Amoxicillin-loaded bionanocomposite hydrogels: swelling, dehydration, and in vitro drug release kinetics and mechanism.

This study deals with preparing and characterizing polyvinyl alcohol/egg white/montmorillonite bionanocomposite hydrogels as antibacterial drug delivery systems. The cyclic freezing/thawing method was utilized to fabricate the hydrogels. To study the performance of the prepared hydrogels as drug delivery systems, amoxicillin, as a model antibiotic drug, was loaded into the hydrogels by mixing with the precursor polymer solution and gelation. From the diverse microstructural characterization techniques, i.e. XRD, SEM, AFM, DLS, and gel fraction estimation, it was possible to infer that montmorillonite has been successfully incorporated into the hydrogel network and acted as an additional crosslinker to bind the chains of egg white and polyvinyl alcohol. Scrutinizing the physical properties of the produced hydrogels demonstrated that increasing incorporated montmorillonite content adversely affects the prepared hydrogels' swelling ability and prolongs their dehydration period. Additionally, the Swelling characteristics of the hydrogels were evaluated at different pHs. Results showed an increase in the swelling ability of all samples by raising the pH value of the medium. Additionally, it was proved that both swelling and dehydration of the hydrogels follow non-Fickian diffusion. In vitro drug delivery experiments demonstrated that the cumulative fractional release of amoxicillin was adversely dependent on the amount of incorporated montmorillonite into the hydrogels and positively dependent on the pH of the release solution. It was also found that, in all examined samples, the mechanism by which the release of clindamycin happens is non-Fickian or anomalous transport.

Clindamycin releasing bionanocomposite hydrogels as potential wound dressings for the treatment of infected wounds.

The bionanocomposite hydrogels based on polyvinyl alcohol and egg white (as the matrix) and montmorillonite nanoclay (as reinforcement) were fabricated via the freezing-thawing technique. The prepared bionanocomposite hydrogels were loaded with clindamycin, as an effective antibiotic, to attain new potential wound dressings for healing the infected wounds. The microstructural properties of the bionanocomposite hydrogel wound dressings were characterized using the X-ray diffractometry, transmission electron microscopy, atomic force microscopy and gel fraction measurement. It was shown that all of the bionanocomposite hydrogel wound dressings had an exfoliated morphology and the montmorillonite layers acted as additional crosslinking zones to interconnect the polyvinyl alcohol and egg white chains. The characteristics of the prepared wound dressings were investigated using different experiments, including the water content, drying, water vapor transmission rate (WVTR), transparency and in vitro drug release tests. It was found that the equilibrium water content and WVTR were tended to decrease by increasing the loading level of montmorillonite in samples. The results showed that the drying period of bionanocomposite hydrogel wound dressings was prolonged by increasing the content of the incorporated montmorillonite. In vitro drug delivery experiments showed the cumulative fractional release of clindamycin and the clindamycin diffusion coefficient were decreased either by increasing the weight percentage of the incorporated montmorillonite into the wound dressings or by decreasing the pH of the release medium. It was also shown that the mechanism governing the release of clindamycin in all examined samples was the non-Fickian (anomalous) transport.

Capecitabine-loaded anti-cancer nanocomposite hydrogel drug delivery systems: in vitro and in vivo efficacy against the 4T1 murine breast cancer cells.

In this work, nanocomposite hydrogel drug delivery systems based on polyvinyl alcohol and montmorillonite loaded with the capecitabine, as an anti-cancer drug, were developed for oral administration. The gel fraction and swelling ability of the prepared nanocomposite hydrogels were experimentally measured. In vitro release kinetics of capecitabine in nanocomposite hydrogel drug delivery systems were studied. In vitro flow cytometry assay was utilized to exhibit the anti-cancer activity of the prepared nanocomposite hydrogel drug delivery systems against 4T1 cancer cell line. The anti-tumor efficacy of the nanocomposite hydrogel drug delivery systems was also studied in vivo on animal models. The results showed that the amount of montmorillonite incorporated into the nanocomposite hydrogel drug delivery systems could be recognized as a key parameter to adjust the values of the gel fraction, swelling and capecitabine release rate in a manner which by increasing the montmorillonite content, the gel fraction is increased while the swelling and drug release rate are decreased. The flow cytometry results demonstrated the better anti-cancer activity of the capecitabine-loaded nanocomposite hydrogel drug delivery systems as compared with the pure capecitabine. The in vivo assays indicated that the administration of nanocomposite hydrogel drug delivery systems had a significant effect on the reduction of the tumor growth in animal models as compared with pure capecitabine administration. In general, the prepared nanocomposite hydrogel drug delivery systems exhibited a suitable efficacy against 4T1 cancer cell line both in vitro and in vivo and they could be considered as promising candidates for controlled release of anti-cancer drugs in chemotherapy with enhanced therapeutic effects.

In vitro and in vivo assays on egg white/polyvinyl alcohol/clay nanocomposite hydrogel wound dressings.

Novel nanocomposite hydrogel wound dressings on the basis of egg white and polyvinyl alcohol, as matrix, and natural Na-montmorillonite clay, as reinforcing agent, were prepared and their performances on wound healing investigated in vitro and in vivo. In vitro cytotoxicity assay revealed non-cytotoxic activity and excellent biocompatibility level of prepared nanocomposite hydrogel wound dressings. The bacterial penetration assay showed the prepared nanocomposite hydrogel wound dressings are excellent barriers against microorganisms and could protect the wound from infection during the wound healing. In vivo animal study showed that the wound healing process was considerably faster in wounds covered with nanocomposite hydrogel wound dressings compared to the conventional wound dressing, i.e. sterile gauze, due to creation of a moist environment on the wound surface and faster migration rate of the epidermal cells. The mechanical properties of healed wounds with nanocomposite hydrogel wound dressings were better than those control wounds covered with sterile gauze due to their better collagen formation ability as a result of created moist healing condition as well as the presence of egg white, as a source of proteins, in their structures.

Egg white/poly (vinyl alcohol)/MMT nanocomposite hydrogels for wound dressing.

Nanocomposite hydrogels on the basis of egg white and poly (vinyl alcohol) (PVA) containing 0, 5, and 10 wt.% of montmorillonite (MMT) nanoclay were prepared by a facile cyclic freezing-thawing technique and their properties investigated for wound dressing application. The morphological, structural, thermal, physical, and in vitro cytotoxic properties of the prepared nanocomposite hydrogel wound dressings (NHWDs) were experimentally studied. The NHWDs had an exfoliated morphology with a porous structure having pores sizes in the nanometric scale. It was shown that MMT acted as cross-linker in the network of NHWDs and improved their thermal stabilities. The prepared wound dressings were transparent and their equilibrium water contents and water vapor transmission rates, as two important factors of wound dressings, were very close to the properties of human skin which means that the prepared wound dressings could interact appropriately with the damaged tissues of wounds and protect them like an artificial skin during the wound healing process. The in vitro cytotoxicity assay also confirmed the non-cytotoxic nature of the prepared NHWDs. It was finally concluded that the prepared egg white/PVA/MMT nanocomposite hydrogels are promising materials to be used as novel wound dressings in wound and burn care.

Effect of Polyvinyl Alcohol (PVA) Containing Artemether in Treatment of Cutaneous Leishmaniasis Caused by Leishmania major in BALB/c Mice.

BACKGROUND: Polyvinyl alcohol (PVA) is one of the well-known polymers, which has been used in numerous biomedical applications because of its good biocompatibility. OBJECTIVES: Due to problems made by the therapeutics already used for leishmaniasis, the aim of this study was to evaluate the effect of PVA containing artemether in treating cutaneous leishmaniasis in BALB/c mice. MATERIALS AND METHODS: Aqueous solution of PVA was prepared by mixing with Double Distilled Water. After preparation of PVA, 4.33 mg of each drug (main drug artemether and control drug 14% glucantime) was added to 100 g of prepared PVA-honey solution. The solution was incubated at 37°C and the release of artemether was evaluated by measuring absorbance at 260 nm wave length. In this study for treatment of mice lesion, we used PVA containing artemether and glucantime and this method was compared with ointment treatment. RESULTS: Mean diameters of lesions in mice treated with artemether were smaller than the control group and the differences were significant (P < 0.05). The mean lesion size of mice treated with PVA containing artemether in comparison with the group treated with ointment of artemether were smaller and the differences were significant (P < 0.05). CONCLUSIONS: PVA containing artemether is a new method for treatment of cutaneous leishmaniasis and according to the obtained results, artemether is an appropriate and effective drug, especially when used with PVA as a lesion dressing; thus we suggest that this method can be applied for the treatment of cutaneous leishmaniasis.

In vivo and cytotoxic assays of a poly(vinyl alcohol)/clay nanocomposite hydrogel wound dressing.

In the present work, a nanocomposite hydrogel wound dressing was prepared on the basis of poly(vinyl alcohol) using organically-modified montmorillonite as nanoclay by the freezing-thawing cyclic method. In vivo assays were performed to evaluate its performance as an applicable wound dressing on animals. It showed an improved healing process for wounds covered by the prepared nanocomposite hydrogel compared with control wounds covered by sterile gauze. Significant improvements, such as better creation of moist surfaces on the wound with less scar formation, shorter duration of healing operation and better closing of the wound edges with enhanced tensile properties of the healed wound, i.e., tensile strength and elongation-at-break, were observed using the prepared nanocomposite hydrogel in comparison to the sterile gauze. An in vitro cytotoxic assay was also utilized to determine the biocompatibility of the prepared nanocomposite hydrogel. It showed that the prepared nanocomposite hydrogel is non-toxic and can be used as a biocompatible wound dressing in practical wound management.