Ceiba pentandra cellulose crosslinked with citric acid for drug release systems

Progress on green crosslinking of polysaccharide hydrogels for drug delivery and tissue engineering applications

Natural polysaccharides are being studied for their biocompatibility, biodegradability, low toxicity, and low cost in the fabrication of various hydrogel devices. However, due to their insufficient physicochemical and mechanical qualities, polysaccharide hydrogels alone are not acceptable for biological applications. Various synthetic crosslinkers have been tested to overcome the drawbacks of standalone polysaccharide hydrogels; however, the presence of toxic residual crosslinkers, the generation of toxic by-products following biodegradation, and the requirement of toxic organic solvents for processing pose challenges in achieving the desired non-toxic biomaterials. Natural crosslinkers such as citric acid, tannic acid, vanillin, gallic acid, ferulic acid, proanthocyanidins, phytic acid, squaric acid, and epigallocatechin have been used to generate polysaccharide-based hydrogels in recent years. Various polysaccharides, including cellulose, alginate, pectin, hyaluronic acid, and chitosan, have been hydrogelized and investigated for their potential in drug delivery and tissue engineering applications using natural crosslinkers. We attempted to provide an overview of the synthesis of polysaccharide-based hydrogel systems (films, complex nanoparticles, microspheres, and porous scaffolds) based on green crosslinkers, as well as a description of the mechanism of crosslinking and properties with a special emphasis on drug delivery, and tissue engineering applications.

Tensile Strength Improvements of Ramie Fiber Threads through Combination of Citric Acid and Sodium Hypophosphite Cross-Linking

Ramie (Boehmeria nivea) is believed to be one of the strongest natural fibers, but it still remains behind synthetic materials in terms of tensile strength. In this study, ramie materials were prepared to evaluate the modification crosslinking effect of natural fiber. The aim is to optimize various concentrations of citric acid (CA) crosslinking by adding Sodium hypophosphite (NaPO2H2), which is activated at different temperatures, to obtain the highest tensile mechanical strength. This crosslinking effect has been confirmed by FTIR to show the esterification process in the molecular structure of cellulose. The changes in the character of the fiber surface were analyzed by SEM. The tensile strength increased from 62.33 MPa for 0% CA to 124-172.86 MPa for decorticated fiber with a CA concentration of 0.75-1.875% (w/w). A significant increase in tensile strength was observed more than 19 times when CA/SHP 1% was treated at an activation temperature of 110 °C with a superior tensile strength of 1290.63. The fiber crosslinked with CA/SHP should be recommended for application of Natural Fiber Reinforced Polymer Composite (NFRPC), which has the potential to use in functional textile and industrial sector automotive or construction.

Bacterial cellulose-based composites as vehicles for dermal and transdermal drug delivery: A review

In recent years, a significant amount of drugs have been taken orally, which are not as effective as desired. To solve this problem, bacterial cellulose-based dermal/transdermal drug delivery systems (BC-DDSs) with unique properties such as cell compatibility, hemocompatibility, tunable mechanical properties, and the ability to encapsulate various therapeutic agents with the controlled release have been introduced. A BC-dermal/transdermal DDS reduces first-pass metabolism and systematic side effects while improving patient compliance and dosage effectiveness by controlling drug release through the skin. The barrier function of the skin, especially the stratum corneum, can interfere with drug delivery. Few drugs can pass through the skin to reach effective concentrations in the blood to treat diseases. Due to their unique physicochemical properties and high potential to reduce immunogenicity and improve bioavailability, BC-dermal/transdermal DDSs are widely used to deliver various types of drugs for disease treatment. In this review, we describe the different types of BC-dermal/ transdermal DDSs, along with a critical discussion of the advantages and disadvantages of these systems. After the general presentation, the review is focused on recent advances in the preparation and applications of BC-based dermal/transdermal DDSs in various types of disease treatment.

Microbial cellulosic pad encompassing alpha-arbutin in Tragacanth gum as the controlled delivery system

This research focuses on preparing a natural-based drug delivery system for α-arbutin (AR) as a skin lightening. Bacterial cellulose nanofibers (BC) pad was used for controlled-AR release through two approaches. First was the dip-drying method (P-BC), in which AR cross-linked to BC pads using citric acid (CA). The second was simultaneously entrapping of AR in Tragacanth gum (AR-TG) and stabilized on BC (BC-T) through the ultrasonic-assisted microemulsion method. UV-Vis spectra revealed better control of AR release in BC-T in the first hour. High cell viability (above 70 %) of the pads containing 1-3 % AR was reported using MTT assay. The in-vitro permeation study indicated the proper AR penetration in the treated pads. The Fickian diffusion model was determined as a fitted model for all pads in the drug release kinetics. FTIR, XRD, and TGA analyses further characterized the pads. FESEM images verified AR-TG and BC structures with average diameters of 410.7 ± 25.4 and 34.5 ± 7.51 nm, respectively. The hydrophilicity and mechanical properties of the pads were also investigated. Finally, the high biocompatibility, initial controlled release, and proper permeation suggested BC-T as a more promising delivery platform for AR.

An application of citric acid as a carrier for solid dispersion to improve the dissolution and uric acid-lowering effect of kaempferol

Kaempferol (KPF) is a flavonoid compound, which has a variety of pharmacological activities, and widely exists in daily diet. However, its application is limited due to poor solubility. Citric acid (CA) is a common food additive with high solubility. In this study, solid dispersion (SD) was prepared with CA as the carrier to improve the solubility of KPF. KPF-CA-SD (weight ratio 1:20) was obtained by ultrasonic for 20 min at 40 °C. The in vitro dissolution of KPF in SD was increased from about 50% to more than 80%. The physicochemical characterizations were analyzed by X-ray diffraction, differential scanning calorimetry, Fourier transform infrared spectroscopy, and scanning electron microscope. In hyperuricemia mice, KPF-SD (equivalent to 100 mg/kg KPF) can effectively reduce serum uric acid and exert nephroprotective effects. In conclusion, the preparation of SD with CA might provide a safe and effective selection to facilitate application of KPF in food and medicine.