Modeling drug release through stimuli responsive polymer hydrogels

A temperature and pH dual-responsive injectable self-healing hydrogel prepared by chitosan oligosaccharide and aldehyde hyaluronic acid for promoting diabetic foot ulcer healing

Chronic wound, such as skin defect after burn, pressure ulcer, and diabetic foot ulcer is very difficult to cure. Its pathological process is often accompanied with local temperature rise, pH decrease, and other phenomena. Owing to their outstanding hydrophilic, biocompatibility, and responsive properties, hydrogels could accelerate the healing process. In this study, we chose chitosan oligosaccharide (COS) grafted with Pluronic F127 (F127-COS). Aldehyde hyaluronic acid (A-HA) oxidized by NaIO4. And added boric acid (BA) to prepare a thermosensitive and pH-responsive injectable self-healing F127-COS/A-HA/COS/BA (FCAB) hydrogel, loaded with drug deferoxamine (DFO) in order to have an accurate release and promote angiogenesis of diabetic foot ulcer. In vitro experiments had verified that the FCAB hydrogel system loaded with DFO (FCAB/D) could promote migration and angiogenesis of HUVEC. A diabetes rat back wound model further confirmed its role in promoting angiogenesis in wound repair process. The results showed that the FCAB/D hydrogel exhibited unique physicochemical properties, excellent biocompatibility, and significantly enhanced therapeutic effects for diabetic foot ulcer.

Application of 3D Bioprinting in Urology

Tissue engineering is an emerging field to create functional tissue components and whole organs. The structural and functional defects caused by congenital malformation, trauma, inflammation or tumor are still the major clinical challenges facing modern urology, and the current treatment has not achieved the expected results. Recently, 3D bioprinting has gained attention for its ability to create highly specialized tissue models using biological materials, bridging the gap between artificially engineered and natural tissue structures. This paper reviews the research progress, application prospects and current challenges of 3D bioprinting in urology tissue engineering.

Swelling and glyphosate-controlled release behavior of multi-responsive alginate-g-P(NIPAm-co-NDEAm)-based hydrogel

Intelligent controlled release systems (ICRS) displayed great achievement in agriculture by enhancing the utilization efficiency of agrochemicals. In this work, an intelligent graft copolymer (Alg-g-P(NIPAm-co-NDEAm)) with alginate (Alg) backbone and thermo-responsive poly(N-isopropyl acrylamide-co-N,N-diethylacrylamide) (P(NIPAm-co-NDEAm)) side chain was constructed as the matrix of ICRS through redox copolymerization, and its thermo-induced responsive property was studied. Then, the copolymer was mixed with a promising photothermal material semi-coke (SC) to form hydrogel beads (Ca-Alg-g-P(NIPAm-co-NDEAm)/SC) by ion crosslinking. The water absorbency of beads under different stimuli (pH, temperature, and light) presented outstanding responsive performance and the swelling mechanism was analyzed through coupling theory. Furthermore, the release of glyphosate (Gly) from Ca-Alg-g-P(NIPAm-co-NDEAm)/SC under environmental stimuli displayed regulatable behaviors. This multi-responsive hydrogel bead shows bright prospect in the sustainable advancement of crop production.

Composite Polymers from Leather Waste to Produce Smart Fertilizers

The leather industry is facing important environmental issues related to waste disposal. The waste generated during the tanning process is an important resource of protein (mainly collagen) which can be extracted and reused in different applications (e.g., medical, agricultural, leather industry). On the other side, the utilization of chemical fertilizers must be decreased because of the negative effects associated to an extensive use of conventional chemical fertilizers. This review presents current research trends, challenges and future perspectives with respect to the use of hide waste to produce composite polymers that are further transformed in smart fertilizers. Hide waste contains mostly protein (collagen that is a natural polymer), that is extracted to be used in the cross-linking with water soluble copolymers to obtain the hydrogels which are further valorised as smart fertilizers. Smart fertilizers are a new class of fertilizers which allow the controlled release of the nutrients in synchronization with the plant's demands. Characteristics of hide and leather wastes are pointed out. The fabrication methods of smart fertilizers and the mechanisms for the nutrients release are extensively discussed. This novel method is in agreement with the circular economy concepts and solves, on one side, the problem of hide waste disposal, and on the other side produces smart fertilizers that can successfully replace conventional chemical fertilizers.

Mathematical Model for Estimating Parameters of Swelling Drug Delivery Devices in a Two-Phase Release

Various swelling drug delivery devices are promising materials for control drug delivery because of their ability to swell and release entrapped therapeutics, in response to physiological stimuli. Previously, many mathematical models have been developed to predict the mechanism of drug release from a swelling device. However, some of these models do not consider the changes in diffusion behaviour as the device swells. Therefore, we used a two-phase approach to simplify the mathematical model considering the effect of swelling on the diffusion coefficient. We began by defining a moving boundary problem to consider the swelling process. Landau transformation was used for mitigating the moving boundary problem. The transformed problem was analytically solved using the separation of variables method. Further, the analytical solution was extended to include the drug release in two phases where each phase has distinct diffusion coefficient and continuity condition was applied. The newly developed model was validated by the experimental data of bacterial cellulose hydrogels using the LSQCURVEFIT function in MATLAB. The numerical test showed that the new model exhibited notable improvement in curve fitting, and it was observed that the initial effective diffusion coefficient of the swelling device was lower than the later effective diffusion coefficient.

Research progress in the application of in situ hydrogel system in tumor treatment

The in situ hydrogel drug delivery system is a hot research topic in recent years. Combining both properties of hydrogel and solution, in situ hydrogels can provide many advantages for drug delivery application, including easy application, high local drug concentration, prolonged drug retention time, reduced drug dose in vivo, good biocompatibility and improved patient compliance, thus has potential in tumor treatment. In this paper, the related literature reports in recent years were reviewed to summarize and discuss the research progress and development prospects in the application of in situ hydrogels in tumor treatment.

An overview on the mathematical modeling of hydrogels' behavior for drug delivery systems

Hydrogels-based systems (HBSs) for drug delivery are nowadays extensively used and the interest in modeling their behavior is dramatically increasing. In this review a critical overview on the modeling approaches is given, quantitatively and qualitatively analyzing the publications on the subject, the trend of the publications per year and the type of modeling approaches. It was found that, despite the drug release fitting models (i.e. Higuchi's equation) are the most abundant, their use for HBSs is decreasing in the last years and luckily, considering the limiting assumption on which they were built, they will be confined to simple mathematical fitting equations. Within the mechanistic models the "multi-component" with the swelling approximation (mass transport only) and with the mechanics (fully coupled) are experiencing the highest growth rate, with much more interest toward the last one that, in the next years could be able to provide a first principles model. Statistical models, especially based on the response surface methodology, are rapidly spreading in the scientific community mainly thanks to their ability to be predictive, regardless of the phenomenology, in the analyzed design space with very low efforts. Neural Networks models for HBSs, in countertrend with their use in the pharmaceutical industry, have never take off preferring less data demanding statistical models.