Angshuman Ray Chowdhuri

Synthesis of highly fluorescent nitrogen and phosphorus doped carbon dots for the detection of Fe3+ ions in cancer cells

Highly fluorescent nitrogen and phosphorus-doped carbon dots with a quantum yield 59% have been successfully synthesized from citric acid and di-ammonium hydrogen phosphate by single step hydrothermal method. The synthesized carbon dots have high solubility as well as stability in aqueous medium. The as-obtained carbon dots are well monodispersed with particle sizes 1.5-4 nm. Owing to a good tunable fluorescence property and biocompatibility, the carbon dots were applied for intercellular sensing of Fe(3+) ions as well as cancer cell imaging.

Carbon Dots Embedded Magnetic Nanoparticles @Chitosan @Metal Organic Framework as a Nanoprobe for pH Sensitive Targeted Anticancer Drug Delivery

Recently, nanoscale metal organic frameworks (NMOFs) have been demonstrated as a promising carrier for drug delivery, as they possess many advantages like large surface area, high porosity, and tunable functionality. However, there are no reports about the functionalization of NMOFs, which combines cancer-targeted drug delivery/imaging, magnetic property, high drug loading content, and pH-sensitive drug release into one system. Existing formulations for integrating target molecules into NMOF are based on multistep synthetic processes. However, in this study, we report an approach that combines NMOF (IRMOF-3) synthesis and target molecule (Folic acid) encapsulation on the surface of chitosan modified magnetic nanoparticles in a single step. A noticeable feature of chitosan is control and pH responsive drug release for several days. More importantly, doxorubicin (DOX) was incorporated into magnetic NMOF formulation and showed high drug loading (1.63 g DOX g(-1) magnetic NMOFs). To demonstrate the optical imaging, carbon dots (CDs) are encapsulated into the synthesized magnetic NMOF, thereby endowing fluorescence features to the nanoparticles. These folate targeted magnetic NMOF possess more specific cellular internalization toward folate-overexpressed cancer (HeLa) cells in comparison to normal (L929) cells.

A ZnO decorated chitosan–graphene oxide nanocomposite shows significantly enhanced antimicrobial activity with ROS generation

The rise in antimicrobial resistance requires the development of new antibacterial agents. Herein, we develop nanocomposites by growing zinc oxide nanoparticles on the surface of chitosan (CS) modified graphene oxide (GO), obtaining GO@CS/ZnO as a novel antibacterial material. The crystal structures, surface functional groups and morphology were analyzed by using X-ray diffraction (XRD) pattern, Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM) images, respectively. The Minimum Inhibitory Concentration (MIC) and the Minimum Bactericidal Concentration (MBC) of GO@CS/ZnO show more antibacterial potency towards both Gram-negative bacteria Escherichia coli (E. coli) and Gram-positive bacteria Staphylococcus aureus (S. aureus). In this study the GO@CS/ZnO expresses its more potency than reported graphene based nanocomposites. Investigation of intercellular reactive oxygen species (ROS) generation, NO generation and catalase activity in E. coli and S. aureus reveal that GO@CS/ZnO treatment also augments the intracellular bacterial killing by inducing reactive oxygen species production that causes oxidative damage. The minimal inhibition concentrations (MIC) of GO@CS/ZnO against E. coli and S. aureus are only 2.5 μg mL−1 and 5 μg mL−1 respectively. Compared with graphene based nanocomposite, which have been widely used as antibacterial agents, our GO@CS/ZnO shows better antibacterial effect. We envision that this study offers novel insights into antimicrobial actions and also demonstrates GO@CS/ZnO is a novel class of topical antibacterial agent in the areas of healthcare and environmental engineering.

Single step synthesis of carbon dot embedded chitosan nanoparticles for cell imaging and hydrophobic drug delivery

The florescent carbon dot conjugated chitosan nanoparticles are developed for the cellular imaging and delivery of poorly water soluble drug telmisartan (TEL). In this work, the florescent chitosan nanoparticles are synthesized in a single step. The presence of surface functional groups and conjugation of the nanoparticles are investigated by FTIR spectroscopy. Dynamic light scattering and TEM analysis are performed to determine the size of the nanoparticles. To investigate the surface morphology FESEM analysis is also performed. The cytotoxicity of the nanoparticles is examined by MTT assay using normal lymphocytes and KG1A cancer cell lines. The intracellular cellular uptake is studied by fluorescence microscopy and flow cytometry analysis. The interactions between the nanoparticles and the drug are investigated by Gaussian 09 and visualized by GaussView 5 program package.

One-pot synthesis of carbon dot-entrenched chitosan-modified magnetic nanoparticles for fluorescence-based Cu2+ ion sensing and cell imaging

In this work, a new synthetic approach is developed for the synthesis of fluorescent magnetic nanoparticles which are explored for the detection of mostly abundant transition metal Cu2+ ions and cell imaging. These fluorescent magnetic nanoparticles are synthesized by decoration of carbon dots (CDs) on carboxymethyl chitosan-wrapped Fe3O4 nanoparticles (NPs) in a one-pot method. The fluorescent magnetic nanoparticles are characterized by Fourier transform infrared spectroscopy (FTIR), X-ray powder diffraction (XRD), a vibrating sample magnetometer (VSM), field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), dynamic light scattering (DLS) and photoluminescence study. Importantly, the fluorescent magnetic nanoparticles exhibit excellent selectivity for the determination of Cu2+ ions over other metal ions. The fluorescence intensity was found to be successfully quenched by adding different concentrations of Cu2+ ions. Here, the reduction of fluorescence intensity proves the detection of Cu2+ ions in a linear range of 0.01–200 µM, with a detection limit of 0.56 µM at a signal-to-noise ratio of 3. The fluorescent magnetic nanoparticles were successfully applied to cell imaging and subsequently conjugated with folic acid for cancer cell imaging, which suggests that the synthesized nanoparticles have great potential for diagnostic purposes.

Fabrication of a magnetic nanoparticle embedded NH2-MIL-88B MOF hybrid for highly efficient covalent immobilization of lipase

Metal–organic frameworks (MOFs), a class of porous hybrid materials composed of metal ions and organic ligands, have been studied for a variety of applications. In this work, for the first time, magnetic MOFs are developed for lipase immobilization. A general one-step in situ hydrothermal route is developed for the construction of MOFs encapsulating superparamagnetic Fe3O4 nanoparticles. The integration of Fe3O4 nanoparticles into the MOFs exhibits many interesting inherent properties including a porous nature, easy functionalization as well as strong superparamagnetism. Here Candida rugosa lipase (CRL) is covalently attached to amino-rich magnetic MOFs. The resulting magnetic MOFs are characterized by means of field emission scanning electron microscopy (FESEM), Fourier transform infrared spectroscopy (FT-IR), thermogravimetric analysis (TGA) and vibrating sample magnetometer (VSM) measurements. Then the enzymatic activities of the immobilized CRL are compared with free CRL. The immobilized CRL presented a wider pH tolerance and excellent thermal stability than free CRL. The Michaelis–Menten kinetic constant (Km) and maximum reaction velocity (Vmax) for both free and immobilized lipase are investigated. The loading amount of CRL on the magnetic MOFs was 280 mg per g of support and the immobilized CRL was efficiently recycled for up to nine cycles.

Theoretical and experimental study of folic acid conjugated silver nanoparticles through electrostatic interaction for enhance antibacterial activity

In this paper, folic acid conjugated silver nanoparticles (Ag NPs) are developed for enhancing antibacterial activity. Here triethylamine is used as a capping agent as well as reducing agent during the synthesis of silver nanoparticles. Folic acid is conjugated on the surface of the functionalized silver nanoparticles through electrostatic interaction. The folic acid conjugated silver nanoparticles are characterized in terms of size and morphology by transmission electron microscopy (TEM) and field emission scanning electron microscopy (FESEM) respectively. The phase formation and surface functional groups of nanoparticles are analyzed by X-ray diffraction (XRD) and Fourier transform infrared (FTIR) spectroscopy respectively. Minimum inhibitory concentration study, minimum bactericidal concentration, growth pattern analysis and fluorescence carbon dot tagged nanoparticles uptake study reveal that the folic acid conjugated silver nanoparticles show good prospects against both Gram-negative (Escherichia coli) and Gram-positive (Staphylococcus aureus) bacteria.

Chitosan conjugated chloroquine: proficient to protect the induction of liver apoptosis during malaria.

Chitosan has impelled continuous motion by its unique physicochemical and biological characteristics. In our study, chitosan-tripolyphosphate (CS-TPP) particles was conjugated with an undervalued antimalarial drug, chloroquine to find out the proficiency against ROS mediated caspase activation and apoptosis in liver during Plasmodium berghei NK65 infection. The transmission electron microscopic image illustrated the size range of particle was less than 50 nm and the particle showed the blood compatibility. ROS generation, mitochondrial membrane potential, anti apoptotic and pro apoptotic protein level of CS-TPP conjugated chloroquine treated group revealed that CS-TPP conjugation amplified the protective capability of chloroquine. FACS study by annexin v-FITC and PI staining reveals chloroquine treatment reduces significantly (P<0.05) the apoptotic cells by 25.31%; whereas chitosan-tripolyphosphate conjugated nanochloroquine decreases by 61.56% apoptotic cell against P. berghei induced liver apoptosis. This study suggests that proficiency of conventional antimalarial drug may escalate by delivery with chitosan nanoparticles to portray defense possessions against malarial damage.

One-step synthesis of amikacin modified fluorescent carbon dots for the detection of Gram-negative bacteria like Escherichia coli

In this paper, we report a one-step strategy to synthesize amikacin modified fluorescent carbon dots (CDs@amikacin) for assaying pathogenic bacteria, Escherichia coli. Amikacin is a well-known aminoglycoside antibiotic but here we used it as a binding ligand towards E. coli. Here the synthesized carbon dots are used to detect E. coli accompanied with a linear range of 3.904 × 105 to 7.625 × 102 cfu per mL as well as a detection limit of 552 cfu per mL. CDs@amikacin were well dispersed in water with an average particle diameter of ∼2.5 nm and exhibited a quantum yield of 12.35% at a excitation wavelength of 340 nm. The synthesis of CDs@amikacin and their use in the detection of E. coli are simple, cheap and effective process. This study is also successfully applied to the sensing of E. coli in different fruit juice samples like apple, pineapple and orange. We believe that this analytical method can be used in the field of public health as well as food safety.