Detection of picomolar concentrations of lead in water using albumin-based fluorescence sensor

Variation of Stokes Shift and Peak Wavelength Shift as a Sensing Probe for Detection of Lead in Water Using Laser Induced Fluorescence Resonance Energy Transfer

Water contamination through the dissolved toxic heavy metal ions is becoming a serious issue seeking the worldwide attention of the researchers. The tap water used for drinking is primarily exposed to the household plumbing system and may dissolve toxic lead metal through pipes, soldered joints and that may cause a number of diseases in children, adults and pregnant women. Thus detecting lead is getting utmost importance among the researchers. Present work explains a method of detecting trace concentration of lead in water using laser induced fluorescence resonance energy transfer (LIFRET). The fluorescence resonance energy transfer (FRET) is observed between 1, 8- naphthalimide as donor and rhodamine-B as an acceptor by exciting it with a laser radiation of 405 nm. With the addition of the lead contained water in pure solution of the FRET pair the emission peak wavelength shifts from 630.27 nm of its value for pure solution. The amount of stoke shift decreases with increase in lead concentration with a gradual increase in intensity of the fluorescence spectra. Based on variation of stoke shift and peak wavelength shift of FRET spectra a novel and specific method is described for the detection of lead up to its maximum permissible limit of 0.00001 g l-1 set by the world health organization(WHO). The method described is relatively cost effective, handy and may have reasonably effective in situ measurement for detecting lead in the contaminated areas.

Pb2+binding to lentil lectin and its influence on the protein aggregation

The Pb²⁺binds through the side chain carboxylate and imidazole moieties of the lentil lectin by bringing somesecondarystructural changes. As a result of this the original aggregates of the simple protein disaggregates upon binding to Pb²⁺.

Raman spectroscopy provides a powerful diagnostic tool for accurate determination of albumin glycation

We present the first demonstration of glycated albumin detection and quantification using Raman spectroscopy without the addition of reagents. Glycated albumin is an important marker for monitoring the long-term glycemic history of diabetics, especially as its concentrations, in contrast to glycated hemoglobin levels, are unaffected by changes in erythrocyte life times. Clinically, glycated albumin concentrations show a strong correlation with the development of serious diabetes complications including nephropathy and retinopathy. In this article, we propose and evaluate the efficacy of Raman spectroscopy for determination of this important analyte. By utilizing the pre-concentration obtained through drop-coating deposition, we show that glycation of albumin leads to subtle, but consistent, changes in vibrational features, which with the help of multivariate classification techniques can be used to discriminate glycated albumin from the unglycated variant with 100% accuracy. Moreover, we demonstrate that the calibration model developed on the glycated albumin spectral dataset shows high predictive power, even at substantially lower concentrations than those typically encountered in clinical practice. In fact, the limit of detection for glycated albumin measurements is calculated to be approximately four times lower than its minimum physiological concentration. Importantly, in relation to the existing detection methods for glycated albumin, the proposed method is also completely reagent-free, requires barely any sample preparation and has the potential for simultaneous determination of glycated hemoglobin levels as well. Given these key advantages, we believe that the proposed approach can provide a uniquely powerful tool for quantification of glycation status of proteins in biopharmaceutical development as well as for glycemic marker determination in routine clinical diagnostics in the future.

Structural changes of human serum albumin in response to a low concentration of heavy ions

Lead ions in solution interact strongly with human serum albumin and modify the properties and function of albumin molecules. In the present study, we used optical spectroscopic techniques to explore the binding sites of lead, present in albumin. Structural and chemical analysis of albumin molecules using fluorescence and Raman spectroscopy, predicted the modification of two major amino acids in albumin due to lead binding. No secondary structural changes are observed in the protein molecule, which is further confirmed using circular dichroism absorption measurements. The results indicate that loss of charge from the binding site of albumin by the charged lead ions, give rise to dipole interaction which acts as the major contributor to promote protein agglomeration.