Taous Khan

MicroRNAs: synthesis, mechanism, function, and recent clinical trials.

MicroRNAs (miRNAs) are a class of small, endogenous RNAs of 21-25 nucleotides (nts) in length. They play an important regulatory role in animals and plants by targeting specific mRNAs for degradation or translation repression. Recent scientific advances have revealed the synthesis pathways and the regulatory mechanisms of miRNAs in animals and plants. miRNA-based regulation is implicated in disease etiology and has been studied for treatment. Furthermore, several preclinical and clinical trials have been initiated for miRNA-based therapeutics. In this review, the existing knowledge about miRNAs synthesis, mechanisms for regulation of the genome, and their widespread functions in animals and plants is summarized. The current status of preclinical and clinical trials regarding miRNA therapeutics is also reviewed. The recent findings in miRNA studies, summarized in this review, may add new dimensions to small RNA biology and miRNA therapeutics.

Nanoreinforced bacterial cellulose–montmorillonite composites for biomedical applications

Polymer composites containing solid clay nanoparticles have attracted immense attention due to the reinforced physico-mechanical properties of the final product. Bacterial cellulose-montmorillonite (BC-MMT) composites were prepared by impregnation of BC sheets with MMT suspension. FE-SEM showed that MMT adsorbed onto the surface as well as penetrated into the matrix of the BC sheets. Peaks for both BC and MMT were present in the FT-IR spectrum of the composite. XRD also showed diffraction peaks for MMT and BC with a slight decrease in the composite crystallinity from 63.22% of pure BC to 49.68% of BC-MMT3. The mechanical and thermal properties of BC-MMT composites were significantly improved compared to those of the pure BC. Tensile strength for composites was increased up to 210 MPa from 151.3 Mpa (BC) while their degradation temperature extended from 232 °C (BC) up to 310 °C. Similarly, the water holding capacity was decreased while the water release rate was improved for the BC-MMT composites as compared to the pure BC.

Advances in biomedical and pharmaceutical applications of functional bacterial cellulose-based nanocomposites

Bacterial cellulose (BC) synthesized by certain species of bacteria, is a fascinating biopolymer with unique physical and mechanical properties. BCs applications range from traditional dessert, gelling, stabilizing and thickening agent in the food industry to advanced high-tech applications, such as immobilization of enzymes, bacteria and fungi, tissue engineering, heart valve prosthesis, artificial blood vessels, bone, cartilage, cornea and skin, and dental root treatment. Various BC-composites have been designed and investigated in order to enhance its biological applicability. This review focuses on the application of BC-based composites for microbial control, wound dressing, cardiovascular, ophthalmic, skeletal, and endodontics systems. Moreover, applications in controlled drug delivery, biosensors/bioanalysis, immobilization of enzymes and cells, stem cell therapy and skin tissue repair are also highlighted. This review will provide new insights for academia and industry to further assess the BC-based composites in terms of practical applications and future commercialization for biomedical and pharmaceutical purposes.

Applications of bacterial cellulose in food, cosmetics and drug delivery

Bacterial cellulose (BC) is a versatile biopolymer with better material properties, such as purity, high degree of porosity, relative high permeability to liquid and gases, high water-uptake capacity, tensile strength and ultrafine network. This review explores the applications of BC and its hydrogels in the fields of food, cosmetics and drug delivery. Applications of BC in foods are ranging from traditional dessert, low cholesterol diet, vegetarian meat, and as food additive and dietary aid to novel applications, such as immobilization of enzymes and cells. Applications in cosmetics include facial mask, facial scrub, personal cleansing formulations and contact lenses. BC for controlled drug delivery, transdermal drug delivery, dental drug delivery, protein delivery, tissue engineering drug delivery, macromolecular prodrug delivery and molecularly imprinted polymer based enantioselective drug delivery are also discussed in this review. The applications of BC in food and cosmetics provide the basis for BC-based functional foods, nutraceuticals, cosmeceuticals and medicated cosmetics. On the basis of current studies, the BC-based drug delivery could be further fine-tuned to get more sophisticated control on stimuli-responsive drug release. Along with the currently available literature, further experiments are required to obtain a blueprint of drug in vivo performance, bioavailability and in vitro–in vivo correlation.

Bacterial cellulose-zinc oxide nanocomposites as a novel dressing system for burn wounds

Bacterial cellulose possesses physical and mechanical properties of an ideal wound dressing material but lack of antimicrobial activity limits its biomedical applications. Therefore, in current study, the inherent wound healing characteristics of bacterial cellulose and antimicrobial properties of zinc oxide nanoparticles were combined. The reinforcement (impregnation) of zinc oxide nanoparticles into bacterial cellulose sheets was confirmed through various characterization techniques. The antimicrobial capacity of bacterial cellulose-zinc oxide nanocomposites was tested against common burn pathogens. The in-vivo wound healing and tissue regeneration of the nanocomposites was investigated in burn BALBc mice model. Characterization techniques confirmed the successful impregnation of nanoparticles into bacterial cellulose. Bacterial cellulose-zinc oxide nanocomposites exhibited 90%, 87.4%, 94.3% and 90.9% activity against Escherichia coli, Pseudomonas aeruginosa, Staphylococcus aureus and Citrobacter freundii, respectively. Bacterial cellulose-zinc oxide nanocomposites treated animals showed significant (66%) healing activity. The histological analysis revealed fine tissue regeneration in composites treated group. These findings suggest that bacterial cellulose-zinc oxide nanocomposites could be a novel dressing material for burns.

Effects of glucuronic acid oligomers on the production, structure and properties of bacterial cellulose.

The addition of certain supplementary carbon sources to the culture media can influence the production, structural features and mechanical properties of bacterial cellulose (BC). In this study, different concentrations (0, 1, 2 and 4%) of a by-product, single sugar α-linked glucuronic acid-based oligosaccharide (SSGO), were added to the culture media during the production of BC. Production with 1% (BC1), 2% (BC2) and 4% (BC3) SSGO led to increases in BC production of 10.45, 12.74 and 9.01 g/L, respectively, after 10 days of cultivation under static conditions, while it was only 7.4 g/L when no SSGO was added (BC0). The structures of BC0, BC1, BC2, and BC3 were confirmed by XRD and FT-IR analysis. FE-SEM micrographs showed increased fibril thickness and decreased pore size in the SSGO added samples. The tensile strength of the BC0 was 16.73 MPa, while it was 25.05 MPa for BC1. However, with further increases in the concentration of SSGO, the tensile strength decreased to 20.76 and 19.77 MPa for BC2 and BC3, respectively. The results of this study provide further insight into the additive role of SSGO and improvement of the physico-mechanical properties of BC.

Effect of post-synthetic processing conditions on structural variations and applications of bacterial cellulose

Physicochemical properties of materials can be amended by altering their physical structure through different processing conditions. The present study was conducted to investigate the post-synthesis structural variations and physico-mechanical properties of bacterial cellulose (BC) sheets prepared using different drying methods. Wet BC sheets of the same origin were freeze dried (BC-FD), dried at room temperature (25 °C) (BC-DRT), and dried at elevated temperature (50 °C) (BC-DHT). FE-SEM micrographs revealed that BC-DRT and BC-DHT had a more tightly packed and compact structure than the loosely held fibrils of BC-FD. XRD analysis revealed the relative crystallinity of the BC sample to be 64.60, 59.16, and 47.20 % for BC-DHT, BC-DRT and BC-FD, respectively. The water holding capacity (WHC) of the BC-FD was higher than that of the other two samples. Four consecutive drying and rewetting cycles demonstrated that the WHC of all samples decreased with each cycle. The WHC of BC-DRT and BC-DHT was reduced to almost 0 after the first drying cycle, but the BC-FD samples were able to regain some of their WHC. The tensile strength and elongation modulus were in the order of BC-DHT > BC-DRT > BC-FD. Overall, the results of this study revealed that the post-synthetic processing conditions had a strong effect on the structure and physico-mechanical properties of BC.

MicroRNA and diseases: Therapeutic potential as new generation of drugs

MicroRNA (miRNA) is a small non-coding regulatory RNA of 21-25 nucleotides (nts) in length. miRNA works as a post-transcriptional regulator of a specific mRNA by inducing degradation or translation repression resulting in gene silencing. A large number of miRNA have been reported and many more are yet to be discovered. Aberrant expression of miRNA has been linked to numerous diseases. Attempts have been made to attenuate miRNA misregulation under pathophysiological conditions. Additionally, the potential use of miRNA in the diagnosis and treatment of diseases has been studied. Several preclinical and clinical results have been obtained, and miRNA-based therapeutics are still under investigations. In this review, the role of miRNA in a variety of pathological conditions has been summarized. Recent findings from preclinical and clinical investigations examining the role of miRNA as diagnostic markers, and their potential as drug candidates, are also highlighted. The current results summarized in this review may elucidate new dimensions of miRNA therapeutic and diagnostic techniques for biomedical academic and industry research.

Antihaemorrhagic potentials of Fagonia cretica against Naja naja karachiensis (black Pakistan cobra) venom

Plants have been extensively used as a remedy for the treatment of snake bites. The aim of this study was to determine the antivenom potentials of methanolic extract from the aerial parts (leaves and twigs) of Fagonia cretica L. on a haemorrhage induced by venom from Naja naja karachiensis. The haemorrhagic response of venom was dose dependent from 0.1 to 4.0 µg per 1.5 µL phosphate buffer saline (PBS) on vitelline veins of fertilised hens’ eggs in their shells. The extract effectively eliminated and neutralised, in a dose-dependent manner, the haemorrhagic activity of snake venom. The minimum effective neutralising dose of F. cretica extract was found to be 15 µg per 1.5 µL PBS. The extract possesses potentials as haemorrhagic inhibitor against snake venom compared to the standard antiserum and various plants reported in the literature. This study also provides a scientific base for the use of F. cretica in traditional medicine for the treatment of snake bite.

Evaluation of sediments of the waste from beer fermentation broth for bioethanol production

As our previous studies showed, the waste from beer fermentation broth (WBFB) is a potential resource for bio-ethanol production. The original WBFB was superior to the supernatant in this regard. The current study investigates the potential of the WBFB sediment alone for bio-ethanol production after it has been diluted with distilled water or a chemically-defined medium. The effect of stock time on WBFB sediments for ethanol production was also studied. The fermentations were carried out using 50 ml vials placed in a bioreactor in static conditions. There was relatively little increase in ethanol production with fermentation time (up to 2 h) and stock time (up to 7 days) using 20% (v/v) sediment in distilled water which did not contain any nutrients or enzymes. A 2.09% increase in ethanol production was recorded after 2 h fermentation with 20% (v/v) WBFB sediments (1 day old) in a chemically-defined medium. The increase was 3.25% for WBFB sediments with a stock time of three days in a chemically-defined medium. The results also showed some residual activity of starch hydrolyzing enzymes in the sediments, especially at 60 °C. The overall results of this study revealed that the sediments alone were capable of bio-ethanol production even though they were five-fold diluted with distilled water or the chemically-defined medium.