Research progress of metal-organic framework nanozymes in bacterial sensing, detection, and treatment.

The high efficiency and specificity of enzymes make them play an important role in life activities, but the high cost, low stability and high sensitivity of natural enzymes severely restrict their application. In recent years, nanozymes have become convincing alternatives to natural enzymes, finding utility across diverse domains, including biosensing, antibacterial interventions, cancer treatment, and environmental preservation. Nanozymes are characterized by their remarkable attributes, encompassing high stability, cost-effectiveness and robust catalytic activity. Within the contemporary scientific landscape, metal-organic frameworks (MOFs) have garnered considerable attention, primarily due to their versatile applications, spanning catalysis. Notably, MOFs serve as scaffolds for the development of nanozymes, particularly in the context of bacterial detection and treatment. This paper presents a comprehensive review of recent literature pertaining to MOFs and their pivotal role in bacterial detection and treatment. We explored the limitations and prospects for the development of MOF-based nanozymes as a platform for bacterial detection and therapy, and anticipate their great potential and broader clinical applications in addressing medical challenges.

Enhanced Electrochemical Characterization of the Immune Checkpoint Protein PD-L1 using Aptamer-Functionalized Magnetic Metal-Organic Frameworks.

Programmed death ligand 1 (PD-L1) is highly expressed in cancer cells and participates in the immune escape process of tumor cells. However, as one of the most promising biomarkers for cancer immunotherapy monitoring, the key problem ahead of practical usage is how to effectively improve the detection sensitivity of PD-L1. Herein, an electrochemical aptasensor for the evaluation of tumor immunotherapy is developed based on the immune checkpoint protein PD-L1. The fundamental principle of this method involves the utilization of DNA nanotetrahedron (NTH)-based capture probes and aptamer-modified magnetic metal-organic framework nanocomposites as signaling probes. A synergistic enhancement is observed in the electrocatalytic effect between Fe3O4 and UiO-66 porous shells in Fe3O4@UiO-66 nanocomposites. Therefore, the integration of aptamer-modified Fe3O4@UiO-66@Au with NTH-assisted target immobilization as an electrochemical sensing platform can significantly enhance sensitivity and specificity for target detection. This method enables the detection of targets at concentrations as low as 7.76 pg mL-1 over a wide linear range (0.01 to 1000 ng mL-1). The authors have successfully employed this sensor for in situ characterization of PD-L1 on the cell surface and for monitoring changes in PD-L1 expression during drug therapy, providing a cost-effective yet robust alternative to highly expensive and expertise-dependent flow cytometry.

An impedance labeling free electrochemical aptamer sensor based on tetrahedral DNA nanostructures for doxorubicin determination.

Based on the electrochemical impedance method, a marker-free biosensor with aptamer as a biometric element was developed for the determination of doxorubicin (DOX). By combining aptamer with rigid tetrahedral DNA nanostructures (TDNs) and fixing them on the surface of gold electrode (GE) as biometric elements, the density and directivity of surface nanoprobes improved, and DOX was captured with high sensitivity and specificity. DOX was captured by immobilized aptamers on the GE, which inhibited electron transfer between the GE and [Fe(CN)6]3-/4- in solution, resulting in a change in electrochemical impedance. When the DOX concentration was between 10.0 and 100.0 nM, the aptasensor showed a linear relationship with charge transfer resistance, the relative standard deviation (RSD) ranged from 3.6 to 5.9%, and the detection limit (LOD) was 3.0 nM. This technique offered a successful performance for the determination of the target analyte in serum samples with recovery in the range 97.0 to 99.6% and RSD ranged from 4.8 to 6.5%. This method displayed the advantages of fast response speed, good selectivity, and simple sensor structure and showed potential application in therapeutic drug monitoring.

General Synthesis of N-CF3 Heteroaryl Amides via Successive Fluorination and Acylation of Sterically Hindered Isothiocyanates.

We report the one-pot synthesis of N-CF3 heteroaryl amides (NTFMHA) from heteroaryl carboxylic acids and sterically hindered isothiocyanates, including various amino acid analogues, in the presence of AgF. The key to this reaction is the utilization of free heteroaryl acyl chlorides, rather than their corresponding hydrochloride salts. This method represents a complementary method of our previous work and enables modification to a variety of previously inaccessible structures, including α-tertiary amines and N-CF3-modified pharmaceuticals.

Recent progress in aptamer-based microfluidics for the detection of circulating tumor cells and extracellular vesicles.

Liquid biopsy is a technology that exhibits potential to detect cancer early, monitor therapies, and predict cancer prognosis due to its unique characteristics, including noninvasive sampling and real-time analysis. Circulating tumor cells (CTCs) and extracellular vesicles (EVs) are two important components of circulating targets, carrying substantial disease-related molecular information and playing a key role in liquid biopsy. Aptamers are single-stranded oligonucleotides with superior affinity and specificity, and they can bind to targets by folding into unique tertiary structures. Aptamer-based microfluidic platforms offer new ways to enhance the purity and capture efficiency of CTCs and EVs by combining the advantages of microfluidic chips as isolation platforms and aptamers as recognition tools. In this review, we first briefly introduce some new strategies for aptamer discovery based on traditional and aptamer-based microfluidic approaches. Then, we subsequently summarize the progress of aptamer-based microfluidics for CTC and EV detection. Finally, we offer an outlook on the future directional challenges of aptamer-based microfluidics for circulating targets in clinical applications.

A Multicomponent Nucleic Acid Enzyme-Cleavable Quantum Dot Nanobeacon for Highly Sensitive Diagnosis of Tuberculosis with the Naked Eye.

Clinical tuberculosis (TB) screening and diagnosis are crucial for controlling the spread of this life-threatening infectious disease. In this work, a novel, rapid, and simple colorimetric detection platform for TB was developed based on a quantum dot-based nanobeacon (QD-NB) and multicomponent nucleic acid enzyme (MNAzyme). In the presence of target DNA (IS1081 gene fragment), the recombinase polymerase amplification (RPA) was performed and the amplicons were chemically DNA-denatured and then subjected to MNAzyme reaction. RNA-cleaving MNAzyme assembly included the recognition of target DNA and hybridization with a QD-NB fluorescence probe. Under the addition of Mg2+, the RNA-containing QD-NB as a cleavable substrate could be broken into two DNA fragments, leading to green fluorescence release due to their departure from a black hole quencher (BHQ2). The TB detection could be achieved with the naked eye under a portable and inexpensive UV flashlight. Our results demonstrated that QD-NB-based MNAzyme colorimetric assays improved the detection sensitivity by 1 order of magnitude compared with the detection using RPA. The limit of detection (LOD) of the visual reading was as low as 2 copies/µL (3.3 amol/L). Excellent specificity and reproducibility could also be achieved. Furthermore, the practical application of the colorimetric method for TB diagnosis was verified by 36 clinical TB patients and 20 healthy individuals. The developed QD-NB-based MNAzyme colorimetric assays provided a rapid, convenient, sensitive, and accurate alternative for clinical TB screening and diagnosis.

A novel and cost-efficient allele-specific PCR method for multiple SNP genotyping in a single run.

Cost-effective methods for DNA genotyping were needed because single nucleotide polymorphisms (SNPs) were essential biomarkers associated with many diseases. Allele-specific PCR (AS-PCR) has the advantages of mature instruments and high sensitivity. But conventional AS-PCR needs to multiply the number of reactions or primers for multiple targets, which complicates the operation and increases the cost. Herein, we proposed a novel AS-PCR method for multiple SNP genotyping in a single run. Wild-type allele-specific primer (WT primer) was designed for each target gene. The sample and WT primers only needed to undergo multiplexed AS-PCR once simultaneously. After AS-PCR, the concentration of remaining primers varied among the samples of each genotype combination, due to the different matching performance between template and WT primers. The remaining primers then triggered multiplexed molecular beacon-rolling circle amplification, and the molecular beacons labelled with different fluorescent dyes corresponded to different targets. The fluorescence ratios of the sample to the positive control were used as the genotyping indexes. This method was able to detect samples with concentrations as low as 10 fM. We successfully applied the method to the multiple genotyping of 23 hair root samples for ADH1B and ALDH2 genes, obtaining completely consistent results with sequencing. The reagent cost was 0.6 dollar for one sample, showing a good cost performance. This proposed approach had a great application prospect in simultaneously rapid and accurate genotyping of multi-SNPs, and provided a new method for personalized health management.

Engineering an endonuclease-assisted rolling circle amplification synergistically catalyzing hairpin assembly mediated fluorescence platform for miR-21 detection.

As one of the earliest miRNAs discovered in the human genome, miRNA-21 can provide vital information for the early diagnosis, drug treatment, and prognosis of cancers. Herein, we construct a fast, time-saving fluorescence detection system for miRNA-21 detection by coalescing the improved endonuclease-mediated rolling circle amplification with catalytic hairpin assembly (RCA-NESA-CHA). Firstly, the target miRNA cyclized the padlock, initiating rolling circle amplification (RCA) and extending a long-concatenated DNA. The modified Protector bonded with the long-strand DNA to generate an endonuclease-specific site and trigger the nicking process. Finally, DNA products with repetitive sequences not only recombined with the padlock to reactivate a new recycle of RCA but also triggered the catalytic hairpin assembly to form the H1-H2 complex, realizing the cooperative amplification of the signal. In this system, RCA-NESA and CHA were integrated into one step, which essentially simplifies the sensing process. Moreover, the introduction of the Protector would inhibit the extension reaction caused by the combination of the padlock and the RCA products, slowing down the non-specific reaction time and improving the sensitivity of the fluorescence detection system. Under the optimal experimental conditions, the fluorescence system achieved a limit-of-detection of 0.025 amol miR-21 in a 40 µL sample and successfully applied to miR-21 detection in serum samples from breast cancer patients, showing good agreement with the results of RT-PCR, which exhibited great potential in biomedical research and clinical diagnosis.

Fluorescence Biosensor for One-Step Simultaneous Detection of Mycobacterium tuberculosis Multidrug-Resistant Genes Using nanoCoTPyP and Double Quantum Dots.

The diagnosis of multidrug-resistant tuberculosis (MDR-TB) is crucial for the subsequent drug guidance to improve therapy and control the spread of this infectious disease. Herein, we developed a novel florescence biosensor for simultaneous detection of Mycobacterium tuberculosis (Mtb) multidrug-resistant genes (rpoB531 for rifampicin and katG315 for isoniazid) by using our synthesized nanocobalt 5,10,15,20-tetra(4-pyridyl)-21H,23H-porphine (nanoCoTPyP) and double quantum dots (QDs). Several nanoCoTPyPs with different charges and morphology were successfully prepared via the surfactant-assisted method and their quenching ability and restoring efficiency for DNA detection were systematically analyzed. It was found that spherical nanoCoTPyP with positive charge exhibited excellent quenching effect and sensing performance for the two DNAs' detection due to its affinity differences towards single-stranded DNA (ssDNA) and double-stranded DNA (dsDNA). ssDNA attached on QDs (QDs-ssDNA) was specifically hybridized with targets to form QDs-dsDNA, resulting in fluorescence recovery due to the disruption of the interactions between nanoCoTPyP and ssDNA. Two drug-resistant genes could be simultaneously quantified in a single run and relatively low limits of detection (LODs) were obtained (24 pM for T1 and 20 pM for T2). Furthermore, the accuracy and reliability of our method were verified by testing clinical samples. This simple and low-cost approach had great potential to be applied in clinical diagnosis of MDR-TB.

Coulometric back titration based on all-solid-state electrodes for phenylephrine hydrochloride determination.

Existing coulometric titration generally used liquid reference electrodes, with limitations of frequent maintenance and liquid leakage risk and requiring vertical working position. Herein, we proposed an all-solid coulometric titration based on the glassy carbon electrode (GCE) and preliminarily utilized it in phenylephrine hydrochloride (PHE) analysis with a universal back titration program. Subsequently, the long-term stability of the GCE in bromine and iodine solution was evaluated comprehensively by electrochemical characterization and titration measurement. The results presented an excellent linear relationship between electrolysis time and PHE concentration from 0.3 to 20 mM, with a limit of detection of 0.07 mM (3 S0/S). It also showed an excellent standard recovery rate and a short testing time within 10 min. Compared with bromometry in the pharmacopoeia, the all-solid coulometric titration exhibited higher accuracy and precision in formulation detection with simpler operation. The long-term stability experiments indicated that the potential difference mutation was unaffected by the electrochemical property of the GCE. Conclusively, this enabling work provided an all-solid coulometric titration for drug determination without maintenance in the long term and contributed to its further integration and industrialization.

Determination of tuberculosis-related volatile organic biomarker methyl nicotinate in vapor using fluorescent assay based on quantum dots and cobalt-containing porphyrin nanosheets.

Methyl nicotinate (MN) is a representative and typical volatile organic marker of Mycobacterium tuberculosis, and the specific detection of MN in human breath facilitates non-invasive, rapid, and accurate epidemic screening of tuberculosis infection. Herein, we constructed a fluorescent assay consisted of CdTe quantum dots (QD) and cobalt-metalized tetrakis(4-carboxyphenyl) porphyrin (CoTCPP) nanosheets to determine methyl nicotinate (MN) in vapor samples. Red-emission QD (λex=370 nm, λem=658 nm) acts as signal switches whose fluorescence signals can be effectively quenched by CoTCPP nanosheets but restored in the presence of MN. The strategy relied on the distinct binding affinity of cobalt ion and MN. MN restored the fluorescence of QD quenched by CoTCPP in a concentration-dependent manner, which exhibited a well-linear relationship in the range 1-100 µM, and a limit of detection of 0.59 µM. The proposed platform showed sensitivity and selectivity to detect MN in vapor samples with satisfactory RSD below 3.33%. The method is cheap, simple, and relatively rapid (detected within 4 min), which suggests a potential in tuberculosis diagnosis in resource- and professional-lacked areas.

Detection of Mycobacterium Tuberculosis IS6110 gene fragment by fluorescent biosensor based on FRET between two-dimensional metal-organic framework and quantum dots-labeled DNA probe.

Herein, a universal fluorescent biosensor was developed for detecting Mycobacterium Tuberculosis (MTB) specific insertion sequence IS6110 gene fragment based on Förster resonance energy transfer (FRET) strategy. CdTe quantum dots (QDs), with excellent luminous performance, were used to label single-stranded DNA (ssDNA) as fluorescence donor (QDs-DNA), in which the ssDNA was complementary to the IS6110 gene fragment. A new type of two-dimensional metal-organic framework (Cu-TCPP) was served as an acceptor. The Cu-TCPP exhibited a higher affinity towards ssDNA than double-stranded DNA (dsDNA). In the absence of targets, the fluorescence of QDs-DNA was quenched - due to the π-π stacking interactions between Cu-TCPP and ssDNA. Otherwise, QDs-DNA hybridized with the target to form a double helix and the fluorescence maintained in a target-concentration dependent manner. Excess QDs-DNA would be quenched and produced negligible background signal. The fluorescent sensor possessed a linear range from 0.05 nM to 1.0 nM with a low detection limit of 35 pM. Furthermore, we successfully applied this biosensing system to detect clinical sputum samples. This method displayed high sensitivity, specificity and great potentials in the early diagnosis of Tuberculosis.

DNA functionalized double quantum dots-based fluorescence biosensor for one-step simultaneous detection of multiple microRNAs.

The disease diagnosis by detecting single microRNAs (miRNAs) can produce high false positive rate. Herein, a novel fluorescence biosensor method for one-step simultaneous detection of multiple miRNAs was proposed by using single-stranded DNA (ssDNA) functionalized double quantum dots (QDs) and black hole quencher (BHQ)-decorated magnetic nanobeads (MNs). MNs were linked with two black hole quenchers (BHQ1 and BHQ3) via a complementary DNA (cDNA). The ssDNA/cDNA hybridization contributed to the fluorescence quenching of double QDs due to the fluorescence resonance energy transfer (FRET) between double QDs and BHQ. In the presence of target miRNA-33 (miR-33) and miRNA-125b (miR-125b), the ssDNA1 and ssDNA2 were respectively hybridized with miR-33 and miR-125b to form more stable duplexes. Thus, the double QDs were released into supernatant after the magnetic separation, leading to the fluorescence signals recovery at 537 nm and 647 nm. A wide linear range (0.5 nM-320 nM for miR-33 and 0.1 nM-250 nM for miR-125b) and low limits of detection (0.09 nM for miR-33 and 0.02 nM for miR-125b) were achieved. Moreover, our approach has been demonstrated to simultaneously detect miR-33 and miR-125b in cell extracts. With advantages of high sensitivity, strong specificity, low background and low cost, the strategies show great potentials for the detection of various targets in bioanalysis and disease diagnosis.

Sensitive analysis of doxorubicin and curcumin by micellar electromagnetic chromatography with a double wavelength excitation source.

Doxorubicin has been extensively used to treat cancers, and there are recent findings that the anticancer activities can be enhanced by curcumin. Although the two compounds have native fluorescence, they can hardly be quantified directly simultaneously using the laser-induced fluorescence (LIF) detection method. To avoid complex fluorescence derivatization and introduction of interfering components, a highly sensitive double wavelength excitation source LIF (D-W-Ex-LIF) detector composed of a 445-nm and 488-nm commercial laser diode was constructed to detect them simultaneously. Rhodamine 6G was selected as an internal standard, because its fluorescence can be excited at 445 nm and 488 nm. The native fluorescence of doxorubicin and curcumin and their resolution were enhanced by introducing mixed micelles. The optimal electrophoretic separation buffer was 10 mM borate buffer containing 20 mM Triton X-100, 5 mM sodium dodecyl sulfate, and 30% (v/v) methanol at pH 9.00. Therefore, the developed method was specific, accurate, and easily operable. Its limits of detection for doxorubicin and curcumin in human urine samples were 4.00 × 10-3 and 1.00 × 10-2 µg/mL, respectively, and the limits of quantification were 1.00 × 10-2 and 3.00 × 10-2 µg/mL, respectively. The recoveries were 94.9-109.1%. Graphical abstract.

A Redox-induced Dual-mode Colorimetric and Fluorometric Method based on N-CDs and MnO2 for Determination of Isoniazid in Tablets and Plasma Samples.

We develop a simple hydrothermal method to prepare a novel nitrogen-doped carbon dots (N-CDs) originated from green carbon source Liu-bao tea and ethylene diamine. The N-CDs emits strong and stable blue fluorescence (Em = 440 nm) under the excitation wavelength of 350 nm with a quantum yield of 35%. And it is used as an excellent fluorescent output for the sensitive and visual dual-mode determination of isoniazid. The fluorescence of N-CDs is "turned off" first by manganese dioxide (MnO2) nanosheets due to inner filter effect, MnO2 nanosheets can also oxidize TMB (3,3',5,5'- tetramethylbenzidine) to blue oxTMB. Isoniazid, however, can reduce MnO2 nanosheets to Mn2+, turning on the fluorescence again. The color of the solution fades from blue to colorless because less TMB can be oxidized. Under the optimal conditions, the dual-mode method has a satisfying linear relationship ranging from 2.0 to 120.0 µM with a limit of detection of 0.7 µM (S/N = 3). And it has been applied successfully to colorimetric and fluorescent determination of isoniazid in tablets and clinical plasma samples, with recoveries ranging from 94.0% to 102.4%. The properties of N-CDs and MnO2 nanosheets were thoroughly characterized using TEM, FT-IR, XPS, AFM and fluorescence spectrophotometer, the quenching mechanism was also discussed.

An integrated microfluidics for assessing the anti-aging effect of caffeic acid phenethylester in Caenorhabditis elegans.

Aging is a fundamental and fascinating process. Anti-aging research tried to find the mysteries about the human lifespan. To investigate the longevity-extending role of caffeic acid phenethylester (CAPE) and reveal the possible regulation mechanism, the long-term cultivation under well-defined environments, real-time monitoring, and live imaging is highly desired. In this paper, a well-designed microfluidic device was proposed to analyze the anti-aging effect of CAPE in Caenorhabditis elegans. With the combined use of multiple functional units, including micro-pillar, worm responder, a branching network of distribution channels, and microchambers, the longitudinal measurements of the exact number of worms throughout the whole lifespans is possible. Meanwhile, the brief cooling function of temperature-controllable system can achieve temporary and repeated immobilization of nematodes for fluorescence imaging. Our research data showed that CAPE can increase the survival of worms under normal and stress condition, including heat stress and paraquat-induced oxidative stress. The further studies revealed the anti-aging mechanism of CAPE. This proposed strategy and device would be a useful platform to facilitate future anti-aging studies and the finding of new lead compounds.

Allele-specific PCR with a novel data processing method based on difference value for single nucleotide polymorphism genotyping of ALDH2 gene.

Single nucleotide polymorphism (SNP) analysis based on allele-specific polymerase chain reaction (AS-PCR) is a relatively effective and economical method compared with other genotyping technologies such as DNA sequencing, DNA hybridization and isothermal amplification strategies. But AS-PCR is limited by its labor-intensive optimization of reaction parameters and time-consuming result assessment. In this study, we put forward a novel idea of data processing to address this problem. SNP analysis was accomplished by AS-PCR with endpoint electrochemical detection. For each sample, two separate reactions were run simultaneously with two sets of allele-specific primers (wild-type primers for W system and mutant primers for M system). We measured their redox current signals on screen-printed electrodes once AS-PCR finished and calculated the difference value of current signals between two systems to determine the genotyping result. Based on the difference value of fluorescent signals, real-time fluorescent PCR was used to study reaction parameters in AS-PCR. With screened parameters, we obtained the genotyping results within 50 min. 36 hair-root samples from volunteers were analyzed by our method and their genotypes of ALDH2 gene (encoding aldehyde dehydrogenase 2) were totally identical with data from commercialized sequencing. Our work first employed difference value between two reaction systems to differentiate allele and provided a novel idea of data processing in AS-PCR method. It is able to promote the quick analysis of SNP in the fields of health monitor, disease precaution, and personalized diagnosis and treatment.

One-Step Electrodeposition of Silver Nanostructures on 2D/3D Metal-Organic Framework ZIF-67: Comparison and Application in Electrochemical Detection of Hydrogen Peroxide.

Metal-organic frameworks (MOFs) have been widely used as supporting materials to load or encapsulate metal nanoparticles for electrochemical sensing. Herein, the influences of morphology on the electrocatalytic activity of Co-containing zeolite imidazolate framework-67 (ZIF-67) as supporting materials were studied. Three types of morphologies of MOF ZIF-67 were facilely synthesized by changing the solvent because of the influence of the polar solvent on the nucleation and preferential crystal growth. Two-dimensional (2D) ZIF-67 with microplate morphology and 2D ultrathin ZIF-67 nanosheets were obtained from pure H2O (H-ZIF-67) and a mixed solution of dimethylformamide and H2O (D-ZIF-67), respectively. Three-dimensional ZIF-67 with rhombic dodecahedron morphology was obtained from pure methanol (M-ZIF-67). Then, one-step electrodeposition of silver nanostructures on ZIF-67-modified glassy carbon electrode (Ag/ZIF-67/GCE) was performed for the reduction of hydrogen peroxide (H2O2). Cyclic voltammetry can be used to investigate the electrocatalytic activity of Ag/ZIF-67/GCE, and Ag/H-ZIF-67/GCE displayed the best electrocatalytic property than Ag/D-ZIF-67/GCE and Ag/M-ZIF-67/GCE. The electrochemical H2O2 sensor showed two wide linear ranges of 5 µM to 7 mM and 7 to 67 mM with the sensitivities of 421.4 and 337.7 µA mM-1 cm-2 and a low detection limit of 1.1 µM. In addition, the sensor exhibited good selectivity, high reproducibility, and stability. Furthermore, it has been utilized for real-time detection of H2O2 from HepG2 human liver cancer cells. This work provides a novel strategy for enhancing the detection performance of electrochemical sensors by changing the crystalline morphologies of supporting materials.

A simple and highly sensitive masking fluorescence detection system for capillary array electrophoresis and its application to food and medicine analysis.

A high sampling rate, good stability, high throughput masking fluorescence detection system with easy positioning of each channel for capillary array electrophoresis was prepared and studied. A special mask combined with convex lenses was designed to modulate signals, without using any extra device to position each channel. The signal of each channel was detected by a photomultiplier tube, classified and saved by software. The design was used to evidently reduce the rotational vibration of optical components and to stabilize the system, so a high sampling rate was obtained by increasing the DC motor speed. To improve the optical system, optical fibers instead of conventional bulky optical components were used to transmit optical signal and to collect fluorescences in multiple directions, which greatly raised the sensitivity. Other important parameters including sampling rate, rotating speed and driven voltage laser diode (LDs) have also been investigated. Under optimal conditions, the performance of the detection system was evaluated. This novel system had a well-designed structure, and allowed independent multiple capillary operations and easy microanalysis. Its limit of detection for rhodamine 6G was 2.0 × 10-2 µg/mL.

A sensitive photochemical reaction-capacitively coupled contactless conductivity detection system for HPLC and its application in determination of Cyclosporin A.

High performance liquid chromatography (HPLC) post-column photochemical reaction (PR) coupled capacitively coupled contactless conductivity detector (C4D) was used for the first time in analysis of weak ultraviolet (UV)-absorbing, non-fluorescence and nonpolar compound. A series of conditions including the radiation power of light source, the length of the reaction tube and the thickness of detection tube were investigated. HPLC-PR-C4D system was successfully applied to the determination of Cyclosporin A (CsA). Consequently, under optimal conditions, the detection system exhibited a detection limit of 0.04 µg/mL and wide linear range from 0.5 µg/mL to 100 µg/mL for CsA detection. Application of the HPLC-PR- C4D system to pharmaceutical formulation and biological samples revealed the system developed maybe reliably applied to clinical studies.