| || Carbon Nanotubes: Detection of Chemical and Biological Warfare Agents
Author : Om Kumar;Singh, Yamini;Rao, V.K.;Vijayaraghavan, R.
Source : Defence Science Journal ; Vol:58(5) ; 2008 ; pp 617-625
Keywords : CNTs;SWCNT;MWCNT;Arc discharge;Laser ablation;Chemical vapour deposition;Functionalisation;Chemical warfare agents;DNA;Protein and antibodies
Abstract : Discovery of carbon nanotubes has great impact on the development of newer methodologies and devices useful for the analysis of various types of chemicals. The functionalisation of CNTs with biomolecules related to chemical and biological warfare agents makes these useful for the detection of these agents. The detection sensitivity can be increased manyfold. Various types of chemical and biological sensors were developed using various type of carbon nanotubes as well as nano particles of different metals.
| || Detection of Ricin in Water Samples using Disposable Screen-Printed Electrodes
Author : Suresh, S.;Om Kumar;Kolhe, Pawan;Rao, V. Kameswara;Sekhar, K.
Source : Defence Science Journal ; Vol:57(6) ; 2007 ; pp 839-844
Subject : 60 Biotechnology;61 Medical Sciences
Keywords : Screen-printed electrode;Amperometric immunosensor;Ricin;Ppotentiostat;Plant toxin;ELISA
Abstract : Ricin is a highly toxic plant toxin, which is extracted from the beans of the castor plant, Ricinus communis. Ricin is thousand times more poisonous than cyanide and thirty times more potent than nerve gases. The toxin (ricin) could be used to contaminate food or water, causing panic. Attempts were made for the detection of ricin in water samples by utilising amperometric immunosensors. Single-use screen-printed electrodes were made using polystyrene and graphite. These electrodes were tested for their ability to detect 1-naphthol which is the product of the reaction between 1-naphthyl phosphate and the enzyme alkaline phosphatase conjugate. An indirect enzyme-linked immunosorbent assay (ELISA) system was used to detect ricin. First, ricin antigen was incubated on the screen-printed electrode. This was followed by blocking with BSA and incubation with antibody raised against ricin in rabbit. The last step wass the incubation with anti-antibody of rabbit conjugated to enzyme alkaline phosphatase. This electrode is inserted in an electrochemical cell containing diethanolamine buffer and a potential of 0.4 V wrt reference electrode (Ag/AgCl) was applied using a potentiostat. Various experiments were carried out for optimising the conditions like substrate concentration, amount of antibody raised against ricin, anti-antibody alkaline phosphatase conjugate, and blocking agents. It was found that the response of amperometric sensor is proportional to the logarithmic of ricin concentration from 100 ng/ml to 3200 ng/ml. Using traditional methods, it is possible to detect ricin concentration up to 300 ng/ml in 18 h, while with amperometric immunosensor, one can detect ricin as low as 40 ng/ml within 90 min. The details of making the screen-printed electrodes, characterisation, optimisation of various conditions for the highest sensitivity have been discussed.
| || Effect on Physiological Variables and Urinary Metabolites following a Single Dermal Application of Sulphur Mustard in Rats
Author : Om Kumar;Vijayaraghavan, R.
Source : Defence Science Journal ; Vol:47(3) ; 1997 ; pp 389-394
Subject : 577 Biochemistry;57 Biological Sciences
Keywords : Sulphur mustard ;Urinary excretions
Abstract : The effect of single dermal application of different doses of sulphur mustard (2,2'-dichlorodiethyl sulphide, SM), i.e.5, 10 and 20 mg/kg body weight on some physiological variables, viz., body weight, intake of food and water, and excretion of excreta and urine was studied for one week. Levels of urinary metabolites, uric acid, urea, protein, creatine and creatinine were measured at 0, 1, 2, and 7 days in albino rats of Wister strain. A progressive dose-dependent fall in body weight was observed from day onwards after SM application. Feed and water intake were reduced significantly. Excretion of urine and exdreta was also affected adversely. The level of uric acid, a metabolite of purine bases, increased 24 hr post-exposure, in a time and dose-dependent manner. Excretion of urea decreased and the level of creatine increased drastically on 7th day. However, urinary excretions of protein and creatinine did not change. The study shows that single application of SM in rats induces a catabolic state.