Colorimetric detection of L-histidine based on the target-triggered self-cleavage of swing-structured DNA duplex-induced aggregation of gold nanoparticles

A tunable LDI-MS platform assisted by metal-phenolic network-coated AuNPs for sensitive and customized detection of amino acids

This study introduces a novel approach for the sensitive and accurate detection of small molecule metabolites, employing metal-phenolic network (MPN) functionalized AuNPs as both adsorbent and matrix to enhance laser desorption/ionization mass spectrometry (LDI-MS) performance. The MPN comprising tannic acid (TA) and transition metal ions (Fe3+, Co2+, Ni2+, Cu2+, or Zn2+) was coated on the surface of AuNPs, forming metal-TA network-coated AuNPs (M-TA@AuNPs). The M-TA@AuNPs provided a tunable surface for specific interactions with analytes, displaying distinct enrichment efficacies for different amino acids, especially for Cu-TA@AuNPs exhibiting the highest affinity for histidine (His). Under the optimized condition, the proposed method enabled ultrasensitive detection of His, with good linearity (R2 = 0.9627) in the low-concentration range (50 nM-1 μM) and a limit of detection (LOD) as low as 0.9 nM. Furthermore, the method was successfully applied to detect His from human urine samples, showcasing its practical applications in clinical diagnostics, particularly in the realm of amino acid-based targeted metabolomics.

Magnetic Titanium Dioxide Nanocomposites as a Recyclable SERRS Substrate for the Ultrasensitive Detection of Histidine

A highly sensitive, selective and recyclable histidine detection method based on magnetic Fe3O4@mTiO2 (M-TiO2) nanocomposites with SERRS was developed. Mesoporous M-TiO2 nanoparticles were functionalized with 4-aminothiophenol and then coupled with histidine through an azo coupling reaction in 5 min, producing the corresponding azo compound. The strong and specific SERRS response of the azo product allowed for ultrasensitive and selective detection for histidine with an M-TiO2 device loaded with Ag NPs due to the molecular resonance effect and plasmonic effect of Ag NPs under a 532 nm excitation laser. The sensitivity was further enhanced with the magnetic enrichment of M-TiO2. The limit of detection (LOD) was as low as 8.00 × 10-12 mol/L. The M-TiO2 demonstrated applicability towards histidine determination in human urine without any sample pretreatment. Additionally, the M-TiO2 device can be recycled for 3 cycles with the photodegradation of the azo product under UV irradiation due to TiO2-assisted and plasmon-enhanced photocatalysis. In summary, a multifunctional and recyclable M-TiO2 device was synthesized based on azo coupling and SERRS spectroscopy for ultra-sensitive and specific histidine sensing. In addition, the proposed system demonstrated the potential for the multiplex determination of toxic compounds in the fields of food safety, industrial production and environmental protection, which benefit from the fingerprint property and universality of SERRS.

Gold Nanoparticles-Based Colorimetric Assays for Environmental Monitoring and Food Safety Evaluation

Recent years have witnessed an exponential increase in the research on gold nanoparticles (AuNPs)-based colorimetric sensors to revolutionize point-of-use sensing devices. Hence, this review is compiled focused on current progress in the design and performance parameters of AuNPs-based sensors. The review begins with the characteristics of AuNPs, followed by a brief explanation of synthesis and functionalization methods. Then, the mechanisms of AuNPs-based sensors are comprehensively explained in two broad categories based on the surface plasmon resonance (SPR) characteristics of AuNPs and their peroxidase-like catalytic properties (nanozyme). SPR-based colorimetric sensors further categorize into aggregation, anti-aggregation, etching, growth-mediated, and accumulation-based methods depending on their sensing mechanisms. On the other hand, peroxidase activity-based colorimetric sensors are divided into two methods based on the expression or inhibition of peroxidase-like activity. Next, the analytes in environmental and food samples are classified as inorganic, organic, and biological pollutants, and recent progress in detection of these analytes are reviewed in detail. Finally, conclusions are provided, and future directions are highlighted. Improving the sensitivity, reproducibility, multiplexing capabilities, and cost-effectiveness for colorimetric detection of various analytes in environment and food matrices will have significant impact on fast testing of hazardous substances, hence reducing the pollution load in environment as well as rendering food contamination to ensure food safety.

A novel electrochemical sensor for the determination of histidine based on a molecularly imprinted copolymer

The present study aimed to report a novel electrochemical sensor through electropolymerization of o-aminophenol (o-AP) and m-dihydroxy benzene (m-DB) as monomers on the surface of the glassy carbon electrode (GCE) for the determination of histidine (His) as a template molecule. The developed sensor exhibited satisfactory sensitivity and high selectivity, and also offered a linear range between 0.005 and 10.0 μM with a detection limit of 0.9 nM. Finally, it is worth mentioning that we also aimed at employing the proposed sensor for the detection of His in blood serum samples.

Surface Plasmon Resonance Sensor for Novel Detection of Histidine Based on the Hg2+ Induced Aggregation of AuNPs Followed by Preconcentration with Chitosan Gel as Solid-phase Biosorbent

This research work aims to propose an extraction method using chitosan as the sorbent and gold nanoparticles (AuNPs) as the colorimetric sensor for the development of a simple, cost-effective, rapid, sensitive, and selective detection method for histidine. The colorimetric assay is based on the aggregation of AuNPs in the presence of Hg2+ ions and histidine. The state of AuNPs generally changes from dispersion to aggregation. The change in state is accompanied by a corresponding change in color (from red wine to blue). Therefore, the solid phase extraction (SPE) method using chitosan as the sorbent was used to extract the AuNPs to improve the sensitivity of detection. It was found that the extraction by means of a sensor system using chitosan could increase the detection signal for histidine by 10 times. The calibration curve, which is the plot of absorbance ratio (A650/A528) against the concentration of histidine, shows a linear relation in the concentration range of 100 - 800 nM. The limit of detection (LOD) and limit of quantitation (LOQ) of the method were found to be 99.88 and 107.45 nM, respectively. Good recoveries were also obtained (range: 99.75 - 104.43%) with relative standard deviations (RSDs) below 5.89% in real water samples. Moreover, this method can be used for the selective detection of histidine even in the presence of other amino acids. The proposed method has been successfully used in the determination of histidine in mineral water samples.

A rapid and ultrasensitive colorimetric biosensor based on aptamer functionalized Au nanoparticles for detection of saxitoxin

Saxitoxin (STX) is one of the most important marine toxins which affects the safety of domestic water. Rapid, sensitive and selective recognition of STX is crucial in environment monitoring. Here, we demonstrate a facile and ultrasensitive colorimetric sensor based on gold nanoparticles (Au NPs) and aptamer (Au NPs-aptamer biosensor) for specific and quantitative detection of STX. The aptamer reacts specifically with STX, resulting in the aggregation of Au NPs and the color change of the Au NP solution. The lowest detection concentration of the colorimetric sensor is 10 fM (3 fg mL-1), and a good linear relationship (R 2 = 0.9852) between the absorbance ratio and STX concentrations (10 fM to 0.1 μM) indicates that our Au NPs-aptamer biosensor can be used for quantitative sensing of STX. The detection time of STX is 30 minutes, and the sensor is successfully applied in the specific detection of STX in seawater. The Au NP-aptamer biosensor shows great potential in practical applications to monitor environmental pollution, marine aquaculture pollution, and seafood safety.

A novel label-free fluorescent detection of histidine based upon Cu2+-specific DNAzyme and hybridization chain reaction

A novel label-free fluorescent sensor for histidine was developed based upon Cu²⁺-specific DNAzyme, hybridization chain reaction(HCR) and triplex DNA. Cu²⁺ can bind to the histidine, in the presence of histidine, leading to the inhibition of the cleavage of substrate strand of Cu²⁺-dependent DNAzyme, then the intact substrate strand trigger the HCR between H1 and H2. The HCR product can be recognized by triplex-forming oligonucleotide (TFO) through triplex formation and reported by the fluorescence of berberine, the fluorescence intensity of the sensing system was proportional to the concentration of histidine during the range of 5.7-455 nmol L^-1, with a detection limit of 2.0 nmol L^-1.

Colorimetric detection of Ba2+, Cd2+ and Pb2+ based on a multifunctionalized Au NP sensor

A colorimetric method for the detection of three kinds of ions in water with one kind of detection reagent was developed.