Dielectric properties and in vitro hemocompatibility of Nd:YAG laser-irradiated polyethylene terephthalate

Surface properties and morphology of the biomaterial play an essential role in the polymer-material interaction. In this work, laser surface modification of polyethylene terephthalate as a polymer with distinguished mechanical properties was carried out using (neodymium-doped yttrium aluminum garnet) Nd:YAG laser (1.064 µm) with different output power (0.3, 3, and 6 W). The structural, surface, and dielectric properties of PET before and after laser irradiation have been studied using attenuation total reflection-Fourier transform infrared (ATR-FTIR), dielectric spectroscopy (DS), scanning electron microscope (SEM), and contact angle measurements. Moreover, the anticoagulant properties of the laser-irradiated PET was determined through measuring the prothrombin time (PT), partial thromboplastin time (PTT), and international normalized ratio (INR). In vitro platelet adhesion test was used to assess the platelets adhered to the surface of the samples; in addition to hematological study. It was found that contact angle (θ) measurements of laser-irradiated PET samples decreased compared to the unirradiated PET. The irradiated samples at 0.3 W have the lowest contact angle which is a clear indication that surface treatment with Nd:YAG laser brought about improving the wettability of the polymer. From the dielectric measurements, both values of permittivity and dielectric loss decrease by increasing the laser power. The electrical conductivity decreases with increasing laser power, but still in the same order 10-14 S/cm. The decrease in electrical conductivity σ may be due to the cross-linking of the polymeric matrix which led to a decrease in the total polarity and consequently decrease in electrical conductivity. The magnitude of σ obtained is highly recommended to be used for insulator purposes in addition to the main purpose that is blood contact.

Sodium alginate nanoparticles as a new transdermal vehicle of glucosamine sulfate for treatment of osteoarthritis

Glucosamine sulfate (GS) has been used orally for the treatment of osteoarthritis (OA). However, it may be susceptible to the liver first pass phenomenon, which greatly affects its bioavailability, in addition to its side effects on the gastrointestinal tract. Alginate nanoparticles (Alg NPs) were investigated as a new drug carrier for transdermal delivery of GS to improve its effectiveness and reduce side effects. GS-Alg NPs were characterized by encapsulation efficiency, NP yield, particle size and surface charge properties. The in vitro release studies of GS and the ex vivo permeability through rat skin were determined using a UV-Vis spectrophotometer. GS-Alg NPs are within the nanometer range of size. High negative surface charge values are obtained and indicate the high suspension stability of the prepared formulation. The in vitro release studies showed that GS is released from Alg NPs in a sustained and prolonged manner. The ex vivo permeability of GS through rat skin is enhanced significantly after encapsulation in the negatively charged Alg NPs. We successfully reported a highly stable nanoparticlulate system using Alg NPs that permits the encapsulation of GS for topical administration, overcoming the disadvantages of oral administration.

Evaluation of zinc level in skin of patients with necrolytic acral erythema

BACKGROUND

Necrolytic acral erythema (NAE) is considered a cutaneous sign of hepatitis C virus infection. Its exact pathogenesis is still not fully understood, with some reports about decreased serum zinc levels but none about its level in the skin.

OBJECTIVES

To assess skin (lesional and perilesional) and serum zinc levels in patients with NAE and compare them with levels in control subjects.

METHODS

Fifteen patients with NAE and 10 healthy controls were included in this study. Assessment of zinc level, in serum by graphite furnace atomic absorption spectrophotometry and in lesional and perilesional skin biopsies by flame atomic absorption spectrometry, was done in all subjects. Re-evaluation of serum and lesional skin zinc level was done after oral zinc treatment.

RESULTS

Mean±SD zinc levels were significantly lower in patients (serum 0·44 ± 0·13 mg L(-1) ; lesional skin 42·6 ± 18·9 mg L(-1) ; perilesional skin 32·5 ± 17·2 mg L(-1) ) than controls (serum 1·17 ± 0·29 mg L(-1) ; skin 100·1 ± 2·77 mg L(-1) ), with a positive correlation between lesional and perilesional skin zinc (r = 0·91, P < 0·01). Oral zinc supplementation significantly increased serum and skin zinc levels (by 159% and 4%, respectively; P < 0·05).

CONCLUSIONS

NAE is associated with decreased serum and skin zinc levels. Oral zinc supplementation corrects decreased levels of plasma and skin zinc much earlier than the desired clinical benefits appear.

Biophysical studies on chitosan-coated liposomes

Liposomes have been used as delivery vehicles for stabilizing drugs, overcoming barriers to cellular and tissue uptake, and for directing their contents toward specific sites in vivo. Chitosan is a biological macromolecule derived from crustacean shells and has several emerging applications in drug development, obesity control, and tissue engineering. In the present work, the interaction between chitosan and dipalmitoyl phosphatidylcholine (DPPC) liposomes was studied by transmission electron microscopy (TEM), zeta potential, solubilization using the nonionic detergent octylglucoside (OG), as well as Fourier transform infrared (FTIR) spectroscopy and viscosity measurements. The coating of DPPC liposomes by a chitosan layer was confirmed by electron microscope images and the zeta potential of liposomes. Coating of liposome by chitosan resulted in an increase in liposomal size by addition of a layer of 92 +/- 27.1 nm. The liposomal zeta potential became increasingly positive as chitosan concentration increased from 0.1 to 0.3% w/v, then it held at a relatively constant value. The amount of detergent needed to completely solubilize the liposomal membrane was increased after coating of liposomes with chitosan, indicating an increased membrane resistance to the detergent and hence a change in the natural membrane permeation properties. In the analysis of FTIR spectra of DPPC, the symmetric and antisymmetric CH(2) (at 2,800-3,000 cm(-1)) bands and the C=O (at 1,740 cm(-1)) stretching band were investigated in the absence and presence of the chitosan. It was concluded that appropriate combining of the liposomal and chitosan characteristics might be utilized for the improvement of the therapeutic efficacy of liposomes as a drug delivery system.