Study of the Fabrication Technology of Hybrid Microfluidic Biochips for Label-Free Detection of Proteins

A study of the peculiarities and a comparative analysis of the technologies used for the fabrication of elements of novel hybrid microfluidic biochips for express biomedical analysis have been carried out. The biochips were designed with an incorporated microfluidic system, which enabled an accumulation of the target compounds in a biological fluid to be achieved, thus increasing the biochip system’s sensitivity and even implementing a label-free design of the detection unit. The multilevel process of manufacturing a microfluidic system of a given topology for label-free fluorometric detection of protein structures is presented. The technological process included the chemical modification of the working surface of glass substrates by silanization using (3-aminopropyl) trimethoxysilane (APTMS), formation of the microchannels, for which SU-8 technologies and a last generation dry film photoresist were studied and compared. The solid-state phosphor layers were deposited using three methods: drop application; airbrushing; and mechanical spraying onto the adhesive surface. The processes of sealing the system, installing input ports, and packaging using micro-assembly technologies are described. The technological process has been optimized and the biochip was implemented and tested. The presented system can be used to design novel high-performance diagnostic tools that implement the function of express detection of protein markers of diseases and create low-power multimodal, highly intelligent portable analytical decision-making systems in medicine.

Green Chemical Synthesis of N-Cholyl-L-Cysteine Encapsulated Gold Nanoclusters For Fluorometric Detection of Mercury Ions

Here we report a simple, single-step, cost-effective, environmentally friendly, and biocompatible approach using sodium salt of N-cholyl-L-cysteine (NaCysC) capped gold nanoclusters (AuNCs) with green emission properties at above the CMC in aqueous medium under UV-light irradiation. The primary and secondary CMC of NaCysC was found to be 4.6 and 10.7 mM respectively using pyrene as fluorescent probe. The synthesized AuNCs exhibit strong emission maxima at 520 nm upon excitation of 375 nm with a large Stokes shift of 145 nm. The surface functionality and morphology of NCs are studied by Fourier transform infrared spectroscopy, dymanic light scattering studies and transmission electron microscopy. The formation of AuNCs was completed within 5 h and exhibit high stability for more than 6 months. The NaCysC templated AuNCs selectively quenches the Hg2+ ions with higher sensitivity in aqueous solution over the other metal ions. The fluorescence analysis of Hg2+ showed a wide linear range from 15 to 120 µM and a detection limit was found to be 15 nM.

Solvent Controlled Colorimetric And Fluorometric Detection of Fe2+ and Cu2+ Ions By Naphthaldimine-Glucofuranose Conjugate

The sensing properties of naphthaldimine-glucofuranose conjugates 1 and 2 towards metal ions were investigated by 1H NMR titration, FTIR, absorbance, and fluorescence spectroscopic methods. The absorbance and fluorescence studies indicated that compound 1 formed coordination with Fe2+ and Cu2+ ions in DMSO through color changes yellow to brown and colorless, respectively. The Job's plots using absorbance data showed metal-ligand binding ratio is 1:1 for both cases. The formation of 1-Fe2+ and 1-Cu2+ complexes have been analyzed by absorption and emission spectroscopy, high-resolution mass spectrometry (HRMS) data, FTIR, 1H NMR titration experiment, and DFT calculations. The detection limits of naphthaldimine sugar conjugate 1 towards Fe2+/Cu2+ were calculated from UV-vis and fluorescence data according to the standard method. The sugar-naphthaldimine conjugate 2 has been used to establish the binding mode of 1 with Fe2+ or Cu2+ ions in DMSO.