Non-Fickian mass transfer in swelling polymeric non-porous membranes

Constructing an Ultra-Rapid Nanoconfinement-Enhanced Fluorescence Clinical Detection Platform by Using Machine Learning and Tunable DNA Xerogel "Probe"

Low mass transfer efficiency and unavoidable matrix effects seriously limit the development of rapid and accurate determination of biosensing systems. Herein, we have successfully constructed an ultra-rapid nanoconfinement-enhanced fluorescence clinical detection platform based on machine learning (ML) and DNA xerogel "probe", which was performed by detecting neutrophil gelatinase-associated lipocalin (NGAL, protein biomarker of acute kidney injury). By regulating pore sizes of the xerogels, the transfer of NGAL in xerogels can approximate that in homogeneous solution. Due to electrostatic attraction of the pore entrances, NGAL rapidly enriches on the surface and inside the xerogels. The reaction rate of NGAL and aptamer cross-linked in xerogels is also accelerated because of the nanoconfinement effect-induced increasing reactant concentration and the enhanced affinity constant KD between reactants, which can be promoted by ∼667-fold than that in bulk solution, thus achieving ultra-rapid detection (ca. 5 min) of human urine. The platform could realize one-step detection without sample pretreatments due to the antiligand exchange effect on the surface of N-doped carbon quantum dots (N-CQDs) in xerogels, in which ligand exchange between -COOH and underlying interfering ions in urine will be inhibited due to higher adsorption energy of -COOH on the N-CQD surface relative to the interfering ions. Based on the ML-extended program, the real-time analysis of the urine fluorescence spectra can be completed within 2 s. Interestingly, by changing DNA, aptamer sequences, or xerogel fluorescence intensities, the detection platform can be customized for targeted diseases.

Chemically Crosslinked Amphiphilic Degradable Shape Memory Polymer Nanocomposites with Readily Tuned Physical, Mechanical, and Biological Properties

Facile surgical delivery and stable fixation of synthetic scaffolds play roles just as critically as degradability and bioactivity in ensuring successful scaffold-guided tissue regeneration. Properly engineered shape memory polymers (SMPs) may meet these challenges. Polyhedral oligomeric silsesquioxanes (POSSs) can be covalently integrated with urethane-crosslinked polylactide (PLA) to give high-strength, degradable SMPs around physiological temperatures. To explore their potential for guided bone regeneration, here we tune their hydrophilicity, degradability, cytocompatibility, and osteoconductivity/osteoinductivity by crosslinking star-branched POSS-PLA with hydrophilic polyethylene glycol diisocyanates of different lengths and up to 60 wt % hydroxyapatite (HA). The composites exhibit high compliance, toughness, up to gigapascal storage moduli, and excellent shape recovery (>95%) at safe triggering temperatures. Water swelling ratios and hydrolytic degradation rates positively correlated with the hydrophilic crosslinker lengths, while the negative impact of degradation on the proliferation and osteogenesis of bone marrow stromal cells was mitigated with HA incorporation. Macroporous composites tailored for a rat femoral segmental defect were fabricated, and their ability to stably retain and sustainedly release recombinant osteogenic bone morphogenetic protein-2 and support cell attachment and osteogenesis was demonstrated. These properties combined make these amphiphilic osteoconductive degradable SMPs promising candidates as next-generation synthetic bone grafts.

Synthetic biodegradable polyesters for implantable controlled-release devices

INTRODUCTION

: Implantable devices can be designed to release drugs to localized regions of tissue at sustained and reliable rates. Advances in polymer engineering have led to the design and development of drug-loaded implants with predictable, desirable release profiles. Biodegradable polyesters exhibit chemical, physical, and biological properties suitable for developing implants for pain management, cancer therapy, contraception, antiviral therapy, and other applications.

AREAS COVERED

: This article reviews the use of biodegradable polyesters for drug-loaded implants by discussing the properties of commonly used polymers, techniques for implant formulation and manufacturing, mechanisms of drug release, and clinical applications of implants as drug delivery devices.

EXPERT OPINION

: Drug delivery implants are unique systems for safe and sustained drug release, providing high bioavailability and low toxicity. Depending on the implant design and tissue site of deployment, implants can offer either localized or systemic drug release. Due to the long history of use of degradable polyesters in medical devices, polyester-based implants represent an important class of controlled release technologies. Further, polyester-based implants are the largest category of drug delivery implants to reach the point of testing in humans or approval for human use.