Fluorescence Enhancement Effect Research Articles

Determination of sudan III using nitrogen and sulfur co-doped carbon quantum dots with fluorescence enhancement effect

Sudan III, a synthetic azo dye, is commonly used for coloring oils, waxes, and various plastics. However, its unauthorized presence in food and food products poses serious health hazards, including potential carcinogenic effects. In this study, we investigated the application of nitrogen and sulfur co-doped carbon quantum dots (N,S-CQDs) as a fluorescence sensor to detect trace amounts of sudan III. When exposed to trace amounts of sudan III, the fluorescence signal of N,S-CQDs was significantly enhanced. Under optimal conditions (pH 5.0 and an incubation time of 4 minutes), the fluorescence enhancement of N,S-CQDs showed a linear relationship with sudan III concentration in the range of 7.5 x 10-10 to 1.0 x 10-8 M, with a limit of detection of 2.0 x 10-10 M (equivalent to 0.07 ppb). The method demonstrated high accuracy (recovery from 91.5% to 103.5%), good reproducibility (RSD < 3.86%), and excellent selectivity for sudan III over other azo dyes. We successfully applied this developed method to analyze sudan III in chili sauce and chili powder samples, cross-checking differences between results less than 10% with LC-MS/MS analysis.

Photonic Microbead Array Digital Time-Resolved Fluorescence Ultrasensitive Platform for Simultaneous Detection of Multiple Mycotoxins.

Limitations in the sensitivity, linear detection range, and cross-reaction of lateral flow immunoassays mainly hamper their application in rapid screening for multiple targets. In this work, we designed a new time-resolved fluorescence immunoassay (TRFIA) platform to overcome these limitations. This platform uses europium chelate polystyrene (PS@Eu) nanoparticles conjugated with monoclonal antibodies to sense multiple mycotoxins. We employed a competitive TRFIA protocol in which the conjugated PS@Eu was used on the surfaces of photonic microbead arrays (PMAs). The TRFIA signal of PMAs on the pad was recorded with the digital time-resolved fluorescence reader. The developed TRFIA shows wide detection linear ranges (0.01-1000 ng/mL for DON, 0.1-100 ng/mL for OTA, and 0.01-100 ng/mL for AFB1), low limits of detection (LODs) (7.9 pg/mL for DON, 18 pg/mL for OTA, and 7.7 pg/mL for AFB1), good specificity, good recovery ratios (76.68-117.26%), and good reproducibility in grain samples. The simulated fluorescence enhancement effect of PMA indicated that the electric field distribution on the surface of PS@Eu on PMA is twice higher than that on the surface of PS@Eu. The new TRFIA for three kinds of mycotoxins was 1000-fold more sensitive than the classical TRFIA, and it has great potential application in rapid screening for multiple targets.

A novel ultra-long carbon-chain salamo-like fluorescent chemosensor with good flexibility: Synthesis, crystal structure, Pb2+ ion recognition and mechanism exploration

A novel ultra-long carbon-chain salamo-like fluorescent chemical probe DMS containing ten methylene groups (DMS, 6,6′-dimethoxy-2,2′-[1,10-(decanedioxy)bis(nitromethyldyne)]diphenol), was synthesized based on the 3‑methoxy salicylaldehyde unit, and its single crystals were obtained. The single crystal structure for the probe DMS molecule was determined. Research has shown that the fluorescent probe DMS can achieve efficient and selective recognition of Pb2+ ions, with a binding constant Ka = 1.42 × 104 M-1. The detection limit is as low as LOD = 1.31 × 10–7 M, and quantification limit is as low as LOQ = 4.36 × 10–7 M The possible identification mechanism of the fluorescent chemosensor DMS to Pb2+ions was analyzed and studied through fluorescence titration test, nuclear magnetic changes and Job′s plot exprements, DFT calculation et al. The results indicated that the fluorescent chemosensor DMS forms a coordination compound with Pb2+through 1:1 coordination, enhancing its fluorescence and resulting in the coordinated fluorescence enhancement effect.

A highly selective and recyclable fluorescent sensor based on a Salamo-Salen-Salamo type ligand for continuous detection of Al3+ and phosphates in drug

In this work, a fluorescence chemical sensor continuous detection Al3+ and phosphates by a Salamo-Salen-Salamo type compound (SL) was employed. The sensor continuously recognized Al3+ and phosphates with good selectivity and fast response time, and a low limit of detection of 0.25 μΜ and 0.96 μM, at the same time accompanied by a naked-eye identification specificity. The detection mechanism of SL towards Al3+ is due to the chelating fluorescence enhancement effect and ICT effect, and continuously towards phosphates is due to the collapse of the SL-Al3+ and coordination interaction between Al3+ and phosphates, by Fourier-transform infrared spectroscopy, X-ray photoelectron spectroscopy, other spectral characterization and DFT calculation as evidence. In addition, the sensor had good recyclability and reusability. The distribution of Al3+ and phosphates in zebrafish cells was effectively monitored by confocal microscopy based on the good biocompatibility and tissue permeability of SL. Furthermore, the feasibility of using sensor SL to detect the content of Al3+ and phosphate ions in certain drugs was quantitatively analyzed through experiments. It was found SL had a good result in practical application.

Copper(II), zinc(II) and cadmium(II) complexes with the O-picolyl ether of chiral α-aminooxime of natural (+)-limonene: synthesis, structures, luminescence and cytotoxicity

Copper(II), zinc(II) and cadmium(II) complexes, [CuLCl2], [ZnLCl2] and [CdLCl2], with a new derivative of chiral α-aminooxime of natural (+)-limonene bearing a pycolyl group (L) were synthesized. The complexes are mononuclear, the L molecules act as N,N,N-tridentate chelating ligands. The computations support the fact that the N,N,N–chelation by a metal ion is thermodynamically preferred over the N,N–chelation for all complexes. The ligand L and the complexes [ZnLCl2] and [CdLCl2] exhibit fluorescence, with the emission spectra depending on the excitation wavelength. L emits in close to white region, while the Zn(II) and Cd(II) complexes demonstrate blue emission. Due to chelation-induced fluorescence enhancement effect, the fluorescence quantum yield increases when going from L to [ZnLCl2] and [CdLCl2]. The complex [CdLCl2] displays cytotoxicity against the HepG2 cell line (IC50 = 14.3 ± 1.5 μM), which is almost twice as high as that of cisplatin. The human breast adenocarcinoma cell line (MCF-7) is more sensitive to [CuLCl2] (IC50 = 43.4 ± 0.4 μM) than to [CdLCl2].

An eugenol-sulfonyl based fluorescent probe for recognition of Al3+ in real sample analysis and biological application

The present work describes an eugenol-sulfonyl based fluorescence chemosensor, H4L [H4L=6,6′-((1E,1′E)-((sulfonylbis(6-hydroxy-3,1- phenylene))bis(azanylylidene))bis(methanylylidene))bis(4-allyl-2-methoxyphenol)], which shows maximum emission intensity towards Al3+ ion in presence of other competing metal ions. Upon excitation at 440 nm H4L exhibits a significant rise in fluorescence at 547 nm upon gradual addition of Al3+ ion in the HEPES buffer at pH=7.4 (MeOH:H2O, 4:1, (v/v)). The increasing value of fluorescence is mainly due to chelation enhanced fluorescence effect (CHEF). Complete characterization of the probe (H4L) and metal bound complex (1) have been determined using a range of methods including UV–Vis absorption titration, fluorescence titration, NMR, ESI-mass, etc. Thus 1:2 binding stoichiometry between H4L and metal ion has been also proved. Another important aspect: regeneration and reversibility of H4L are investigated in presence of Na2EDTA. H4L exhibits ∼ 10−6 M order detection limit and significant binding constant (∼106 M−1) for the Al3+ ion, suggesting its potential use in bio-imaging studies. The probe was effectively used in real samples as well as paper strip to locate the Al3+ ion.

A novel organic chromo-fluorogenic optical sensor for detecting chromium ions

Sensing trivalent chromium ion (Cr(III)) is widely applied in different areas, such as clinical analysis, marine, environmental monitoring, or even chemical industry applications. Cr(III) has a significant role in the physiological process of human life. It is classified as an essential micronutrient for living organisms. Herein, we developed and designed a novel optical Cr(III) ions sensor film. The investigated sensor has a relatively small dynamic range of 1.24 × 10−3 to 0.5 μM. We report a highly sensitive optical sensor film for Cr(III) ions based on diethyl 3,4-diaminothieno[2,3-b]thiophene-2,5-dicarboxylate (3D) probe. The optical characteristics of the chemical probe exhibit substantial emission at 460 nm under 354 nm excitation. Besides, the interaction of the Cr(III) ions with 3D involves a complex formation with a 2:1 (metal: ligand) ratio, which is convoyed by the main peak enhancement that centered at 460 nm of 3D, and the main peak is red-shifted to 480 nm. The easily discernible fluorescence enhancement effect is a defining characteristic of the complexation reaction between the 3D probe and Cr(III). On the basis of the substantial fluorescence mechanism caused by the formation of a (Cr(III)-3D complex, which inhibits the photo-induced electron transfer (PET) process, the devised optical sensor was proposed. This film exhibits exceptional sensitivity and selectivity due to its notable fluorescence properties, stock shift of less than 106 nm, and detection capabilities at a significantly low detection limit of 0.37 × 10−3 μM. The detection procedure is executed by utilizing a physiological pH medium (pH = 7.4) with a relative standard deviation RSDr (1 %, n = 3). In addition, the 3D sensor demonstrates a high degree of affinity for Cr(III), as determined by the calculation of its binding constant to be 1.40 × 106. We present an impressive optical sensor that is constructed upon a three-dimensional molecule.

Highly stable Tb(III) metal-organic framework derived from a new benzothiadiazole functionalized ligand for fluorescence recognition of ascorbic acid

Because ascorbic acid (AA) is one of the basic elements to maintain the normal physiological functions of human body, it is urgent to develop a material that can achieve efficient, rapid and in-situ detection for AA. A new fluorescence organic compound 4′,4′′′-(benzo[c][1,2,5]thiadiazole-4,7-diyl)bis([1,1′-biphenyl]-4-carboxylic acid) (H2BTBC) based on benzothiadiazole group has been synthesized, which can detect Fe3+ ions by fluorescence turn-off effect with a detection limit of 0.015 μM, as well as recognize linear amines by fluorescence turn-on effect. Moreover, a highly stable Tb(III) metal–organic framework has been solvothermally prepared with H2BTBC, namely {[(CH3)2NH2]2[Tb2(BTBC)4]∙solvents}n (JXUST-39), which can selectively detect AA among biological fluids by fluorescence enhancement effect with a detection limit of 0.077 μM. In addition, the mechanism for JXUST-39 detecting AA is possibly the cooperative effect of absorbance-caused enhancement and charge transfer between JXUST-39 and AA. Moreover, LED lamp beads, fluorescent films and fluorescent detection test paper based on JXUST-39 were prepared to achieve portable detection via fluorescence enhancement effect.

Comparison of Double-Stranded DNA at the 5' and 3' Ends of the G-Triplex and Its Application in the Detection of Hg(II).

Leveraging the fluorescence enhancement effect of the G-triplex (G3)/thioflavin T (ThT) catalyzed by the adjacent double-stranded DNA positioned at the 5' terminus of the G3, the G3-specific oligonucleotide (G3MB6) was utilized to facilitate the rapid detection of mercury (Hg(II)) through thymine-Hg(II)-thymine (T-Hg(II)-T) interactions. G3MB6 adopted a hairpin structure in which partially complementary strands could be disrupted with the presence of Hg(II). It prompted the formation of double-stranded DNA by T-Hg(II)-T, inducing the unbound single strand of G3MB6 to spontaneously form a parallel G3 structure, producing a solid fluorescence signal by ThT. Conversely, fluorescence was absent without Hg(II), since no double strand and formation of G3 occurred. The fluorescence intensity of G3MB6 exhibited a positive correlation with Hg(II) concentrations from 17.72 to 300 nM (R2 = 0.9954), boasting a notably low quality of limitation (LOQ) of 17.72 nM. Additionally, it demonstrated remarkable selectivity for detecting Hg(II). Upon application to detect Hg(II) in milk samples, the recovery rates went from 100.3% to 103.2%.

Rapid differential diagnosis of periprosthetic joint infection by microdroplet reaction on portable biochip and indicator

Periprosthetic joint infection (PJI) is a catastrophic complication after joint arthroplasty. A key step to treat PJI is accurate diagnosis. However, according to the existing guidelines, no biomarker has been used to diagnose PJI alone and autoimmune diseases such as rheumatoid arthritis (RA) often interfere with the diagnosis. Patients with PJI often still face issues such as misdiagnosis and delayed treatment after a comprehensive scoring diagnosis. Thus, a rapid quantitative detection method based on excellent biomarker is needed. Here, an all-printed photonic crystal (PC) biochip is reported. Through the fluorescence enhancement effect of the photonic crystals and the design of the hydrophilic and hydrophobic patterning structure, trace detection of lactoferrin (LTF) in a drop of viscous synovial fluid can be achieved within 10 min by the biochip. The detection limit is as low as 4.6 ng/mL. For more intuitive results, portable testing equipment is developed with indicator light displays of three colors (green = NPJI, yellow = RA, and red = PJI) to indicate the diagnosis depending on the biochip’s fluorescence intensity. Furthermore, 79 clinical synovial fluid samples are tested with PC biochips, and the PC results are in good agreement with the ELISA results. Due to the microdroplet reaction on PCs, biochips are suitable for the detection of the selected markers in the synovial fluid. The use of the three-color portable testing equipment avoids the need for professional testing devices. Overall, this strategy provides a new paradigm for the early and differential diagnoses of PJI.

Rapid detection and differentiation of chlortetracycline and tetracycline by N,P-Ti3C2 QDs

Ti3C2 QDs with good water solubility and photoluminescence properties was prepared by nitrogen and phosphorus doping (N,P-Ti3C2 QDs). The probe has a fluorescence emission peak at 420 nm and emits bright blue fluorescence, which can distinguish and detect two antibiotics with similar structures, chlortetracycline (CTC) and tetracycline (TC). The fluorescence enhancement effect can be realized by the interaction with CTC. The linear range is 2–22 μM, and the detection limit is as low as 0.53 μM. And the change of fluorescent color from bright blue to bright purple can be observed with the naked eye. At the same time, with the addition of TC, the fluorescence of N,P-Ti3C2 QDs can be quenched by static quenching effect, and the fluorescence color changes from bright blue to yellowish green. The detection range is 4.1–20.5 μM, and the detection limit is as low as 0.16 μM.Therefore, on this basis, a strategy for simultaneous detection and recognition of CTC and TC is proposed. The method has been successfully applied to the determination of CTC and TC in milk samples. This paper provides a new detection method for the identification of tetracycline antibiotics and taps the application potential of Ti3C2 QDs in food detection.

Hollow SiO2 photonic crystal - graphene quantum dots composite and its application in multi-level intelligent anti-counterfeiting through regulation synergistic effect of structural color and fluorescence

The research on composite materials with rainbow color (structural color) and ultraviolet excitation characteristics (fluorescence) is the development direction of the new generation of functional photonic engineering materials. Herein, composite materials composed of hollow SiO2 photonic crystals (PCs) with nanometer thickness and PEGDA gel containing graphene quantum dots (GQDs) were prepared to achieve fluorescence regulation effect and thus apply in multi-level intelligent anti-counterfeiting. Due to the SiO2 shell thickness of 20–41 nm, the Bragg diffraction law explained that the material underwent secondary refraction, resulting in a wide photonic band gap (PBG). On the other hand, due to the comparison of refractive index between air (n = 1) and composite material (n = 1.46), the transmittance of the composite materials were only 21 %–26 %, indicating strong refractive ability. Therefore, we constructed a PC structure with a wide photonic bandgap (PBG) to provide better wavelength selectivity and coverage range, which would significantly increase the effect of structural color on fluorescence. Based on the unique quantum dot size effect of GQDs, we also investigated the fluorescence enhancement effect with 157 nm FWHM located on PC materials. Therefore, artificial design and control of both fluorescence enhancement and fluorescence suppression had been achieved through multi-level regulation of structural color. We further utilized these properties to create multi-level anti-counterfeiting verification patterns, such as a 3 × 3 digital encoding matrix. The authenticity of the product information must be verified through stepwise identification under specified conditions. This intelligent anti-counterfeiting technology offers a novel approach to safeguard information security.

Fluorion-deprotonated fluorescent sensor for the highly sensitivity detection of trace water in chemical reagents and application in inkless writing

A simple diphenylimidazole-based colorimetric and fluorescent sensor (DIB) was successfully synthesized by one step reaction. DIB exhibited excellent selectivity and sensitivity for F- over various other anions with fluorescence enhancement effect. The limit of detection of DIB towards F- was evaluated to be 9.18 × 10-8 M. A plausible sensing mechanism of DIB towards F- had been proposed on the basis of spectral analysis and 1H NMR titration experiments, which the results suggested that the recognition process could be attributed to the deprotonation of imidazole group. Interestingly, the F- induced deprotonation system of DIB·F could be employed as reversible sensor for trace water with high sensitivity and instant response. The color change easily recognized by the naked eye and low limit of detection (0.0022 %) improved the detection performance of DIB·F for water. Importantly, the DIB·F system had been successfully applied for the quantitative analysis of water content in experimental chemical reagents. In addition, sensor DIB and DIB·F-incorporated filter papers could be utilized as inkless writing display device for F- and water detection, respectively, with reusability.

Ni–Zn bimetal-organic framework nanoprobes reinforced polymeric coating to achieve dual-responsive warning of coating damage and interfacial corrosion

Coating microdefects and localized corrosion in coating/metal system are inevitable, accelerating the degradation of metal infrastructure. Early evaluating coating microdefects and detecting corrosion sites are urgent yet remain challenge to achieve. Herein, we propose a robust, universal and efficient fluorescence-based strategy for hierarchical warning of coating damage and metal corrosion by introducing the concepts of damage-induced fluorescence enhancement effect (DIE) and ionic-recognition induced quenching effect (RIQ). The coatings with dual-responsiveness for coating defect and steel corrosion are constructed by incorporating synthesized nanoprobes composed of metal organic frameworks (Ni–Zn-MOFs) loaded with Rhodamine B (RhB@MOFs). The initial damage to the coating causes an immediate intensification of fluorescence, while the specific ionic-recognition characteristic of RhB with Fe3+ results in an evident fluorescence quenching, enabling the detection of coating damage and corrosion. Importantly, this nanoprobes are insensitive to the coating matrix and exhibit stable corrosion warning capability across various coating systems. Meanwhile, electrochemical investigations indicate that the impedance values of RM/EP maintain above 108 ​Ω ​cm2 even after 60 days of immersion. Therefore, the incorporation of fluorescent nanoprobes greatly inhibits the intrusion of electrolytes into polymer and improves the corrosion protection performance of the coating. This powerful strategy towards dual-level damage warning provides insights for the development of long-term smart protective materials.

Dual-channel fluorescent probe utilizing hydrazone for Zn2+ and Hg2+ detection: Exploring distinct signaling mechanisms and applications in bioimaging and latent fingerprint analysis

A facile Schiff base probe C1 has been developed and evaluated using 1H, 13C NMR, and mass spectroscopy. Fluorescence investigations were conducted to determine probe-sensing behavior. Probe C1 demonstrated sensitive, and selective recognition of Zn2+ and Hg2+ ions by using two distinct processes (i.e., chelation enhanced fluorescence effect and fluorescence quenching) over other cations in ACN-H2O (8:2, v/v). The Zn2+ and Hg2+ detection limits of 0.042 and 0.081 μM are achieved with the probe C1. C1 has a binding constant of 3.33 × 103 M−1 for Zn2+ and an emission quenching constant of 1.22 × 104 M−1 for Hg2+. A Jobs plot was used to determine the binding stoichiometry of C1 and Zn2+/Hg2+ ions ratio is 1:1. By using Zn2+/Hg2+ and EDTA additions alternately, the probe's reusability was investigated. Moreover, the probe was found to be highly cytocompatibility using an MTT assay in a mouse fibroblast cell line (NIH3T3). Further, the probe was found to visualize Zn2+ and Hg2+ ions inside the cells, indicating the potential application of the probe as an intracellular probe to detect Zn2+ and Hg2+ ions. The probe shows very good solid-state emission behavior, this motivates us to develop latent fingerprint detection and anticounterfeiting applications.

Enhanced Efficiency of Pd(0)-Based Single Chain Polymeric Nanoparticles for in Vitro Prodrug Activation by Modulating the Polymer's Microstructure.

Bioorthogonal catalysis employing transition metal catalysts is a promising strategy for the in situ synthesis of imaging and therapeutic agents in biological environments. The transition metal Pd has been widely used as a bioorthogonal catalyst, but bare Pd poses challenges in water solubility and catalyst stability in cellular environments. In this work, Pd(0) loaded amphiphilic polymeric nanoparticles are applied to shield Pd in the presence of living cells for the in situ generation of a fluorescent dye and anticancer drugs. Pd(0) loaded polymeric nanoparticles prepared by the reduction of the corresponding Pd(II)-polymeric nanoparticles are highly active in the deprotection of pro-rhodamine dye and anticancer prodrugs, giving significant fluorescence enhancement and toxigenic effects, respectively, in HepG2 cells. In addition, we show that the microstructure of the polymeric nanoparticles for scaffolding Pd plays a critical role in tuning the catalytic efficiency, with the use of the ligand triphenylphosphine as a key factor for improving the catalyst stability in biological environments.

Spatial confinement of styryl pyridine salt derivative in MCM-22 molecular sieve network for boosted fluorescence emission and stable ratiometric sensing of bacillus anthracis biomarkers

In this work, a stable ratiometric nanofluorescent probe for the detection of 2,6-dipicolinic acid (DPA), a Bacillus anthracis biomarker, was developed based on confinement-induced emission enhancement of cationic styrylpyridine salt derivative L in MCM-22 molecular sieve pores. The cationic L and the lanthanide Tb3+ were loaded into the pores of the molecular sieve by electrostatic interaction with the negatively charged AlO4 tetrahedron unit, and L exhibited enhanced red fluorescence emission as a stable fluorescence reference mark in the nanoprobe platform due to the restricted molecular torsion of L in the pores of MCM-22. At the same time, the characteristic green fluorescence emission of Tb3+ can be excited by energy transfer due to the “antenna effect” of DPA. The prepared Tb-L@MCM-22 nanoprobe showed specific selectivity and stable fluorescence ratiometric detection of DPA in tap water, lake water, bovine serum and actual bacterial spores. Benefiting from the confinement-induced fluorescence enhancement effect of L in the MCM-22 molecular sieve pores, the obtained Tb-L@MCM-22 can provide a stable reference signal for the fluorescence ratiometric detection of DPA with a limit of detection (LOD) of 78.6 nM and 1.310 × 104 spores per mL. More importantly, combining of the Tb-L@MCM-22 based DPA detection test strips with a smartphone app demonstrated a stable, convenient and rapid method for detecting of anthrax biomarkers.

The design of multifunctional fluorescent probe for detecting Zn2+/ ClO−/H2O and application in high-security level information encryption

In this article, a Schiff base-structured compound (TNB) was synthesized using 3-hydroxy-2-naphthaldehyde hydrazone and 2-hydroxy-5-tert-butylbenzaldehyde as starting materials. The structure of TNB was characterized using NMR spectroscopy, high-resolution MS, and IR spectroscopy. Studies showed that TNB can selectively recognize Zn2+/ClO− in solvent system of H2O/DMSO. Fluorescence and UV–vis spectrophotometry were used to investigate the spectral properties of TNB. TNB displayed a significant fluorescence enhancement effect when bound to Zn2+, while binding to ClO− resulted in fluorescence quenching. Job’s plot and NMR titration were used to study the binding mechanism of TNB with Zn2+/ClO−. Linear standard curves were fitted for different Zn2+/ClO− concentrations corresponding to fluorescence intensity, and detection limits (LOD) were determined as 5.0300 × 10−9 mol/L (Zn2+) and 3.1700 × 10−9 mol/L (ClO−). Furthermore, TNB was used to determine trace water in organic solvents. The fluorescence intensity changes with water content were measured in three organic solvents (THF, DMSO, and acetone). Detection limits (LOD) were calculated as 1.4 × 10−4 % (THF), 8.3 × 10−4 % (DMSO), and 1.2 × 10−3 % (acetone). Using the characteristic reactions of TNB with Zn2+, a two-dimensional code information encryption technology was developed and can be used for high-security information encryption and transmission.

Rapid determination of histamine in cheese by employing fluorescence enhancement of quantum dots-molecularly imprinted polymer

A fluorescent surface imprinted polymer was prepared by grafting Cadmium Telluride (CdTe) quantum dots into the methacrylic acid polymerization on the surface of silica. And a rapid turn-on fluorescence biosensor based on fluorescence enhancement effect was developed for the rapid and sensitive detection of histamine, which only took 8 min with a sensitive detection limit of 14.3 μmol/L. The cheese samples were tested by employing the fluorescent imprinted polymer, and the recovery was obtained in the range of 92.1–102%. The proposed histamine biosensing method shows great advantages, including no need for derivatization and reduced consumption of organic reagents. This has an important guiding role in the rapid detection of biological amines and other fluorescent responsive substances in complex systems.

Machine learning-assisted visual sensor array for identifying the origin of Lilium bulbs

In this work, we constructed a machine learning-assisted dual-channel visual sensor array for identifying the origin of Lilium bulbs (BH). Nanogold clusters (AuNCs) and quantum dots (QDs) were selected and combined into sensor arrays. The amino acids existed in lilium bulbs could induce aggregation-induced fluorescence enhancement effect (AIEE) of AuNCs through hydrogen bonding. The hydrogen protons released from the amino acids and phenolic acids could interact with the COO- group of QDs, resulting in aggregation-caused quenching (ACQ) of QDs. Due to the different contents of amino acids and phenolic acids in BH from different origins, the sensor array can produce distinct and different fluorescent colors, such as red, blue, green and purple. In conjunction with pattern recognition by the RF model, the sensor array clearly identifies the origin of BH with 94.4% prediction accuracy. The visual sensor array constructed in this work exhibited the advantages of simplicity, speed, accuracy and portability, showing potential application prospects in identifying the origin of food and traditional Chinese medicine.