Localized and controlled delivery of nitric oxide to the conventional outflow pathway via enzyme biocatalysis: towards therapy for Glaucoma

Nitric oxide (NO) has been shown to lower intraocular pressure (IOP), however its therapeutic effects on outflow physiology are location- and dose-dependent. Here, a NO delivery platform that directly targets the resistance-generating region of the conventional outflow pathway and locally liberates a controlled dose of NO is reported. An increase in outflow facility (decrease in IOP) is demonstrated in mouse model

Biocleavable Polycationic Micelles as Highly Efficient Gene Delivery Vectors

An amphiphilic disulfide-containing polyamidoamine was synthesized by Michael-type polyaddition reaction of piperazine to equimolar N, N′-bis(acryloyl)cystamine with 90% yield. The polycationic micelles (198 nm, 32.5 mV), prepared from the amphiphilic polyamidoamine by dialysis method, can condense foreign plasmid DNA to form nanosized polycationic micelles/DNA polyelectrolyte complexes with positive charges, which transfected 293T cells with high efficiency. Under optimized conditions, the transfection efficiencies of polycationic micelles/DNA complexes are comparable to, or even higher than that of commercially available branched PEI (Mw 25 kDa)

Subcompartmentalized polymer hydrogel capsules with selectively degradable carriers and subunits

Subcompartmentalized hydrogel capsules (SHCs) with selectively degradable carriers and subunits are designed for potential applications in drug delivery and microencapsulated biocatalysis. Thiolated poly(methacrylic acid) and poly(N-vinyl pyrrolidone) are used to assemble 3-mm-diameter carrier capsules and 300-nm-diameter subunits, independently stabilized by a diverse range of covalent linkages. This paper presents examples of SHCs with tens of subcompartments and their successful drug loading, as well as selective degradation of the SHC carrier and/or subunits in response to multiple chemical stimuli. © 2010 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim

Macromolecular design of poly(vinyl alcohol) by RAFT polymerization

C1 - Journal Articles RefereedModern tools of polymer design yield superior PVA with drastically enhanced utility in biomedicine.</p

Exploiting fluorescent polymers to probe the self-assembly of virus-like particles

The inside surfaces of the protein shells of many viruses are positively charged, thereby enhancing the self-assembly of capsid proteins around their (oppositely charged) RNA genome. These proteins have been shown to organize similarly around a variety of nonbiological, negatively charged, polymers, for example, poly(styrene sulfonate) (PSS), forming virus-like particles (VLPs). We have demonstrated recently that the VLPs formed from cowpea chlorotic mottle virus (CCMV) capsid protein increase in size (from T=2 to T=3 structures) upon increase in PSS molecular weight (from 400 kDa to 3.4 MDa), and that the total charge on the PSS exceeds that of the capsid protein by as much as a factor of 9. Here, we extend studies of this kind to PSS molecules that are sufficiently small that two or more can be packaged into VLPs. The use of 38 kDa PSS polymers that have been fluorescently labeled with Rhodamine B allows us to determine the number of PSS molecules per capsid. Electron micrographs of the VLPs show a bimodal distribution of particle diameters, with one peak centered around 19 nm, typical of a T=1 triangulation number, and the other around 21 nm, consistent with a pseudo T=2 structure; increasing the molar ratio of protein to PSS in the reaction mix shifts the VLP distribution from T=1 to T=2 structures. By combining fluorescence and gel electrophoresis measurements, it is determined that, on average, there are two polymers in each T=1 capsid and three in each T=2, with the PSS charge less than that of the capsid protein by as much as a factor of 2. VLPs of this kind provide a versatile model system for determining the principles underlying self-assembly of controlled numbers of cargo molecules in nanocontainers of increasing size

Macromolecule functionalization of disulfide-bonded polymer hydrogel capsules and cancer cell targeting

We present a generic and versatile method for functionalization of disulfide-stabilized PMA hydrogel capsules (HCs) with macromolecules, including a number of specific antibodies to cancer cells. Functionalization was achieved by reversible addition-fragmentation chain transfer (RAFT) polymerization of poly(N-vinyl pyrrolidone) (PVPON), which introduced biorelevant heterotelechelic end groups (thiol and amine) to the polymer chain. The PVPON with heterotelechelic end groups was conjugated to the outermost layer of PMA HCs through the thiol groups and reacted with biotin via the amine groups to generate PMA/PVPON biotin HCs. On the basis of the high specific interaction and high affinity between biotin and avidin, and its derivates, such as NeutrAvidin (NAv), we functionalized the PMA HCs with biotinylated antibodies. We demonstrate significantly enhanced cellular binding and internalization of the antibody (Ab)-functionalized capsules compared with control human immunoglobulin (IgG)-functionalized capsules, suggesting these capsules can specifically interact with cells through antibody/antigen recognition. We anticipate that the versatility of the functionalization approach reported in this study will assist in targeted therapeutic delivery applications. © 2012 American Chemical Society

Enzyme prodrug therapy engineered into electrospun fibers with embedded liposomes for controlled, localized synthesis of therapeutics

Enzyme prodrug therapy (EPT) enables localized conversion of inert prodrugs to active drugs by enzymes. Performance of EPT necessitates that the enzyme remains active throughout the time frame of the envisioned therapeutic application. β-glucuronidase is an enzyme with historically validated performance in EPT, however it retains its activity in biomaterials for an insufficiently long period of time, typically not exceeding 7 d. Herein, the encapsulation of β-glucuronidase in liposomal subcompartments within poly(vinyl alcohol) electrospun fibers is reported, leading to the assembly of biocatalytically active materials with activity of the enzyme sustained over at least seven weeks. It is further shown that liposomes provide the highly beneficial stabilization of the enzyme when incubated in cell culture media. The assembled biocatalytic materials successfully produce antiproliferative drugs (SN-38) using externally administered prodrugs (SN-38-glucuronide) and effectively suppress cell proliferation, with envisioned utility in the design of cardiovascular grafts