A novel robust hydrogel-assisted paper-based sensor based on fluorescence UiO-66-NH2@ZIF-8 for the dual-channel detection of captopril.

Captopril (CP) is commonly used as an active enzyme inhibitor for the treatment of coronary heart disease, hypertension and angina pectoris. The development of sensitive and efficient method for CP analysis is of great importance in biomedical research. Herein, we fabricated a sensitive and robust hydrogel-assisted paper-based sensor based on fluorescence UiO-66-NH2@ZIF-8 and Co, N-doped carbon nanozymes with oxidase-mimicking activity for accurate monitoring of captopril. The hydrogel-assisted paper-based sensor appeared a visible pink signal due to the catalytic oxidation of colorless N,N-diethyl-p-phenylenediamine (DPD) to oxDPD by Co, N-doped carbon-based nanozymes, and resulted in the fluorescence quenching of UiO-66-NH2@ZIF-8. In the presence of captopril, the oxidation of chromogenic substrate DPD by Co, N-doped nanozymes in the hydrogel-assisted paper-based sensor was hindered and accompanied by a change in the visible color, leading to recovery of the fluorescence of UiO-66-NH2@ZIF-8, and the change in the fluorescence color could also be observed. Therefore, the quantitative detection of captopril is achieved by taking a smartphone photograph and converting the image parameters into data information using ImageJ software. The portable hydrogel-assisted paper sensor provided sensitive detection of captopril in two modes based on visible color change as well as fluorescence color change with limits of detection of 0.45 µM and 0.47 µM, respectively. This hydrogel-assisted paper-based sensor has been successfully applied to the accurate monitoring of captopril in human serum, providing a potential avenue for in situ detection of captopril.

Development of a "turn off" fluorescent molecularly imprinted nanoparticle-based sensor for selective captopril quantification in synthetic urine and wastewater samples.

The combination of silica nanoparticles with fluorescent molecularly imprinted polymers (Si-FMIPs) prepared by a one-pot sol-gel synthesis method to act as chemical sensors for the selective and sensitive determination of captopril is described. Several analytical parameters were optimized, including reagent ratio, solvent, concentration of Si-FMIP solutions, and contact time. Fourier-transform infrared spectroscopy (FT-IR), transmission electron microscopy (TEM), and the ninhydrin assay were used for characterization. The selectivity was evaluated against molecules belonging to other drug classes, such as fluoroquinolones, nonacid nonopioids, benzothiadiazine, alpha amino acids, and nitroimidazoles. Under optimized conditions, the Si-FMIP-based sensor exhibited a working range of 1-15 µM, with a limit of detection (LOD) of 0.7 µM, repeatability of 6.4% (n = 10), and suitable recovery values at three concentration levels (98.5% (1.5 µM), 99.9% (3.5 µM), and 99.2% (7.5 µM)) for wastewater samples. The sensor provided a working range of 0.5-15 µM for synthetic urine samples, with an LOD of 0.4 µM and a repeatability of 7.4% (n = 10) and recovery values of 93.7%, 92.9%, and 98.0% for 1.0 µM, 3.5 µM, and 10 µM, respectively. In conclusion, our single-vessel synthesis approach for Si-FMIPs proved to be highly effective for the selective determination of captopril in wastewater and synthetic urine samples.

Captopril oral solution for pediatric use: formulation, stability study and palatability assessment in vivo

Abstract he aim of this work was to develop an oral solution of captopril at 5 mg/mL preservative-free. Two formulations were prepared, one containing sweetener (formulation 1) and the other without this excipient (formulation 2). The results found of validation parameters from analytical method performed by HPLC for captopril were, linearity 0.9998, the limit of detection 15.71 µg/mL, the limit of quantification 47.60 µg/mL, repeatability 1.05%, intermediate precision 2.42%, accuracy intraday 101,53%, accuracy inter-day 99.85%. Moreover, the results found for captopril disulfide were, linearity 0.9999, limit of detection 0.65 µg/mL, limit of quantification 1.96 µg/mL, repeatability 2.28%, intermediate precision 1.51%, accuracy intraday 101.36%, accuracy inter-day 100.29%. The appearance of formulations was clear and colorless, pH measures were 3.12 and 3.04, dosage of captopril and captopril disulfide were 99.45% and 99.82%, 0.24% and 0.12% for formulation 1 and formulation 2, respectively. The stability study demonstrated that the concentration of captopril and captopril disulfide in the formulations was > 90% and below 3%, respectively. The in vivo palatability study in animals and humans showed that Formulation 1 containing the sweetener had better acceptance. Thus, the sweetener was able to improve the unpleasant taste of the formulation

Introducing hierarchical hollow MnO2 microspheres as nanozymes for colorimetric determination of captopril.

A simple sensor was developed for the colorimetric determination of captopril (CPT). Herein, hierarchical hollow MnO2 microspheres (HH-MnO2) were applied as nanozymes with peroxidase-mimetic activity. Free cation radicals with a strong absorption signal (λmax at 653 nm) were generated via a redox reaction between 3, 3', 5, 5'-tetramethylbenzidine (TMB) and HH-MnO2. Captopril could successfully prevent the generation of blue-colored free cation radicals. The influence of CPT concentration on the absorption of the generated radicals was monitored by UV-Vis spectroscopy. The corresponding linear concentration range was from 1.0 to 30.0 µg mL-1 (4.6-138.1 µmol L-1), and the detection limit was found to be 0.26 µg mL-1 (1.2 µmol L-1). As a practical usage, the developed sensor was effectively utilized to measure the content of CPT in pharmaceutical formulations.

Colorimetric captopril assay based on oxidative etching-directed morphology control of silver nanoprisms.

Oxidative etching is an effective approach to control the morphology of nanomaterials. Taking silver nanocrystals (AgNCs) as an example, oxidative etching-directed morphological transformation from a triangular prism shape to a disk shape is achieved and then applied to the determination of captopril. As a mediator, trace amount of halides play important roles in the shape-controlled evolution of AgNCs. Etching causes the color of the triangular silver nanoprims (AgNPRs) to change from blue to yellow on formation of round nanodisks. On addition of captopril, the oxidative etching of the AgNPRs is prevented owing to the protection by the drug via Ag-S bonding. In this case, the solution color does not change. This finding was used to design an assay of captopril that has a linear response in the 10-600 nM concentration range and a 2 nM limit of detection. This method also allows digital camera read-out. It was successfully applied to quality control of captopril in tablets. Graphical abstractOxidative etching-directed morphological transformation of silver nanocrystals is well manipulated and successfully applied in colorimetric determination of captopril in tablets.

Facile Preparation of Boron and Nitrogen Codoped Green Emission Carbon Quantum Dots for Detection of Permanganate and Captopril.

A hydrothermal strategy for preparing boron and nitrogen codoped carbon quantum dots was studied using the precursors of p-amino salicylic acid, boric acid and ethylene glycol dimethacrylate. The boron and nitrogen codoped carbon quantum dots have high fluorescence intensity, good monodispersity, high stability, superior water solubility, and a fluorescence quantum yield of 19.6%. Their average size is 5 nm. Their maximum excitation and emission wavelengths are 380 and 520 nm, respectively. Permanganate (MnO4-) quenched boron and nitrogen codoped carbon quantum dots fluorescence through inner filter effect and static quenching effects. The linear relation between quenching efficiency and MnO4- concentration ranged from 0.05 to 60 µmol/L with a detection limit of 13 nmol/L. In the presence of captopril, MnO4- was reduced to Mn2+ and the fluorescence of boron and nitrogen codoped carbon quantum dots was recovered. The linear range between recovery and captopril concentration was from 0.1 to 60 µmol/L. The limit of detection was 0.03 µmol/L. The developed method can be employed as a sensitive fluorescence sensing platform for MnO4-. It has been successfully used for captopril detection in mouse plasma.

2D-Single-crystal hexagonal gold nanosheets for ultra-trace voltammetric determination of captopril.

Two dimensional single-crystal hexagonal gold nanosheets (SCHGNSs) were prepared by microwave heating of a solution of HAuCl4 in an ionic liquid. The SCHGNSs were characterized by field emission electron microscopy, energy-dispersive X-ray spectroscopy, X-ray diffraction, atomic force microscopy and electrochemical impedance spectroscopy. The SCHGNSs were then used to modify a graphite paste electrode for voltammetric determination of the hypertension drug captopril (CAP). The modified electrode showed a well-defined oxidation peak (at 0.41 V vs. Ag/AgCl) at pH 7.0 using differential pulse voltammetry. Under the optimum conditions, the response is linear in the 2-400 nM and 4.0-50 µM CAP concentration range, and the detection limit (at S/N = 3) is 0.3 nM. The sensor was successfully applied to the determination of CAP in pharmaceutical tablets and in spiked urine. Graphical abstract Schematic presentation of the preparation of single crystal hexagonal gold nanosheets and their use to modify a carbon paste electrode for ultra-trace voltammetric determination of the drug captopril.

Application of a nano-structured molecularly imprinted polymer as an efficient modifier for the design of captopril drug selective sensor: Mechanism study and quantitative determination.

In the present study, electrochemical studies and potentiometric determination of captopril (CAP) drug were presented using a glassy carbon electrode (GCE) and carbon paste electrode (CPE), respectively; which is modified with a synthetic nano-structured molecularly imprinted polymer (MIP). CAP-MIP sample with an average particle size of 95 nm was synthesized using a precipitation polymerization method. The electrochemical behavior of CAP was studied on a MIP modified GCE, in an aqueous solution at pH 3.0. The electron transfer coefficient (α) was determined for the CAP drug, using electrochemical approaches. The prepared CAP-MIP was also used as a modifier in a CPE to design a selective CAP sensor, before its potentiometric determination. The modified CPE exhibits a good electrochemical response with a Nernstian slope of 59.15 ±â€¯1.5 mV per decade over a wide linearity in the concentration range of 3.0 × 10-9-1.0 × 10-1 mol L-1. The cyclic voltammetry results were in good agreement with the electrochemical studies for the 1H+/1e- process. The designed electrode indicates a reasonable selectivity for CAP over other studied drugs such as ibuprofen, paracetamol, acyclovir, pyrazinamide, dimenhydrinate, and naproxen as well as with an excellent applicability in some pharmaceutical products.

Photoluminescent coral-like carbon-branched polymers as nanoprobe for fluorometric determination of captopril.

The authors describe the synthesis of fluorescent coral-like carbon nano-branched polymers (PCNBPs) co-doped with nitrogen and phosphorus. Uric acid and phosphoric acid act as nitrogen and phosphorus sources, respectively. The PCNBPs have a coral-like branched structure, are cross-connected, and < 20 nm in skeleton diameter. Their blue fluorescence, best measured at excitation/emission wavelengths of 330/425 nm, is quenched by mercury (II) ions due to the specifically restricted rigid conformation caused by the interaction of phosphorus, nitrogen, and oxygen groups on the surface of the PCNBPs. Fluorescence is selectivity quenched by Hg(II) but restored in addition of the hypertension drug captopril (CAP) in the range 50 nM to 40 µM concentration range. Fluorescence recovery is attributed to the effectively specific interactions between the thiol group of CAP and Hg(II). The method was applied to the determination of the concentration of Cap in pharmaceutical samples, and recoveries were between 97.6 and 105.1%. Graphical abstract Fluorescent coral-like carbon nano-branched polymers (PCNBPs) co-doped with nitrogen and phosphorus are described. Their fluorescence is selectivity quenched by Hg(II) but restored in addition of the hypertension drug captopril (Cap) in the range 50 nM to 40 µM concentration range.

Smartphone application for captopril determination in dosage forms and synthetic urine employing digital imaging.

A simple, accurate, and low-cost analytical procedure for captopril determination through digital imaging is presented. The method relies on the spot test reaction between captopril and palladium (II) chloride, which produces a yellow and water-soluble complex with maximum absorption at 380 nm. A smartphone camera and a portable apparatus built for internal lighting control were put together to acquire digital images of reaction mixtures. Digital image processing through the RGB approach was used to establish a quantitative relationship between color intensity and captopril concentration. Under the most suitable operational and experimental conditions, an analytical curve was built monitoring the Blue channel within the concentration range of 3.12 × 10-5 to 1.21 × 10-3 mol L-1. Limits of detection and quantification were equal to 8.06 × 10-6 and 2.69 × 10-5 mol L-1, respectively. Recovery percentage in synthetic urine samples ranged from 97.1% to 102.9%. Results were compared with a reference method and no significant differences were detected at the 95% confidence level. The developed method presents budgetary and environmental advantages concerning the use of cheap and easy-handled devices and the consumption of very low volumes of reagent (800 µL per determination). It can be a useful analytical tool for laboratories with limited financial resources while abiding by green chemistry principles.

The determination of pharmaceutically active thiols using hydrophilic interaction chromatography followed postcolumn derivatization with o-phthaldialdehyde and fluorescence detection.

A rapid, precise and specific hydrophilic interaction chromatography (HILIC) combined with postcolumn derivatization using o-phthaldialdehyde and fluorescence detection was developed and validated for the determination of selected pharmaceutically active thiols. The analysis was carried out on a Diol HILIC column using a mobile phase consisting of acetonitrile and solution of 10 mmol/L citric acid adjusted with 1-propylamine to pH 5.5 in ratio 75:25 (v/v) for separation of cysteine and homocysteine and in ratio 85:15 (v/v) for separation of N-acetyl-l-cysteine and captopril. The postcolumn derivatization reaction was performed at room temperature using reagent (5 mmol/L OPA in 0.05 mol/L 4- (2-hydroxyethyl) piperazine-1-ethanesulfonic acid at pH 7) delivered at the flow rate of 0.3 mL/min. Fluorescence detection was carried out at excitation and emission wavelength of 345 nm and 450 nm, respectively. The effect of chromatographic conditions including acetonitrile content, salt concentration in the mobile phase and mobile phase pH on the retention of tested thiols was investigated. The postcolumn reaction conditions such as reaction temperature, derivatization reagent flow rate, o-phthaldialdehyde concentration and derivatization reagent pH were deeply studied. The developed method was validated in terms of linearity, accuracy, precision and selectivity according to the International Conference on Harmonisation guidelines. The HILIC method was successfully applied for the analysis of commercially available samples of pharmaceutically active thiols such as captopril, N-acetyl-l-cysteine (NAC) and cysteine.

A Capillary Zone Electrophoresis Method with Multiresponse Chemometric Optimization for the Simultaneous Determination of Zofenopril Calcium and Hydrochlorothiazide in Presence of Hydrochlorothiazide Major Impurities.

In the present decade, great importance has been focused on the development of green analytical methods (GAM) as eco-friendly techniques. Minimizing the wastes, analysis time, hazardous reagents, sample size and energy are the main important principles for development of GAM. This manuscript describes a green, novel, rapid, accurate and reliable capillary zone electrophoresis method (CZE) for the simultaneous separation and determination of zofenopril calcium (ZOF) and hydrochlorothiazide (HCT) in presence of two major impurities of HCT, namely; chlorothiazide (CT) and salamide (DSA). Uncoated fused-silica capillary (50 µm i.d. × 48.5 cm and 40 cm effective length) was used. The main factors affecting the separation were the buffer concentration, pH of the buffer and applied voltage. Optimization of the experimental conditions was performed by applying response surface methodology (RSM). The experiments were designed using central composite face-centered design (CCD). The model obtained from the design described the linear, non-linear and interaction effects of factors on the responses. The optimum conditions given by the design were running buffer of sodium borate (pH 9.15; 10 mM) and 17 kV as positive mode applied voltage. Upon applying these conditions, baseline separation for the four compounds with short analysis time of 5.0 min was achieved. UV detection was performed at 225.0 nm and the capillary temperature was maintained at 25°C. The method was validated and applied for quantitative determination of the studied drugs according to the International Conference on Harmonization (ICH) guidelines. Good linearity was obtained in the range of 10.0-100.0 µg/mL for both ZOF and HCT. As for CT and DSA (HCT impurities), linearity range was 5.0-100.0 µg/mL. The proposed method was successfully applied for the analysis of these drugs in their synthetic mixtures and in their co-formulated pharmaceutical formulations.

A Validated High-Performance Thin-Layer Chromatographic Method for the Simultaneous Determination of Zofenopril Calcium and Hydrochlorothiazide in the Presence of the Hydrochlorothiazide Impurities: Chlorothiazide and Salamide.

The chromatographic analysis of either process-related impurities or degradation products is very important in the pharmaceutical industry. In this work, a simple, selective, and sensitive HPTLC method was developed and validated for the simultaneous determination of zofenopril calcium (ZOF) and hydrochlorothiazide (HCT) in the presence of the HCT impurities: A) chlorothiazide (CT) and B) salamide, in raw materials and in pharmaceutical formulation. The separation was carried out on HPTLC silica gel 60 F254 using ethyl acetate-glacial acetic acid-triethylamine (10 + 0.1 + 0.1, v/v/v) as a developing system. The separated bands were scanned densitometrically at 270 nm. Polynomial equations were used for the regression. Calibration curves were constructed for ZOF, HCT, CT, and salamide in the ranges of 0.5-10, 0.2-4, 0.05-1.4, and 0.05-1.0 µg/band, respectively. Different parameters affecting the suggested method, including developing systems of varying composition/ratios and different detection wavelengths, were studied to achieve the best resolution and precision with good sensitivity. System suitability parameters were also tested. The proposed method was validated as per the International Conference on Harmonization guidelines and was successfully applied for the quantification of the studied drugs in their pharmaceutical formulation, with no interference from excipients observed. The results obtained by the developed HPTLC method were compared statistically with those obtained by the reported HPLC method using Student's t and F ratio tests, and no significant difference was obtained, indicating the ability of the proposed method to be used for routine analysis of drug product.

Simultaneous determination of ACE inhibitors and dexibuprofen in active pharmaceutical ingredient, formulations and human serum by RP-HPLC.

The contemporary work describes a rapid and cost effective reversed phase High Performance Liquid Chromatography (RP-HPLC) method for the quantification of Captopril, Lisinopril and Dexibuprofen (DXP) simultaneously in dosage formulations, active pharmaceutical ingredients and human serum. The chromatographic system included LC-20A pump, Sil-20A auto sampler and SPD-20A UV/visible detector. The estimation was carried out by using a C18 (5µm, 250 ×4.6 mm) column with mobile phase methanol: water (80:20 v/v, pH 3.0) at 230 nm with a flow rate of 1.0 ml•min-1. The retention time of Dexibuprofen was 5.4 min while that of Captopril and Lisinopril were found to be 3.2 and 1.8 minutes respectively. There was no considerable variation exists in between the tested drug spiked in serum and the extent recovered, without interference of serum in concurrent approximation. The method developed was found to be precise, selective and validated for precision, linearity, specificity, accuracy, limit of detection and limit of quantitation. There is no such method reported earlier for the determination of ACE Inhibitors and DXP simultaneously. The present study helps in assessing the co-administration of both drugs in treatment and can be employed for quality control analysis and drug-drug interaction studies.

Laser induced thermal lens microscopy for highly sensitive determination of captopril.

In this work, a combined flow injection-photo thermal lens microscopy (FI-PTLM) system was used for highly sensitive determination of captopril as an angiotensin-converting enzyme inhibitor. Captopril has no absorption in the visible range, but due to its thiol group could interact with gold nanoparticles (GNPs). GNPs, because of their surface plasmon resonance (SPR), have absorption in the visible range, but their interaction with a low concentration of captopril shows no effective change in UV-Vis spectrophotometry because their aggregation is slight. On the contrary, at the same condition, the PTLM with a visible light source enables sensitive measurement of this compound. The thiol group of captopril binds to the surface of GNPs and decreases the SPR. At the optimum condition in the focal volume of 2.68 fL (f=10-15), the obtained range of linearity was 50-800 nM. The developed method was successfully applied for the determination of captopril in human serum and pharmaceutical samples.

Amplified nanostructure electrochemical sensor for simultaneous determination of captopril, acetaminophen, tyrosine and hydrochlorothiazide.

A novel nanomaterial-based voltammetric sensor has been developed for use a highly sensitive tool for the simultaneous determination of captopril (CA), acetaminophen (AC), tyrosine (TY) and hydrochlorothiazide (HCTZ). The device is based on the application of NiO/CNTs and (2-(3,4-dihydroxyphenethyl)isoindoline-1,3-dione) (DPID) to modify carbon paste electrodes. The NiO/CNTs nanocomposite was synthesized through a direct chemical precipitation approach and was characterized with X-ray powder diffraction (XRD), and scanning electron microscopy (SEM). The NiO/CNTs/DPID/CPEs were found to facilitate the analysis of CA, AC, TY and HCTZ in the concentration ranges of 0.07-200.0, 0.8-550.0, 5.0-750.0 and 10.0-600.0µM with the respective detection limits of 9.0nM, 0.3µM, 1.0µM and 5.0µM. The developed NiO/CNTs/DPID/CPEs were used for the determination of the mentioned analytes in pharmaceutical and biological real samples.

Electrochemically reduced graphene and iridium oxide nanoparticles for inhibition-based angiotensin-converting enzyme inhibitor detection.

In this work, a novel biosensor based on electrochemically reduced graphene oxide and iridium oxide nanoparticles for the detection of angiotensin-converting enzyme inhibitor drug, captopril, is presented. For the preparation of the biosensor, tyrosinase is immobilized onto screen printed electrode by using 1-Ethyl-3-(3-dimethylaminopropyl)-carbodiimide and N-Hydroxysuccinimide coupling reagents, in electrochemically reduced graphene oxide and iridium oxide nanoparticles matrix. Biosensor response is characterized towards catechol, in terms of graphene oxide concentration, number of cycles to reduce graphene oxide, volume of iridium oxide nanoparticles and tyrosinase solution. The designed biosensor is used to inhibit tyrosinase activity by Captopril, which is generally used to treat congestive heart failure. It is an angiotensin-converting enzyme inhibitor that operates via chelating copper at the active site of tyrosinase and thioquinone formation. The captopril detections using both inhibition ways are very sensitive with low limits of detection: 0.019µM and 0.008µM for chelating copper at the active site of tyrosinase and thioquinone formation, respectively. The proposed methods have been successfully applied in captopril determination in spiked human serum and pharmaceutical dosage forms with acceptable recovery values.

The use of experimental design for the development of a capillary zone electrophoresis method for the quantitation of captopril.

A capillary zone electrophoresis (CZE) method for the quantitation of captopril (CPT) using UV detection was developed. Influence of electrolyte concentration and system variables on electrophoretic separation was evaluated and a central composite design (CCD) was used to optimize the method. Variables investigated were pH, molarity, applied voltage and capillary length. The influence of sodium metabisulphite on the stability of test solutions was also investigated. The use of sodium metabisulphite prevented degradation of CPT over 24 hours. A fused uncoated silica capillary of 67.5cm total and 57.5 cm effective length was used for analysis. The applied voltage and capillary length affected the migration time of CPT significantly. A 20 mM phosphate buffer adjusted to pH 7.0 was used as running buffer and an applied voltage of 23.90 kV was suitable to effect a separation. The optimized electrophoretic conditions produced sharp, well-resolved peaks for CPT and sodium metabisulphite. Linear regression analysis of the response for CPT standards revealed the method was linear (R2 = 0.9995) over the range 5-70 µg/mL. The limits of quantitation and detection were 5 and 1.5 µg/mL. A simple, rapid and reliable CZE method has been developed and successfully applied to the analysis of commercially available CPT products.

Cyclodextrin- and solvent-modified micellar electrokinetic chromatography for the determination of captopril, hydrochlorothiazide and their impurities: A Quality by Design approach.

A fast and selective capillary electrophoresis method has been developed for the simultaneous determination of the antihypertensive drugs captopril and hydrochlorothiazide and their related impurities in a combined dosage form. Method development was carried out implementing each step of Quality by Design workflow, the new paradigm of quality outlined in International Conference on Harmonisation Guidelines. Captopril is characterized by the lack of a strong chromophore and contains a proline-similar moiety, which gives rise to the presence of interconverting cis-trans isomers and leads to the possible interference between electrophoretic migration and reaction of isomerization. The scouting phase was dedicated to the investigation of several operative modes in order to overcome detection and isomerization issues. The best performances were obtained with sodium cholate-based micellar electrokinetic chromatography with the addition of n-butanol and γ-cyclodextrin. Critical quality attributes were represented by the critical resolution values and by analysis time. Critical process parameters were defined as temperature, voltage, concentration and pH of borate buffer, concentration of sodium cholate, n-butanol and γ-cyclodextrin. Screening experimental design was applied for investigating knowledge space. Response surface methodology pointed out several significant interaction effects, and with Monte-Carlo simulations led to map out the design space at a selected probability level. Robustness testing was carried out and a control strategy based on system suitability tests was defined. The selected working conditions gave a complete separation of the analytes in less than three minutes. The method was validated and applied to the analysis of a real sample of coformulation tablets.

Reusable fluorescent sensor for captopril based on energy transfer from photoluminescent graphene oxide self-assembly multilayers to silver nanoparticles.

In this work we designed a self-assembly multilayers, in which photoluminescent graphene oxide was employed as a fluorescence probe. This multilayers film can effectively recognize captopril by resonance energy transfer from graphite oxide to silver nanoparticles. A new interfacial sensing method for captopril with high signal to noise ratio was established, by means of that multilayers was quenched by silver nanoparticles and subsequently recovered by adding captopril. The linear relation between intensity and captopril concentration was good, and the detection limit was found to be 0.1578 µM. Also, this novel detection platform demonstrated intriguing reusable properties, and the sensor could be repeated more than ten times without obviously losing its sensing performance.