A new microfluidic-chip device followed by sensitive image analysis of smart phone for simultaneous determination of dyes with different acidic-basic properties

On-site visual quantification of alkaline phosphatase activity in cells using a smartphone-based approach

Alkaline phosphatase (ALP) is a critical biomarker associated with various physiological and pathological processes, making its detection essential for disease diagnosis and biomedical research. In this study, we developed a novel, simple, and portable visual quantification method for ALP activity in cells using an efficient Cu0.9Zn0.1S nanomaterial with peroxidase-like properties, integrated into a smartphone-based platform for enhanced usability. The Cu0.9Zn0.1S nanomaterial catalyzes the breakdown of H₂O₂, generating ·OH radicals that oxidize the colorless substrate TMB into blue oxTMB, which is subsequently reduced back to TMB by ascorbic acid (AA). We employed an indirect colorimetric approach for ALP detection, leveraging ALP's ability to catalyze the dephosphorylation of l-ascorbic acid-2-phosphate (AAP) to produce AA. This method enabled highly sensitive and precise quantification of ALP with a detection limit of 0.47 mU/L and a linear range from 0.001 to 100 U/L. The established smartphone platform not only facilitated real-time data processing but also transformed the detection system into a portable and accessible laboratory. The method was successfully applied to detect ALP in various cancer cell lines, with the highest levels found in HepG2 cells. Moreover, the results were consistent with those obtained using traditional kit-based methods, highlighting the accuracy and reliability of our approach. The system was also applied to evaluate ALP inhibitors, demonstrating its versatility in biomedical applications. This innovative, cost-effective, and highly sensitive colorimetric sensing strategy offers immense potential for clinical diagnostics, cancer research, and inhibitor screening, particularly in on-site, resource-limited, or emergency scenarios.

Selective microextraction of erythrosine (E127) in foodstuffs using a new generation high-density type-V deep eutectic solvent

A novel and selective (deep eutectic solvent) DES-based microextraction method was established for the first time, utilizing a synthesized new generation High-Density Type-V DES for monitoring the dye Erythrosine (E127) in various foodstuffs and drugs. Type-V DES was created from acetophenone and diphenylamine at 3:1 M ratio. The pH, DES amount, and vortex time were optimized using Box-Behnken Design (BBD) of Response Surface Methodology (RSM). The quadratic microextraction model with R2 = 0.9982 was obtained. The limit of detection, preconcentration factor and linear dynamic range were determined to be 12 μg/L, 50 and 41-4000 μg/L, respectively. Effects of matrix components were examined. The developed High-Density Type-V Deep Eutectic Solvent Microextraction (HD-V-DES-ME) method was applied to foodstuffs and drugs to monitor their E127 contents and subsequently validated by applying spiked tests to real samples, with recoveries ranging between 94 and 101 %. The indexes of environmental friendliness and practicality for the method were evaluated using the Analytical GREEnness metric approach tool (AGREE) and the Blue Applicability Grade Index tool (BAGI), respectively.

Portable sensing of hydrogen peroxide using MOF-based nanozymes

Hydrogen peroxide (H2O2) is extensively used in water treatment and food preservation for its pathogen-killing efficacy. Excessive H2O2 intake, however, can lead to poisoning with symptoms such as abdominal pain and breathing difficulties. Additionally, small amounts of H2O2 may be generated during food preservation, necessitating careful control to meet safety regulations. Real-time detection of H2O2 is crucial for process safety and compliance. In this study, a Zr-MOF-based colorimetric fluorescent nanozyme sensor (NH2-UiO-67(Zr/Cu)) along with a smartphone-assisted portable device were developed for detecting H2O2. The sensor, NH2-UiO-67(Zr/Cu), combines the stable structural properties of Zr-MOF with ligand-generated fluorescence and exhibits peroxidase-like activity. The sensor demonstrated a detection range of 0-1000 μM, with limits of detection (LOD) of 0.0057 μM for the colorimetric assay and 0.0020 μM for the fluorescence assay. Additionally, we designed and developed a portable, smartphone-assisted device using 3D printing technology. This device offers a detection range of 0-750 μM, with LODs of 0.0093 μM in colorimetric mode and 0.0311 μM in fluorescence mode. The developed colorimetric fluorescent nanozyme sensor and portable device show significant potential for the rapid on-site detection of H2O2, offering a more convenient and reliable approach for quick identification of analytes in practical applications.

Electroextraction of Large Volume Samples Using Paper Points Coupled With Hollow Fiber Membranes: Study of Parameters and Strategies to Enhance Analytical Performance

Electroextraction (EE) encompasses a range of sample preparation methods whose effectiveness, selectivity, and efficiency are significantly influenced by the physical-chemical characteristics of analytes, samples, and instrumental conditions. This article explores, for the first time, various strategies aimed at enhancing the extraction efficiency of a recent approach of EE utilizing a paper point (PP) combined with a hollow fiber (HF) (abbreviated as PP-HF-EE) to extract various cationic and anionic model compounds from water samples. The study also explores, experimentally, the impact of agitation, organic filter composition, PP diameter, and PP brand on extraction performance, and proves that all these factors are quite important, especially when digital image analysis is utilized for determination. Furthermore, this work demonstrates the ease and feasibility of simultaneously extracting cations and anions using PP-HF-EE and proposes a straightforward method to enhance analyte concentration on the vertex of the PP through a base-to-vertex focusing. Lastly, it is demonstrated, using capillary electrophoresis coupled to a UV-Vis detector, that for PP-HF-EE, the extraction efficiency and pre-concentration factor are less dependent on other parameters when multiple PPs per sample are utilized, with signal enhancement values of up to 111 and 339 for nortriptyline and haloperidol, respectively. All the findings and strategies presented herein constitute significant contributions that can facilitate future research in method development, particularly in the utilization of PP-HF-EE and similar EE approaches.

Electroextraction of methylene blue from aqueous environmental samples using paper points coupled with hollow fiber membranes

This article introduces a novel approach by coupling paper points with hollow fiber membrane for electroextraction (PP-HF-EE). The method was innovatively applied to extract methylene blue (MB) from large water volumes (up to 580 mL). A comprehensive study of six key parameters - organic filter, acceptor and donor phase composition, extraction time, applied voltage, and sample volume - was conducted using conventional flatbed scanning and digital image analysis. Our results revealed that extraction performance was primarily influenced by time, with low voltages (50 V) and low-conductivity organic filters (1-decanol) yielding comparable results to higher settings (300 V or 1-pentanol). Under optimized conditions (50 V, 60 min, 1-decanol as the organic filter), analytical performance parameters were assessed, demonstrating acceptable precision (RSD <18% for intra- and inter-day measurements) within a linear range of 5-100 μg L-1 (r = 0.98). PP-HF-EE demonstrated reliability through stable and reproducible electric current measurements during all extraction studies. Utilizing an extremely cost-effective detection system, PP-HF-EE achieved detection limits in the low ppb range, highlighting its potential as a promising variation of electromembrane extraction for environmental sample analysis.

Multiphase electroextraction of malachite green from surface water and its determination using digital imaging and chemometric tools

This study introduces a novel method for the quantification of malachite green (MG), a pervasive cationic dye, in surface water by synergizing multiphase electroextraction (MPEE) with digital image analysis (DIA) and partial least square discriminant analysis. Aimed at addressing the limitations of conventional DIA methods in terms of quantitation limits and selectivity, this study achieves a significant breakthrough in the preconcentration of MG using magnesium silicate as a novel sorbent. Demonstrating exceptional processing efficiency, the method allows for the analysis of 10 samples within 20 min, exhibiting remarkable sensitivity and specificity (over 0.95 and 0.90, respectively) across 156 samples in both training and test sets. Notably, the method detects MG at low concentrations (0.2 µg L-1) in complex matrices, highlighting its potential for broader application in environmental monitoring. This approach not only underscores the method's cost-effectiveness and simplicity but also its precision, making it a valuable tool for the preliminary testing of MG in surface waters. This study underscores the synergy among MPEE, DIA, and chemometric tools, presenting a cost-efficient and reliable alternative for the sensitive detection of water contaminants.

3D-printed stereolithographic fluidic devices for automatic nonsupported microelectromembrane extraction and clean-up of wastewater samples

BACKGROUND

There is a quest of novel functional and reliable platforms for enhancing the efficiency of microextraction approaches in troublesome matrices, such as industrial wastewaters. 3D printing has been proven superb in the analytical field to act as the springboard of microscale extraction approaches.

RESULTS

In this work, low-force stereolithography (SL) was exploited for 3D printing and prototyping bespoke fluidic devices for accommodating nonsupported microelectromembrane extraction (μEME). The analytical performance of 3D-printed μEME devices with distinct cross-sections, including square, circle, and obround, and various channel dimensions was explored against that of commonly used circular polytetrafluoroethylene (PTFE) tubing in flow injection systems. A computer-controlled millifluidic system was harnessed for the (i) automatic liquid-handling of minute volumes of donor, acceptor, and organic phases at the low μL level that spanned from 3 to 44 μL in this work, (ii) formation of three-phase μEME, (iii) in-line extraction, (iv) flow-through optical detection of the acceptor phase, and (v) solvent removal and regeneration of the μEME device and fluidic lines. Using methylene blue (MB) as a model analyte, experimental results evinced that the 3D-printed channels with an obround cross-section (2.5 mm × 2.5 mm) were the most efficient in terms of absolute extraction recovery (59%), as compared to PTFE tubing of 2.5 mm inner diameter (27%). This is attributed to the distinctive convex interface of the organic phase (1-octanol), with a more pronounced laminar pattern, in 3D-printed SL methacrylate-based fluidic channels against that of PTFE tubing on account of the enhanced 1-octanol wettability and lower contact angles for the 3D-printed devices. The devices with obround channels were leveraged for the automatic μEME and in-line clean-up of MB in high matrix textile dyeing wastewater samples with relative recoveries ≥81%, RSD% ≤ 17.1% and LOD of 1.3 mg L-1. The 3D-printed nonsupported μEME device was proven superb for the analysis of wastewater samples with an elevated ionic strength (0.7 mol L-1 NaCl, 5000 mg L-1 Na2CO3, and 0.013 mol L-1 NaOH) with recorded electric currents below 12 μA.

NOVELTY

The coupling of 3D printing with nonsupported μEME in automatic flow-based systems is herein proposed for the first time and demonstrated for the clean-up of troublesome samples, such as wastewaters.

Electromembrane extraction of peptides based on hydrogen bond interactions

BACKGROUND

Electromembrane extraction (EME) of peptides reported in the scientific literature involve transfer of net positively charged peptides from an aqueous sample, through a liquid membrane, and into an aqueous acceptor solution, under the influence of an electrical field. The liquid membrane comprises an organic solvent, containing an ionic carrier. The purpose of the ionic carrier is to facilitate peptide solvation in the organic solvent based on ionic interactions. Unfortunately, ionic carriers increase the conductivity of the liquid membrane; the current in the system increases, the electrolysis in sample and acceptor is accelerated, and the extraction system tend to be unstable and suffers from drifting pH.

RESULTS

In the present work, a broad selection of organic solvents were tested as pure liquid membrane for EME of peptides, without ionic carrier. Several phosphates provided high mass transfer, and tri(pentyl) phosphate was selected since this solvent also provided high operational stability. Among 16 different peptides used as model analytes, tri(pentyl) phosphate extracted those with net charge +1 and with no more than two polar side chains. Tri(pentyl) phosphate served as a very strong hydrogen bond acceptor, while the protonated peptides were hydrogen bond donors. By such, hydrogen bonding served as the primary interactions responsible for mass transfer. Tri(pentyl) phosphate as liquid membrane, could exhaustively extract leu-enkephalin, met-enkephalin, and endomorphin from human blood plasma and detected by LC-MS/MS. Calibration curves were linear (r² > 0.99) within a concentration range from 1 to 500 ng/mL, and a relative standard deviation within 12% was observed for precision studies.

SIGNIFICANCE

The current experiments are important because they indicate that small peptides of low polarity may be extracted selectively in EME based on hydrogen bond interactions, in systems not suffering from electrolysis.

Environmental Applications of Electromembrane Extraction: A Review

Electromembrane extraction (EME) is a miniaturized extraction technique that has been widely used in recent years for the analysis and removal of pollutants in the environment. It is based on electrokinetic migration across a supported liquid membrane (SLM) under the influence of an external electrical field between two aqueous compartments. Based on the features of the SLM and the electrical field, EME offers quick extraction, effective sample clean-up, and good selectivity, and limits the amount of organic solvent used per sample to a few microliters. In this paper, the basic devices (membrane materials and types of organic solvents) and influencing factors of EME are first introduced, and the applications of EME in the analysis and removal of environmental inorganic ions and organic pollutants are systematically reviewed. An outlook on the future development of EME for environmental applications is also given.