Ekta Roy

Dual-Responsive Polymer Coated Superparamagnetic Nanoparticle for Targeted Drug Delivery and Hyperthermia Treatment

In this work, we have prepared water-soluble superparamgnetic iron oxide nanoparticles (SPIONs) coated with a dual responsive polymer for targeted delivery of anticancer hydrophobic drug (curcumin) and hyperthermia treatment. Herein, superparamagnetic mixed spinel (MnFe2O4) was used as a core material (15-20 nm) and modified with carboxymethyl cellulose (water-soluble component), folic acid (tagging agent), and dual responsive polymer (poly-N isopropylacrylamide-co-poly glutamic acid) by microwave radiation. Lower critical solution temperature (LCST) of the thermoresponsive copolymer was observed to be around 40 °C, which is appropriate for drug delivery. The polymer-SPIONs show high drug loading capacity (89%) with efficient and fast drug release at the desired pH (5.5) and temperature (40 °C) conditions. Along with this, the SPIONs show a very fast increase in temperature (45 °C in 2 min) when interacting with an external magnetic field, which is an effective and appropriate temperature for the localized hyperthermia treatment of cancer cells. The cytocompatibility of the curcumin loaded SPIONs was studied by the methyl thiazol tetrazolium bromide (MTT) assay, and cells were imaged by fluorescence microscopy. To explore the targeting behavior of curcumin loaded SPIONs, a simple magnetic capturing system (simulating a blood vessel) was constructed and it was found that ∼99% of the nanoparticle accumulated around the magnet in 2 min by traveling a distance of 30 cm. Along with this, to explore an entirely different aspect of the responsive polymer, its antibacterial activity toward an E. coli strain was also studied. It was found that responsive polymer is not harmful for normal or cancer cells but shows a good antibacterial property.

Multifunctional magnetic reduced graphene oxide dendrites: Synthesis, characterization and their applications

This article has been retracted: please see Elsevier Policy on Article Withdrawal (https://www.elsevier.com/about/our-business/policies/article-withdrawal). This article has been retracted at the request of the Editor-in-Chief following concerns raised by a reader. The article uses an electron micrograph identical to another publication despite being labelled as different samples. Fig. 3F is the same as Fig. 1D published in Biosensors and Bioelectronics Volume 89 Part1, 15 March 2017, Pages 620-626, 10.1016/j.bios.2015.12.085. In addition, the extraordinary similarities observed between the data presented in Fig. 3C and in Fig. 3C in ACS Biomater. Sci. Eng., 2017, 3 (9), pp 2120–2135, 10.1021/acsbiomaterials.7b00089, Fig. 4A in Colloids and Surfaces B: Biointerfaces, Volume 142, 1 June 2016, Pages 248-258 10.1016/j.colsurfb.2016.02.053 and Fig. 4C in Biosensors and Bioelectronics, Volume 97, 15 November 2017, Pages 208-217, 10.1016/j.bios.2017.06.003 are highly unlikely. This problem with the data casts doubt on all the data, and accordingly also the conclusions based on that data, in this publication. As such this article represents a severe abuse of the scientific publishing system. The scientific community takes a very strong view on this matter and apologies are offered to readers of the journal that this was not detected during the submission process.

Amino acid derived highly luminescent, heteroatom-doped carbon dots for label-free detection of Cd2+/Fe3+, cell imaging and enhanced antibacterial activity

A facile, economic and one-step synthesis strategy was applied for the synthesis of highly fluorescent water-soluble heteroatom doped carbon dots (CDs) from eight different amino acids viz., arginine, cysteine, glutamic acid, glutamine, aspartic acid, lysine, tyrosine, and methionine. Based on the higher quantum yield (38%) cysteine derived CDs were selected to explore their multi-functional behavior viz., sensing of metal ions, cell imaging and cytocompatibility study for MCF7 cancer cells. The cysteine derived CDs exhibit high sensitivity and selectivity toward Cd2+ and Fe3+ ions with a detection limit as low as 2.0 and 3.0 μg L−1 in the linear range of 6.0–268.0 μg L−1 and 6.0–250.0 μg L−1, respectively. In addition, the CDs were applied for cell imaging, demonstrating their potential as excellent probes for high contrast cell imaging. Moreover, to explore an entirely different application of CDs (i.e. antibacterial and photocatalytic activity); a nanocomposite of Au/CDs was also prepared. It was observed that a very low minimum inhibition concentration value (20.0 ng mL−1) was required to inhibit the growth of E. coli. Similarly, the photocatalytic activity of Au/CDs nanocomposite was also studied for H2O2 decomposition.

Imprinted ZnO nanostructure-based electrochemical sensing of calcitonin: a clinical marker for medullary thyroid carcinoma

The present work describes an exciting method for the selective and sensitive determination of calcitonin in human blood serum samples. Adopting the surface molecular imprinting technique, a calcitonin-imprinted polymer was prepared on the surface of the zinc oxide nanostructure. Firstly, a biocompatible tyrosine derivative as a monomer was grafted onto the surface of zinc oxide nanostructure followed by their polymerization on vinyl functionalized electrode surface by activator regenerated by electron transfer-atom transfer radical polymerization (ARGET-ATRP) technique. Such sensor can predict the small change in the concentration of calcitonin in the human body and it may also consider to be as cost-effective, renewable, disposable, and reliable for clinical studies having no such cross-reactivity and matrix effect from real samples. The morphologies and properties of the proposed sensor were characterized by scanning electron microscopy, cyclic voltammetry, difference pulse voltammetry and chronocoulometry. The linear working range was found to be 9.99 ng L(-1) to 7.919 mg L(-1) and the detection limit as low as 3.09±0.01 ng L(-1) (standard deviation for three replicate measurements) (S/N=3).

A fluorescent molecularly-imprinted polymer gate with temperature and pH as inputs for detection of alpha-fetoprotein

This article has been retracted: please see Elsevier Policy on Article Withdrawal (https://www.elsevier.com/about/our-business/policies/article-withdrawal). This article has been retracted at the request of the Editor following concerns raised by a reader. The article reuses an electron micrograph from a previous publication while claiming that these are different particles. Fig. 1C/D were reused from Fig. 2B published in Biosensors and Bioelectronics, Volume 73, 15 November 2015, Pages 234–244, https://doi.org/10.1016/j.bios.2015.06.005. This problem with the data presented casts doubt on all the data, and accordingly also the conclusions based on that data, in this publication. As such this article represents a severe abuse of the scientific publishing system. The scientific community takes a very strong view on this matter and apologies are offered to readers of the journal that this was not detected during the submission process.

An imprinted Ag@CdS core shell nanoparticle based optical-electrochemical dual probe for trace level recognition of ferritin

In this work, we present a new approach to prepare the Ag@CdS core-shell fluorescent nanoparticles wrapped with molecularly imprinted polymer for ferritin macromolecule by capping with vinyl derivative of cysteine. The imprinted Ag@CdS nanoparticle was prepared via activator regenerated by electron transfer-atom transfer radical polymerization (ARGET-ATRP) method onto the surface of vinyl silane modified pencil graphite electrode. Combination of Ag and CdS in a single motif causes the dual behavior of core shell nanoparticle, which shows enhanced fluorescence as well as electrochemical properties. The performance of the obtained imprinted sensor was investigated by cyclic voltammetry, electrochemical impedance spectroscopy, chronocoulometry, differential pulse voltammetry and fluorescence spectrophotometry. Under the optimal experimental conditions, the current response of the electrochemical sensor was linear to ferritin concentrations in the range from 1.99 to 23.43 µg L⁻¹, with the detection limit of 0.65 µg L⁻¹. Similarly, a linear response was obtained between fluorescence quenching of imprinted Ag@CdS and concentration of ferritin in the range from 4.0 to 91.0 µg L⁻¹, with limit of detection (LOD) of 1.3 µg L⁻¹. The method was successfully applied to the analysis of blood serum samples of five different men and women with acceptable recoveries of 99.7% and 100.3% (RSD in %=1.0-2.0).

Gold nanoparticle mediated designing of non-hydrolytic sol-gel cross-linked metformin imprinted polymer network: a theoretical and experimental study.

A sensitive and selective electrochemical sensor based on molecularly imprinted polymers was developed for trace level detection of metformin-an antidiabetic drug. For the first time, we have applied non-hydrolytic sol-gel matrix as a cross-linking agent in the field of molecular imprinting. To create the sol-gel matrix and enhance the electro-conductivity of the proposed sensor citrate-capped gold nanoparticle were used. The morphologies and properties of the sensor were characterized by scanning electron microscopy, cyclic voltammetry, electron impedance spectroscopy, chronocoulometry and differential pulse voltammetry. Energy of the HOMO and LUMO orbitals and Müllikens atomic charges of template molecule were also calculated using density functional theory utilizing B3LYP with 3-21G-basis set. The theoretical results allied to the diagnostic criteria of the cyclic voltammetry indicate that the metformin redox mechanism is associated to the irreversible oxidation process of metformin-imino-group to N-hydroxyimino-group. The results demonstrated that the prepared sensor had excellent selectivity and high sensitivity for metformin in the linear range from 0.02 to 80 ng ml(-1) with a detection limit of 0.005 ng ml(-1) (S/N=3). The sensor was also successfully employed to detect metformin in pharmaceutical sample.

A metronidazole-probe sensor based on imprinted biocompatible nanofilm for rapid and sensitive detection of anaerobic protozoan

A novel and simple molecularly imprinted polymer (MIP) based electrochemical sensor is developed for indirect detection of anaerobic protozoans (Entamoeba histolytica and Giardia lamblia) using metronidazole (MDZ) as an electroactive probe molecule. Before electropolymerization, a computational approach was applied to screen functional monomers and polymerization solvents for rational design of a MDZ selective MIP. Based on the theoretical calculations, glutamic acid and water were found to be the best functional monomers and solvent for polymerization, respectively. A thin film of polyglutamic acid along with gold nanoparticles and MDZ was cast onto the surface of a pencil graphite electrode by cyclic voltammetry method for the fabrication of the electrochemical sensor. Surface morphology of the MDZ-imprinted polymer modified electrode was analyzed with a scanning electron microscope, whereas cyclic voltammetry, chronocoulometry and differential pulse stripping voltammetry were performed for qualitative and quantitative analysis of MDZ. The MDZ-imprinted sensor presented a linear response to MDZ in the concentration range from 9.87 ng L−1 to 130.0 mg L−1 with a limit of detection of 1.0 ng L−1 (S/N = 3). The MDZ-selective sensor was further successfully applied to the determination of anaerobic protozoans and showed high sensitivity and reproducibility (liner range from 1.6 to 1.6 × 107 CFU mL−1 with a detection limit of 2.0 CFU mL−1). The research in this study has offered a rapid, accurate and sensitive electrochemical method for quantitative determination of MDZ as well as anaerobic protozoans in a single format.

Nano-iniferter based imprinted sensor for ultra trace level detection of prostate-specific antigen in both men and women.

In this work, a sensitive and selective electrochemical sensor for detection of prostate specific antigen (PSA) was developed using surface imprinting and nanotechnology. The multiwalled carbon nanotubes (MWCNTs) decorated with manganese nanoparticles was functionalized with thio-group to make a nano-iniferter. This nano-iniferter was used as a platform to synthesize a three-dimensional molecularly imprinted polymer matrix for PSA by controlled radical polymerization technique. The PSA-sensor displayed good analytical performance for the detection of PSA by square wave and differential pulse stripping voltammetric techniques. The limit of detection was calculated as low as 0.25pgL(-1) (from SWSV) and 3.04pgL(-1) (from DPSV) at signal to noise ratio of 3. The proposed sensor was successfully applied for the determination of PSA in human blood serum, urine, and forensic samples without any cross-reactivity. Thus this sensor offers high selectivity, sensitivity, simplicity and clinical applicability for PSA determination in sera of both the men and women, which have not been reported together in the previously reported systems. The sensor may be used as a better alternative for the commercially available ELISA kits for PSA determination.

Single cell imprinting on the surface of Ag-ZnO bimetallic nanoparticle modified graphene oxide sheets for targeted detection, removal and photothermal killing of E. Coli

A very cost-effective, fast, sensitive and specific imprinted polymer modified electrochemical sensor for the targeted detection, removal and destruction of Escherichia coli bacteria was developed onto the surface of Ag-ZnO bimetallic nanoparticle and graphene oxide nanocomposite. The nanocomposite played a dual role in this work, as a platform for imprinting of bacteria as well as a participated in their laser-light induced photo killing. In terms of sensing, our proposed sensor can detect E. Coli as few as 10CFUmL-1 and capture 98% of bacterial cells from their very high concentrated solution (105CFUmL-1). Similarly to the quantitative detection, we have also investigated the quantitative destruction of E. Coli and found that 16.0cm2 area of polymer modified glass plate is sufficient enough to kill 105CFUmL-1 in the small time span of 5 minutes. The obtained results suggest that our proposed sensor have potential to serve as a promising candidate for specific and quantitative detection, removal as well as the destruction of a variety of bacterial pathogens.