L-Cys Concentrations Research Articles

In-situ grown MXene@PDA/MOF composites constructed electrochemical sensor for detecting trace l-cysteine

In this study, novel honeycomb-like morphology MXene@PDA/MOF composites were prepared in situ on the surface of MXene@PDA (polydopamine), combined with 2-methylimidazole and Zn2+. The characterizations of morphology and electrochemical properties show that MXene@PDA/MOF has large specific surface areas and outstanding electroconductibility. Furthermore, the MXene@PDA/MOF-based sensor was fabricated to detect l-cysteine (L-Cys). The response of differential pulse voltammetry (DPV) shows the current intensity increases as l-Cys concentration. Under the optimum conditions, DPV response shows a fine linear relationship with l-Cys concentration in a range of 0.01 – 5.0 μmol L−1 with the detection limit of 3.74 × 10−9 mol L−1. This sensor was used to detect l-Cys in real samples with recoveries of 100.34 % – 101.68 %. Thus, the MXene@PDA/MOF-based electrochemical sensor exhibits excellent selectivity, reproducibility, stability, and practicability.

Development of a dual-emitting nanohybrids ratiometric fluorescent probe for highly sensitive detection of L-cysteine based on Cu-Ag alloy nanoclusters and carbon quantum dots

In this study, we successfully synthesized Cu-Ag alloy nanoclusters (CuAgCs) by introducing Ag, which exhibited superior stability compared to Cu nanoclusters (CuNCs). Additionally, carbon quantum dots (CQDs) with an impressive quantum yield of 26% were prepared. By combining short-wavelength CQDs with long-wavelength CuAgNCs, ratiometric fluorescent probes capable of dual emission with peaks at 468 nm (F468) and 560 nm (F560) were developed for detecting L-cysteine (L-Cys). The detection mechanism involves the aggregation-induced emission enhancement (AIEE) effect of CuAgNCs in the presence of L-Cys, resulting in an increase in F560 while F468 remains unchanged. The fluorescence intensity ratio F560/F468 exhibits a linear relationship with L-Cys concentration in the range of 0–60 μM, with a low detection limit of 0.367 μM. Notably, the practical applicability of the fluorescent probe was validated through successful detection in real samples, achieving a high recovery rate of 98.7%-109%. These results demonstrate the promising potential of the developed fluorescent probe for practical applications.

A Naked-Eye Colorimetric Ratio Method for the Selective and Sensitive Detection of L-Cys Based on a Silver Nanoflakes–Chromium (III) Ion System

As a necessary sulfhydryl amino acid, L-cysteine (L-Cys) maintains many physiological functions in the biological system. However, abnormal L-Cys levels can cause a variety of diseases. In our work, a highly sensitive and selective assay has been developed for sensing L-Cys using the morphological transformation of silver-based materials induced by Cr3+. In this sensing system, Cr3+ could etch the silver nanoflakes into silver nanoparticles, accompanied by a change in absorbance, which decreases at 395 nm, creates a new peak at 538 nm, and keeps increasing the absorbance with the addition of Cr3+ concentration. Meanwhile, under the naked eye, the solution color changes from bright yellow to dark purple. Because of the strong affinity between L-Cys and Cr3+, L-Cys could inhibit the induction of Cr3+ on silver-based materials, thereby preventing changes in the configuration, absorption spectrum, and color of silver-based materials. Taking advantage of this point, we can quantitatively detect the concentration of L-Cys. A linear relationship between the absorbance ratio (A538 nm/A395 nm) and L-Cys concentration was found in the range of 0.1–0.9 μM, and the detection limit was 41.2 nM. The strategy was applied to measure L-Cys spiked in beer and urine samples, with recovery from 93.80 to 104.03% and 93.33% to 107.14% and RSD from 0.89 to 2.40% and 1.80% to 6.78%, respectively. This detection strategy demonstrates excellent selectivity and sensitivity, which makes it a practical and effective method for the detection of L-Cys in real samples.

Enhancing the catalytic performance of MOF-polymer@AuNP-based nanozymes for colorimetric detection of serum L-cysteine.

The dispersion of gold nanoparticles (AuNPs) on a metal-organic framework (MOF) surface greatly affects the catalytic activity of the material. However, regulating the catalytic performance of AuNP-MOF composite-based nanozymes is a great challenge. Herein, poly(dimethylvinyloxazolinone) (PV) was chemically bonded on the surface of UiO-66-NH2 (U66), followed by modification of pepsin (Pep) on the PV chains. U66-PV-Pep@AuNP composite nanozymes were fabricated after the AuNPs formed in situ with Pep as the capping and reducing reagent. Compared to Pep@AuNPs that were physically adsorbed onto the surface of U66, the U66-PV-Pep@AuNP composites exhibited superior peroxidase (POD)-mimetic activity in the oxidation of 3,3'5,5'-tetramethylbenzidine (TMB) with H2O2. Considering the surface dispersion uniformity and local concentration of Pep@AuNPs on the surface of the U66-PV-Pep@AuNP composites, the principle for improving the catalytic performance of the proposed nanozymes was explored. Furthermore, it was observed that the introduction of L-cysteine (L-Cys) into the U66-PV-Pep@AuNP-TMB-H2O2 system significantly reduced its oxidation activity and faded the color, allowing the development of a highly selective and sensitive colorimetric method for L-Cys detection. The UV-vis absorption intensity of oxTMB showed a good linear relationship with the concentration of L-Cys in the range of 2.5-40.0 μM (R2 = 0.996), with a detection limit of 0.33 μM. The proposed protocol using U66-PV-Pep@AuNP nanozymes was applied to monitor rat serum L-Cys following intraperitoneal injection. This study paves the way for the design and construction of MOF-polymer@AuNP nanozymes for drug detection in real bio-samples.

Ni2P nanocrystallines anchored on black phosphorus nanosheets enable highly selective and sensitive non-enzymatic electrochemical detection of L-cysteine over glutathione

Selective and sensitive determination of L-cysteine (L-Cys) plays an important role in clinical diagnoses and regulation of L-Cys level. However, glutathione (GSH) interferes greatly with the L-Cys detection due to their similar electrochemically active functional sulfhydryl groups and the high abundance of GSH in biological samples. Herein, Ni2P nanocrystallines anchored on black phosphorus nanosheets (Ni2P @ BPNSs) electrocatalysts were prepared by an in-situ solvothermal method using BPNSs as phosphorus sources and substrate. The electrochemical behaviors of Ni2P @ BPNSs with different Ni2P contents were studied for L-Cys determination. The experimental and DFT calculation results reveal the extraordinary electrocatalytic and selective sensing mechanism of Ni2P @ BPNSs toward L-Cys is attributed to the high selective adsorption and electrocatalytic activity of Ni active sites, and BPNSs matrix. The electrochemical sensor displays low detection limit (2 nM), more negative oxidation potential (+0.30 V), extremely broad linear range (0.02 −1000 μM), excellent sensitivity (396.00 μA mM−1 cm−2), and extraordinary selectivity. The sensor has been practically applied in detection of L-Cys concentrations in serum and urine samples. This work opens the avenues for the engineering design of metal atoms decorated BP materials in biosensors with enhanced sensing performance by adjusting the properties of materials, allowing for more selective and sensitive analyte detection.

L-cysteine-regulated in situ formation of Prussian blue/Turnbull’s blue nanoparticles as the colorimetric probe for the detection of copper ion

A fast, simple, sensitive, and selective colorimetric method for the detection of Cu 2+ was developed using Prussian blue/Turnbull’s blue nanoparticles (PBNPs/TBNPs) as the probe. The colorimetric sensor is based on the following principle. Cu 2+ can induce the aggregation of L-cysteine (L-cys) modified-PBNPs/TBNPs (L-cys-PBNPs/TBNPs), resulting in an obvious red shift of its maximum absorption peak. Thus, the concentration of Cu 2+ can be determined based on the peak shift in the UV–Vis spectra. The optimal pH, concentration of L-cys, reaction temperature between L-cys-PBNPs/TBNPs and Cu 2+ , the formation time of L-cys-PBNPs/TBNPs, and the reaction time between L-cys-PBNPs/TBNPs and Cu 2+ of the method were determined to be pH 4.5, 2.0 mM, 20 °C, 5.0 min, and 2.0 min, respectively. A good linearity for the colorimetric determination of Cu 2+ at the range of 0.25–2.5 μM (R 2 = 0.986) was obtained, with a limit of detection (LOD) of 0.12 μM. Moreover, the negligible response of other metal ions demonstrates good selectivity and specificity of the sensor. In addition, the method was employed in the detection of Cu 2+ in lake water samples, and the spiked recoveries are in the range of 96.7–106.6% with a relative standard deviation less than 7.4%. Therefore, the colorimetric method is applicable for Cu 2+ detection in real water samples of high sensitivity and selectivity.

A novel raiometric fluorescence probe based on silicon quantum dots and copper nanoclusters for visual assay of l-cysteine in milks

l-cysteine (l-Cys) plays an important role in many physiological processes. The previously reported methodologies for l-Cys detection have many drawbacks, and thus the development of specific/sensitive approaches is crucial for its direct/quick assay in food matrices. Herein, silicon quantum dots (SiQDs) and glutathione-stabilized copper nanoclusters (CuNCs) were successfully synthesized and integrated as a ratiometric fluorescent probe for assay l-Cys assay in milks. The fluorescence of SiQDs was quenched by CuNCs through fluorescence resonance energy-transfer process. Upon addition of l-Cys, the 440-nm fluorescence of SiQDs changed insignificantly, while the 650-nm fluorescence of CuNCs decreased significantly. Ratiometric fluorescence signal was linear in the l-Cys concentration range of 0.25 μM to 2.5 mM with a detection limit of 75 nM and visual color changes from red to blue. The probe can realize rapid and portable detection without the participation of intermediate ions, and has good selectivity and accuracy for l-cysteine in milk samples.

A highly selective and sensitive "on-off" fluorescent probe for detecting cadmium ions and l-cysteine based on nitrogen and boron co-doped carbon quantum dots.

Cadmium ions (Cd2+) have caused relatively serious pollution, threatening human health and ecosystems. l-Cysteine (l-Cys) is an essential amino acid in living organisms and concentration of l-Cys is closely related to some human diseases. In this work, we first introduced 2-amino-3-hydroxypyridine and sodium borohydride as the nitrogen source and boron source to fabricate boron and nitrogen co-doped carbon quantum dots (N,B-CQDs) with high fluorescence quantum yield (21.2%), which were synthesized through a simple, low-consumption and pollution-free one-pot hydrothermal method. The obtained N,B-CQDs are able to detect Cd2+ rapidly and sensitively through fluorescence enhancement, which may be ascribed to chelation enhanced fluorescence that is induced by the formation of the N,B-CQDs/Cd2+ complex. Simultaneously, N,B-CQDs can be used to detect l-cysteine because significant fluorescence quenching was observed when l-Cys was added into the N,B-CQDs/Cd2+ system. In the two fluorescence “turn-on” and “turn-off” processes, this fluorescent probe obtained a good linear relationship over Cd2+ concentration ranging from 2.5 µM to 22.5 µM with a detection limit of 0.45 µM, while the concentration of l-cysteine showed a linear relationship in the range of 2.5–17.5 µM with a detection limit of 0.28 µM. The sensor has been successfully used to detect Cd2+ and l-cysteine in real samples with satisfying results.

Helically Grooved Gold Nanoarrows: Controlled Fabrication, Superhelix, and Transcribed Chiroptical Switching

Plasmonic chiroptical materials, coupled by chirality and surface plasmons, have been attracting great interest due to their potential applications, such as photonics, chiral recognition, asymmetri...

Effects of L-cysteine on the photoluminescence, electronic and cytotoxicity properties of ZnS:O quantum dots

l-cysteine capped ZnS:O quantum dots (QDs) were prepared by two steps. The effects of l-cysteine (L-cys) on the crystal structure, size, water-dispersibility, photoluminescence (PL) and cytotoxicity were studied. It was found that the surface modification of L-cys on ZnS:O QDs did not change the crystal structure, and their average crystallite size increased with the increase of L-cys content. Moreover, the water-dispersibility and photostability of ZnS:O QDs can be improved by L-cys modification. The results displayed that the PL intensity was remarkably enhanced with the increase of L-cys concentration. The most intense emission was obtained when the mass ratio of L-cys:ZnS:O = 1.2:1, and was about 5 times stronger than that of uncoated ZnS:O QDs. First-principles calculations were used to explain the origin of high PL intensity. Also, it showed that the L-cys capped ZnS:O QDs were nontoxic and maintained remarkable cell viability and morphology up to the concentration of QDs was 200 mg/mL for HeLa cells. This work suggested that L-cys capped ZnS:O QDs had favorable biocompatibility and may be used for in vitro cell imaging of HeLa cells.

A novel "on-off-on" fluorescence assay for the discriminative detection of Cu(ii) and l-cysteine based on red-emissive Si-CDs and cellular imaging applications.

Copper ions (Cu2+) and l-cysteine (l-Cys) in the human body always play critical roles in various physiological processes, while abnormal Cu2+ and l-Cys concentrations in the biological system lead to many diseases. In this manuscript, Si-doped carbon dots (Si-CDs) with near-infrared fluorescence were designed for the detection of Cu2+ and l-Cys through the fluorescence "on-off-on" mode. The carbon dots exhibited not only excellent optical merits including good stability against photobleaching and high chemical stability, but also superior biological compatibility. Interestingly, due to the abundant amino groups distributed on the surface of Si-CDs, they could bind to copper ions to form cupric amine complexes and then quench the fluorescence of Si-CDs due to an electron transfer process. In addition, upon the addition of l-Cys, the FL intensity of Si-CDs could be effectively recovered accompanied with complexation between Cu2+ and the functional groups in l-Cys, due to which Cu2+ was removed from the surface of Si-CDs. Notably, as far as we know, these are the first red-emitting carbon dots for copper ion and l-Cys assays in water samples and human plasma samples. Furthermore, this strategy was successfully applied to the determination of Cu2+ and l-Cys in living systems, demonstrating great practicability in biomedical applications.

Fluorescence turn-on sensing of L-cysteine based on FRET between Au-Ag nanoclusters and Au nanorods.

The applications of metallic nanoclusters and nanoparticles in biological sensing have attracted special attention owing to their optical interaction based on fluorescence and surface plasmon resonance (SPR). In this work, we designed a fluorescent nanoprobe for the determination of L-cysteine (L-Cys) based on fluorescence resonance energy transfer (FRET) from gold‑silver bimetallic nanoclusters (Au-Ag NCs) to gold nanorods (AuNRs). Firstly, the negatively charged Au-Ag NCs protected by bovine serum albumin (BSA) are directly adsorbed on the surface of the positively charged AuNRs through electrostatic interaction, and the FRET effect leads to distinct fluorescence quenching of Au-Ag NCs at 615nm. The SPR wavelength of AuNRs is dependent on the aspect ratio, so the SPR of AuNRs could be tuned to have a better spectral overlap with fluorescence of Au-Ag NCs, which enhances the fluorescence quenching effect. Because the SH group of L-Cys has an affinity with gold, the addition of L-Cys can result in the release of Au-Ag NCs from the surface of AuNRs via forming AuS bonds. Thus, the introduction of L-Cys could effectively restore the fluorescence emission of the AuNRs/Au-Ag NCs system because of the restraint of FRET effect. Under the optimized conditions, the fluorescence recovery of AuNRs/Au-Ag NCs probe exhibits a linear response to L-Cys concentration ranging from 5 to 100μM, and the corresponding theoretical detection limit (LOD) is 1.73μM. Meanwhile, this method displays excellent sensitivity and selectivity for L-Cys over other amino acids, and it has been successfully applied to detect L-Cys in real samples.

A far-red FRET fluorescent probe for ratiometric detection of l-cysteine based on carbon dots and N-acetyl-l-cysteine-capped gold nanoparticles.

A novel far-red fluorescence resonance energy transfer (FRET) fluorescent probe for ratiometric detection of l-cysteine (l-Cys) has been designed. The system was established a FRET assembly by positively charged carbon dots (CDs) and negatively charged N-acetyl-l-cysteine capped gold nanoparticles (NAC-AuNPs). The fluorescence of CDs at 539 nm could be effectively quenched in the presence of NAC-AuNPs owing to FRET process, while the emission of NAC-AuNPs at 630 nm was appeared. Subsequently, the interactions between l-Cys and NAC-AuNPs resulted in the decreased emission intensity of NAC-AuNPs, but the emission intensity of CDs kept almost constant due to the continuous FRET efficiency. The ratio of emission intensities at 539 and 630 nm (I539/I630) exhibited a linear correlation to the l-Cys concentration in the range of 1.0-110 μM with the detection limit of 0.16 μM. Moreover, this far-red ratiometric sensor also revealed excellent selectivity toward l-Cys over other amino acids, which showed very high potential in the practical application for diagnosing of cysteine-related disease.

Efficient inner filter effect sensors based on CdTeS quantum dots and Ag nanoparticles for sensitive detection of l-cysteine

In the design of new fluorescence sensors, exploration of new sensors with excellent performances and smart designs for the detection of ions and biomolecules is of continuing interest. Therefore, we designed an inner filter effect (IFE) based sensor by effectively combining between CdTeS quantum dots (QDs) and Ag nanoparticles (NPs). Ternary alloyed CdTeS QDs were synthesized by two steps and using 3-mercaptopropionic acid (MPA) as stabilizer, polyvinylpyrrolidone (PVP) stabilized Ag NPs were prepared by crystal-seed. The emission peak of CdTeS QDs and the absorption peak of Ag NPs could availably overlap by changing the Te/S molar ratios and l-ascorbic acid (AA) concentrations. The CdTeS QDs/Ag NPs (QNs) with an obviously emission at 580 nm were used as IFE-based sensors for l-cysteine (L-Cys). The QNs fluorescence was increasing with addition of l-Cysteine (L-Cys), the fluorescence (PL) intensity (F/F0) was linearly proportional to the L-Cys concentrations ranging from 20 μM to 400 μM with the correlation coefficient (R2) of 0.9942 and the detection limit was calculated to be 0.025 μM (S/N = 3), where F and F0 were the PL intensity in the presence and absence of L-Cys at 580 nm, respectively. Moreover, there was no interference to some potential interfering substances, which showed high sensitivity and selectivity for L-Cys.

A facile and selective approach for enrichment of l-cysteine in human plasma sample based on zinc organic polymer: Optimization by response surface methodology

In this research, a facile and selective method was described to extract l-cysteine (l-Cys), an essential α-amino acid for anti-ageing playing an important role in human health, from human blood plasma sample. The importance of this research was the mild and time-consuming synthesis of zinc organic polymer (Zn-MOP) as an adsorbent and evaluation of its ability for efficient enrichment of l-Cys by ultrasound-assisted dispersive micro solid-phase extraction (UA-DMSPE) method. The structure of Zn-MOP was investigated by FT-IR, XRD and SEM. Analysis of variance (ANOVA) was applied for the experimental data to reach the best optimum conditions. The quantification of l-Cys was carried out by high performance liquid chromatography with UV detection set at λ=230nm. The calibration graph showed reasonable linear responses towards l-Cys concentrations in the range of 4.0–1000μg/L (r2=0.999) with low limit of detection (0.76μg/L, S/N=3) and RSD≤2.18 (n=3). The results revealed the applicability and high performance of this novel strategy in detecting trace l-Cys by Zn-MOP in complicated matrices.

Fluorescence “on-off” Responses of BSA-Cu System Towards Hydrogen Peroxide and L-Cysteine and Their Analysis Applications

The synthesis of copper nanoclusters (CuNCs) and its application as optical probe have attracted great attention. In this work, it was found that bovine serum albumin (BSA) reacted with copper ion (Cu2+) in a base medium to form a stable BSA-Cu complex, and the introduction of hydrogen peroxide (H2O2) could remarkably accelerate the formation of CuNCs. At the same time, the fluorescence intensity increased rapidly. Based on the fluorescence “on” response of BSA-Cu system, a kinetics method was developed for the fluorescent detection of H2O2. The fluorescence intensity of BSA-Cu linearly increased with the increase of H2O2 concentration in the range from 1.0 × 10−6 M to 1.5 × 10−3 M with the detection limit of 3.1 × 10−7 M (S/N = 3). After that, the collected BSA-Cu solution was placed until its fluorescence intensity reached the maximal value, during which the Cu2+ ions were fully changed into CuNCs. The experiment results demonstrated that the addition of L-cysteine (L-cys) into the solution led to an obvious fluorescence quenching. Based on the fluorescence “off” response of BSA-Cu system, an analytical method was established for the fluorescent determination of L-cys. The fluorescence intensity linearly reduced with the increase of L-cys concentration in the range of 2.0 × 10−4–1.0 × 10−2 M with the detection limit of 5.7 × 10−5 M (S/N = 3). Finally, the resulted BSA-Cu waste was treated by high temperature ashing and then dissolved with sulfuric acid, thus the CuNCs were turned into Cu2+ ions. The obtained Cu2+ solution continued to be used for the detection of H2O2 and L-cys in the next cycle. In this work, the cycle detection of H2O2 and L-cys and reuse of copper could be achieved through the conversion between Cu2+ and CuNCs. This method, with characteristics of high sensitivity, low cost and environment-friendliness, can be widely used for routine analysis of H2O2 and L-cys.

Biofuel cell based self-powered sensing platform for L-cysteine detection.

L-cysteine (L-Cys) detection is of great importance because of its crucial roles in physiological and clinical diagnoses. In this study, a glucose/O2 biofuel cell (BFC) was assembled by using flavin adenine dinucleotide-dependent glucose dehydrogenase (FAD-GDH)-based bioanode and laccase-based biocathode. Interestingly, the open circuit potential (OCP) of the BFC could be inhibited by Cu(2+) and subsequently activated by L-Cys, by which a BFC-based self-powered sensing platform for the detection of L-Cys was proposed. The FAD-GDH activity can be inhibited by Cu(2+) and, in turn, subsequent reversible activation by L-Cys because of the binding preference of L-Cys toward Cu(2+) by forming the Cu-S bond. The preferential interaction between L-Cys and Cu(2+) facilitated Cu(2+) to remove from the surface of the bioanode, and thus, the OCP of the system could be turned on. Under optimized conditions, the OCP of the BFC was systematically increased upon the addition of the L-Cys. The OCP increment (ΔOCP) was linear with the concentration of L-Cys within 20 nM to 3 μM. The proposed sensor exhibited lower detection limit of 10 nM L-Cys (S/N = 3), which is significantly lower than those values for other methods reported so far. Other amino acids and glutathione did not affect L-Cys detection. Therefore, this developed approach is sensitive, facile, cost-effective, and environmental-friendly, and could be very promising for the reliable clinically detecting of L-Cys. This work would trigger the interest of developing BFCs based self-powered sensors for practical applications.

Structural Dynamics of Proteins using Novel Visible Fluorescence Probes

Fluorescence spectroscopy has been widely used in life science. In this paper, some fluorescent molecules have been designed and synthesized to interact with biological thiol groups, in order to further study protein structural changes at different environment. 4-(2-(1,10c-dihydropyren-1-yl)vinyl)-1-methylpyridinium iodide (4-PBPMI) and 2-(2-(1,10c-dihydropyren-1-yl)vinyl)-1-methylpyridinium iodide (2-PBPMI), whose absorption and fluorescence spectra are in ultraviolet and visible region respectively, have been shown to very sensitively probe L-Cysteine (L-Cys) due to the strong interaction between thiols and vinyl. We reported here the systematic measurements of steady state fluorescence of PBPMIs in the mixtures with various proportions of glycerol and water, and time resolved fluorescence decay using a time correlated single photon counting apparatus on the 100ps to 30ns time scale. The probes are excellent to monitor the L-Cys concentrations and environment simultaneously. For example, with the increasement of the concentration of L-Cys, the emission intensities of PBPMIs in ultraviolet got a great enhancement as well as absorptions. Meanwhile, in visible region, the intensities were decreased sharply. Further experiments and discussion will be made to study structural dynamics of proteins with disulfide bondsand free thiols. The results may motivate additional experimental and theoretical research on the molecular-level design of luminescent probes in biophysics.

Controlled growth of flower-like SnS2 hierarchical structures with superior performance for lithium-ion battery applications

Controlled growth of flower-like SnS2 hierarchical structures was obtained by a facile hydrothermal method with the mixture solution of SnCl4 and L-cysteine (L-cys). The results of electron microscopy and X-ray diffraction characterization indicated that morphology, structure, and crystallinity of the hierarchical structures were seriously dependent on the concentration of L-cys, mole ratio of Sn4+ to L-cys and temperature. Electrochemical tests demonstrated that the flower-like SnS2 hierarchical structures exhibited superior cycling performance for anode materials of Li-ion batteries, which retained a high reversible capacity of 418 mAhg−1 and stable cyclic retention at 100th cycle. These results show that the flower-like SnS2 hierarchical structures were suitable for using as anode material in lithium-ion batteries.

Nanoparticle coated paper-based chemiluminescence device for the determination of l-cysteine

A laminated paper-based analytical device (LPAD) combined with gold nanoparticles (AuNPs) catalyzed luminol chemiluminescence (CL) system for the determination of L-cysteine (L-cys) was presented here. It is based on the principle that L-cys can greatly inhibit CL signal of AuNPs-luminol-H2O2 system. The paper-based device was fabricated by a low-cost cutting method, followed by lamination with two polyester films. This approach of cutting/lamination to fabricate LPAD is very similar to making a lamination picture. A good linear relationship was obtained between the CL intensity and the concentrations of L-cys in the range from 1.0×10(-8) M to 1.0×10(-6) M with a detection limit at 8.2×10(-10) M (S/N=3). This study shows the successful integration of the LPAD and the CL method. It will be of interest for use in areas such as disease diagnosis in the future.