Shea, T. M.; Cui, Y.; Zhou, Z. H.; Sofroniew, M. V.; Deming, T. J. J. Amer. Chem. Soc., 2017, 139, 15114–15121.