Antimicrobial properties of CuO nanorods and multi-armed nanoparticles against B. anthracis vegetative cells and endospores.

Two different kinds of CuO nanoparticles (NPs) namely CuO nanorods (PS2) and multi-armed nanoparticles (P5) were synthesized by wet and electrochemical routes, respectively. Their structure, morphology, size and compositions were characterized by SEM, EDX and XRD. The NPs demonstrated strong bactericidal potential against Bacillus anthracis cells and endospores. PS2 killed 92.17% of 4.5 × 10(4) CFU/mL B. anthracis cells within 1 h at a dose of 1 mg/mL. Whereas P5 showed a higher efficacy by killing 99.92% of 7 × 10(5) CFU/mL B. anthracis cells within 30 min at a dose of 0.5 mg/mL and 99.6% of 1.25 × 10(4) CFU/mL B. anthracis cells within 5 min at a dose of 2 mg/mL. More than 99% of spores were killed within 8 h with 2 mg/mL PS2 in LB media.

Surface plasmon resonance characterization of monoclonal and polyclonal antibodies of malaria for biosensor applications.

Surface plasmon resonance (SPR) screening of monoclonal and polyclonal antibodies of Plasmodium falciparum (MoabPf and PoabPf) for recombinant Histidine rich protein-II antigen (Ag) of Pf (rHRP-II Ag) was conducted in a real-time and label-free manner to select an appropriate antibody (Ab) for biosensor applications. In this study 4-mercaptobenzoic acid (4-MBA) modified gold SPR chip was used for immobilizing the Ag and then Ab was interacted. SEM image showed modification of SPR chip with 4-MBA and EDAX confirmed the presence of 4-MBA on the SPR chip. Equilibrium constant (KD) and maximum binding capacity of analyte (Bmax) values for the interaction of MoabPf or PoabPf with the immobilized rHRP-II Ag were calculated and found to be 0.517 nM and 48.61 m° for MoabPf and 2.288 nM and 46.80 m° for PoabPf, respectively. In addition, thermodynamic parameters such as ΔG, ΔH and ΔS were determined for the interaction between rHRP-II Ag and MoabPf or PoabPf and the values revealed that the interaction is spontaneous, exothermic and driven by entropy. The kinetics and thermodymanic results of this study revealed that the interaction between MoabPf and rHRP-II Ag is more effective than that of PoabPf due to the fact that MoabPf was derived from a single epitope (single clone) whereas the PoabPf was from the mixture of a number of epitopes (polyclones). Finally, SPR methodology was developed for the sensing of malarial antibodies. The limit of detection was found to be 5.6 pg with MoabPf which was found to be the best in our study.

Amperometric immunosensor based on gold nanoparticles/alumina sol-gel modified screen-printed electrodes for antibodies to Plasmodium falciparum histidine rich protein-2.

We report herein the amperometric immunosensor for antibodies to Plasmodium falciparum histidine rich protein-2 (PfHRP-2). Screen-printed electrodes (SPEs) were modified with alumina sol-gel (Al(2)O(3) sol-gel) derived film and gold nanoparticles i.e. AuNPs/Al(2)O(3)sol-gel/SPE. A thin film was formed by dripping Al(2)O(3) sol on SPE followed by electrochemical deposition of gold nanoparticles (AuNPs). The modified SPEs were characterized by scanning electron microscopy/energy dispersive X-ray analysis (SEM-EDAX), Raman spectra and voltammetric experiments. Antibodies in rabbit serum sample were allowed to react with the PfHRP-2 protein that was immobilized on the modified SPE to form antigen-antibody immune complex (PfHRP-2/anti-PfHRP-2). The bound antibodies were quantified by alkaline phosphatase (AP) enzyme labeled secondary antibodies (anti-rabbit immunoglobulins-AP conjugate). Enzymatic substrate, 1-naphthyl phosphate was converted to 1-naphthol by AP and an electroactive product was quantified using amperometry. The performances of the developed immunosensor and Dot-ELISA were tested against different dilutions of hyper immune serum (rabbit anti-PfHRP-2). Dot ELISA and the developed immunosensor (AuNPs/Al(2)O(3)sol-gel/SPE) results for the hyper immune serum containing anti-PfHRP-2 were distinctly positive when diluted upto 8 times (1 : 12800 dilution) and 11 times (1 : 102400 dilution), respectively. The developed immunosensor was applied for antibodies to PfHRP-2 in human clinical samples.

Highly sensitive amperometric immunosensor for detection of Plasmodium falciparum histidine-rich protein 2 in serum of humans with malaria: comparison with a commercial kit.

A disposable amperometric immunosensor was developed for the detection of Plasmodium falciparum histidine-rich protein 2 (PfHRP-2) in the sera of humans with P. falciparum malaria. For this purpose, disposable screen-printed electrodes (SPEs) were modified with multiwall carbon nanotubes (MWCNTs) and Au nanoparticles. The electrodes were characterized by cyclic voltammetry, scanning electron microscopy, and Raman spectroscopy. In order to study the immunosensing performances of modified electrodes, a rabbit anti-PfHRP-2 antibody (as the capturing antibody) was first immobilized on an electrode. Further, the electrode was exposed to a mouse anti-PfHRP-2 antibody from a serum sample (as the revealing antibody), followed by a rabbit anti-mouse immunoglobulin G-alkaline phosphatase conjugate. The immunosensing experiments were performed on bare SPEs, MWCNT-modified SPEs, and Au nanoparticle- and MWCNT-modified SPEs (Nano-Au/MWCNT/SPEs) for the amperometric detection of PfHRP-2 in a solution of 0.1 M diethanolamine buffer, pH 9.8, by applying a potential of 450 mV at the working electrode. Nano-Au/MWCNT/SPEs yielded the highest-level immunosensing performance among the electrodes, with a detection limit of 8 ng/ml. The analytical results of immunosensing experiments with human serum samples were compared with the results of a commercial Paracheck Pf test, as well as the results of microscopy. The specificities, sensitivities, and positive and negative predictive values of the Paracheck Pf and amperometric immunosensors were calculated by taking the microscopy results as the "gold standard." The Paracheck Pf kit exhibited a sensitivity of 79% (detecting 34 of 43 positive samples; 95% confidence interval [CI], 75 to 86%) and a specificity of 81% (correctly identifying 57 of 70 negative samples; 95% CI, 76 to 92%), whereas the developed amperometric immunosensor showed a sensitivity of 96% (detecting 41 of 43 positive samples; 95% CI, 93 to 98%) and a specificity of 94% (correctly identifying 66 of 70 negative samples; 95% CI, 92 to 99%). The developed method is more sensitive and specific than the Paracheck Pf kit.