Low Detection Limit Research Articles

A robust ultra performance liquid chromatography method for dacarbazine quantification in nanosponge formulation: A quality by design approach

A new, user-friendly Ultra Performance Liquid Chromatography (UPLC) method was developed using Analytical Quality by Design (QbD) for precise analysis of Dacarbazine in both bulk powder and Dacarbazine-loaded Nanosponges. This method follows ICH guidelines and uses a statistically designed approach to optimize the separation conditions for Dacarbazine. A central composite design was implemented to identify the ideal combination of organic solvent (mobile phase composition) and flow rate. The UPLC method was successfully optimized for rapid separation (1.3 minutes) for Dacarbazine using a mobile phase consisting of 70% Methanol: 30% Orthophosphoric acid (0.1%) at a flow rate of 1.0 mL/min, using a Hypersil C18 column. The method exhibited excellent linearity with a correlation coefficient value of 0.997 across a concentration range of 4-20 μg/mL, accuracy (drug recovery of 96-100%) and sensitivity (LOD 1.15 μg/mL, LOQ 3.50 μg/mL) and it successfully quantified the drug in the formulated Dacarbazine-loaded Nanosponges. This QbD-driven UPLC method offers a valuable tool for reliable Dacarbazine quality control in pharmaceuticals providing rapid analysis, high accuracy, and low detection limits.

Mix-and-Read Digital MicroRNA Analysis Based on Flow Cytometric Counting of Target-Clicked Nanobead Dimer.

A one-step, enzyme-free, and highly sensitive digital microRNA (miRNA) assay is rationally devised based on flow cytometric counting of target miRNA-clicked nanobead dimers via a facile mix-and-read manner. In this strategy, highly efficient miRNA-sandwiched click chemical ligation of two DNA probes may remarkably stabilize and boost the dimer formation between two kinds of fluorescence-coded nanobeads, and the number of as-produced bead dimers will be target dose-responsive, particularly when the trace number of miRNA is much less than that of employed nanobeads. Finally, each fluorescence-coded bead dimer can be easily identified and digitally counted by a powerful flow cytometer (FCM) and accordingly, the amount of target miRNA can be accurately quantified in a digital way. This new digital miRNA assay can be accomplished with a facile mix-and-read operation just by simply mixing the target miRNA with two kinds of preprepared DNA probe-functionalized nanobeads, which do not require any nucleic acid amplification, purification, and complex operation procedures. In spite of the extremely simple one-step operation, benefiting from the low-background but high target-mediated click ligation efficiency, and the powerfully digital statistical capability of FCM, this strategy achieves high sensitivity with a quite low detection limit of 5.2 fM target miRNA as well as high specificity and good generality for miRNA analysis, pioneering a new direction for fabricating digital bioassays.

Solvent-regulated Formation of Metal/Metal-oxo Nodes in Two Indium Metal-organic Frameworks: Syntheses, Structures, Selective Gas Adsorption and Fluorescence Sensor Properties.

Two water-stable indium metal-organic frameworks, (NH2Me2)3[In3(BTB)4]·12DMA·4.5H2O (In-MOF-1) and (NH2Me2)9[In9O6(BTB)8(H2O)4(DMSO)4]·27DMSO·21H2O (In-MOF-2) (BTB = 4,4¢,4¢¢-benzene-1,3,5-tribenzoate) with 3D interpenetrate structure has been constructed by regulating solvents. Structure analysis revealed that In-MOF-1 has a three-dimensional (3D) structure with a single metal core, while In-MOF-2 features an octahedron cage constructed by three kinds of metal clusters to further form a 3D structure. The fluorescence investigations show that In-MOF-1 and In-MOF-2 are potential MOF-based fluorescent sensors to detect acetone and Fe3+ ions in EtOH or water with high sensitivity, excellent selectivity, recyclability and a low detection limit. Moreover, the fluorescence mechanisms of In-MOF-1 and In-MOF-2 toward acetone and Fe3+ ions were further explained. In addition, In-MOF-2 has higher thermal and framework stability than In-MOF-1. The activated In-MOF-2 presents a high BET surface area of 998.82 m2g-1 and a pore size distribution of 8 to 16 Å. At the same time, In-MOF-2 exhibits high selective CO2 adsorption for CO2/CH4 and CO2/N2, respectively. Furthermore, the adsorption sites and adsorption isotherms were predicted using Grand Canonical Monte Carlo (GCMC) simulations, and the adsorption energy of the lowest-energy adsorption configuration was calculated using molecular dynamics (MD) simulations.

High-Efficient Electrochemiluminescence of DNA-Au Ag Nanoclusters with Au NPs@Ti3C2 as a Novel Coreaction Accelerator for Ultrasensitive Biosensing.

In this work, an ultrasensitive electrochemiluminescence (ECL) biosensor was constructed based on DNA-stabilized Au Ag nanoclusters (DNA-Au Ag NCs) as the efficient luminophore and Au NPs@Ti3C2 as a new coreaction accelerator for determining microRNA-221 (miRNA-221) related to liver cancer. Impressively, DNA-Au Ag NCs were stabilized by the high affinity of the periodic 3C sequence, exhibiting an excellent ECL efficiency of 27% compared with classical BSA-Au Ag NCs (16%). Moreover, the Au NPs@Ti3C2 nanocomposites, as a new coreaction accelerator, were first introduced to accelerate the production of abundant sulfate free radicals (SO4•-) for promoting the ECL efficiency of DNA-Au Ag NCs in the DNA-Au Ag NCs/Au NPs@Ti3C2/S2O82- ternary system due to the energy band of Au NPs@Ti3C2 being well-matched with the frontier orbital of S2O82-. Furthermore, the trace target (miRNA-221) could drive the rolling circle amplification to generate an amount of output DNA with periodic 3C and 10A sequences. Through covalent bonds on the surface of poly A and Au NPs, the distance between the luminophor and the coreaction accelerator could be narrowed to further enhance the detection sensitivity. As a result, the constructed sensor has been applied for the ultrasensitive detection of miRNA-221 with a low detection limit of 50 aM and successfully monitored miRNA-221 in MHCC-97L and HeLa cell lysates. This strategy could be utilized for guiding the synthesis of light-emitting DNA-metal NCs, which has great potential in the construction of ultrasensitive biosensors for the early diagnosis of diseases.

Innovative Wearable Sweat Sensor Array for Real-Time Volatile Organic Compound Detection in Noninvasive Diabetes Monitoring.

Wearable sweat sensors are reshaping healthcare monitoring, providing real-time data on hydration and electrolyte levels with user-friendly, noninvasive devices. This paper introduces a highly portable two-channel microfluidic device for simultaneous sweat sampling and the real-time detection of volatile organic compound (VOC) biomarkers. This innovative wearable microfluidic system is tailored for monitoring diabetes through the continuous and noninvasive tracking of acetone and ammonia VOCs, and it seamlessly integrates with smartphones for easy data management. The core of this system lies in the utilization of carbon polymer dots (CPDs) and carbon dots (CDs) derived from monomers such as catechol, resorcinol, o-phenylenediamine, urea, and citric acid. These dots are seamlessly integrated into hydrogels made from gelatin and poly(vinyl alcohol), resulting in an advanced solid-state fluorometric sensor coating on a cellulose paper substrate. These sensors exhibit exceptional performance, offering linear detection ranges of 0.05-0.15 ppm for acetone and 0.25-0.37 ppm for ammonia, with notably low detection limits of 0.01 and 0.08 ppm, respectively. Rigorous optimization of operational parameters, encompassing the temperature, sample volume, and assay time, has been undertaken to maximize device performance. Furthermore, these sensors demonstrate impressive selectivity, effectively discerning between biologically similar substances and other potential compounds commonly present in sweat. As this field matures, the prospect of cost-effective, continuous, personalized health monitoring through wearable VOC sensors holds significant potential for overcoming barriers to comprehensive medical care in underserved regions. This highlights the transformative capacity of wearable VOC sweat sensing in ensuring equitable access to advanced healthcare diagnostics, particularly in remote or geographically isolated areas.

A Lanthanide-Incorporated Phospho(III)tungstate Aggregate Constructed from [HPIIIW8O31]10- and [W11O39]12- Building Blocks and Its Nanocomposite with CdS for Ultrasensitive Photoelectrochemical Detection of Oxytetracycline.

A novel tartronic acid decorated hexa-CeIII-incorporated phospho(III)tungstate aggregate (C4H12NO)6Na18H2[(HPW8O31)2[W11O39]2(H2TAD)4(H2O)4W4Ce6H2P2O14]·84H2O (1, H3TAD = tartronic acid) was synthesized by a one-step assembly strategy. Its main skeleton is constructed from two [W11O39]12- fragments, two [HPIIIW8O31]10- segments and one H2TAD--ornamented dodecanuclear heterometallic [W4Ce6H2PIII2O14(H2TAD)4(H2O)4]18+ cluster. In the structure, the [HPIIIO3]2- groups not only work as the heteroatom template to induce the formation of lacunary [HPIIIW8O31]10- segments but also function as the connector to bridge Ce3+ cations. With the help of a reaction strategy of combining ultrasonication treatment with the continuous ion layer adsorption method, the 1/CdS composite was constructed and exhibits prominent photoelectrochemical activity. The 1/CdS composite was used as a photoelectrochemical sensor for oxytetracycline detection at 0 V (vs Ag/AgCl), which displays excellent properties with quick response and low limit of detection (0.042 nM). This work can provide some helpful references in the construction of novel PIII-induced polyoxometalates consisting of different building blocks and can extend the applications of polyoxometalate-based nanocomposites into photoelectrochemical detection for antibiotics as well as biomolecules.

HKUST‐1 Derived Cu2S‐Cu3P@C Nanomatrix Electrode Material for Non‐Enzymatic Electrochemical Glucose Sensing

AbstractRobust Cu2S‐Cu3P@C Nanomatrix electrode material has been synthesized via a two‐step process involving carbonization of Cu‐MOF, HKUST‐1, followed by simultaneous phosphorization and sulphurization of the carbonized product. This seamless approach leads to the efficient incorporation of highly active Cu2S‐Cu3P hybrid nanostructures within a conductive carbon matrix, exhibiting exceptional electrochemical glucose sensing performance. Synergistic interactions between Cu2S‐Cu3P and the carbon matrix boost glucose electro‐oxidation kinetics. The resulting Cu2S‐Cu3P@C displays a broad linear response (0.005–5 mM), low detection limit (2.3 μM), and high sensitivity (10,790 μA mM−1 cm−2), with excellent selectivity towards glucose even in the presence of interferents. This biomimetic Cu2S‐Cu3P@C nanomatrix catalyst holds promise for biosensor development in bioanalysis and clinical diagnosis.

Hierarchical WS2-WO3 Nanohybrids with Flower-like p-n Heterostructures for Trimethylamine Detection

The detection of trimethylamine (TMA) is critically important due to its toxic and flammable nature, which poses significant risks to human health and the environment. However, achieving high response, rapid kinetics, selectivity, and low operating temperatures in TMA sensing remains challenging. In this study, WS2/WO3 nanohybrids with flower-like hierarchical structures were synthesized via an in situ sulfurization process, utilizing varying amounts of thioacetamide to control the sulfurization state of WO3. These novel hierarchical WS2/WO3 nanohybrids exhibit remarkable selectivity towards TMA, as well as rapid response and recovery characteristics. Specially, the optimal WS2/WO3 sensor, composed of 5% WS2/WO3 nanohybrids, demonstrates exceptional TMA sensing performance, including a high response (19.45 at 10 ppm), good repeatability, reliable long-term stability, and a low theoretical detection limit (15.96 ppb). The superior sensing capabilities of the WS2/WO3 nanohybrids are attributed to the formation of p-n heterojunctions at the interface, the unique hierarchical structures, and the catalytic activity of WS2. Overall, this work provides a straightforward and versatile approach for synthesizing multifunctional nanomaterials by combining metal oxide micro-flowers with transition metal dichalcogenide nanoflakes for applications in monitoring TMA in complex environments.

Rapid nanomolar detection of cocaine in biofluids by electrochemical aptamer-based sensor with low-temperature effect for drugged driving screening.

Cocaine is one of the most abused illicit drugs, and its abuse damages the central nervous system and can even lead directly to death. Therefore, the development of simple, rapid and highly sensitive detection methods is crucial for the prevention and control of drug abuse, traffic accidents and crime. In this work, an electrochemical aptamer-based(EAB) sensor based on the low-temperature enhancement effect was developed for the direct determination of cocaine in bio-samples. The signal gain of the sensor at 10°C was greatly improved compared to room temperature, owing to the improved affinity between the aptamer and the target. Additionally, the electroactive area of the gold electrode used to fabricate the EAB sensor was increased 20 times by a simple electrochemical roughening method. The porous electrode possesses more efficient electron transfer and better antifouling properties after roughening. These improvements enabled the sensor to achieve rapid detection of cocaine in complex bio-samples. The low detection limits (LOD) of cocaine in undiluted urine, 50% serum and 50% saliva were 70nM, 30nM and 10nM, respectively, which are below the concentration threshold in drugged driving screening. The aptasensor was simple to construct and reusable, which offers potential fordrugged driving screening in the real world.

WSe2 Negative Capacitance Field-Effect Transistor for Biosensing Applications.

Field-effect transistor (FET) biosensors based on two-dimensional (2D) materials are highly sought after for their high sensitivity, label-free detection, fast response, and ease of on-chip integration. However, the subthreshold swing (SS) of FETs is constrained by the Boltzmann limit and cannot fall below 60 mV/dec, hindering sensor sensitivity enhancement. Additionally, the gate-leakage current of 2D material biosensors in liquid environments significantly increases, adversely affecting the detection accuracy and stability. Based on the principle of negative capacitance, this paper presents for the first time a two-dimensional material WSe2 negative capacitance field-effect transistor (NCFET) with a minimum subthreshold swing of 56 mV/dec in aqueous solution. The NCFET shows a significantly improved biosensor function. The pH detection sensitivity of the NCFET biosensor reaches 994 pH-1, nearly an order of magnitude higher than that of the traditional two-dimensional WSe2 FET biosensor. The Al2O3/HfZrO (HZO) bilayer dielectric in the NCFET not only contributes to negative capacitance characteristics in solution but also significantly reduces the leakage in solution. Utilizing an enzyme catalysis method, the WSe2 NCFET biosensor demonstrates a specific detection of glucose molecules, achieving a high sensitivity of 4800 A/A in a 5 mM glucose solution and a low detection limit (10-9 M). Further experiments also exhibit the ability of the biosensor to detect glucose in sweat.

A phytic acid-based CoMn bimetallic metal-organic aerogel (PA-CoMn-1 : x : 2 - x) as a modifier for electrochemical detection of non-steroidal anti-inflammatory drug 4-acetaminophenol.

Metal phosphides and phosphate-based materials have received significant attention due to their high electrocatalytic activity, adjustable structure composition and stability. Herein, we introduce a phytic acid-based CoMn bimetallic metal-organic (PA-CoMn) aerogel as an electrode modifier, derived from PA and mixed transition metal ions (Co2+, Mn2+). We explored its performance in the sensitive sensing of non-steroidal anti-inflammatory drug 4-acetaminophenol (4-AP) for the first time. We investigated the electrochemical behavior of the modified screen-printed carbon electrode (SPCE) by cyclic voltammetry (CV) and differential pulse voltammetry (DPV). The PA-CoMn-1 : 1.5 : 0.5 aerogel/Nafion/SPCE proved to be highly sensitive and selective towards the detection of 4-AP. A double linear response was recorded for 4-AP over the range of 1 μM to 0.1 mM and lower detection limits (LOD) of 0.2133 μM. The applicability of the PA-CoMn-1 : 1.5 : 0.5 aerogel/Nafion/SPCE in the detection of 4-AP in commercial drug samples with good recoveries was investigated, confirming the great potential of PA-CoMn-1 : 1.5 : 0.5 aerogel/SPCE in clinical applications.

In Situ Defect Engineering of Fe-MIL for Self-Enhanced Peroxidase-Like Activity.

Defect engineering is an effective strategy to enhance the enzyme-like activity of nanozymes. However, previous efforts have primarily focused on introducing defects via de novo synthesis and post-synthetic treatment, overlooking the dynamic evolution of defects during the catalytic process involving highly reactive oxygen species. Herein, a defect-engineered metal-organic framework (MOF) nanozyme with mixed linkers is reported. Over twofold peroxidase (POD)-like activity enhancement compared with unmodified nanozyme highlights the critical role of in situ defect formation in enhancing the catalytic performance of nanozyme. Experimental results reveal that highly active hydroxyl radical (•OH) generated in the catalytic process etches the 2,5-dihydroxyterephthalic acid ligands, contributing to electronic structure modulation of metal sites and enlarged pore sizes in the framework. The self-enhanced POD-like activity induced by in situ defect engineering promotes the generation of •OH, holding promise in colorimetric sensing for detecting dichlorvos. Utilizing smartphone photography for RGB value extraction, the resultant sensing platform achieves the detection for dichlorvos ranging from 5 to 300ngmL-1 with a low detection limit of 2.06ngmL-1. This pioneering work in creating in situ defects in MOFs to improve catalytic activity offers a novel perspective on traditional defect engineering.

Dual-mode detection of glucose based on pistol-like DNAzyme-mediated exonuclease-assisted signal cycle.

Detecting glucose accurately and sensitively from clinical samples like tears and saliva is still difficult. We have created a sensor that can detect glucose with high sensitivity and accuracy by combining the use of glucose oxidase (GOx) to catalyze glucose, a pistol-like DNAzyme (PLDz) to transform the signal, gold nanoparticles (AuNPs) to enhance the optical properties and the exonuclease-III (Exo-III) to amplify the signal. As a result, the proposed method exhibits a low detection limit of 7.5pM and a wide detection range covering seven orders of magnitude. The suggested dual-mode strategy provides a sensitive, precise and specific detection method for glucose. Another advantage is that the dual-mode technique significantly improves the precision and consistency of the measurements, demonstrating its immense potential for use in biomedical research and clinical diagnostics.

Transparent Perovskite Wafers via Nanocrystals Ordered Coalescence Toward Sensitive and Stable X‐Ray Detection and Imaging

AbstractMetal halide perovskite wafers have shown significant potential in large‐area X‐ray detection and imaging. However, a distinct difference in optical transparency between state‐of‐the‐art perovskite wafers and single crystals indicates the inferior crystal quality of perovskite wafers, which limits the performance and stability of wafer‐based X‐ray detectors. Here, nano‐sized MAPbBr3 powders are utilized to fabricate dense perovskite wafers by low‐temperature hot‐pressing with high transparency above 60% within the 552–800 nm wavelength range. Adjacent nanocrystals assemble following the ordered coalescence mechanism, resulting in the exclusion of nanoscopic pores and crystallographic reorientation. The transparent MAPbBr3 wafer‐based detectors achieve an impressively high X‐ray sensitivity of 1.14 × 105 µC Gyair−1 cm−2 and a low detection limit of 149 nGyair s−1, which is superior to opaque MAPbBr3 wafer detectors (5.64 × 104 µC Gyair−1 cm−2 and 316.7 nGyair s−1) and comparable to MAPbBr3 single‐crystal detectors. Moreover, the detectors demonstrate high uniformity and outstanding stability under continuous X‐ray irradiation of a total dose of up to 5.9 Gyair, equaling to 29 500 times posteroanterior chest examinations. The high sensitivity and low detection limit of the detectors lead to clear X‐ray imaging performance.

Disposable electrochemical sensors based on reduced graphene oxide/polyaniline/poly(alizarin red S)-modified integrated carbon electrodes for the detection of ciprofloxacin in milk.

Anelectrochemical sensor based on an electroactive nanocomposite was designedfor the first timeconsisting of electrochemically reduced graphene oxide (ERGO), polyaniline (PANI), and poly(alizarin red S) (PARS) for ciprofloxacin (CIPF) detection. The ERGO/PANI/PARS-modified screen-printed carbon electrode (SPCE) was constructed through a three-step electrochemical protocol and characterized using FTIR, UV-visible spectroscopy, FESEM, CV, LSV, and EIS. The new electrochemical CIPF sensor demonstrated a low detection limit of 0.0021μM, a broad linear range of 0.01 to 69.8μM, a high sensitivity of 5.09 μA/μM/cm2, and reasonable selectivity and reproducibility. Moreover, the ERGO/PANI/PARS/SPCE was successfully utilized to determine CIPF in milk with good recoveries and relative standard deviation (< 5%), which were close to those with HPLC analysis.

Ultrafast Scintillator Based on Zirconium‐Doped Cesium Zinc Chloride Single Crystals and Their Charge Carrier Dynamics

AbstractScintillators have been widely used for high‐energy radiation imaging. It is in great demand and challenge to develop scintillator materials with fast decay time, high scintillation light yield, and low detection limit for high‐resolution imaging applications such as time‐of‐flight positron emission tomography. However, it is still a challenge to develop the ultrafast carrier dynamics to achieve 100% ultrafast decay time with high scintillation light yield. To meet the demand, a series of component‐tunable Cs2ZnCl4: x%Zr single crystals as promising ultrafast scintillators is successfully developed. With 8% of Zr‐dopant (Cs2ZnCl4: 8%Zr), the single crystal exhibits high light yield (28000 photons MeV−1) and low detection limit (51 nGy s−1) under X‐ray excitation. Photo‐induced transient absorption signals on sub‐nanosecond and nanosecond scales ensure almost 100% fast decay time (≈3 ns) in nanoseconds under γ‐ray excitation. In particular, the different radiative transition processes are achieved under ultraviolet and high‐energy radiation due to the tunable carrier dynamics from the shallow trapped state to the self‐trapped exciton (STE) state.

Defect-Engineered WO3-x Architectures Coupled with Random Forest Algorithm Enables Real-Time Seafood Quality Assessment.

Reliable and real-time monitoring of seafood decay is attracting growing interest for food safety and human health, while it is still a great challenge to accurately identify the released triethylamine (TEA) from the complex volatilome. Herein, defect-engineered WO3-x architectures are presented to design advanced TEA sensors for seafood quality assessment. Benefiting from abundant oxygen vacancies, the obtained WO2.91 sensor exhibits remarkable TEA-sensing performance in terms of higher response (1.9 times), faster response time (2.1 times), lower detection limit (3.2 times), and higher TEA/NH3 selectivity (2.8 times) compared with the air-annealed WO2.96 sensor. Furthermore, the definite WO2.91 sensor demonstrates long-term stability and anti-interference in complex gases, enabling the accurate recognition of TEA during halibut decay (0-48 h). Coupled with the random forest algorithm with 70 estimators, the WO2.91 sensor enables accurate prediction of halibut storage with an accuracy of 95%. This work not only provides deep insights into improving gas-sensing performance by defect engineering but also offers a rational solution for reliably assessing seafood quality.

Colorimetric aptasensor based on self-screened aptamers and cascaded catalytic reaction for the detection of quarantine plant bacteria

Quarantine plant bacteria (QPB) are significant component of invasive alien species that result in substantial economic losses and serious environmental damage. Herein, a colorimetric aptasensor has been proposed based on the sandwich structure and the cascaded catalytic strategy for on-site detecting Xanthomonas hyacinthi, a type of QPB, in natural environments. The self-screened aptamer obtained through SELEX can bind to specific sites on the surface of viable organism with high affinity and specificity, which guarantees the selectivity of aptasensor. As an important part of the aptasensor, MIL-88-NH2(Fe) not only acts as a multifunctional carrier for both aptamers and glucose oxidase, but also catalyzes enzyme-like reaction because of specific surface area, amino and peroxidase-like activity. The present of Xanthomonas hyacinthi can trigger the formation of a sandwich structure and the occurrence of cascade catalytic reaction, enabling the detection with UV–Vis spectra and naked eyes. The proposed aptasensor presents a low detection limit of 2 cfu/mL and a wide linear range of 10 -107 cfu/mL. Compared to traditional detection methods for QPB, the reasonable design, high selectivity and convenience significantly improve the detection efficiency and contribute to environmental protection.

New method for rapid detection and simultaneous determination of prohibited adrenergic drugs in sports using thin layer chromatography and image processing

This study presents a new method for simultaneous determination of fenoterol, procaterol, clenbuterol, terbutaline and isoprenaline drugs using thin-layer chromatography assisted by image analysis (HPTLC-IA) combined with sensitive detection modes. Separation of the selected drugs was obtained using HPTLC Silica gel 60 F254 plates and mixture of isopropyl alcohol, ethyl acetate and ammonia (20:25:1.5 v/v/v) as mobile phase. UV detection mode combined with the use of 2,2-diphenyl-1-picrylhydrazyl (DPPH•) and 2,2'-azino-bis (3-ethylbenzothiazoline)-6-sulfonic acid (ABTS+•) radicals were applied for the first time for sensible detection of the separated drugs. Grey, green, red and blue scales respectively were selected for image analysis and accurate quantification of spot area. According to the obtained result, the use of DPPH• and ABTS+• reagents revealed a higher sensitivity in detection and accurate quantification of the analyzed drugs. Lower limit of detection (LOD = 0.07 ± 0.03 µg/spot; 0.09 ± 0.03 µg/spot and 0.10 ± 0.04 µg/spot) was obtained for fenoterol, procaterol and terbutaline using the ABTS+• radical and red scale selection for image processing. With the exception of isoprenaline, the proposed HPTLC-IA method showed a good separation of fenoterol, procaterol, clenbuterol and terbutaline drugs from other compounds in urine samples. Good recovery was obtained for these drugs in spiked urine samples.

Bismuth oxide nanoparticles enabled sensitive electrochemical determination of Vitamin B12

The intake and monitoring of vitamin B12 levels are highly essential to maintain a healthy body condition. Herein, we report bismuth oxide nanoparticles (Bi2O3 NPs) facilitated electrochemical sensing of vitamin B12 with admirable sensitivity, selectivity, and low detection limit. A facile hydrothermal method was adopted for synthesizing Bi2O3 NPs and their physico-chemical properties were analyzed using various techniques. The electrochemical sensing of vitamin B12 was validated through cyclic voltammetry and differential pulse voltammetry techniques. The sensing results illustrate that the modified electrode exhibits a wide linear range between 10 nM and 275 nM with a low detection limit value of 3.66 nM. In addition to the enhanced electrocatalytic behavior, the Bi2O3 NPs have also enabled the discrimination of vitamin B12 from various potential interfering molecules (even adding a 5-fold concentration). The developed sensor also exhibits better stability, selectivity, and reproducibility towards the target analyte. Finally, the fabricated electrode was applied for the determination of vitamin B12 in serum, and plasma samples, and the results were highly satisfactory with recovery values of 98.4 % to 99.8 %.