Fluorometric determination of tyramine by molecularly imprinted upconversion fluorescence test strip

Ultra-Sensitive Portable Visual Paper-Based Viral Molecularly Imprinted Sensor without Autofluorescence Interference

Detection of the virus is the primary factor to discover and block the occurrence and development of the virus epidemic. Here, an ultrasensitive paper-based virus molecular imprinting sensor is developed to detect two viruses simultaneously in which the detection limit of the influenza virus (H5N1) is 16.0 aM (9.63 × 103 particles/mL) while that of the Hepatitis B Virus (HBV) is 129 fM (7.77 × 107 particles/mL). This paper-based sensor is low cost and is easy to cut, store, and carry. In addition, the visual semiquantitative detection of two viruses is achieved by using two aptamer-functionalized persistent luminescent nanoparticles as signal probes. These probes and the imprinted cavities on the paper-based material formed sandwich-type double recognition of the target viruses. This sensor has extremely high sensitivity to the H5N1 virus, which is of great value to solve the influenza epidemic with the most outbreaks in history, and also opens up a new way for the prevention and control of other virus epidemics. This cheap and portable visual sensor provides the possibility for self-service detection and can greatly reduce the pressure on medical staff and reduce the risk of virus infection caused by the concentration of people to be tested.

Recent Developments in the Detection of Organic Contaminants Using Molecularly Imprinted Polymers Combined with Various Analytical Techniques

Molecularly imprinted polymers (MIPs) encompass a diverse array of polymeric matrices that exhibit the unique capacity to selectively identify a designated template molecule through specific chemical moieties. Thanks to their pivotal attributes, including exceptional selectivity, extended shelf stability, and other distinct characteristics, this class of compounds has garnered interest in the development of highly responsive sensor systems. As a result, the incorporation of MIPs in crafting distinctive sensors and analytical procedures tailored for specific analytes across various domains has increasingly become a common practice within contemporary analytical chemistry. Furthermore, the range of polymers amenable to MIP formulation significantly influences the potential utilization of both conventional and innovative analytical methodologies. This versatility expands the array of possibilities in which MIP-based sensing can be employed in recognition systems. The following review summarizes the notable progress achieved within the preceding seven-year period in employing MIP-based sensing techniques for analyte determination.

Advances and perspectives in the analytical technology for small peptide hormones analysis: A glimpse to gonadorelin

In the last twenty years, we have witnessed an important evolution of bioanalytical approaches moving from conventional lab bench instrumentation to simpler, easy-to-use techniques to deliver analytical responses on-site, with reduced analysis times and costs. In this frame, affinity reagents production has also jointly advanced from natural receptors to biomimetic, abiotic receptors, animal-free produced. Among biomimetic ones, aptamers, and molecular imprinted polymers (MIPs) play a leading role. Herein, our motivation is to provide insights into the evolution of conventional and innovative analytical approaches based on chromatography, immunochemistry, and affinity sensing referred to as peptide hormones. Indeed, the analysis of peptide hormones represents a current challenge for biomedical, pharmaceutical, and anti-doping analysis. Specifically, as a paradigmatic example, we report the case of gonadorelin, a neuropeptide that in recent years has drawn a lot of attention as a therapeutic drug misused in doping practices during sports competitions.

Selective and ratiometric fluorescence sensing of bisphenol A in canned food based on portable fluorescent test strips

In this study, a conversion method and molecular imprinting technology were used to design molecularly imprinted polymers (MIP)-based ratiometric fluorescence test papers. The ZnO quantum dots (ZnO QDs) acted as the background quantum dots and ZIF-8 raw material. Carbon dots (CDs) were used as the identification signals. The imprinting layer achieved a selective function. Therefore, a ZnO@ZIF-8/CDs@MIPs sensor was designed for the detection of Bisphenol A (BPA). The sensor exhibited a fast response time for BPA detection. In addition, the sensor demonstrated that effective detection of BPA can still be achieved in complex environments. The detection limit of this sensor was 0.778 nM with a linear range of 0-60 nM. The corresponding test solutions exhibited clear changes from blue to yellow. The selectivity experiments results demonstrated that ZnO@ZIF-8/CDs@MIPs only exhibit excellent selective recognition effect for BPA. ZnO@ZIF-8/CDs@MIPs-2 was used for the detection of BPA in canned food and compared with the results of HPLC detection of BPA. The two spiked recovery ranges were 96.58-102.04% and 97.43-103.82%, respectively. In addition, the prepared ZnO@ZIF-8/CDs@MIPs-2 test paper visually recognized BPA under ultraviolet light. This study provides guidelines for the design and application of fluorescent test papers for quick detection in practical applications.

An up-conversion test paper based on "switch-off" of fluorescence is constructed to sensitively and selectively detect cancer-causing dye Sudan III in lipstick

Cancer-causing dye Sudan III is banned adding to cosmetics, so a method for detecting trace Sudan III in cosmetics is established. A single dispersed up-conversion molecularly imprinted fluorescent nanoprobe is constructed and coated on the filter paper. The mechanism for detecting Sudan III by this composite fluorescent nanoprobes-paper is systematically analyzed. The fluorescent response (max emission peak is at 541 nm) is linearly related to 10-1000 nM Sudan III, and Sudan III can be selectively recognized (imprinting factor increased to 4.1). The limit of detection and quantitation are further reduced to 2.89 nM and 9.63 nM, respectively. The recoveries of Sudan III in lipstick samples are between 93.18 and 108.3%, and relative standard deviation is less than or equal to 4.6%. Trace Sudan III in cosmetics are detected accurately and sensitively by this method due to up-conversion nanoparticles with little interference of background fluorescence and molecularly imprinted polymers with selective enrichment.

Quantification of tyramine in different types of food using novel green synthesis of ficus carica quantum dots as fluorescent probe

Tyramine (TYM) is catecholamine releasing compound, tyramine rich food causing hypertensive crisis due to combination with monoamine oxidase inhibitor (MAOIs). So, Analysis of TYM in tyramine rich food (old cheese, cured meat, sausage, pickled olive and canned fish) and environment is very essential for hypertensive patients and improvement food industries. In this work, TYM was analyzed in different types of food using novel green synthesis carbon dots from ficus carica (Fig fruits). The gradual addition of TYM to PA@CQDs led to enhancement of the quantum dots fluorescence due to formation of hydrogen bonding between quantum dots and TYM. The calibration graph plotted in the range 5-400 ng mL^-1 . The method was applied to determination of TYM in different types of food as old cheese, cured meat, sausage, pickled olive and canned fish. The lower limit of quantitation (LOQ) was found to be 1.68 ng mL^-1 . The method successfully applied for the quantification of TYM in varying types of food with high sensitivity and high economic effect due to the reusability of the quantum dots. The optical and morphological characters of quantum dots were studied carefully.

Application of up-conversion molecularly imprinted nanoprobe for selective recognition and straightforward detection of 4-aminobiphenyl

A new method was developed for selectively and rapidly detecting carcinogen 4-aminobiphenyl, with lower limit of detection and wider linear range. Up-conversion nanoparticles β-NaGdF₄:Yb³⁺, Er³⁺ was the first time to choose as light-emitting signal component. Molecularly imprinted polymers (MIPs) with specific recognition ability were successfully coated on the surface of β-NaGdF₄:Yb³⁺, Er³⁺ to obtain a nano fluorescent probe for detecting 4-aminobiphenyl. The effect of addition amount of β-NaGdF₄:Yb³⁺, Er³⁺ on the detection ability of β-NaGdF₄:Yb³⁺, Er³⁺@MIPs was studied, and composite fluorescence nanoprobe with the best performance was obtained. β-NaGdF₄:Yb³⁺, Er³⁺@MIPs were characterized by transmission electron microscopy, X-ray powder diffractometer, Fourier transform infrared spectroscopy and thermogravimetric analysis. The fluorescence intensity of β-NaGdF₄:Yb³⁺, Er³⁺@MIPs decreased significantly compared with molecularly non-imprinted polymers β-NaGdF₄:Yb³⁺, Er³⁺@NIPs (the maximum emission peak is at 541 nm) in the presence of 4-aminobiphenyl. Adsorption isotherm and adsorption kinetics between UCNP@MIPs and 4-ABP have been investigated and a satisfactory imprinting factor is 2.5. The detection mechanism is proved to be based on Langmuir adsorption and internal filtration effect. Under optimal experimental conditions, the limit of detection and quantification are 0.16 μM and 0.53 μM, respectively. The linear range of response is 1-50 μM, and RSD is less than 6.7%. This method was applied to determining river water samples in order to evaluate the practicability, and the good recovery rate is between 98.89% and 109.7%. These evidences demonstrate that β-NaGdF₄:Yb³⁺, Er³⁺@MIPs is successfully used for the detection of 4-aminobiphenyl.