Sachin Tyagi

Synthesis and characterization of highly luminescent N-doped carbon quantum dots for metal ion sensing

ABSTRACT In the present study, highly luminescent N-doped carbon quantum dots were synthesized by surface passivation of citric acid using Ethylenediamine. As synthesized NCQDs were characterized using different techniques as TEM, DLS zetasizer, UV-Visible spectroscopy and Photoluminescence spectroscopy. N-CQDs were found to have the approx 6.7 nm diameter and spherical shape as confirmed from TEM. UV-Vis absorption spectra at wavelength 350 nm (λmax = 350 nm) confirmed their formation in the solution. From photoluminescence spectroscopy, it was found these NCQDs emits at wavelength 450 nm ((λex = 350 nm, λem = 450 nm). As-synthesized N-doped CQDs were successfully used for fe3+ ion detection relying on the quenching mechanism.

Fluorescent Sensing Assay for Trinitrotoluene Using Fluorescein Isothiocyanate Conjugated Mesoporous MCM-41 Particles

In the present study, Trinitrotoluene (TNT) has been detected by the formation of Meisenheimer complex using Fluorescein isothiocyanate (FITC) dye loaded Mesoporous silica particles (MCM-41). FITC dye loaded mesoporous silica particles (MCM-41/FITC) have been synthesized using (3-Aminopropyl)trimethoxysilane, APTMS (λex = 490 nm and λem = 512 nm). TNT forms Meisenheimer complex with the amine group of APTMS present on MCM-41 particles. The loading of FITC in the pores of MCM-41 particles has been confirmed by different advanced characterization techniques. The average diameter of mesoporous MCM-41 particles was found about 130 nm. Pore volume is observed to decrease from 1.06 cm3/g to 0.49 cm3/g after FITC loading. The selective detection of TNT up to 0.1 ppb level makes MCM-41/FITC particles a potential sensing material for TNT detection.

Synthesis and characterization of RADAR absorbing BaFe12O19/NiFe2O4 magnetic nanocomposite

ABSTRACT Magnetic composite comprising nickel ferrite and barium hexaferrite; BaFe12O19/NiFe2O4 nanoparticles having super paramagnetic nature were synthesized by co-precipitation method. The resulting precursors were heat treated (HT) at 800, 1000 and 1200°C for 4 h in nitrogen atmosphere. The ‘as synthesized’ particles have size in the range of 20–22 nm with spherical shape. Further, this spherical shaped nanoparticle changes their morphology to hexagonal plate shape with increase in HT temperatures. The effect of such a systematic morphological transformation of nanoparticles on magnetic and microwave absorption properties were estimated in X band.

Surface modification of nanoscale iron carboxylate metal organic framework with polyethylene glycol

ABSTRACT MIL-101-Fe (Materials of Institute Lavoisier) metal organic framework (MOF) was synthesized by solvothermal method. Further, surface of the as prepared MIL-101-Fe is with Polyethylene glycol (PEG). FESEM and TEM micrograph of MIL-101- Fe and PEGylated MIL-101-Fe particles showed hexagonal shaped morphology with particle size in the range of 400–500 nm and 600-700 nm respectively. The DLS spectra also show the similar results. This increase in size of the particles indicates the presence of PEG layer on the surface of the MOFs. FTIR characterization was further conducted to detect the functional groups of the MIL-101(Fe) and after PEG coating. These results confirm the presence of PEG in MIL-101(Fe) framework.

Synthesis and Characterization of RADAR Absorbing BaFe12O19/ZnFe2O4 Magnetic Nanocomposite

Magnetic composite comprising zinc ferrite and barium hexaferrite; BaFe12O19/ZnFe2O4 nanoparticles having super paramagnetic nature were synthesized by co-precipitation of iron, zinc and barium chloride salts using 7.5 M sodium hydroxide solution. The resulting precursors were heat treated (HT) at 800 and 1200°C for 4 h in nitrogen atmosphere. The hysteresis loops showed an increase in saturation magnetization from 1.040 to 52.938 emu/g with increasing heat treatment (HT) temperatures. The ‘as synthesized’ particles have size in the range of 20–22 nm with spherical and needle shapes. Further, these spherical and needle shaped nanoparticles tend to change their morphology to hexagonal plate shape with increase in HT temperatures. The effect of such a systematic morphological transformation of nanoparticles on microwave absorption properties were estimated in X band (8.2–12.2 GHz). The maximum reflection loss of the composite reaches-23.12 dB (more than 99% power attenuation) at 10.46 GHz which make it a potential material in the area of stealth technology.

Synthesis and Characterization of Zinc Oxide Nanoparticles for Ethanol Detection

Pure phase, zinc oxide (ZnO) nanoparticles were synthesized at lower temperature by microwave assisted auto combustion synthesis method. As-synthesized particles had sizes ~50 nm with spherical shape. Gas responses of the nanocrystalline ZnO film were measured by exposing the film to ethanol gas vapors. It was found that the sensors exhibited various sensing responses to ethanol gas at different operating temperature. The lower limit of detection was observed to be at 170 °C for 200 ppm ethanol.

Development of Biocompatible Iron-Carboxylate Metal Organic Frameworks for pH-Responsive Drug Delivery Application

Metal organic frameworks (MOFs), MIL-101-Fe (Materials of Institute Lavoisier), have been synthesized by solvothermal method. The as-synthesized MIL-101-Fe particles are observed to have hexagonal shaped morphology with average particle size ranging from 480 to 500 nm. The functionalization of the surface of as-synthesized MIL-101-Fe particles was done with the integration of amine group into the framework to facilitate the conjugation of the drug and other entities. Further, the drug conjugated MOF particles were coated with polyethyleneglycol (PEG) layer so as to extend the drug release time by controlling the faster pH mediated MOF degradation in biological buffers. pH dependent drug release study of the MOF particles was carried out at 3 different pH values, i.e., 5, 6 and 7.4. The drug release profiles showed that the drug released from NH₂-MIL-101-Fe takes less time which was further increased after coating the NH₂-MIL-101-Fe with polyethyleneglycol (PEG@Drug@NH₂-MIL-101-Fe). This confirmed that PEG coated particles have great stability for drug delivery application.

Synthesis and Characterization of Carbon Nanotubes Doped Hydroxyapatite Nanoceramic for Orthopedic Applications

Nano-sized bioceramic hydroxyapatite (HAp) reinforced with carbon nanotubes (CNT) is synthesized using the sol–gel technique with phosphoric acid and calcium nitrate tetrahydrate as a phosphorous and calcium precursor, respectively. The ‘as synthesized’ nanocomposite powder is characterized for phase and structural analysis using X-ray diffractometry, FTIR and Raman spectroscopy. The morphological analysis of HAp/CNT nanocomposite is done using field emission scanning electron microscopy. The tribological properties including wear rate and coefficient of friction are done by coating HAp and HAp/CNT nanocomposite on implant material (SS 316L) using spin coating technique. The wear is reduced by 24.57% for HAp-coated SS316L and 29.6% for HAp-5% CNT-coated SS316 substrate. The addition of CNT in HAp matrix leads to lowering of the coefficient of friction.

Introduction to semiconductor nanomaterial and its optical and electronics properties

Semiconductor nanoparticles is an important class of nanostructured materials that have a plethora of interesting physical, chemical, mechanical, optical, and electronic, properties. This chapter provides an overview of research pertaining to various nanostructured materials in general and core–shell nanoparticles (CSNs) in particular. Different classification criteria of nanostructured materials based on their sources, dimensions, structural configurations, and nature of core/shell materials have been discussed. Semiconducting core–shell nanoparticles are segregated into different types based on the energy levels of the core and shell materials. Optical and electronic properties of CSNs along with synthesis techniques are discussed in details. Moreover, semiconductor core–shell nanostructure materials highlight the key developments and current status in fields, such as electronic, health, agricultural, food processing, sustainable energy, and environmental catalysis. This chapter covers an introduction to the field of semiconductor and core–shell nanostructures and provides comprehensive understanding to various aspects of these materials in details.

Synthesis & characterization of iron-carboxylate nanoscale metal organic frameworks for drug delivery

MIL-101-Fe (Materials of Institute Lavoisier) nanoscale-metal organic frameworks (NMOFs) were synthesized by solvothermal method with constant heating at 200°C in silicon oil bath. The as prepared MIL-101-Fe nanoparticles are observed to have particle size in the range of 200-210 nm with multiple shape morphology. Further as prepared MIL-101-Fe are functionalized by incorporating amine group into the framework. Drug loaded NMOF were coated with silica to control the rate of release of drug by avoiding rapid degradation of the NMOF in alkaline pH of PBS buffer. The drug release profile showed that the drug from MIL-101-Fe is released completely in ~32 hrs while for SiO2@Drug@ MIL-101-Fe is extended upto 75 hrs. Silica coated SiO2@Drug@ NH2-MIL-101-Fe particles had adequate stability for drug delivery application.