Fatty acid-modified poly(glycerol adipate) microparticles for controlled drug delivery

Development of Poly(sorbitol adipate)-g-poly(ethylene glycol) Mono Methyl Ether-Based Hydrogel Matrices for Model Drug Release

Hydrogels were prepared by Steglich esterification and by crosslinking pre-synthesized poly(sorbitol adipate)-graft-poly(ethylene glycol) mono methyl ether (PSA-g-mPEG) using different-chain-length-based disuccinyl PEG. PSA and PSA-g-mPEG were investigated for polymer degradation as a function of time at different temperatures. PSA-g-mPEG hydrogels were then evaluated for their most crucial properties of swelling that rendered them suitable for many pharmaceutical and biomedical applications. Hydrogels were also examined for their Sol-Gel content in order to investigate the degree of cross-linking. Physical structural parameters of the hydrogels were theoretically estimated using the modified Flory-Rehner theory to obtain approximate values of polymer volume fraction, the molecular weight between two crosslinks, and the mesh size of the hydrogels. X-ray diffraction was conducted to detect the presence or absence of crystalline regions in the hydrogels. PSA-g-mPEG hydrogels were then extensively examined for higher and lower molecular weight solute release through analysis by fluorescence spectroscopy. Finally, the cytotoxicity of the hydrogels was also investigated using a resazurin reduction assay. Experimental results show that PSA-g-mPEG provides an option as a biocompatible polymer to be used for pharmaceutical applications.

Harnessing the power of polyol-based polyesters for biomedical innovations: synthesis, properties, and biodegradation

Polyesters based on polyols have emerged as promising biomaterials for various biomedical applications, such as tissue engineering, drug delivery systems, and regenerative medicine, due to their biocompatibility, biodegradability, and versatile physicochemical properties. This review article provides an overview of the synthesis methods, performance, and biodegradation mechanisms of polyol-based polyesters, highlighting their potential for use in a wide range of biomedical applications. The synthesis techniques, such as simple polycondensation and enzymatic polymerization, allow for the fine-tuning of polyester structure and molecular weight, thereby enabling the tailoring of material properties to specific application requirements. The physicochemical properties of polyol-based polyesters, such as hydrophilicity, crystallinity, and mechanical properties, can be altered by incorporating different polyols. The article highlights the influence of various factors, such as molecular weight, crosslinking density, and degradation medium, on the biodegradation behavior of these materials, and the importance of understanding these factors for controlling degradation rates. Future research directions include the development of novel polyesters with improved properties, optimization of degradation rates, and exploration of advanced processing techniques for fabricating scaffolds and drug delivery systems. Overall, polyol-based polyesters hold significant potential in the field of biomedical applications, paving the way for groundbreaking advancements and innovative solutions that could revolutionize patient care and treatment outcomes.

Taste-Masked Flucloxacillin Powder Part 2: Formulation Optimisation Using the Mixture Design Approach and Storage Stability

Flucloxacillin is prescribed to treat skin infections but its highly bitter taste is poorly tolerated in children. This work describes the application of the D-optimal mixture experimental design to identify the optimal component ratio of flucloxacillin, Eudragit EPO and palmitic acid to prepare flucloxacillin taste-masked microparticles that would be stable to storage and would inhibit flucloxacillin release in the oral cavity while facilitating the total release of the flucloxacillin load in the lower gastrointestinal tract (GIT). The model predicted ratio was found to be very close to the stoichiometric equimolar component ratio, which supported our hypothesis that the ionic interactions among flucloxacillin, Eudragit EPO and palmitic acid underscore the polyelectrolyte complex formation in the flucloxacillin taste-masked microparticles. The excipient-drug interactions showed protective effects on the microparticle storage stability and minimised flucloxacillin release at 2 min in dissolution medium. These interactions had less influence on flucloxacillin release in the dissolution medium at 60 min. Storage temperature and relative humidity significantly affected the chemical stability of the microparticles. At the preferred storage conditions of ambient temperature under reduced RH of 23%, over 90% of the baseline drug load was retained in the microparticles at 12 months of storage.

The role of copper chromite nanoparticles on physical and bio properties of scaffolds based on poly(glycerol-azelaic acid) for application in tissue engineering fields

Tissue engineering combines suitable cells, engineering methods, and proper biochemical factors to develop functional and biological tissues and repair damaged tissues. In this study, we focused on synthesizing and characterizing a nanocomposite scaffold based on glycerol and azelaic acid (Gl-Az) combined with copper chromite (CuCr₂O₄) nanoparticles in order to increase the osteogenic differentiation efficiency of human adipose-derived stem cells (hADSCs) on fabricated scaffolds. The degradability and hydrophobicity properties as well as mechanical and thermal behaviors of nanocomposite scaffolds were investigated. Next, the cell toxicity of glycerol, azelaic acid and CuCr₂O₄ nanoparticles was studied by MTT assay test and acridine orange staining. Finally, the osteogenic differentiation of hADSCs on Gl-Az-CuCr₂O₄ scaffolds was examined using alkaline phosphatase activity (ALP) and calcium content. The obtained results demonstrated that Gl-Az-1%CuCr₂O₄ not only showed appropriate mechanical strength, biocompatibility and degradability but also influenced the capability of hADSCs to differentiate into osteogenic lineages. The hADSCs culture in Gl-Az-1%CuCr₂O₄ showed a significant increase in ALP activity levels and calcium biomineralization after 14 days of osteogenic differentiation. In conclusion, the Gl-Az-1%CuCr₂O₄ nanocomposite could be used as a biocompatible and degradable scaffold to induce the bone differentiation of hADSCs and it could be a promising scaffold in bone regenerative medicine.

Development and Characterization of Novel In-Situ-Forming Oleogels

PLGA-based in situ forming implants (ISFI) often require a high amount of potentially toxic solvents such as N methyl-Pyrrolidone (NMP). The aim of the present study was to develop lipid in-situ-forming oleogels (ISFOs) as alternative delivery systems. 12-Hydroxystearic acid (12-HSA) was selected as the oleogelling agent and three different oleoformulations were investigated: (a) 12-HSA, peanut oil (PO), NMP; (b) 12-HSA, medium-chain triglycerides (MCT), ethanol; (c) 12-HSA, isopropyl myristate (IPM), ethanol. The effects of the 12-HSA concentration, preparation method, and composition on the mechanical stability were examined using a texture analysis and oscillating rheology. The texture analysis was used to obtain information on the compression strength. The amplitude sweeps were analyzed to provide information on the gel strength and the risk of brittle fractures. The frequency sweeps allowed insights into the long-term stability and risk of syneresis. The syringeability of the ISFOs was tested, along with their acute and long-term cytotoxicity in vitro. The developed ISFOs have the following advantages: (1) the avoidance of highly acidic degradation products; (2) low amounts of organic solvents required; (3) low toxicity; (4) low injection forces, even with small needle sizes. Therefore, ISFOs are promising alternatives to the existing polymer/NMP-based ISFIs.

Macro- and Nanoscale Effect of Ethanol on Bovine Serum Albumin Gelation and Naproxen Release

We report extended ethanol-induced gelation procedures of bovine serum albumin (BSA) at 37 °C and investigate the release behavior of a spin-labeled naproxen derivative (SL-NPX) from these hydrogels. The macroscopic mechanical properties of these gels during formation were studied using rheology, while a nanoscopic, more molecular view was obtained by analyzing the secondary structure of the protein during gelation via infrared (ATR-IR) spectroscopy. To evaluate the potential use of BSA hydrogels in controlled drug delivery, SL-NPX-BSA interaction was investigated in detail by continuous-wave electron paramagnetic resonance (CW EPR) spectroscopy, which provides information on the interaction of the small drug molecules and the hydrogel. In addition to CW EPR spectroscopy, dynamic light scattering (DLS), which provides insight into the size and nature of released components, was applied to characterize the combined influence of incubation time, ethanol, SL-drug, and BSA concentration on release behavior. It was found that the alteration of initial drug loading percentage, hydrogel incubation time as well as BSA and alcohol concentrations affect and thus tune the release rate of SL-NPX from BSA hydrogels. These results lead to the conclusion that BSA hydrogels as controlled release systems offer a remarkable fine-tuning capability for pharmaceutical applications due to the variety of gelation parameters.

Droplet Microfluidic Optimisation Using Micropipette Characterisation of Bio-Instructive Polymeric Surfactants

Droplet microfluidics can produce highly tailored microparticles whilst retaining monodispersity. However, these systems often require lengthy optimisation, commonly based on a trial-and-error approach, particularly when using bio-instructive, polymeric surfactants. Here, micropipette manipulation methods were used to optimise the concentration of bespoke polymeric surfactants to produce biodegradable (poly(d,l-lactic acid) (PDLLA)) microparticles with unique, bio-instructive surface chemistries. The effect of these three-dimensional surfactants on the interfacial tension of the system was analysed. It was determined that to provide adequate stabilisation, a low level (0.1% (w/v)) of poly(vinyl acetate-co-alcohol) (PVA) was required. Optimisation of the PVA concentration was informed by micropipette manipulation. As a result, successful, monodisperse particles were produced that maintained the desired bio-instructive surface chemistry.