Label-free quantum dot conjugates for human protein IL-2 based on molecularly imprinted polymers

Abstract

Herein, the development of a fluorescent-based sensor by combining quantum dots (QDs) with molecularlyimprinted technology (MIT), intensively optimized to generate exceptional operating features is presented. This sensor is designed to target human interleukin-2 (IL-2) in synthetic human serum. IL-2 is a regulatory protein released as a triggered response from the immune system towards an inflammation.For this purpose, cadmium telluride (CdTe) QDs are prepared with 3-mercaptopropionic acid (MPA) and modified afterwards to produce an IL-2 imprinted polymer with methacrylic acid and N,N´-methylenebis(acrylamide), upon removal of the template under optimized conditions. During IL-2 rebinding, the fluorescence intensity of CdTe@MPA QDs is quenched in a concentration dependent manner. Using surface imprinting technology, the optimal fluorescence signals yielded a linear response versus logarithm of IL-2 concentration from 35 fg/ml to 39 pg/ml, in a 1000-fold diluted synthetic human serum. The limit of detection obtained is 5.91 fg/ml, lying below the concentration levels of IL-2 with clinical interest for cancer diagnosis (9.4-19.2 pg/ ml).Overall, the method presented herein is a demonstration that the combination of MIP and QDs for protein detection constitutes a powerful tool in clinical analysis, providing low cost, sensitive and quick responses. The same concept may be further extended to other proteins of interest.

The Recent Advances of Fluorescent Sensors Based on Molecularly Imprinted Fluorescent Nanoparticles for Pharmaceutical Analysis

“…As the same synthetic approach to the small molecules, a MIFN sensor was designed by using CdTe QDs, human interleukin-2 (IL-2), MAA and MBA as fluorescent sources, template, functional monomer and crosslinker, respectively. This sensor recognized and determined IL-2 in synthetic human serum with an LOD of 5.91 fg/mL, which was below the concentration levels of IL-2 with clinical interest for cancer diagnosis (9.4-19.2 pg/mL) [64] .…”

Imprinted Fluorescent Cellulose Membranes for the On-Site Detection of Myoglobin in Biological Media

“…3-Mercaptopropionicacid-capped cadmium telluride QDs, CdTe@MPA QDs, and the correspondent imprinted conjugates MIP@QDs and nonimprinted conjugates NIP@QDs were prepared by FRP. The protein Myo was imprinted on the surface of raw QDs in PBS 10 mM, pH 6.4, according to a previous protocol . Briefly, 5.36 × 10 –6 M of raw CdTe@MPA QDs were modified by the active ester method through reaction with freshly prepared solutions of N-(3-dimethylaminopropyl)-N′-ethylcarbodiimide (1.59 × 10 –6 M) and N-hydroxy succinimide (7.15 × 10 –6 M) in PBS 10 mM, pH 6.4, 30 min r.t. After centrifugation and discarding the supernatant, Myo solution (5.50 × 10 –5 M) was added and incubated with AEMH·HCl (1.51 × 10 –5 M), 1 h (r.t.) in PBS 10 mM, pH 6.4.…”

“…The imprinting process can be performed in both 3D and 2D levels, but the major difficulty arises in the removal of the protein templates after polymerization. To address this problem, three solutions are possible, namely, (i) surface imprinting, − (ii) epitope imprinting, and (ii) solid-phase approach …”

Photoactivated cell-killing amino-based flavylium compounds

“…Based on the absorbance maxima of the different compounds (Fig. S2 ), the measurement of the quantum yield (QY) of the synthesized flavylium derivatives was performed using a calibrated Quantaurus-QY stand-alone integrating sphere setup C11347-11 (Hamamatsu Photonics, Hamamatsu, Japan) equipped with an integration sphere, a monochromator, a spectrograph, a 150 W xenon light source and a silicon charge coupled device 16 . Each compound was dissolved in DMSO and diluted to ensure an absorbance of 0.1 from the λ max of excitation forward.…”