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The current work proposes a novel determination method for enantiomeric excess (ee) in (mono- and di-) amines using molecular self-assembly. A pyridine-attached binaphthyl derivative ((R)-1) exhibits fluorescence responses based on imine formation between the aldehyde group of (R)-1 and target chiral amines (i.e. cyclohexane diamine (CHDA), 2-amino-1,2-diphenylethanol (ADPE), 1,2-diphenylethylenediamine (DPDA), 1-amino-2-indanol (AID), and leucinol) in the presence of zinc(II) ions (Zn2+). Because of the multi-optical responses which are derived from the variation of chiral complexes, pattern recognition-based discrimination (i.e. linear discriminant analysis (LDA)) has been achieved for five types of enantiomeric pairs of amines. Possessing such a discrimination capability in combination with data processing (LDA and an artificial neural network) allows accurate determination (prediction error < 1.8%) of the % ee of individual targets such as CHDA which is one of the main components of pharmaceutical drugs. The simple molecular self-assembled system enabled simultaneous multi-chiral discrimination and % ee determination of unknown samples.

In therapies involving therapeutic antibodies, therapeutic drug monitoring (TDM) has the potential to substantially increase clinical efficacy and to enable more economical drug use, because the clearance from the bloodstream after administration is patient dependent. Since TDM must be performed continuously and over extended time periods, it should ideally be achieved through an economical and easy to perform point-of-care (POC) assay. Here, we introduce a new analytical method for POC TDM of the clinically important therapeutic antibody cetuximab, using microfluidic thread-based analytical devices (µTADs) as a platform for a bioluminescence resonance energy-transfer (BRET) switching sensor protein for simple quantitative antibody detection. The µTAD is pre-treated with NaCl for blood plasma separation and a BRET switching sensor protein and its substrate for cetuximab detection, integrating all elements required for a reagent-free, single-step assay. A change in bioluminescence emission color depending on cetuximab concentrations occurs after whole blood application. The device design enables the quantification of cetuximab within the therapeutically relevant blood concentration range in 2.5 min using only 2 µL of whole blood. The results obtained are independent of the blood volume. This µTAD can be stored for about one month at − 20 °C, a temperature compatible with commonly available freezers. The application of mathematical morphology recognition (MMR)-integrated image processing techniques for the automatic selection of regions of interest (ROIs) yields results with minimal error. The simplicity of use, rapidity, and cost-effectiveness of this µTAD are expected to offer the possibility of achieving TDM of therapeutic antibodies at POC for individual patients.

This manuscript reports on the application of chemometric methods for the development of an optimized microfluidic paper-based analytical device (μPAD). As an example, we applied chemometric methods for both device optimization and data processing of results of a colorimetric uric acid assay. Box-Behnken designs (BBD) were utilized for the optimization of the device geometry and the amount of thermal inkjet-deposited assay reagents, which affect the assay performance. Measurement outliers were detected in real time by partial least squares discriminant analysis (PLS-DA) of scanned images. The colorimetric assay mechanism is based on the on-device formation of silver nanoparticles (AgNPs) through the interaction of uric acid, ammonia, and poly(vinyl alcohol) with silver ions under mild basic conditions. The yellow color originating from visible light absorption by localized surface plasmon resonance of AgNPs can be detected by the naked eye or, more quantitatively, with a simple flat-bed scanner. Under optimized conditions, the linearity of the calibration curve ranges from 0.1-5 × 10 -3 mol L -1 of uric acid with a limit of detection of 33.9 × 10 -6 mol L -1 and a relative standard of deviation 4.5% (n = 3 for determination of 5.0 × 10 -3 mol L -1 uric acid). Graphical abstract A chemometrics-assisted microfluidic paper-based analytical device was developed as a low-cost and rapid platform for the determination of uric acid (UA). The detection method is based on the chemical interaction of UA, ammonia, and polyvinyl alcohol under mild basic condition with silver ions inducing formation of yellow silver nanoparticles (AgNPs).