M. Shahnawaz Khan

Near infrared (NIR) laser mediated surface activation of graphene oxide nanoflakes for efficient antibacterial, antifungal and wound healing treatment.

Photothermal treatment of graphene oxide (GO) for antibacterial, antifungal and controlling the wound infection treatment using near infrared laser (NIR, Nd-YAG (λ=1064 nm) were reported. Various pathogenic bacteria (Pseudomonas aeruginosa, Staphylococcus aureus) and fungi (Saccharomyces cerevisiae and Candida utilis) were investigated. The cytotoxicity was measured using the proteomic analysis by matrix assisted laser desorption/ionization mass spectrometry (MALDI-MS), optical density (OD600), standard microdilution procedures, transmission electron microscopy (TEM) and epifluorescence microscopy. The laser mediated the surface activation of GO offer high efficiency for antifungal and antibacterial. Wide broad cells with various instruments approved that graphene oxide is promising material for nanomedicine in the near future.

Graphene oxide as a nanocarrier for gramicidin (GOGD) for high antibacterial performance

As a powerful and novel nanocarrier, graphene oxide (GO) is employed to load a water insoluble antibacterial drug, gramicidin (GD), for effective antibacterial treatments. The loaded amount of GD on the surface of GO was calculated and was found to be 14% (wt%). The antibacterial activity of GO modified GD (GOGD) was measured against Pseudomonas aeruginosa and Staphylococcus aureus using plate counting, optical density (OD600), transmission electron microscopy (TEM), fluorescence (2D, 3D) and matrix assisted laser desorption/ionization mass spectrometry (MALDI-MS). The use of multiple analytical approaches adds certainty to the cytotoxicity assessments of GOGD, which shows better efficiency than GO and GD. GOGD has potential wide-ranging effects against different bacterial strains. Nano-cytotoxicity mechanism was discussed in detail, and controversies in earlier results were refuted.

Design, characterization and applications of new ionic liquid matrices for multifunctional analysis of biomolecules: a novel strategy for pathogenic bacteria biosensing.

The design, preparation and performance for novel UV-light absorbing (room-temperature) ionic liquid matrices (UV-RTILMs) for matrix assisted laser desorption/ionization mass spectrometry (MALDI-MS) were reported. A series of UV-RTILMs was prepared by ultrasonication of equimolar of acid (mefenamic acid) and bases (aniline (ANI), pyridine (Pyr), dimethyl aniline (DMANI) and 2-methyl picoline (2-P)). The UV-RTILMs have not only significant absorbance at the desired wavelength (337 nm of the N2 Laser), but also have available protons that can easily undergo proton transfer reactions to ionize the target molecules. The novel UV-RTILMs have the ability to ionize different and wide classes of compounds such as drugs, carbohydrate, and amino acids. The new UV-RTILMs series have been successfully and selectively applied for biosensing the lysates of pathogenic bacteria in the presence of the cell macromolecules. A new strategy for biosensing pathogens was presented via sensing the pathogens lysate in the cell suspension. The new materials can effectively detect the bacterial toxins without separation or any pretreatment. They offered excellent ionization of labile oligosaccharides with protonated peaks. They could significantly enhance the analyte signals, produce homogeneous spotting, reducing spot-to-spot variation, excellent vacuum stability, higher ion peak intensity, and wide application possibility. The physical parameters such as molar refractivity, molar volume, parachor, surface tension, density and polarizability were calculated and tabulated. The new UV-RTILMs could offer excellent reproducibility and great repeatability and they are promising matrices for wide applications on MALDI-MS.

Controlled delivery of dopamine hydrochloride using surface modified carbon dots for neuro diseases.

Delivery of therapeutic agents using water-soluble, highly biocompatible Carbon dots (C-dots) is an efficient strategy to control drug release under physiological milieu. Dopamine hydrochloride (DA), the most important inotropic vasopressor agent used in neurological diseases. In our study DA is anchored to water-soluble carbon dots for controlled release under mimicked in vitro physiological conditions. The tenure of the DA release at pH 7.4 was greatly extended to 60 h for C-dots-DA, in comparison with the control DA alone. The statistical calculation was used to comprehend the release pattern of the DA, which exhibited the pattern of Hixson-Crowell model of release. In order to understand the impact of the C-dots-DA conjugate under physiological conditions, Neuro 2A cells were taken under consideration. The conjugate C-dots-DA was found to be biocompatible against Neuro 2A cells. The survival rate was found to be 74% at maximum concentration of 9 μg mL(-1). In vivo toxicity was studied using thin section of tissues after staining with Hematoxyline and Eosin Yellow (H&E). As per microscopic observations, conjugates did not inflict any anatomical distortions or hostile effects on tissues. Body weight of mice was also taken into consideration after injecting 20 μg mL(-1) of nano-conjugates via tail vein. The impact of nano-conjugate on body weight was found to be negligible after 45 days of observation.

ZnO nanoparticle-modified polymethyl methacrylate-assisted dispersive liquid–liquid microextraction coupled with MALDI-MS for rapid pathogenic bacteria analysis

A new and fast nano-based approach to extract pathogenic bacteria lysates from aqueous samples is reported. Zinc oxide nanoparticles modified with polymethyl methacrylate (ZnO@PMMA) were synthesized and applied to dispersive liquid–liquid microextraction (DLLME) in order to detect and extract bacteria. The extracted lysates were further identified by matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS). The results indicated that the presented approach is a simple, rapid and efficient microextraction technique for the analysis of pathogenic bacteria lysate (Staphylococcus aureus and Pseudomonas aeruginosa). Under optimal conditions, the minimum detectable concentrations are 9.7 × 103 and 1.7 × 104 cfu mL−1 for S. aureus and P. aeruginosa, respectively. The ZnO@PMMA nanoparticles provide multifunctional forces to strengthen the interactions with the cell lysate. The large surface area of ZnO@PMMA enhances the separation efficiency and improves the sensitivity and quality of MALDI-MS spectra. The method was validated by the analysis of real samples, such as tap and drinking water. Data revealed that ZnO@PMMA-DLLME is a promising microextraction technique for pathogenic bacteria analysis, which may be utilized in clinical investigations in the near future.

Synthesis of mesoporous titanium oxide for release control and high efficiency drug delivery of vinorelbine bitartrate

The present study reports a facile method for fabrication of mesoporous titanium oxide (mTiO2) and its application for delivery of the potential anticancer drug vinorelbine bitartrate (VB) under physiological conditions. The mTiO2 was functionalized with hexamethylene tetramine (HMTA), which can release formaldehyde in the acidic environment of cancer cells. Due to the highly porous nature of mTiO2, the drug loading capacity of mTiO2-HMTA was extremely high (about 73%) and the release of the drug was consistent for a long time (about 72 h). The release of VB was pH dependent and found to be higher under slightly acidic conditions thus mimicking a cancer environment. The role of HMTA in the present context is to trigger the release of formaldehyde under acidic conditions (pH 6.5), which was responsible for killing cancer cells, whereas working synergistically with VB. The toxicity of the conjugate was assessed using HeLa and Vero cells. In the case of normal cells, the nano-conjugates were completely biocompatible (>75%). In vivo-toxicity was checked by staining thin slices of the tumor tissues using H&A staining. More damage was found in the case of the tumor cells due to inimical action of formaldehyde.

Graphene oxide@gold nanorods for chemo-photothermal treatment and controlled release of doxorubicin in mice Tumor

Graphene oxide (GO) is a close derivative of graphene has unlocked many pivotal steps in drug delivery due to their inherent biocompatibility, excellent drug loading capacity, and shows antibacterial, antifungal properties etc. We used a novel plant material called Gum arabic (GA) to increase the solubility of GO as well as to chemically reduce it in the solution. GA functionalized GO (fGO) exhibited increased absorption in near infra-red region (NIR) which was exploited in photothermal therapy for cancer. In order to understand the shape and size effect of GO which may affect their rheological properties, we have conjugated them with gold nanorods (GNRs) using in situ synthesis of GO@GNRs via seed mediated method. To the above conjugate, Doxorubicin (DOX) was attached at ambient temperature (28±2°C). The release kinetics of DOX with the effect of NIR exposure was also carefully studied via in vitro photothermal killing of A549 cell lines. The enhancement in NIR induced drug release and photothermal property was observed which indicates that the fGO@GNRs-DOX method is an ideal choice for chemotherapy and photothermal therapy simultaneously.

Probing the cytotoxicity of CdS–MPA and CdSe–MUA QDs on the bacterial pathogen Staphylococcus aureus using MALDI-MS

Two quantum dots, CdS QDs capped with “mercaptopropionic acid” (MPA) and CdSe capped with “mercaptoundecanoic acid” (MUA), were synthesized and their toxicity against the well known bacterial pathogen, Staphylococcus aureus, was compared using matrix assisted laser desorption/ionization mass spectrometry (MALDI-MS), epifluorescence microscopy and spectrophotometric analysis (O.D. 600 nm). CdS–MPA QDs were observed to be more compatible compared to CdSe–MUA QDs. The CdSe–MUA QDs were toxic at all concentrations and at incubation time 0.5 mg mL−1 after prolonged incubation (>12 h). The epifluorescence technique confirmed the results which have been observed in the MALDI-MS studies.

Folic Acid navigated Silver Selenide nanoparticles for photo-thermal ablation of cancer cells

Photothermal ablation of the cancer cells is a non-invasive technique for cancer treatment, involving cellular assassination in presence of photothermal agent. We are reporting silver selenide (Ag2Se) nanoparticles for photothermal therapy using folic acid for selective targeting. The material, when exposed to 808nm laser, the temperature got boosted to 54°C in 6.5min, thus proving its potential for photothermal ablation. The material was highly biocompatible (95%) at highest concentration (10μg/mL) against A 549 cells. However, in presence of laser, the cellular killing was 55%. The mode of death was analyzed using MALDI-TOF MS.

Laser-assisted synthesis of multi-colored protein dots and their biological distribution in experimental mice using a dye tracking method

We report a novel method for the synthesis of ultra-bright green and red colored protein dots (Pr-dots) using continuous and pulse lasers (λ = 534 and 1064 nm) with lysozyme as a precursor in ethanol. The quantum yield of the Pr-dotsRed was calculated to be ∼13% and that of the Pr-dotsGreen was ∼15%. A shift in the fluorescent intensity and the fluorescence color of the Pr-dots under UV light (λem = 365 nm) with respect to changes in the repetition frequency of the laser was observed. After successful synthesis of the Pr-dots, their in vivo bio-kinetics were studied using 5 week old ICR mouse models. The highest accumulation of multi-Pr-dots was observed in the brains of the mice. This method has opened a new door to pursue the application of Pr-dots to ferry drugs across blood–brain barrier (BBB) which is considered very difficult to achieve. Another vital application of the Pr-dots in biological imaging was explored. These multi-colored Pr-dots were used as effective fluorescence probes for the imaging of Vero cells as well as MCF 7 cancer stem cells.