Anand Lodha

Ultrasensitive and specific detection of dimethoate using a p-sulphonato-calix[4]resorcinarene functionalized silver nanoprobe in aqueous solution

We demonstrate a facile strategy for preparing highly stable silver nanoprobe modified p-sulphonato-calix[4]resorcinarene in aqueous media. We also report the efficient and selective sensing properties of the novel assembly for organophosphorus insecticides and its great potential for application to real-time in situ detection of organophosphorus pesticides in waste water.

Fluorescence switch on-off-on receptor constructed of quinoline allied calix[4]arene for selective recognition of Cu2+ from blood serum and F- from industrial waste water.

A novel PET with ICT based substituted calix[4]arene fluroionophore was synthesized and used for detection of Cu(2+) and F(-) by emission spectra. The detection limit of the synthesized receptor was found to be 4.16 nM for Cu(2+) and 2.15 nM for F(-). Moreover, this probe has been applied for recognition of Cu(2+) in blood serum and F(-) from waste water.

A smart and rapid colorimetric method for the detection of codeine sulphate, using unmodified gold nanoprobe

Driven by the need to detect narcotics, we designed a “smart” system for the rapid detection and quantification of codeine sulphate levels using a smartphone, which allows simple, portable, on-spot, rapid and ultrasensitive nanoaggregation colorimetric detection (a lower detection limit of 0.9 μM) using the unique properties of citrate-stabilized gold nanoparticles (AuNPs) as a probe.

Melamine modified gold nanoprobe for “on-spot” colorimetric recognition of clonazepam from biological specimens

Inexpensive, rapid, and reliable methods of detection are crucial to the control of toxicological investigations. Here we report a highly sensitive, selective and cost effective method for the detection of trace amounts of clonazepam based on gold nanoparticles (AuNPs) in the presence of melamine. Hydrogen bonding interactions between clonazepam and melamine resulted in the aggregation of AuNPs and a consequent color change of AuNPs from wine red to blue. The results showed that the absorption ratio (A636/A552) was linear for clonazepam concentrations in the range of 10 × 10(-8) to 1.0 × 10(-9) M (R(2) = 0.999). The detection limit was 8.9 × 10(-10) M (S/N = 3), which was much lower than that of most existing methods. Coexisting substances including alprazolam, diazepam, nitrazepam and lorazepam did not affect the determination of clonazepam. The sensor developed by this new approach could be used as a spot test and a good alternative means for on-site and real time screening of clonazepam. This proposed scheme was also supported by the use of real samples such as skeletal remains and blood to illustrate the applicability of the developed nanosensor by a series of experiments.

Lab-on-phone citrate-capped silver nanosensor for lidocaine hydrochloride detection from a biological matrix

In the present investigation, we applied the application potential of nanomaterials and smartphone analysis to develop a specific, sensitive and portable method. In this study, we report a silver nanoparticles-based colorimetric nanosensor for the determination of lidocaine hydrochloride (LHC) up to 0.05 ng mL−1 with good linear correlation in the range from 0.1 to 4.5 ng mL−1 with a correlation coefficient of 0.9914. Coexisting substances, including acetaminophen, diazepam, nitrazepam, lorazepam, zolpidem, atropine, bupivacaine, clonazepam and morphine did not interfere in the determination of LHC. The developed sensor proved to be a smart alternative lab-on-phone device, which would help in the on-the-spot determination of LHC in forensic toxicological drug screening. Herein, we utilized easily accessible vitreous humor, which is often unnoticed for toxicological drug screening along with blood for real sample analysis.

Smart platform for the time since death determination from vitreous humor cystine

In this work, we report the smart application of AgNPs based sensors for determination of time since death (TSD) via recognition and quantification of vitreous humor (VH) cystine as well as provide the portability for on spot determination of TSD. The lower detection limit was found to be 7.0ng/ml with prominent selectivity. It was found that there is a linear correlation between the VH cystine concentration and TSD as the concentration of cystine increases up to 96h±3.9h. Further for the first time TSD determination is given a smart approach and it proves to have a great utility up to 24h±2.6h. The linear regression equation between TSD (the dependent variable), RGB intensity of cystine concentration till 24h (the independent variable) was found to be TSD=26.69+-0.05*x. The proposed method gives the smart detection, portability, rapidity, sensitivity, selectivity as well as cost effectiveness for determination of time since death.

Novel approach to determine post-mortem interval from ATPase activity

A recurring problem in forensic medicine is the need to fix the time of death within the limits of probability. Errors in overestimating and underestimating the post-mortem interval based on body cooling is common. Post-mortem biochemistry has become a potent additional procedure in forensic death investigation. However, in our experiment, to determine the post-mortem interval we investigated the ATPase activity. The investigation was performed on the liver tissue of 25 corpses (21 men and four women) of age ranging between 40–60 years. The study of ATPase enzymatic activity shows that there is a considerable drop in the levels of ATPase activity with increasing post-mortem interval up to 24 h and this is one of the most reliable methods for estimating time of death.

A pyrenyl linked calix[4]arene fluorescence probe for recognition of ferric and phosphate ions

A pyrenyl linked calix[4]arene fluroionophore has been synthesized and used as a ditopic chemosensing ensemble for Fe3+ and H2PO4− using emission spectra. The detection limit of the synthesized receptor was found to be 0.88 pM for Fe3+ and 1.11 pM for H2PO4−. Moreover, this probe has been applied for recognition of Fe3+ in blood serum and H2PO4− in waste water.

Host-guest mediated sensing of biologically relevant small molecules using supramolecular nanoassembly

Background A high concern for human health and safety has motivated dynamic research on the potential impact of transition metal ions or molecule and their toxic effects. Thus, selective detection of biologically relevant molecule have enormously gained its attention due to involvement in a variety of fundamental environmental and biological process in organism because its deficiency and excess can induce a variety of diseases. Therefore, biomolecule detection have received a great deal of study. Here, we have designed an efficient strategy using supramolecular nanoassembly to detect biologically relevant small molecules with high specificity and selectivity and applicable to the biological milieus.

A real-time smartphone-enabled time since death estimation from vitreous humour protein

Abstract This study reports on a smartphone-based application for the determination of time since death (TSD) from vitreous humour (VH) protein via recognition and quantification using a simple biuret method for on-the-spot analysis. In basic pH, in the presence of protein, the biuret reagent forms a protein-biuret complex resulting in a colour change that is measurable using a UV-vis spectrophotometer. The limit of detection (LOD) for Bovine serum albumin (BSA) was found to be 8 μg/ml and the limit of quantification (LOQ) was found to be 10 μg/ml. The developed method was further validated and applied for TSD determination from VH samples in the range of 3–60 h. The results showed that there is a linear correlation between the VH protein concentration and TSD, as the protein concentration decreases up to 60 h, with the equation TSD = 33.72 + (–0.27) × concentration. Further, in the present study smart approach was applied for the TSD determination. The results obtained showed that the current method proves to have a great utility up to 60 h. The linear regression equation between TSD and RGB (red, green and blue) intensities of protein concentration tup to 60 h ± 4.5 h was found to be TSD = 6.27E2+1.41*RGB intensity. The proposed method provides a smart, rapid and sensitive, as well as cost effective, TSD determination via VH protein.