Utilizing Silk Sericin as a Biomaterial for Drug Encapsulation in a Hydrogel Matrix with Polycaprolactone: Formulation and Evaluation of Antibacterial Activity

Hydrogels have emerged as a potential tool for enhancing bioavailability and regulating the controlled release of therapeutic agents. Owing to its excellent biocompatibility, silk sericin-based hydrogels have garnered interest in biomedical applications. This study focuses on synthesizing a soft hydrogel by blending silk sericin (SS) and polycaprolactone (PCL) at room temperature. The physicochemical characteristics of the hydrogels have been estimated by different analytical techniques such as UV-visible spectroscopy, Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), and scanning electron microscopy (SEM). The rheological studies demonstrate the non-Newtonian behavior of the hydrogels. Further, the porosity analysis indicates a commendable absorption capacity of the hydrogels. The swelling degree of the hydrogels has been checked in both distilled water and buffer solutions of different pHs (2-10). Moreover, the drug release profile of the hydrogels, using diclofenac sodium (DS) as a model drug, has revealed a substantial release of approximately 67% within the first 130 min with a drug encapsulation efficiency of 60.32%. Moreover, both the empty and the drug-loaded hydrogels have shown antibacterial properties against Gram-positive and Gram-negative bacteria, with the drug-loaded hydrogels displaying enhanced effectiveness. Additionally, the prepared hydrogels are biodegradable, demonstrating their future prospects in biomedical applications.

Swelling induced mechanically tough starch-agar based hydrogel as a control release drug vehicle for wound dressing applications

In recent years, polysaccharide-based hydrogels have received increased attention due to their inherent biodegradability, biocompatibility, and non-toxicity. The feasibility of using polysaccharides for the synthesis of hydrogels is dependent on their noteworthy mechanical strength and cell compatibility, which are required for practical applications, especially for biomedical uses. In this study, we demonstrate a facile synthetic route for the construction of a mechanically tough, biocompatible, and biodegradable hydrogel using polysaccharides such as starch and agar. A synthetic monomer-free hydrogel was synthesized using epichlorohydrin as a cross-linker, and a mechanical strength of 9.49 ± 1.29-6.16 ± 0.37 MPa was achieved. The introduction of agar into the hydrogel resulted in agar dose-dependent swelling-induced mechanical strength. Moreover, along with incredible mechanical strength, the hydrogel also exhibited prominent cell viability against human embryonic kidney cells. In addition, the hydrogel showed good encapsulation efficiency for antibacterial drugs like ciprofloxacin hydrochloride hydrate, with controlled releasing ability over a sustained period. The antibacterial activity of the encapsulated drug was observed against Staphylococcus aureus and Bacillus subtilis bacterial strains. Thus, the studied hydrogel with loaded drug exhibited all the required qualities to be utilized as a promising candidate in wound dressing applications.

Self-cross-linked starch/chitosan hydrogel as a biocompatible vehicle for controlled release of drug

A facile one-pot approach was adopted to prepare a polysaccharide-based hydrogel of oxidized starch (OS)-chitosan. The synthetic monomer-free, eco-friendly hydrogel was prepared in an aqueous solution and employed for controlled drug release application. The starch was first oxidized under mild conditions to prepare its bialdehydic derivative. Subsequently, the amino group-containing a modified polysaccharide, "chitosan" was introduced on the backbone of OS via a dynamic Schiff-base reaction. The bio-based hydrogel was obtained via a one-pot in-situ reaction, where functionalized starch acts as a macro-cross-linker that contributes structural stability and integrity to the hydrogel. The introduction of chitosan contributes stimuli-responsive properties and thus pH-sensitive swelling behavior was obtained. The hydrogel showed its potential as a pH-dependent controlled drug release system and a maximum of 29 h sustained release period was observed for ampicillin sodium salt drug. In vitro studies confirmed that the prepared drug-loaded hydrogels showed excellent antibacterial ability. Most importantly, the hydrogel could find potential use in the biomedical field due to its facile reaction conditions, biocompatibility along with the controlled releasing ability of the encapsulated drug.

New Bio-Based Polymer Sorbents out of Terpene Compounds or Vegetable Oils: Synthesis, Properties, Analysis of Sorption Processes

This research presents a synthesis and characterization of new bio-based polymer sorbents. Natural origin substances such as terpenes (citral, limonene, and pinene) or vegetable oils (argan, linseed, and rapeseed oils) were used as monomers, and divinylbenzene was applied as the cross-linker. The newly prepared polymers were characterized by means of ATR-FTIR, TG/DTG and titration methods (acid and iodine values), and N₂ physisorption experiments. Tests of sorption ability were carried out by a dynamic solid phase extraction method using a mixture of four phenols or single-component pharmaceutical solutions (salicylic acid, aspirin, ibuprofen, paracetamol, and ampicillin). The performed studies revealed that the terpene-based polymers possessed better-developed porous structures (420-500 m²/g) with more uniform pores than oil-based ones. However, the surface of the oil-based sorbents was more acidic in nature. The sorption tests showed that both the porosity and acidity of the surface significantly influenced the sorption. Recoveries of up to 90% were obtained for 2,4 dichlorophenol from C-DVB, L-DVB, and Ro-DVB. The lowest affinity to the polymers exhibited phenol (5-45%), aspirin (1-7%), and ampicillin (1-7%). A 70% recovery was achieved for ibuprofen from C-DVB. In-depth data analysis allowed the influence of various factors on the sorption process of test compounds of the studied polymers to be elucidated.

Printable Hydrogels Based on Alginate and Halloysite Nanotubes

The design of hydrogels for the controlled release of active species is an attractive challenge. In this work, we prepared hybrid hydrogels composed of halloysite nanotubes as the inorganic component, and alginate as the organic counterpart. The reported procedure allowed us to provide the resulting materials with a peculiar wire-like shape. Both optical and scanning electron microscopy were used to characterize the morphological properties of the hydrogel wires, whose diameters were ca. 0.19 and 0.47 mm, respectively. The possibility to be exploited as drug delivery systems was carried out by loading the nanoclay with salicylic acid and by studying the release profiles. Thermogravimetric experiments showed that the amount of encapsulated drug was 4.35 wt%, and the salicylic acid was thermally stabilized after the loading into the nanotubes, as observed by the shift of the degradation peak in the differential thermograms from 193 to 267 °C. The kinetics investigation was conducted using UV–Vis spectrophotometry, and it exhibited the profound effects of both the morphology and dimensions on the release of the drugs. In particular, the release of 50% of the payload occurred in 6 and 10 h for the filiform hydrogels, and it was slower compared to the bare drug-loaded halloysite, which occurred in 2 h. Finally, an induction period of 2 h was observed in the release profile from the thicker sample.

Pd-catalyzed cross-coupling of arabinogalactan propargyl ethers with 5-bromosalicylic acid

New salicylate derivatives of arabinogalactan have been synthesized in up to 90% yield by cross-coupling of propargyl ethers of arabinogalactan with 5-bromosalicylic acid salts. The reaction proceeds in the presence of the catalytic system Pd(PPh₃)₄/PPh₃ with CuBr (CuI), and piperidine or 1,8-diazabicyclo-[5.4.0]-undec-7-ene (DBU) as a base in DMSO at 70-95 °С. The propargyl groups of the starting arabinogalactan ethers are converted into propinylsalicylate ones with 35 and 50% conversion depending on the nature of the base used. Degree of arabinogalactan substitution with propynyl salicylate fragments reaches 1.0 and 0.7 in the reactions with piperidine and DBU, respectively. In the case of piperidine, along with the main process, intensive unprecedented (for Sonogashira reaction) hydroamination of propargyl groups is also observed, followed by hydrolysis of unstable enamines. The products have been characterized by IR, ¹Н and ¹³С NMR, UV spectroscopy as well as elemental analysis and gel permeation chromatography. Salicylate derivatives of arabinogalactan show high activity in prolonging the activated partial thromboplastin time (APTT), whereas neither the arabinogalactan nor propargyl ethers of arabinogalactan nor salicylic acid salts have obvious effects.

Polysaccharide based superabsorbent hydrogel from Mimosa pudica: swelling–deswelling and drug release

Polysaccharide based stimuli responsive, superporous and superabsorbent hydrogel for sustained drug release.