Snehasis Mishra

Coumarinyl thioether Schiff base as a turn-on fluorescent Zn(II) sensor and the complex as chemosensor for the selective recognition of ATP, along with its application in whole cell imaging

The coumarinyl thioether Schiff base, H2L, demonstrates turn-on fluorescence sensing towards Zn2+ ion with a limit of detection (LOD) of 0.068 μM. Different physicochemical techniques (mass, 1H NMR, Jobs) support the formation of a 1 : 1 metal-to-ligand complex, [ZnL]. The fluorogenic complex [ZnL] recognizes ATP in the presence of all other common anions, inorganic phosphates and biologically important phosphates (nucleosides, nucleotides). The proposed sensor has efficiently been used for ATP sensing with a LOD of 6.7 μM, which is the lowest in literature. Exogenous zinc ions in SCC084 (human oral carcinoma) cells have been checked through fluorescence cell imaging process by adding H2L in the medium.

Porous Polymer Bearing Polyphenolic Organic Building Units as a Chemotherapeutic Agent for Cancer Treatment

Cancer is one of the most deadly diseases worldwide. Although several chemotherapeutic agents are available at present for its treatment, they have their own limitations. The main problems of these chemotherapeutic agents are cost involvement and severe life-threatening antagonistic effects. Here, we report a new biodegradable N-rich porous organic polymer methylenedianiline-triformyl phloroglucinol (MDTFP-1) synthesized via a Schiff base condensation reaction between two reactive monomers, that is, 4,4′-methylenedianiline and 2,4,6-triformyl phloroglucinol under inert atmosphere. Because this porous polymer contains polyphenolic building units and has a high Brunauer–Emmett–Teller surface area (283 m2 g–1), it has been explored in the anticancer activity using HCT 116, A549, and MIA PaCa-2 cell lines. We have carried out the flow cytometric assessment using Annexin-V-FITC/PI staining through the exposed level of phosphatidylserine in the outer membrane of cells with MDTFP-1-induced apoptosis. Our results suggested that apoptosis of cells have been enhanced in a time-dependent manner in the presence of this novel porous polymer.

Synthesis of a novel glucose capped gold nanoparticle as a better theranostic candidate

Gold nanoparticles are predominantly used in diagnostics, therapeutics and biomedical applications. The present study has been designed to synthesize differently capped gold nanoparticles (AuNps) by a simple, one-step, room temperature procedure and to evaluate the potential of these AuNps for biomedical applications. The AuNps are capped with glucose, 2-deoxy-D-glucose (2DG) and citrate using different reducing agents. This is the first report of synthesis of 2DG-AuNp by the simple room temperature method. The synthesized gold nanoparticles are characterized with UV-Visible Spectroscopy, Fourier transform infrared spectroscopy (FTIR), Transmission electron microscopy (TEM) and selected area electron diffraction (SAED), Dynamic light scattering (DLS), and Energy-dispersive X-ray spectroscopy (SEM-EDS). Surface-enhanced Raman scattering (SERS) study of the synthesized AuNps shows increase in Raman signals up to 50 times using 2DG. 3-(4, 5-dimethylthiozol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) assay has been performed using all the three differently capped AuNps in different cell lines to assess cytotoxcity if any, of the nanoparticles. The study shows that 2DG-AuNps is a better candidate for theranostic application.

A novel nanohybrid for cancer theranostics: folate sensitized Fe2O3 nanoparticles for colorectal cancer diagnosis and photodynamic therapy

Organic-inorganic nanohybrids are becoming popular for their potential biological applications, including diagnosis and treatment of cancerous cells. The motive of this study is to synthesise a nanohybrid for the diagnosis and therapy of colorectal cancer. Here we have developed a facile and cost-effective synthesis of folic acid (FA) templated Fe2O3 nanoparticles with excellent colloidal stability in water using a hydrothermal method for the theranostics applications. The attachment of FA to Fe2O3 was confirmed using various spectroscopic techniques including FTIR and picosecond resolved fluorescence studies. The nanohybrid (FA-Fe2O3) is a combination of two nontoxic ingredients FA and Fe2O3, showing remarkable photodynamic therapeutic (PDT) activity in human colorectal carcinoma cell lines (HCT 116) via generation of intracellular ROS. The light induced enhanced ROS activity of the nanohybrid causes significant nuclear DNA damage, as confirmed from the comet assay. Assessment of p53, Bax, Bcl2, cytochrome c (cyt c) protein expression and caspase 9/3 activity provides vivid evidence for cell death via an apoptotic pathway. In vitro magnetic resonance imaging (MRI) experiments in folate receptor (FR) overexpressed cancer cells (HCT 116) and FR deficient human embryonic kidney cells (HEK 293) reveal the target specificity of the nanohybrid towards cancer cells, and are thus pronounced MRI contrasting agents for the diagnosis of colorectal cancer.

Isoelectronic Pt(II)– and Au(III)–N-heterocyclic carbene complexes: a structural and biological comparison

To elucidate the intrinsic biological activities displayed by platinum versus gold-based organometallic reagents, the isoelectronic and isostructural square planar complexes [Pt(C∩N)(C)Cl][PF6] (2) and [Au(C∩N)(C)Cl][PF6]2 (3), which are supported by a common N-heterocyclic carbene, 1-methyl-2-pyridin-2-yl-2H-imidazo[1,5-a]pyridin-4-ylidene (1), were synthesized. The complexes were characterized using a range of spectroscopic techniques as well as single crystal X-ray diffraction and a series of computational studies were also performed to gain additional insight into their fundamental electronic bonding structures. The cytotoxicities of the complexes were tested in vitro against non-small lung carcinoma (A549), colorectal carcinoma (HCT-116) and human hepatocellular carcinoma (HepG2) cell lines. The measured IC50 values showed that the Au(III)–NHC complex is more potent than its Pt analogue.

Use of rhodamine-allyl Schiff base in chemodosimetric processes for total palladium estimation and application in live cell imaging

Rhodamine derivatives are excellent fluorescent probes and have shown sharp descending trends of emission intensity on interaction with specific analytes, which causes opening of the spirolactam ring. In this study, rhodamine-allyl Schiff base (RD-2) is used as a highly sensitive colorimetric and fluorescent chemosensor for total palladium determination, and is indifferent to oxidation states (0,II,IV). The LOD is 95 nM. In addition, it is also a brilliant sensor for in vitro imaging of Pd2+ in RAW 264.7 (macrophage) cells. The probe RD-2 is structurally characterised by single-crystal X-ray diffraction measurement.