Biocompatible polyvinyl alcohol and RISUG® blend polymeric films with spermicidal potential.

Majority of the commercially available vaginal contraceptives encompasses cervicovaginal membrane disrupting detergent molecules as pharmacologically active ingredients. Development of a tissue-compatible vaginal contraceptive agent is necessary to circumvent the existing demand for female contraception in the reproductive healthcare sector. With this objective, the present study delineates the use of RISUG® based non-hormonal female contraceptive films. RISUG® was blended with polyvinyl alcohol (PVOH) to formulate biodegradable intra-vaginal contraceptive films. The formulated films were characterized for their thermal, physiochemical and biological features. The results showed that both RISUG® and PVOH were miscible and interacted at the intermolecular level. Variations in the concentration of RISUG® resulted in the changes in physicochemical, thermal and rheological characteristics of the formulated blends. In vitro toxicological assay of the polymeric formulations did not show any significant toxicity. However, the blend films retained spermicidal potential of RISUG®. Furthermore, in vivo toxicological evaluation of the polymeric blend in the rat model revealed about their biocompatibility with no significant organ toxicity, hematological and biochemical alterations. These results together confirm the potential applicability of the PVOH:RISUG® blend films as a vaginal contraceptive.

Blue fluorescence as a frequency offset reference in the rubidium 5S-5P-5D transition.

In this work, we address the issue of the suitability of blue fluorescent light as a frequency offset reference during the ladder-level excitation 5S1/2→5P3/2→5D3/2 of Rb85 atoms. A simple pump-probe spectroscopy experiment is performed to generate non-degenerate blue light emission produced by the spontaneous decay route 5D3/2→6P3/2→5S1/2. By varying the relative intensity of the pump-probe combination, we can hover between regimes dominated by mechanisms such as double resonance optical pumping (DROP) and Autler-Townes splitting. The efficacy of the blue fluorescence (420 nm) as a frequency offset reference is pronounced under the DROP regime due to its narrow (∼natural) linewidth. To provide further insight into the stability performance, the pump laser connecting the 5P3/2→5D3/2 transition is stabilized to the peak of the blue light with the help of a probe stabilized to the saturation absorption signal of the 5S1/2→5P3/2 transition. For this purpose, we used the coherence-induced modulation transfer technique. The error frequency noise power spectra and the subsequent Allan variance calculation clearly show that probe fluctuations are transferred to the pump laser because of an existing two-photon coherent coupling.

Organic solvent-free low temperature method of preparation for self assembled amphiphilic poly(ϵ-caprolactone)-poly(ethylene glycol) block copolymer based nanocarriers for protein delivery.

Degradation and denaturation of labile biomolecules during preparation of micelles by organic solvent at high temperature are some of the limitations for fabrication of advanced polymer based protein delivery systems. In this paper, effectiveness of heat-chill method for preparation of micelles containing large labile biomolecules was investigated using insulin as a model protein molecule. Micelles (average size, <120 nm) were prepared using amphiphilic diblock and triblock copolymers of poly(ethylene glycol) (PEG) and poly(ϵ-caprolactone) (PCL). Micelles were prepared by heating PEG-PCL block copolymers with distilled water at 60 °C followed by sudden chilling in an ice-water bath. Effects of molecular architecture on morphology, stability and protein loading capacity of micelles were investigated. Micelles prepared using high molecular weight block copolymers exhibited good colloidal stability, encapsulation efficiency and insulin release characteristics. Insulin retained its secondary structure after micelles preparation as confirmed by CD spectroscopic study. Furthermore, in vitro cytotoxicity test suggested that the prepared micellar nanoparticles possessed biocompatibility. In a nut shell, heat-chill method of micellar nanoparticles preparation is well suited for encapsulating labile proteins and other allied biomolecules which degrade in presence of toxic organic solvents and at elevated temperatures.