ABSTRACT
Grafted synthetic polypeptides hold appeal for extending the range of biophysical properties achievable in synthetic extracellular matrix (ECM) hydrogels. Here, N-carboxyanhydride polypeptide, poly(γ-propargyl-l-glutamate) (PPLG) macromers were generated by fully grafting the "clickable" side chains with mixtures of short polyethylene glycol (PEG) chains terminated with inert (-OH) or reactive (maleimide and/or norbornene) groups, then reacting a fraction of these groups with an RGD cell attachment motif. A panel of synthetic hydrogels was then created by cross-linking the PPLG macromers with a 4-arm PEG star molecule. Compared to well-established PEG-only hydrogels, gels containing PPLG exhibited dramatically less dependence on swelling as a function of cross-link density. Further, PPLG-containing gels, which retain an α-helical chain conformation, were more effective than standard PEG gels in fostering attachment of a human mesenchymal stem cell (hMSC) line for a given concentration of RGD in the gel. These favorable properties of PPLG-containing PEG hydrogels suggest they may find broad use in synthetic ECM.
Subject(s)
Biocompatible Materials/chemistry , Hydrogels/chemistry , Peptides/chemistry , Polyglutamic Acid/analogs & derivatives , Tissue Scaffolds , Amino Acid Motifs , Cell Survival/drug effects , Extracellular Matrix/chemistry , Humans , Hydrogels/pharmacology , Maleimides/chemistry , Mesenchymal Stem Cells/cytology , Mesenchymal Stem Cells/drug effects , Molecular Sequence Data , Norbornanes/chemistry , Peptides/pharmacology , Polyethylene Glycols/chemistry , Protein Structure, Secondary , Tissue EngineeringABSTRACT
Infectious diseases, such as influenza, present a prominent global problem including the constant threat of pandemics that initiate in avian or other species and then pass to humans. We report a new sensor that can be specifically functionalized to detect antibodies associated with a wide range of infectious diseases in multiple species. This biosensor is based on electrochemical detection of hydrogen peroxide generated through the intrinsic catalytic activity of all antibodies: the antibody catalyzed water oxidation pathway (ACWOP). Our platform includes a polymer brush-modified surface where specific antibodies bind to conjugated haptens with high affinity and specificity. Hydrogen peroxide provides an electrochemical signal that is mediated by Resorufin/Amplex Red. We characterize the biosensor platform, using model anti-DNP antibodies, with the ultimate goal of designing a versatile device that is inexpensive, portable, reliable, and fast. We demonstrate detection of antibodies at concentrations that fall well within clinically relevant levels.
Subject(s)
Antibodies, Catalytic/chemistry , Biosensing Techniques/methods , Hydrogen Peroxide/analysis , Immunoglobulin G/analysis , Water/chemistry , Acrylates/chemistry , Biosensing Techniques/instrumentation , Catalysis , Dinitrobenzenes/chemistry , Limit of Detection , Oxidation-Reduction , Polyethylene Glycols/chemistry , Silicon/chemistry , Singlet Oxygen/chemistryABSTRACT
Polymer brushes have many desirable characteristics such as the ability to tether molecules to a substrate or change the properties of a surface. Patterning of polymer films has been an area of great interest due to the broad range of applications including bio-related and medicinal research. Consequently, we have investigated patterning techniques for polymer brushes which allow for two different functionalities on the same surface. This method has been applied to a biosensor device which requires both polymer brushes and a photosensitizer to be polymerized on a patterned gold substrate. Additionally, the nature of patterned polymer brushes as removable thin films was explored. An etching process has enabled us to lift off very thin membranes for further characterization with the potential of using them as Janus membranes for biological applications.
ABSTRACT
Surface modification using end-tethered polymer brushes is an attractive, versatile, and effective method of tailoring the surface properties of a material. However, because the chains are covalently attached, characterization of these films is limited. When polymer brushes are detached in their native state, as opposed to fabricating a cross-linked initiator support, additional analytical techniques can be employed. We report lifting off patterned polymer brush membranes from a silicon oxide surface via a hydrofluoric acid etch. This method allows examination of polymer brushes via TEM and thus provides information regarding the perfection of initiator self-assembled monolayer formation and brush growth, as well as the effect of different cross-linking procedures.