Magnetophoretic circuits for digital control of single particles and cells.

The ability to manipulate small fluid droplets, colloidal particles and single cells with the precision and parallelization of modern-day computer hardware has profound applications for biochemical detection, gene sequencing, chemical synthesis and highly parallel analysis of single cells. Drawing inspiration from general circuit theory and magnetic bubble technology, here we demonstrate a class of integrated circuits for executing sequential and parallel, timed operations on an ensemble of single particles and cells. The integrated circuits are constructed from lithographically defined, overlaid patterns of magnetic film and current lines. The magnetic patterns passively control particles similar to electrical conductors, diodes and capacitors. The current lines actively switch particles between different tracks similar to gated electrical transistors. When combined into arrays and driven by a rotating magnetic field clock, these integrated circuits have general multiplexing properties and enable the precise control of magnetizable objects.

An organic substrate based magnetoresistive sensor for rapid bacteria detection.

A point-of-care diagnostic system has been developed to detect pathogenic bacteria rapidly, of which system contains a magnetoresistive (MR) sensor in cooperation with a magnetic bead coated by specific antibody against bacteria. MR sensor with Teflon passivation layer has been fabricated on organic substrate, being flexible and low cost material, and passivated by Teflon layer for maintaining flexibility. The performance of the MR sensor is demonstrated using Magnetospirillum magneticum AMB-1 and its detection limit was found to be 1.3×10(8) cells/ml. Further, Escherichia coli is captured by immobilised anti-E. coli antibodies on the surface of the sensor and detected using magnetic bead labelled with anti-E. coli antibody. The detection limit of E. coli was found to be 1.2×10(3) cells/ml. The technique is simple, rapid, sensitive and does not require pre-treatment of the sample and can detect a variety of microorganisms. The high performance of sensor fabricated on flexible organic substrate may allow its future use for bio-applications in implantable types of devices.

Phytodegradation of the triphenylmethane dye Malachite Green mediated by cell suspension cultures of Blumea malcolmii Hook.

Cell cultures of Blumea malcolmii Hook., developed in the laboratory, rapidly decolorized textile industry effluent along with a variety of dyes with diverse structural properties. Most rapid decolorization was observed in case of Malachite Green (93.41% decolorization within 24 h). The cells were capable of tolerating and degrading high concentrations of the dye, thus making them remarkable systems for phytoremediation studies. The enzymatic analysis during decolorization of Malachite Green showed the induction of enzymes such as laccase, veratryl alcohol oxidase and DCIP reductase indicating the involvement of these enzymes in the degradation of the dye. The cell cultures also mediated the remediation of textile industry effluent by bringing about a decrease in the BOD, COD and ADMI values of the effluent within 48 h. Phytotransformation was confirmed with the help of HPLC and the probable fate of metabolism of the dye was predicted with the help of GCMS analysis.

Rhamnolipid from Pseudomonas desmolyticum NCIM-2112 and its role in the degradation of Brown 3REL.

The biosurfactant produced by Pseudomonas desmolyticum NCIM 2112 (Pd 2112) was confirmed as rhamnolipid based on the formation of dark blue halos around the colonies in CTAB-methylene blue agar plates and the content of rhamnose sugar. The average yield of rhamnolipid was 0.398 g/l/day when grown on hexadecane as sole carbon source. Pd 2112 emulsification potential associated with cell free culture broth was stable for 72 h using various hydrocarbons and vegetable oils. Chemical structure of the biosurfactant was identified as mono-rhamnolipid (Rha-C(6) -C(8) ) using HPTLC, fourier transform infrared spectroscopy, (1) H and (13) C NMR and gas chromatography-mass spectroscopy analysis. Pd 2112 mono-rhamnolipid (1 mg/ml) had increased permeabilization of Bacillus sp VUS NCIM 5342 and increased decolorization rate of textile dye Brown 3REL by 50%. Extracellular activities of lignin peroxidase and veratryl alcohol oxidase, enzymes involved in dye degradation, were significantly increased in the presence of mono-rhamnolipid by 324.52% and 100% respectively. Scanning electron micro-scopy observations revealed that rhamnolipid did not exert any disruptive action on Bacillus cells as compared to Tween 80. The mono-rhamnolipid of Pd 2112 has potential for its application in biodegradation of textile dyes.

Decolorization of the textile dyes using purified banana pulp polyphenol oxidase.

Polyphenol oxidase (PPO) purified using DEAE-cellulose and Biogel P-100 column chromatography from banana pulp showed 12.72-fold activity and 2.49% yield. The optimum temperature and pH were found to be 30 degrees C and 7.0, respectively for its activity. Catechol was found to be a suitable substrate for banana pulp PPO that showed V(max), 0.041 mM min(-1) and K(m), 1.6 mM. The enzyme activity was inhibited by sodium metabisulfite, citric acid, cysteine, and beta-mercaptoethanol at 10 mM concentration. The purified enzyme could decolorize (90%) Direct Red 5B (160 microg mL(-1)) dye within 48 h and Direct Blue GLL (400 microg mL(-1)) dye up to 85% within 90 h. The GC-MS analysis indicated the presence of 4-hydroxy-benzenesulfonic acid and Naphthalene-1,2,3,6-tetraol in the degradation products of Direct Red 5B, and 5-(4-Diazenyl-naphthalene-1-ylazo)-8-hydroxy-naphthalene-2-sulfonic acid and 2-(4-Diazenyl-naphthalene-1-ylazo)-benzenesulfonic acid in the degradation products of Direct Blue GLL.

Production of polyhydroxyhexadecanoic acid by using waste biomass of Sphingobacterium sp. ATM generated after degradation of textile dye Direct Red 5B.

The degradation of textile effluent using microorganisms has been studied extensively, but disposal of generated biomass after dye degradation is a serious problem. The isolated Sphingobacterium sp. ATM was found to decolorize dye Direct Red 5B (DR5B) and simultaneously it produced polyhydroxyhexadecanoic acid (PHD). The organism decolorized DR5B at 500mgl(-1) concentration within 24h of dye addition and gave optimum production of PHD. The medium contains carbon source as a molasses which was found to be more significant within all carbon sources used. The Nuclear Magnetic Resonance spectroscopy (NMR), Fourier Transform Infrared spectroscopy (FTIR) and Gas Chromatography-Mass Spectroscopy (GC-MS) characterization of polyhydroxyalkanoates obtained revealed the compound as a polyhydroxyhexadecanoic acid. The activity of PHA synthase was found more at 24h after dye addition. The enzymes responsible for dye degradation include veratrol oxidase, laccase, DCIP (2,6-dichlorophenol-indophenol) reductase, riboflavin reductase and azo reductase was found to be induced during decolorization process. The FTIR analysis of samples before and after decolorization of dye confirmed the biotransformation of DR5B. The GC-MS analysis of product obtained led to the identification of two metabolites after biotransformation of dye as p-amino benzenesulfonic acid and naphthalene-1-ol.