Advances on fluorescence chemosensors for selective detection of water.

Water, although an important part of everyday life, is acts as one of the most significant contaminants in various applications such as biomedical monitoring, chemical production, petroleum-based fuel and food processing. In fact, the presence of water in other solvents is a huge concern. For the quantification of trace water content, different methods such as Karl-Fischer, electrochemical, nuclear magnetic resonance, chromatography, and thermogravimetric analysis have been used. Although every technique has its own benefit, each one suffers from several drawbacks that include high detection costs, lengthy procedures and specialized operations. Nowadays, the development of fluorescence-based chemical probes has become an exciting area of research for the quick and accurate estimation of water content in organic solvents. A variety of chemical processes such as hydrolysis reaction, metal ions promoted oxidation reaction, suppression of the -C═N isomerization, protonation and deprotonation reactions, and molecular aggregation have been well researched in the last few years for the fluorescent detection of trace water. These chemical processes eventually lead to different photophysical events such as aggregation-induced emission (AIE), aggregation-induced emission enhancement (AIEE), aggregation-caused quenching (ACQ), fluorescent resonance energy transfer (FRET), charge transfer, photo-induced electron transfer (PET), excited state intramolecular proton transfer (ESIPT) that are responsible for the detection. This review presents a summary of the fluorescence-based chemosensors reported in recent years. The design of water sensors, sensing mechanisms and their potential applications are reviewed and discussed.

Effect of cholesterol supplementation on cryosurvival of goat spermatozoa.

AIM: Sperm membrane cholesterol influences cryodamage during cryopreservation. The present study was carried out to evaluate the effect of varying cholesterol levels in Tris based extenders on the freezability of sexually healthy Malabari buck semen. MATERIALS AND METHODS: A total of 48 ejaculates from two adults healthy sexually healthy Malabari bucks were utilized for the study. The collected and pooled ejaculates were divided into four groups with Group I serving as Control - I, Group II and III were treated with 1 mg and 2 mg of cholesterol-loaded-cyclodextrin (CLC)/120 × 10(6) spermatozoa, respectively, and Group IV, treated with 1 mg methyl-ß-cyclodextrin (MßCD) served as Control - II. Manual freezing was carried out to cryopreserve the treated and control spermatozoa. RESULTS: Treatment of semen samples with CLC resulted in improved maintenance of sperm motility at pre-freeze and post-thaw stages of cryopreservation without affecting hypo-osmotic swelling response. Treatment of semen with 1 mg of CLC/120 × 10(6) spermatozoa was observed to be better than treatment with 2 mg of CLC/120 × 10(6) spermatozoa. In general, MßCD treatment was found to result in significantly lower sperm characteristics than those of Control - I and CLC treatment at pre-feeze and post-thaw stages and when incubated up to 4 h. CONCLUSION: Cholesterol treatment of sexually healthy Malabari buck semen was found to hold promise for improving cryopreservability of spermatozoa.