White light-emitting, biocompatible, water-soluble metallic magnesium nanoclusters for bioimaging applications.

Ultra-small (1.6 nm), water-soluble, white light-emitting (WLE), highly stable (∼8 months) BSA templated metallic (Mg0) nanoclusters (fluorescent magnesium nanoclusters = FMNCs) is developed using the green and facile route. Synthesis was facilitated by the reduction of magnesium salt, where template bovine serum albumin is utilized as a reducing agent and ascorbic acid act as a capping agent to impart stability in water, thereby obtaining stabilized Mg0nanoclusters In solution, stabilized Mg0nanoclusters produce white light (450-620 nm with FWHM ∼120 nm) upon 366 nm light excitation. This white light emission was found to have a CIE coordinate of 0.30, 0.33 [pure white light CIE (0.33, 0.33)]. Taking advantage of WLE and ultrasmall size, FMNCs were used forin vitrofluorescence imaging of HaCaT cell lines, yielding blue (τ= 2.94 ns, with a relative of QY = 1.2 % w.r.t QS), green (τ= 3.07 ns; relative quantum yield of 4.6% w.r.t R6G) and red (τ= 0.3 ns) images. Further, incubation of FMNCs with HEK293 (Human embryonic kidney cell) and cancerous MDA-MB-231 (Breast cancer cell line) human cell lines yielded 100 % cell viability. Current work is envisioned to contribute significantly in the area of science, engineering, and nanomedicine.

Synthesis of biocompatible, BSA capped fluorescent CaCO3 pre-nucleation nanoclusters for cell imaging applications.

Novel, photostable, multicolour fluorescent, highly biocompatible, water soluble, BSA capped pre-nucleation CaCO3 nanoclusters (FCPN) (∼1.3 nm) are developed using a facile biomineralization process. M. oleifera leaf extract and BSA protein are used as sources of ascorbic acid and capping agent, respectively. The developed FCPN shows fluorescence in the blue, green, and yellow/red region with an average life time of 1.05, 6.23 and 30.60 ns, respectively. The MALDI-MS measurements reveal that these nanoclusters are 16, 50, 73, 222 and 936 molecules big. These FCPN, when incubated (up to 7 days) with MG-63 cells, demonstrate an increase in cell viability percentage with time period as compared to their control samples. Furthermore, these incubated cells were investigated using confocal microscopy to estimate the FCPN diffusion penetration depth using CTCF analysis. It has been observed that blue and green emitting FCPN penetrated 6 µm, whereas red emitting FCPN traversed only 4 µm. The relative quantum yield (Rhodamine 6G = 0.92) of FCPN for green emission was found to be 0.0175 in water. The prepared nanoclusters displayed four months shelf-life. These FCPN were prepared using an environmentally benign, inexpensive, green synthetic route without using toxic reducing agents. Furthermore, the current report discusses the detailed results, obtained from X-ray photoelectron spectroscopy, MALDI-MS, Fourier transform infrared spectroscopy, UV-visible, fluorescence spectroscopy, lifetime measurements, electron microscopy, fluorescence microscopy and confocal microscopy.

Thermal degradation kinetics of sugarcane leaves (Saccharum officinarum L) using thermo-gravimetric and differential scanning calorimetric studies.

Pyrolysis of sugarcane (Saccharum officinarum L) leaves (SCL) has been investigated using DTA/TGA and DSC techniques. Proximate and ultimate analyses and calorific value measurement have been carried out using standard protocols. The sugar cane leaves contain 44% cellulose, 22% hemicellulose and 17% lignin. The pyrolysis have been carried out at six heating rates varying from 5 to 40 °C/min. Analysis of the pyrolysis results has been carried using iso-conversional model free methods as well as multiple linear regression method. For the fractional conversion range of 0.05-0.95, the average apparent activation energy values evaluated from iso-conversional methods have ranged from 214.9 to 239.6 kJ/mol where as in the case of multiple linear regression analysis it has ranged from 25.06 to 57.23 kJ/mol. The multi-step reaction mechanism has been investigated using the Criado method. The results of this study are useful for the design of large scale biomass thermal conversion process.