Nanocatalysis of silver-nanobioprobe based supersensitive electrochemical detection of Salmonella serotypes targeting virulence protein.

Herein, we report a supersensitive and specific detection of Salmonella employing nanocatalysis of silver nanoparticle (AgNp). A nanobioprobe was developed employing specific antibody (Ab) that binds to a peptide present in transmembrane protein of Salmonella. We have studied 7 surface-exposed peptide hits from conserved virulence proteins (PagC, ST50, PagN, CdtB and FliC).

A novel strategy to elicit enduring anti-morphine immunity and relief from addiction by targeting Acr1 protein nano vaccine through TLR-2 to dendritic cells.

Morphine addiction poses a significant challenge to global healthcare. Current opioid substitution therapies, such as buprenorphine, naloxone and methadone are effective but often lead to dependence. Thus, exploring alternative treatments for opioid addiction is crucial.

Bifunctionalized nanobioprobe based rapid color-shift assay for typhoid targeting Vi capsular polysaccharide.

Typhoid fever is an acute illness caused by Salmonella Typhi and the current diagnostic gap leads to inaccurate, over-diagnosis of typhoid leading to excessive use of antibiotics. Herein, to address the challenges we describe a new rapid color-shift assay based on a novel bifunctional nanobioprobe (Vi-AgNP probe) that is functionalized with specific biomarker Vi polysaccharide and also has the co-presence of Ag as urease inhibitor. The immunoreactions between the Vi with specific antibodies (Abs) present in typhoid patient sample forms a shielding barrier over Vi-AgNP probe rendering the urease to be active, generating colored output.

Conformational switching of aptamer biointerfacing graphene-gold nanohybrid for ultrasensitive label-free sensing of cardiac Troponin I.

The development of hybrid biofunctionalized nanomaterials has emerged as an attractive substitute for development of advanced biosensing platforms with superior synergistic properties. Herein, we report a label-free ultrasensitive electrochemical aptasensor comprising nanohybrid of graphene oxide (GO) and aptamer conjugated gold nanoparticles (GNP-A) for detection of cardiac biomarker Troponin I (TnI). The GNP-A are homogenously arranged by self-assembly on GO sheet to construct nanohybrid (GO@GNP-A) onto which the biomarker protein is analysed.

Mycobacterium tuberculosis exploits MPT64 to generate myeloid-derived suppressor cells to evade the immune system.

Mycobacterium tuberculosis (Mtb) is a smart and successful pathogen since it can persist in the intimidating environment of the host by taming and tuning the immune system. Mtb releases MPT64 (Rv1980c) protein in high amounts in patients with active tuberculosis (TB). Consequently, we were curious to decipher the role of MPT64 on the differentiating dendritic cells (DCs) and its relation to evading the immune system.

Targeting dendritic cells with TLR-2 ligand-coated nanoparticles loaded with Mycobacterium tuberculosis epitope induce antituberculosis immunity.

Novel vaccination strategies are crucial to efficiently control tuberculosis, as proposed by the World Health Organization under its flagship program "End TB Strategy." However, the emergence of drug-resistant strains of Mycobacterium tuberculosis (Mtb), particularly in those coinfected with HIV-AIDS, constitutes a major impediment to achieving this goal. We report here a novel vaccination strategy that involves synthesizing a formulation of an immunodominant peptide derived from the Acr1 protein of Mtb.

Site-directed dual bioprobes inducing single-step nano-sandwich assay for the detection of cardiac troponin I.

Bioreceptor functionalized metallic nano-colloids have been identified as effective nanobioprobes to realize the detection of an analyte based on a common phenomenon of salt-induced aggregation. In marked contrast to this, we describe a nano-sandwich assay integrating the novel match-pair of aptamer and peptide functionalized gold nanoparticles. The site-directed biomolecular interaction of high affinity aptamer and peptide bioreceptors directed towards distinct sites of cardiac biomarker troponin I; this was found to form a nano-sandwich assay in a peculiar manner.

Deciphering the Antibacterial Role of Peptide From subsp. Ba49 Against .

An increase in antibiotic resistance has led to escalating the need for the development of alternate therapy. Antimicrobial peptides (AMPs) are at the forefront of replacing conventional antibiotics, showing slower development of drug resistance, antibiofilm activity, and the ability to modulate the host immune response. The ESKAPE (, , , , , and species) pathogens that jeopardize most conventional antibiotics are known to be involved in severe respiratory tract, bloodstream, urinary tract, soft tissue, and skin infections.

Colorimetric and electrochemical detection of pathogens in water using silver ions as a unique probe.

The manuscript highlights the efficacy of silver ions to act as a unique probe for the detection of bacterial contamination in water samples. The bacterial cell membrane adherence property of the silver ions was employed to develop two different bacterial detection assays employing colorimetric and electrochemical techniques. In one of the schemes, silver ion was used directly as a detector of bacteria in a colorimetric assay format, and in the other scheme surface-functionalized antibodies were used as a primary capture for specific detection of Salmonella enterica serovar Typhi.

Gold nanoparticle triggered siloxane formation for polymerization based amplification in enzyme free visual immunoassay.

Herein, we report a new signal amplification scheme for quantitative biochemical analysis based on gold nanoparticle (GNPs) catalyzed polymerization of transparent silane solution to milky white and turbid siloxane. Using immunoassay as a proof of concept, GNP labeled immunoprobe was used to bind captured antigen and catalyse the polymerization reaction allowing sensitive biochemical investigation. The polymerization reaction was optimized for standard 96 well polystyrene microtiter plates and we discovered that sodium lactate acts as an enhancer in the polymerization reaction as it reduces detection time to merely 30 min.

Rapid and sensitive colorimetric detection of pathogens based on silver-urease interactions.

Herein, we demonstrate a facile and economic approach for colorimetric detection of microbial pathogens in drinking water, employing silver-urease interactions. In the presence of harmful pathogens, receptor coated silver nanoparticles (AgNPs) preferentially bind to the bacterial surface and urease catalytically elevates the pH of the solution, which is sensed by a pH responsive chromogenic dye. The assay demarcates bacterial contamination levels up to 102 cells mL-1 in a field-friendly method.

Hybrid aptamer-antibody linked fluorescence resonance energy transfer based detection of trinitrotoluene.

Combining synthetic macromolecules and biomolecular recognition units are promising in developing novel diagnostic and analysis techniques for detecting environmental and/or clinically important substances. Fluorescence resonance energy transfer (FRET) apta-immunosensor for explosive detection is reported using 2,4,6-trinitrotoluene (TNT) specific aptamer and antibodies tagged with respective FRET pair dyes in a sandwich immunoassay format. FITC-labeled aptamer was used as a binder molecule in the newly developed apta-immunoassay format where the recognition element was specific anti-TNT antibody labeled with rhodamine isothiocyanate.

Graphene-gated biochip for the detection of cardiac marker Troponin I.

We report lithium ion intercalation mediated efficient exfoliation of graphite to form monolithic graphene sheets which have subsequently been investigated for the development of highly sensitive label-free electrochemical detection platform for cardiac biomarker, Troponin I (cTnI). The spectroscopic and morphological analysis demonstrated the formation of defect free graphene sheets which were successfully employed to fabricate an inter-digited microdevice in a drain-source configuration on a silicon biochip. The graphene gated biochip functionalized with anti-cTnI antibodies used in label free detection of cTnI which exhibited an excellent sensitivity in the picogram range (~1 pg mL(-1)) for cTnI without the use of any enzymatic amplification that promises its potential applicability for bio-molecular detection in clinical diagnosis.

Nanobioprobe mediated DNA aptamers for explosive detection.

Specific nucleic acid aptamers using the microtiter plate based modified SELEX method against explosive trinitrotoluene are reported. Efficient partitioning of dsDNA was carried out using streptavidin labeled gold nanoprobes for the selection of specific aptamers. The selected binders having an affinity of ~10(-7) M were used in the newly developed electrochemical aptasensor, exhibiting a detection limit of around 1 ppb for trinitrotoluene.

Amine functionalized graphene oxide/CNT nanocomposite for ultrasensitive electrochemical detection of trinitrotoluene.

Binding of electron-deficient trinitrotoluene (TNT) to the electron rich amine groups on a substrate form specific charge-transfer Jackson-Meisenheimer (JM) complex. In the present work, we report formation of specific JM complex on amine functionalized reduced graphene oxide/carbon nanotubes- (a-rGO/CNT) nanocomposite leading to sensitive detection of TNT. The CNT were dispersed using graphene oxide that provides excellent dispersion by attaching to CNT through its hydrophobic domains and solubilizes through the available OH and COOH groups on screen printed electrode (SPE).

CdTe nanobioprobe based optoelectrochemical immunodetection of diabetic marker HbA1c.

Highly luminescent water soluble CdTe quantum dots (QDs) were synthesized and conjugated with anti-HbA1c antibody to generate specific nanobioprobe. A sandwich immunoassay model was employed using capture HbA1c antibody as a specific receptor molecule and the QD-labeled secondary antibody as a dual (fluorescence cum electrochemical) tracer to quantify the concentration of HbA1c. A linear increase in current was observed for HbA1c analytical standards with a R(2) value of 0.

Enhancing electrochemical detection on graphene oxide-CNT nanostructured electrodes using magneto-nanobioprobes.

Graphene and related materials have come to the forefront of research in electrochemical sensors during recent years due to the promising properties of these nanomaterials. Further applications of these nanomaterials have been hampered by insufficient sensitivity offered by these nanohybrids for the type of molecules requiring lower detection ranges. Here, we report a signal amplification strategy based on magneto-electrochemical immunoassay which combines the advantages of carbon nanotube and reduced graphene oxide together with electrochemical bursting of magnetic nanoparticles into a large number of metal ions.

Bio-functionalized graphene-graphene oxide nanocomposite based electrochemical immunosensing.

We report a novel in-situ electrochemical synthesis approach for the formation of functionalized graphene-graphene oxide (fG-GO) nanocomposite on screen-printed electrodes (SPE). Electrochemically controlled nanocomposite film formation was studied by transmission electron microscopy (TEM) and Raman spectroscopy. Further insight into the nanocomposite has been accomplished by the Fourier transformed infrared spectroscopy (FTIR), thermal gravimetric analysis (TGA) and X-ray diffraction (XRD) spectroscopy.

Rapid extraction and quantitative detection of the herbicide diuron in surface water by a hapten-functionalized carbon nanotubes based electrochemical analyzer.

A solid phase extraction micro-cartridge containing a non-polar polystyrene absorbent matrix was coupled with an electrochemical immunoassay analyzer (EIA) and used for the ultra-sensitive detection of the phenyl urea herbicide diuron in real samples. The EIA was fabricated by using carboxylated carbon nanotubes (CNTs) functionalized with a hapten molecule (an amine functionalized diuron derivative). Screen printed electrodes (SPE) were modified with these haptenized CNTs and specific in-house generated anti diuron antibodies were used for bio-interface development.

Self-assembly and sensor response of photosynthetic reaction centers on screen-printed electrodes.

Photosynthetic reaction centers were immobilized onto gold screen-printed electrodes (Au-SPEs) using a self-assembled monolayer (SAM) of mercaptopropionic acid (MPA) which was deliberately defective in order to achieve effective mediator transfer to the electrodes. The pure Photosystem II (PS II) cores from spinach immobilize onto the electrodes very efficiently but fair badly in terms of photocurrent response (measured using duroquinone as the redox mediator). The cruder preparation of PS II known as BBY particles performs significantly better under the same experimental conditions and shows a photocurrent response of 20-35 nA (depending on preparation) per screen-printed electrode surface (12.

A novel disposable electrochemical immunosensor for phenyl urea herbicide diuron.

A disposable electrochemical immunosensor has been developed for the determination of phenyl urea herbicide-diuron using a low cost laser ablated gold electrodes (LC-LAGE) fabricated on polystyrene substrate. The electrodes were electrochemically deposited with prussian blue-gold nanoparticle (PB-GNP) film, and a competitive inhibition immunoassay was performed on LC-LAGE by using a specific hapten-protein conjugate. The binding of available diuron specific antibody on conjugate coated electrode was detected using alkaline phosphatase rabbit anti-IgG antibody.

New insights for using self-assembly materials to improve the detection stability in label-free DNA-chip and immuno-sensors.

This paper examines reliable advancements in low-cost DNA- and immuno-chips. Capacitance detection was successfully chosen to develop label-free bio-chips. Probe immobilization was rigorously investigated in order to obtain reliable capacitance measurements.

DNA electronics.

DNA and electronics seem to be two different things, but a series of events has highlighted the unusual ability of DNA to form electronic components