Engineering injectable, biocompatible, and highly elastic bioadhesive cryogels.

The extracellular matrix (ECM), an integral component of all organs, is inherently tissue adhesive and plays a pivotal role in tissue regeneration and remodeling. However, man-made three-dimensional (3D) biomaterials that are designed to mimic ECMs do not intrinsically adhere to moisture-rich environments and often lack an open macroporous architecture required for facilitating cellularization and integration with the host tissue post-implantation. Furthermore, most of these constructs usually entail invasive surgeries and potentially a risk of infection.

Drug Delivery and Drug Efficacy from Amorphous Poly(thioether anhydrides).

The correlation between erosion and drug (lidocaine and 6-mercaptopurine, 6-MP) release from amorphous poly(thioether anhydrides), which are synthesized using radical-mediated thiol-ene polymerization, is reported. Cytotoxicity studies of the polymer toward human fibroblast human dermal fibroblasts adult, melanoma A-375, and breast cancer MCF-7 cells are conducted, and drug efficacy of a cancer and autoimmune disease drug (6-MP) when released from the poly(thioether anhydrides) is examined against two cancerous cell types (A-375 and MCF-7). Erosion and drug release studies reveal that lidocaine release is governed by network erosion whereas 6-MP is released by a combination of erosion and diffusion.

Strategies to prevent dopamine oxidation and related cytotoxicity using various antioxidants and nitrogenation.

Dopamine (DA) plays several important roles in the brain and body and has recently been used as a bioadhesive precursor for medical applications. However, DA oxidizes immediately when exposed to oxygen and rapidly polymerizes into polydopamine (PDA), leading to oxidative stress, cytotoxicity, and loss of DA functionalities. As a result, preventing rapid oxidation of DA is of paramount importance but still remains a major challenge.

Raman Microspectroscopy Study of the Hydrolytic Degradation of Polyanhydride Network Polymers.

Raman microspectroscopy was employed in this work to study the degradation of a polyanhydride network polymer synthesized from 4-pentenoic anhydride and pentaerythritol tetrakis(3-mercaptopropionate) monomers in order to illustrate the utility of this method and improve the understanding of the polyanhydride degradation and erosion. Disk-shaped polymer samples were immersed in buffer solutions for different periods of time, and hydrolytic degradation was monitored spatially and temporally via kinetic Raman studies at various depths of penetration into the samples. Erosion, meanwhile, was monitored via mass loss measurements.

Latest Progress in Electrospun Nanofibers for Wound Healing Applications.

Electrospinning is a versatile technique used to create native tissue-like fibrous scaffolds. Recently, it has gained a large amount of attention for generation of bioactive dressing materials suitable for treatment of both chronic and acute wounds. In this Review, we focus on the latest advances made in the application of electrospun scaffolds for bioactive wound healing.

Quantitative and qualitative toxicological evaluation of thiol-ene "click" chemistry-based polyanhydrides and their degradation products.

Quantitative and qualitative toxicological analyses of crosslinked, surface-eroding polyanhydrides (PAHs) made from thiol-ene "click" polymerizations are reported. The cytotoxicity of these PAHs was investigated against three skin-based cell types; melanoma (A-375), human dermal fibroblast adult (HDFa), and 3T3-J2 (mouse fibroblast) cells, thus providing insight into the potential for these PAHs to be used in dermal drug delivery applications. Apoptosis was evaluated quantitatively and qualitatively using MTT assay and fluorescence microscopic imaging as indication of cytotoxicity.

Anhydride-Based Reconfigurable Shape Memory Elastomers.

Soft shape memory polymers typically embody a permanently memorized geometry that cannot be altered, and therefore a new sample must be fabricated each time a new structure is required. We present a shape memory elastomeric composite featuring thermoplastic fibers as a fixing phase and a polyanhydride-based elastomer as the permanent, elastic phase. Interestingly, dynamic covalent exchange reactions at elevated temperatures ( > 50 °C) among the network chains of the elastomer allow near-complete reconfiguration of the permanent shape in the solid state.

Surface Eroding, Semicrystalline Polyanhydrides via Thiol-Ene "Click" Photopolymerization.

Surface eroding and semicrystalline polyanhydrides, with tunable erosion times and drug delivery pharmacokinetics largely dictated by erosion, are produced easily with thiol-ene "click" polymerization. This strategy yields both linear and cross-linked network polyanhydrides that are readily and fully cured within minutes using photoinitiation, can contain up to 60% crystallinity, and have tensile moduli up to 25 MPa for the compositions studied. Since they readily undergo hydrolysis and exhibit the oft-preferred surface erosion mechanism, they may be particularly useful in drug delivery applications.

Photopolymerized cross-linked thiol-ene polyanhydrides: erosion, release, and toxicity studies.

Several critical aspects of cross-linked polyanhydrides made using thiol-ene polymerization are reported, in particular the erosion, release, and solution properties, along with their cytotoxicity toward fibroblast cells. The monomers used to synthesize these polyanhydrides were 4-pentenoic anhydride and pentaerythritol tetrakis(3-mercaptopropionate). Techniques used to evaluate the erosion mechanism indicate a complex situation in which several phenomena, such as hydrolysis rates, local pH, water diffusion, and solubility, may be influencing the erosion process.

Noncovalent binding and fluorogenic response of cyanine dyes to DNA homoquadruplex and PNA-DNA heteroquadruplex structures.

Two symmetrical cyanine dyes based on benzothiazole heterocycles and a trimethine bridge were found to bind to a parallel-stranded DNA guanine quadruplex based on the MYC oncogene promoter sequence with high nanomolar affinity and 1:1 stoichiometry. The dyes exhibited substantial fluorescence enhancements upon binding. In the presence of homologous guanine-rich peptide nucleic acid oligomers, PNA-DNA heteroquadruplexes were formed.