Understanding sensitivity and cross-reactivity of xylazine lateral flow immunoassay test strips for drug checking applications

The continued prevalence of xylazine in the illicit drug market has necessitated development of quick and simple methods for identification, including lateral flow immunoassays (also known as "test strips"), like those frequently used to detect fentanyl. This study explored the drug checking applicability of the first publicly available xylazine test strips (XTS) using four sub-studies: reproducibility (i.e., consistency of positive results in a highly-concentrated xylazine solution); limit of detection on a calibration curve of xylazine concentrations; cross-reactivity against 77 commonly encountered drugs, cutting agents, and other structurally similar compounds; and applicability for analyzing community-acquired samples-where 100 drug residue samples were analyzed using XTS, direct analysis in real time mass spectrometry (DART-MS), and gas chromatography tandem mass spectrometry (GC-MS/MS). XTS consistently detected xylazine at concentrations ≥2.5 μg/ml, and XTS results were reproducible. Sensitivity and specificity of XTS were calculated by comparing expected versus obtained results based on xylazine concentration of community-acquired samples measured by GC-MS/MS. XTS consistently detected xylazine in samples with concentration >2 μg/ml and yielded a sensitivity of 0.974, specificity of 1.00, and overall accuracy of 0.986. Cross-reactivity with lidocaine, a common cutting agent, and lack of XTS reactivity with other α2 -agonists found in the illicit drug supply highlight the need to offer consumers comprehensive drug checking services that identify a range of substances and better inform them about drug contents.

Development of Colloidal Gold Test Strips for the Detection of Triadimenol Residues in Tobacco

The rapid and accurate determination of triadimenol residues is of great significance. In this study, based on the advantages of high efficiency, rapidity, reliability, simplicity and low cost of immunology, a test strip product for the rapid detection of triadimenol residues in tobacco was designed based on the optimization of conditions such as pH and dosage of diluent, concentration of antibody stock solution, type of confining solution and complex solution, with high specificity, accuracy and The results of 20 samples of fresh and first roasted tobacco were all consistent with the method of gas chromatography, which proved the reliability of the test strips. The detection limit for fresh and roasted tobacco was 5 mg/kg, and the test strips developed in this study are suitable for mass testing of tobacco samples in tobacco-related laboratories because of their short detection time, simple pre-treatment and detection methods, and good application prospects.

Establishment of a Colloidal Gold Immunochromatographic Method for the Detection of Cypermethrin in Tobacco

In this study, the establishment of a colloidal gold immunochromatographic method for the detection of cypermethrin in tobacco was achieved by using colloidal gold immunochromatography: strong specificity and high sensitivity of cypermethrin semi-antigens and encapsulants were prepared during the study. The best colloidal gold solution was prepared by spectrophotometer and transmission electron microscope screening; the preparation process of gold-labeled antibodies was optimized, and finally the product of colloidal gold rapid detection test strips for cypermethrin was developed. The results of technical parameters and detection indexes showed that the detection limit of cypermethrin in tobacco was 1 mg/kg, and there was no cross-reaction with bifenthrin, cypermethrin, cyfluthrin and phenothrin, and the detection results of 30 tobacco samples were consistent with those of gas chromatography.

Development of Colloidal Gold Test Strips for the Detection of Oxamyl Residues in Tobacco

In this study, monoclonal antibodies against oxamyl were prepared, and colloidal gold immunochromatography was used to design a rapid test strip product for the detection of oxamyl in tobacco with high specificity, accuracy and stability without cross-reactivity to commonly used tobacco fungicides based on the optimization of conditions such as pH value of diluent, diluent dosage, concentration of antibody marker, type of confining solution and complex solution. 5 The results of five samples of post-harvest ready-to-bake tobacco and first-harvest tobacco were consistent with the gas chromatographic method, which proved the reliability of the test strips. The limits of detection for the post-harvest and first-harvest tobacco samples were 0.1 mg/kg, and the test strips developed in this study are suitable for mass testing in tobacco laboratories with good application prospects because of their short detection time, simple pre-treatment and detection methods.

Rapid detection of grass carp reovirus type 1 using RPA-based test strips combined with CRISPR Cas13a system

Introduction

Due to the existence of grass carp reovirus (GCRV), grass carp hemorrhagic disease occurs frequently, and its high pathogenicity and infectivity are great challenges to the aquaculture industry. As a highly pathogenic pathogen, the outbreak of hemorrhagic disease often causes tremendous economic losses. Therefore, it is important to rapidly and accurately detect GCRV on site to control timely.

Methods

In this study, recombinant enzyme amplification (RPA) combined with clustered regularly interspaced short palindromic repeats (CRISPR)/Cas13a system was employed to establish a method to detect the vp7 gene of grass carp reovirus type 1. This method can be adopted for judging the results by collecting fluorescence signal, ultraviolet excitation visual fluorescence and test strip.

Results

Combined with the RPA amplification experiment, the detection limit of the RPA-CRISPR method can reach 7.2 × 101 copies/μL of vp7 gene per reaction, and the detection process can be completed within 1 h. In addition, this method had no cross-reaction with the other 11 common aquatic pathogens. Then, the performance of the RPA-CRISPR/Cas13a detection method was evaluated by comparing it with the real-time fluorescence quantitative PCR detection method of clinical samples. The results of RPA-CRISPR/Cas13a detection were shown to be in consistence with the results obtained from the real-time fluorescence quantitative PCR detection. The coincidence rate of this method with 26 GCRV clinical samples was 92.31%.

Discussion

In summary, this method has high sensitivity, specificity and on-site practicability for detecting GCRV type 1, and has great application potential in on-site GCRV monitoring.

Electrochemistry Test Strip as Platform for In Situ Detection of Blood Levels of Antipsychotic Clozapine in Finger-Pricked Sample Volume

With the increasing number of patients suffering from Parkinson's disease, the importance of measuring drug levels in patient body fluids has increased exponentially, particularly for the drug clozapine. There is a growing demand for real-time analysis of biofluids on a single low-cost platform in ultra-low fluid volumes with robustness. This study aims to measure the level of clozapine (Clz) with a portable potentiostat using a practical approach. For this purpose, we developed an inexpensive, portable platform via electrochemistry on a commercial glucose test strip (CTS). CTSs were first modified by removing the enzyme mixture from the surface of the sensing zone, which was followed by modification with Multi walled carbon nanotube (MWCNT) and Nafion. The electrochemical characteristics of CTS electrodes were investigated using cyclic voltammetry (CV) and differential voltammetry (DPV) techniques. The designed sensor displayed decent linear range, detection limit, reproducibility, and reusability results. A linear dynamic range of 0.1-5 μM clozapine was observed under optimized conditions with a good sensitivity (1.295 μA/μM) and detection limit (83 nM). Furthermore, the designed sensing electrode was used to measure the amount of Clz in real samples.

A Highly Sensitive and Selective Fluorescein-Based Cu2+ Probe and Its Bioimaging in Cell

Copper is a vital trace metal in human body, which plays the significant roles in amounts of physiological and pathological processes. The application of copper-selective probe has attracted great interests from environmental tests to life process research, yet a few of sensitive Cu²⁺ tests based on on-site analysis have been reported. In this paper, a novel fluorescein-based fluorescent probe N4 was designed, synthesized, and characterized, which exhibited high selectivity and sensitivity to Cu²⁺ comparing with other metal ions in ethanol–water (1/1, v/v) solution. The probe N4 bonded with Cu²⁺ to facilitate the ring-opening, and an obvious new band at 525 nm in the fluorescence spectroscopy appeared, which could be used for naked-eye detection of Cu²⁺ within a broad pH range of 6–9. Meanwhile, a good linearity between the fluorescence intensity and the concentrations of Cu²⁺ ranged 0.1–1.5 eq. was observed, and the limit of detection of N4 to Cu²⁺ was calculated to be as low as 1.20 μm. In addition, the interaction mode between N4 and Cu²⁺ was found to be 1:1 by the Job's plot and mass experiment. Biological experiments showed that the probe N4 exhibited low biological toxicity and could be applied for Cu²⁺ imaging in living cells. The significant color shift associated with the production of the N4-Cu²⁺ complex at low micromolar concentrations under UV light endows N4 with a promising probe for field testing of trace Cu²⁺ ions.

Lateral Flow Immunoassay of SARS-CoV-2 Antigen with SERS-Based Registration: Development and Comparison with Traditional Immunoassays

The current COVID-19 pandemic has increased the demand for pathogen detection methods that combine low detection limits with rapid results. Despite the significant progress in methods and devices for nucleic acid amplification, immunochemical methods are still preferred for mass testing without specialized laboratories and highly qualified personnel. The most widely used immunoassays are microplate enzyme-linked immunosorbent assay (ELISA) with photometric detection and lateral flow immunoassay (LFIA) with visual results assessment. However, the disadvantage of ELISA is its considerable duration, and that of LFIA is its low sensitivity. In this study, the modified LFIA of a specific antigen of the causative agent of COVID-19, spike receptor-binding domain, was developed and characterized. This modified LFIA includes the use of gold nanoparticles with immobilized antibodies and 4-mercaptobenzoic acid as surface-enhanced Raman scattering (SERS) nanotag and registration of the nanotag binding by SERS spectrometry. To enhance the sensitivity of LFIA-SERS analysis, we determined the optimal compositions of SERS nanotags and membranes used in LFIA. For benchmark comparison, ELISA and conventional colorimetric LFIA were used with the same immune reagents. The proposed method combines a low detection limit of 0.1 ng/mL (at 0.4 ng/mL for ELISA and 1 ng/mL for qualitative LFIA) with a short assay time equal to 20 min (at 3.5 h for ELISA and 15 min for LFIA). The results obtained demonstrate the promise of using the SERS effects in membrane immuno-analytical systems.

Comparative Assessment of Different Gold Nanoflowers as Labels for Lateral Flow Immunosensors

Many studies have found that gold nanoparticles with branched surfaces (nanoflowers) are markers for immunosensors that provide higher sensitivity gains than the commonly used spherical gold nanoparticles. Although the analytical characteristics of nanoparticle-using systems vary significantly depending on their size and shape, the question of choosing the best gold nanoflowers remains open. This work presents a comparative study of a panel of 33 preparations of gold nanoflowers formed by varying several parameters: the size of spherical nanoparticles-nuclei, the concentrations of nuclei, and tetrachloroauric acid during growth. The sizes of the resulting particles, their sorption capacity under antibody immobilization, mobility along membranes for lateral flow assays, and the effects of these parameters on the limits of detection of lateral flow immunoassay are characterized. The optimality of preparations obtained by growing a 0.2% v/v solution of nuclei with a diameter of 10 or 20 nm with tetrachloroauric acid at a concentration of 0.12 mM was shown. With their use, lateral flow immune tests were developed to determine markers of acute myocardial infarction-fatty acids binding protein and troponins I and T. The use of gold nanoflowers obtained under the proposed protocols led to significant gains in the limits of detection-3 to 10 times under visual detection and over 100 times under instrumental detection-compared to spherical gold nanoparticles. The significant increase under instrumental detection is due to the label's low nonspecific binding.

1,2,4-Triaminobenzene as a Fluorescent Probe for Intracellular pH Imaging and Point-of-Care Ammonia Sensing

As one of the health indicators, intracellular pH plays important roles in many processes of cell functions. Abnormal pH changes would result in the occurrence of inflammation, cancer, and other diseases. Thus, it is of significant importance to develop effective techniques for sensitive detection of pH changes for the clinical diagnosis of various diseases related to cells. In this paper, 1,2,4-triaminobenzene hydrochloride was explored as an organic molecular fluorescent probe for sensitive and selective detection of intracellular pH changes for the first time. Due to the protonation and deprotonation of amino groups of the probe, its fluorescent intensity at 599 nm or the ratio of absorbance at 505 and 442 nm has a good linear relationship with pH values in the range of 5.0-7.0. Benefiting from the excellent physical and chemical properties of 1,2,4-triaminobenzene hydrochloride, the fluorescent probe has good water solubility, low toxicity, high photostability, great reversibility, good cell penetration, fast response speed, and so on. As a proof-of-concept demonstration, the proposed probe is employed for the fluorescence imaging of cells and mouse tissue sections with satisfactory performance in pH differentiation. Additionally, the probe was successfully employed to prepare test strips as a kind of point-of-care testing device to detect ammonia, which showed great potential in practical applications.

Water-soluble AIE-active Fluorescent Organic Nanoparticles: Design, Preparation and Application for Specific Detection of Cyanide in Water and Food Samples

A dilactosyl-dicyanovinyl-functionalized tetraphenylethene (TPELC) was designed, synthesized and used for ratiometric sensing of cyanide. TPELC was comprised of three moieties (tetraphenylethylene, dicyanovinyl group and lactose unit) in one molecule, making TPELC water-soluble and aggregation-induced emission (AIE)-active and selectively reactive to cyanide. Compared with other reported fluorescent probes containing dicyanovinyl group, TPELC is the first AIE luminogen to be assembled as fluorescent organic nanoparticles (FONs) for sensing of cyanide in water without the use of surfactant or the help of organic solvents based on the nucleophilic addition reaction. The detection mechanism was verified by liquid chromatograph mass spectrometry experiments and by protonation of cyanide to reduce the nucleophilicity of cyanide. In addition, TPELC was used for detection of the cyanide content of food samples and test strips were developed to simplify the detection procedure.

A Coumarin-Based Fluorescent Probe for Ratiometric Detection of Cu2+ and Its Application in Bioimaging

The fluorescent probe L, based on naphthalimide-modified coumarin, was designed, synthesized, and characterized, which could recognize Cu2+ from other cations selectively and sensitively in HEPES buffer (10 mM, Ph = 7. 4)/CH3CN (1:4, V/V). When the probe L interacted with Cu2+, the color and the fluorescent intensity changed obviously and it provided the naked-eye detection for Cu2+. The recognition mode between them was achieved by Job's plot, IR, MS, SEM, and 1HNMR. In addition, test strips made from L could still interact with Cu2+ in tap water effectively. The limit of detection (LOD) of L was 3.5 × 10-6 M. Additionally, the density functional theory (DFT) calculation method was used to analyze the action mechanism of L toward Cu2+. Importantly, the fluorescent probe L could demonstrate favorable selectivity toward Cu2+ in Caenorhabditis elegans. Thus, L was considered to have some potential for application in bioimaging.

A Fluorescent and Colorimetric Chemosensor for Hg2+ Based on Rhodamine 6G With a Two-Step Reaction Mechanism

A fluorescent and colorimetric chemosensor L based on rhodamine 6G was designed, synthesized, and characterized. Based on a two-step reaction, the chemosensor L effectively recognized Hg²⁺. The interaction between the chemosensor and Hg²⁺ was confirmed by ultraviolet–visible spectrophotometry, fluorescence spectroscopy, electrospray ionization–mass spectrometry, Fourier-transform infrared spectroscopy, and frontier molecular orbital calculations. The chemosensor L was also incorporated into test strips and silica gel plates, which demonstrated good selectivity and high sensitivity for Hg²⁺.

Accuracy of a blood glucose monitoring system that recognizes insufficient sample blood volume and allows application of more blood to the same test strip

Background: Self-monitoring of blood glucose (SMBG) can play a key role in diabetes management. The CONTOUR®NEXT ONE (Ascensia Diabetes Care, Parsippany, NJ, USA) blood glucose monitoring system (BGMS) has been developed for use with CONTOUR®NEXT test strips. The meter connects to the CONTOUR™ Diabetes application on a mobile device, and the Second-Chance® sampling feature recognizes insufficient sample volume, prompting the patient to apply more blood to the same strip if needed (sample re-application).Research design and methods: Two studies evaluated CONTOUR®NEXT ONE BGMS accuracy with sample re-application: a laboratory study (performance under various controlled conditions) and a clinical study (performance in the hands of 52 people with diabetes). A formal International Organization for Standardization (ISO) evaluation has been reported previously; here, accuracy criteria in the laboratory and clinical studies were aligned with ISO 15197:2013 sections 6.3.3 and 8.2, respectively.Results: All results under all conditions in the laboratory study, and with glucose concentrations <100 and ≥100 mg/dL in the clinical study, were within ±15 mg/dL or ±15% of reference measurements. In both studies, all results were within Zone A of the Parkes-Consensus Error Grid.Conclusions: These data demonstrate that the accuracy of the CONTOUR®NEXT ONE BGMS was maintained with sample re-application.

A Highly Selective Turn-on and Reversible Fluorescent Chemosensor for Al3+ Detection Based on Novel Salicylidene Schiff Base-Terminated PEG in Pure Aqueous Solution

The development of highly selective and sensitive chemosensors for Al³⁺ detection in pure aqueous solution is still a significant challenge. In this work, a novel water-soluble polymer PEGBAB based on salicylidene Schiff base has been designed and synthesized as a turn-on fluorescent chemosensor for the detection of Al³⁺ in 100% aqueous solution. PEGBAB exhibited high sensitivity and selectivity to Al³⁺ over other competitive metal ions with the detection limit as low as 4.05 × 10⁻⁹ M. PEGBAB displayed high selectivity to Al³⁺ in the pH range of 5–10. The fluorescence response of PEGBAB to Al³⁺ was reversible in the presence of ethylenediaminetetraacetic acid (EDTA). Based on the fluorescence response, an INHIBIT logic gate was constructed with Al³⁺ and EDTA as two inputs. Moreover, test strips based on PEGBAB were fabricated facilely for convenient on-site detection of Al³⁺.

Enlargement of Gold Nanoparticles for Sensitive Immunochromatographic Diagnostics of Potato Brown Rot

Lateral flow immunoassay (LFIA) is a convenient tool for rapid field-based control of various bacterial targets. However, for many applications, the detection limits obtained by LFIA are not sufficient. In this paper, we propose enlarging gold nanoparticles' (GNPs) size to develop a sensitive lateral flow immunoassay to detect Ralstonia solanacearum. This bacterium is a quarantine organism that causes potato brown rot. We fabricated lateral flow test strips using gold nanoparticles (17.4 ± 1.0 nm) as a label and their conjugates with antibodies specific to R. solanacearum. We proposed a signal enhancement in the test strips' test zone due to the tetrachloroauric (III) anion reduction on the GNP surface, and the increase in size of the gold nanoparticles on the test strips was approximately up to 100 nm, as confirmed by scanning electron microscopy. Overall, the gold enhancement approach decreased the detection limit of R. solanacearum by 33 times, to as low as 3 × 10⁴ cells∙mL⁻1 in the potato tuber extract. The achieved detection limit allows the diagnosis of latent infection in potato tubers. The developed approach based on gold enhancement does not complicate analyses and requires only 3 min. The developed assay together with the sample preparation and gold enlargement requires 15 min. Thus, the developed approach is promising for the development of lateral flow test strips and their subsequent introduction into diagnostic practice.

Urinary albumin strip assay as a screening test to replace quantitative technology in certain conditions

Background The clinical laboratory plays a crucial role in the diagnosis and monitoring of chronic kidney disease. The quantitative measurement of urine albumin in a spot sample, expressed as ratio per creatinine (ACR) is the most frequently used biomarker for such a purpose. Our aim was to evaluate the diagnostic performances of a strip for measuring ACR for differentiating patients who are candidates for subsequent albumin quantification, and to evaluate the economic effects of its implementation. Methods We systematically measured strip analysis when quantitative urinary albumin was requested. Semiquantitative urinary albumin was measured using a UC-3500 (Sysmex, Kobe, Japan), based on the protein error of a pH indicator. We collected and reviewed all the values of quantified urinary albumin and their corresponding results in ACR strip tests. We calculated the diagnostic indicators for ACR at different albumin and creatinine values using the quantitative ACR measurement as a "gold standard". We also studied the economic effects based on both tests prices (€1.31 for quantitative albumin plus creatinine, and €0.04 for an albumin strip). Results The study included 9148 patients (mean age 63, 46.3% men). The results at different albumin and creatinine cutoffs showed the best performance when 10 mg/L and above 50 mg/dL, respectively. Based on our results, we would have saved 3506 urine albumin and creatinine tests in the study period, corresponding to €4226.94. Conclusions The present study supports the use of the ACR strip test to identify pathological albuminuria values to be measured through quantitative methods. Considerable economic savings are possible.

Mix-&-Read Determination of Mercury(II) at Trace Levels with Hybrid Mesoporous Silica Materials Incorporating Fluorescent Probes by a Simple Mix-&-Load Technique

The synthesis, characterization, and application of mesoporous materials containing boron-dipyrromethene (BODIPY) moieties that allow the sensitive and selective detection of HgII in aqueous environments by fluorescence enhancement is reported. For this purpose, BODIPY dye I containing a thia-aza crown ether receptor as the fluorescent probe for the detection of HgII in aqueous environments is encapsulated into mesoporous materials to avoid self-quenching or aggregation in water. Determination of HgII is accomplished within a few seconds with high selectivity and sensitivity, reaching a limit of detection of 12 ppt. The determination of trace amounts of HgII in natural waters and in fish extracts is demonstrated by using our sensing material. The incorporation of the material into several μ-PAD strips yields a portable, cheap, quick, and easy-to-handle tool for trace HgII analysis in water.

Lateral Flow Immunoassay for Rapid Detection of Grapevine Leafroll-Associated Virus

Grapevine leafroll-associated virus 3 (GLRaV-3) is one of the main pathogens of grapes, causing a significant loss in yield and decrease in quality for this agricultural plant. For efficient widespread control of this infection, rapid and simple analytical techniques of on-site testing are requested as a complementary addition for the currently applied hybridization (PCR) and immunoenzyme (ELISA) approaches. The given paper presents development and approbation of the immunochromatographic assay (ICA) for rapid detection of GLRaV-3. The ICA realizes a sandwich immunoassay format with the obtaining complexes ((antibody immobilized on immunochromatographic membrane)⁻(virus in the sample)⁻(antibody immobilized on gold nanoparticles (GNP)) during sample flow along the membrane compounds of the test strip. Three preparations of GNPs were compared for detection of GLRaV-3 at different dilutions of virus-containing sample. The GNPs with maximal average diameters of 51.0 ± 7.9 nm provide GLRaV-3 detection for its maximal dilutions, being 4 times more than when using GNPs with a diameter of 28.3 ± 3.3 nm, and 8 times more than when using GNPs with a diameter of 18.5 ± 3.3 nm. Test strips have been manufactured using the largest GNPs conjugated with anti-GLRaV-3 antibodies at a ratio of 1070:1. When testing samples containing other grape wine viruses, the test strips have not demonstrated staining in the test zone, which confirms the ICA specificity. The approbation of the manufactured test strips indicated that when using ELISA as a reference method, the developed ICA is characterized by a sensitivity of 100% and a specificity of 92%. If PCR is considered as a reference method, then the sensitivity of ICA is 93% and the specificity is 92%. The proposed ICA can be implemented in one stage without the use of any additional reactants or devices. The testing results can be obtained in 10 min and detected visually. It provides significant improvement in GLRaV-3 detection, and the presented approach can be transferred for the development of test systems for other grape wine pathogens.

Mix-&-Read Determination of Mercury(II) at Trace Levels with Hybrid Mesoporous Silica Materials Incorporating Fluorescent Probes by a Simple Mix-&-Load Technique

The synthesis, characterization, and application of mesoporous materials containing boron-dipyrromethene (BODIPY) moieties that allow the sensitive and selective detection of HgII in aqueous environments by fluorescence enhancement is reported. For this purpose, BODIPY dye I containing a thia-aza crown ether receptor as the fluorescent probe for the detection of HgII in aqueous environments is encapsulated into mesoporous materials to avoid self-quenching or aggregation in water. Determination of HgII is accomplished within a few seconds with high selectivity and sensitivity, reaching a limit of detection of 12 ppt. The determination of trace amounts of HgII in natural waters and in fish extracts is demonstrated by using our sensing material. The incorporation of the material into several μ-PAD strips yields a portable, cheap, quick, and easy-to-handle tool for trace HgII analysis in water.

Physicians' Views of Self-Monitoring of Blood Glucose in Patients With Type 2 Diabetes Not on Insulin

This qualitative study examines to what extent and why physicans still prescribe self-monitoring of blood glucose (SMBG) in patients with non-insulin-treated type 2 diabetes (NITT2D) when the evidence shows it increases cost without improving hemoglobin A_1c (HbA_1c), general well being, or health-related quality of life. Semistructured phone interviews with 17 primary care physicians indicated that the majority continue to recommend routine self-monitoring of blood glucose due to a compelling belief in its ability to promote the lifestyle changes needed for glycemic control. Targeting physician beliefs about the effectiveness of self-monitoring of blood glucose, and designing robust interventions accordingly, may help reduce this practice.

A Reversible Bis(Salamo)-Based Fluorescence Sensor for Selective Detection of Cd2+ in Water-Containing Systems and Food Samples

A novel, simple, highly selective, and sensitive fluorescence chemosensor for detecting Cd2+ that was constructed from a bis(salamo)-type compound (H₄L) with two N₂O₂ chelating moieties as ionophore was successfully developed. Sensor H₄L could show fluorescence turn-on response rapidly and significant selectivity to Cd2+ over many other metallic ions (Cu2+, Ba2+, Ca2+, K⁺, Cr3+, Mn2+, Sr2+, Co2+, Na⁺, Li⁺, Ni2+, Ag⁺, and Zn2+), and a clear change in color from colorless to yellow that can be very easily observed via the naked eyes in the existence of Cd2+, while other metallic ions do not induce such a change. Interestingly, its fluorescent intensity was increased sharply with the increased concentration of Cd2+. The detection limit of sensor H₄L towards Cd2+ was down to 8.61 × 10-7 M.

Impact of Xylose on Glucose-Dehydrogenase-Based Blood Glucose Meters for Patient Self-Testing

The pentose xylose is enriched in edible algae, and is increasingly used as a slowly metabolized carbohydrate in functional food. It is known to interfere with glucose-dehydrogenase-based (GDH) blood glucose measurement systems for patients self-testing. The aim of our study was to investigate the extent of xylose interference in commercially available blood glucose meters. A heparinized whole blood sample was manipulated to contain 3 different glucose concentrations (50-80 mg/dL, 130-160 mg/dL, and 250-300 mg/dL) and 4 different xylose concentrations (0 mg/dL, 25 mg/dL, 50 mg/dL, and 100 mg/dL). Each sample was measured 3 times with 2 different strip lots per test meter (AccuChek Aviva, AccuChek Connect, Contour Next, FreeStyle Freedom Lite, FreeStyle Insulinx, MyStar Extra, OneTouch Verio IQ, and Wellion Calla, reference: YSI GlucoStat analyzer). For analysis, we calculated the xylose capture rate, that is, the xylose amount wrongly displayed as glucose. No xylose interference was seen with 4 meters: AccuChek Aviva (mean capture rate 0%), AccuChek Connect (-2%), MyStar Extra (10%), and Wellion Calla (8%). In contrast, substantial interference was observed with Contour Next (100%), FreeStyle Freedom Lite (104%), FreeStyle Insulinx (120%), and OneTouch Verio IQ (162%). We observed xylose interference in several GDH-based meters. This may become important with increased use of xylose in dietary and functional food products, in particular in products designed for weight loss. Our findings may affect the meter selection for patients who are consuming such food products as part of their lifestyle treatment regimen.

Lateral Flow Assay Based on Paper-Hydrogel Hybrid Material for Sensitive Point-of-Care Detection of Dengue Virus

Paper-based devices have been broadly used for the point-of-care detection of dengue viral nucleic acids due to their simplicity, cost-effectiveness, and readily observable colorimetric readout. However, their moderate sensitivity and functionality have limited their applications. Despite the above-mentioned advantages, paper substrates are lacking in their ability to control fluid flow, in contrast to the flow control enabled by polymer substrates (e.g., agarose) with readily tunable pore size and porosity. Herein, taking the benefits from both materials, the authors propose a strategy to create a hybrid substrate by incorporating agarose into the test strip to achieve flow control for optimal biomolecule interactions. As compared to the unmodified test strip, this strategy allows sensitive detection of targets with an approximately tenfold signal improvement. Additionally, the authors showcase the potential of functionality improvement by creating multiple test zones for semi-quantification of targets, suggesting that the number of visible test zones is directly proportional to the target concentration. The authors further demonstrate the potential of their proposed strategy for clinical assessment by applying it to their prototype sample-to-result test strip to sensitively and semi-quantitatively detect dengue viral RNA from the clinical blood samples. This proposed strategy holds significant promise for detecting various targets for diverse future applications.

"Turn-On" Fluorescent Probe for Mercury(II): High Selectivity and Sensitivity and New Design Approach by the Adjustment of the π-Bridge

By intelligent design, a new "turn-on" fluorescent probe (1-CN) was obtained based on the deprotection reaction of the dithioacetal promoted by Hg2+ ions, which could sense mercury ions sensitively and selectively, with the detection limit of 8×10(-7) M. Thanks to the apparent turn-on signal, 1-CN has been successfully applied to rapidly detect trace amounts of mercury ions as test strips and cell image.

Recommending blood glucose monitors, a pharmacy perspective

INTRODUCTION

Selection of what blood glucose monitoring system to utilize has become an issue for physicians, diabetes educators, pharmacists, and patients. The field of competing makes and models of blood glucose monitoring systems has become crowded, with manufacturers touting improvements in accuracy, ease of use/alternate site options, stored results capacity, software evaluation tools, and/or price point.

METHODS

Personal interviews of 12 pharmacists from community and academic practice settings about monitor preference, as well as results from a national survey of pharmacist recommendations, were compared to actual wholesale sales data to estimate the impact of such recommendations on final monitor selection by the patient.

RESULTS

Accu-Chek monitors were recommended 34.65% of the time and represented 28.58% of sales, with a success rate of 82.48% of being the monitor selected. OneTouch monitors had 27.72% of recommendations but represented 31.43% of sales, indicating possible patient brand loyalty or formulary preference for that product. FreeStyle(R) monitors came in third for pharmacist recommendations and were selected by the patient 61.68% of the time when recommended. The category of "other monitor" choices was selected 60.89% of the time by patients given those suggestions. Included in the "other monitor" category was the new disposable monitor marketed as the Sidekick. Based on sales data provided, the Sidekick made up 2.87% of "other monitor" category sales, representing 68% of the "other monitor" segment.

CONCLUSIONS

While patients frequently follow pharmacist monitoring system suggestions, the ultimate deciding factor is most often the final out-of-pocket cost to the patient. As a result, cost of supplies often becomes the most important determining factor in final monitor selection at the patient level. If the patient cannot afford to perform the recommended daily testing intervals, all other determining factors and suggestions become moot.