Development and characterization of novel polyurethane films impregnated with tolfenamic acid for therapeutic applications

Polymer-based biomaterials for chronic wound management: Promises and challenges

Chronic non-healing wounds tender a great challenge to patients, physicians, and wound care professionals. In view of the increasing prevalence of chronic wounds due to ischemia, diabetic foot, venous, and pressure ulcers, their appropriate management requires significant attention. Along with the basic techniques of medical and surgical treatments; an ideal dressing is essential for a speedy recovery and rapid healing of such wounds. Mechanistic understanding of chronic wound pathology will not only help towards future directions for an ideal dressing model but also to resonant advance research related to specific dressings for various wound types. This review provides key insights into causes, pathophysiology, and critical issues pertaining to chronic wounds and their management. It also summarizes the challenges faced for chronic wound treatment and specified factors responsible for delayed healing. Moreover, this review delivers a detailed discussion on available polymeric materials (alginate, chitosan, hyaluronic acid, collagen, polyurethane, cellulose, dextran, gelatin, silk, and polyaniline), their functional characteristics, and usage as chronic wound healing agents for polymeric wound dressing development. Incorporation and comparison of the research studies for their thermal behavior, structural analysis, and microscopic studies by Fourier transform infrared spectroscopy, thermogravimetric analysis and scanning electron microscopy, respectively and swelling studies of different polymeric materials are discussed. Additionally, studies of anatomy cum physiology of wound healing, pathophysiology, tissue engineering and advance healing management approaches makes the content of this review a significant tool for future studies on chronic wounds healing by polymeric wound dressings. In this review, polymeric wound dressings have been explained in terms of their structures, function, chemistry, and key characteristics. These features are directly linked to the polymeric systems' potential in the management of chronic wounds. These polymeric systems have gained promising success in solving real word global health problems. More recently, innovative approaches to fabricate the polymer dressings have been introduced, but their commercial, sustainable, and high-scale production largely remains unexplored. This review also summarizes the promises of polymeric wound dressings and provides a future perspective on how the clinical and commercial landscape could potentially be propelled by utilizing polymers in wound care management.

Non-isocyanate urethane linkage formation using l-lysine residues as amine sources

Bio-based polyurethane materials are broadly applied in medicine as drug delivery systems. Nevertheless, their synthesis comprises the use of petroleum-based toxic amines, isocyanates and polyols, and their biocompatibility or functionalization is limited. Therefore, the use of lysine residues as amine sources to create non-isocyanate urethane (NIU) linkages was investigated. Therefore, a five-membered biscyclic carbonate (BCC) was firstly synthetized and reacted with a protected lysine, a tripeptide and a heptapeptide to confirm the urethane linkage formation with lysine moiety and to optimize reaction conditions. Afterwards, the reactions between BCC and a model protein, elastin-like protein (ELP), and β-Lactoglobulin (BLG) obtained from whey protein, respectively, were performed. The synthesized protein materials were structural, thermally and morphologically characterized to confirm the urethane linkage formation. The results demonstrate that using both simple and more complex source of amines (lysine), urethane linkages were effectively achieved. This pioneering approach opens the possibility of using proteins to develop non-isocyanate polyurethanes (NIPUs) with tailored properties.

Synthesis of Graphene Oxide Based Sponges and Their Study as Sorbents for Sample Preparation of Cow Milk Prior to HPLC Determination of Sulfonamides

In the present study, a novel, simple, and fast sample preparation technique is described for the determination of four sulfonamides (SAs), namely Sulfathiazole (STZ), sulfamethizole (SMT), sulfadiazine (SDZ), and sulfanilamide (SN) in cow milk prior to HPLC. This method takes advantage of a novel material that combines the extractive properties of graphene oxide (GO) and the known properties of common polyurethane sponge (PU) and that makes sample preparation easy, fast, cheap and efficient. The PU-GO sponge was prepared by an easy and fast procedure and was characterized with FTIR spectroscopy. After the preparation of the sorbent material, a specific extraction protocol was optimized and combined with HPLC-UV determination could be applied for the sensitive analysis of trace SAs in milk. The proposed method showed good linearity while the coefficients of determination (R²) were found to be high (0.991-0.998). Accuracy observed was within the range 90.2-112.1% and precision was less than 12.5%. Limit of quantification for all analytes in milk was 50 μg kg^-1. Furthermore, the PU-GO sponge as sorbent material offered a very clean extract, since no matrix effect was observed.

Tolfenamic Acid

Tolfenamic acid (TA) is a nonsteroidal antiinflammatory drug and belongs to the group of fenamates. It is used as a potent pain reliever in the treatment of acute migraine attacks, and disorders like dysmenorrhea, rheumatoid, and osteoarthritis. TA has shown excellent in vitro antibacterial activity against certain ATCC strains of bacteria when complexed with bismuth(III). It has also been reported to block pathological processes associated with Alzheimer's disease. In the recent past, TA has also been used as a novel anticancer agent for the treatment of various cancers. In view of the clinical importance of TA, a comprehensive review of the physical and pharmaceutical properties and details of the various analytical methods used for the assay of the drug in pharmaceutical and biological systems has been made. The methods reviewed include identification tests and titrimetric, spectrophotometric, chromatographic, electrochemical, thermal, microscopic, enzymatic, and solid-state techniques. Along with the analytical profile, the stability and degradation of TA, its pharmacology and pharmacokinetics, dosage forms and dose, adverse effects and toxicity, and interactions have been discussed.

Validation of a UV Spectrometric Method for the Assay of Tolfenamic Acid in Organic Solvents

The present study has been carried out to validate a UV spectrometric method for the assay of tolfenamic acid (TA) in organic solvents. TA is insoluble in water; therefore, a total of thirteen commonly used organic solvents have been selected in which the drug is soluble. Fresh stock solutions of TA in each solvent in a concentration of 1 × 10⁻⁴M (2.62 mg%) were prepared for the assay. The method has been validated according to the guideline of International Conference on Harmonization and parameters like linearity, range, accuracy, precision, sensitivity, and robustness have been studied. Although the method was found to be efficient for the determination of TA in all solvents on the basis of statistical data 1-octanol, followed by ethanol and methanol, was found to be comparatively better than the other studied solvents. No change in the stock solution stability of TA has been observed in each solvent for 24 hours stored either at room (25 ± 1°C) or at refrigerated temperature (2–8°C). A shift in the absorption maxima has been observed for TA in various solvents indicating drug-solvent interactions. The studied method is simple, rapid, economical, accurate, and precise for the assay of TA in different organic solvents.

Preparation and characterization of bioactive composites and fibers for dental applications

OBJECTIVES

The present study was carried out to create composites and fibers using polyurethane (PU) with hydroxyapatite (HA) that could be used for dental applications.

METHODS

Composites with varying HA concentration were prepared by solution casting technique. Similarly, PU-HA fibers with varying PU hard and soft segments and fixed HA concentration were also prepared. Various characterization techniques, such as, X-ray diffractometry, differential scanning calorimetry, scanning electron microscopy and Fourier transform infrared spectroscopy in conjunction with photo-acoustic sampling cell were employed to study the composites and fibers for changes in their physicochemical properties before and after immersion in artificial saliva at 37°C for up to 5 days.

RESULTS

The results indicated formation of amorphous apatite layers with maximum amorphicity in composites containing highest amount of HA with 5 days of immersion in artificial saliva. Similarly, fibers with more PU hard segment resulted in better transformation of crystalline HA to its amorphous state with increasing immersion time thus confirming the bioactive nature of the HA-PU fibers.

SIGNIFICANCE

Concentrations of HA and PU hard segment along with the duration of immersion in artificial saliva are two major factors involved in the modification of solid-state properties of HA. The amorphous apatite layer on the surface is known to have tendency to bind with living tissues and hence the use of optimum amount of HA and PU hard segment in composites and fibers, respectively could help in the development of novel dental filling material.

Improvement of the water solubility of tolfenamic acid by new multiple-component crystals produced by mechanochemical methods

Tolfenamic acid (HTA) is a drug characterized by very poor solubility in water. By mechanochemical methods, new solid-state forms of HTA were obtained, showing better thermal stability than pure HTA and an improved dissolution rate.