Calorimetry is a label-free technique that can provide valuable insight into the thermodynamics of drug binding important to drug design and development. Nonetheless, conventional isothermal titration calorimetry is not used in highthroughput drug screening campaigns due to its high sample consumption and limited throughput. In previous work, we demonstrated an optical analog that involves measurements of the spectral reflectance of thermochromic liquid crystal (TLC) particles, and employs microfluidics to enable rapid measurement of reaction enthalpy in sub-nanoliter aqueous droplets. To optimize system performance, we have evaluated mixing of reactants in droplets with a custom-fabricated microfluidic chip. In addition, we constructed a large area illuminator and dichroic detection blocks to scale to multiple detection points along the droplet travel direction to probe the droplet temperature at several time points. Our platform’s current temperature resolution of 3 mK is on the same order as commercial ITCs and 10-fold better than most nanocalorimeters. This label-free microfluidic calorimeter with scalable optical read-out has the potential to accelerate the process of drug discovery in high-throughput screening campaigns.
Infrared photothermal heterodyne imaging (IR-PHI) is an established all-optical, table-top approach for conducting super-resolution mid-infrared microscopy and spectroscopy on submicrometer-sized particles. The instrument’s capabilities are highlighted by its ability to operate in spectroscopically-crowded environments. This includes specimens obtained from environmental matrices where particulates with different morphologies, chemical compositions, and abundances exist. Here, proof-of-concept IR-PHI measurements have been conducted on anthropogenic micro- and nanoplastics (MNPs) derived from the breakdown of consumer products. In particular, IR-PHI is used to characterize MNPs extracted from steeped plastic teabags and floor dust from a household vacuum. IR-PHI results reveal the presence of complex MNP structures made of polyamide fibers and acrylonitrile butadiene styrene MNPs.
Infrared photothermal heterodyne imaging (IR-PHI) represents a convenient, table top approach for conducting super-resolution imaging and spectroscopy throughout the all-important mid infrared (MIR) spectral region. Although IR-PHI provides label-free, super-resolution MIR absorption information, it is not quantitative. In this study, we establish quantitative relationships between observed IR-PHI signals and relevant photothermal parameters of investigated specimens. Specifically, we conduct a size series analysis of different radii polystyrene (PS) beads to quantitatively link IR-PHI signal contrast to specimen heat capacity, thermo-optic coefficient, MIR peak absorption cross-section, and scattering cross-section at IR-PHI’s probe wavelength.
The paper reports synthesis and co-crystallization of 5 co-crystal of 4-nitrophenol (4N) with five different monoand diaminopyridines (4-aminopyridine (4AP); 3,4-diaminopyridine (34DAP); 2-amino-6-methylpyridine (26MAP); 2,6- diaminopyridine (26DAP); 2-aminopyridine (2AP)) resulted in five adducts with the molar ratio of components 2:1 in final compounds. X-ray analysis confirms the non-centrosymmetric packing of obtained compounds. Two compounds crystallize in the polar acentric P21 and three compounds crystallize in acentric orthorhombic Pna21 space groups. The comparative studies on the laser induced multiple and single shot damage thresholds of named crystals were carried out using radiation of 1064 nm from Nd:YAG laser with pulse width 10 ns. Obtained results show good laser-induced singleshot and multiple-shot damage threshold values for all studied co-crystals and are found up to 3.64 GW/cm2 and 1.77 GW/cm2 respectively.
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