Paper Based Photoluminescent Sensing Platform with Recognition Sites for Tributyltin

Molecularly Imprinted Polymer-Based Luminescent Chemosensors

Molecularly imprinted polymer (MIP)-based luminescent chemosensors combine the advantages of the highly specific molecular recognition of the imprinting sites and the high sensitivity with the luminescence detection. These advantages have drawn great attention during the past two decades. Luminescent molecularly imprinted polymers (luminescent MIPs) towards different targeted analytes are constructed with different strategies, such as the incorporation of luminescent functional monomers, physical entrapment, covalent attachment of luminescent signaling elements on the MIPs, and surface-imprinting polymerization on the luminescent nanomaterials. In this review, we will discuss the design strategies and sensing approaches of luminescent MIP-based chemosensors, as well as their selected applications in biosensing, bioimaging, food safety, and clinical diagnosis. The limitations and prospects for the future development of MIP-based luminescent chemosensors will also be discussed.

Rapid Measurement of Residual Kanamycin Using Highly Specific Biomimetic Recognition Paper-Based Chip

The development of highly specific biomimetic recognition material is a challenge for rapid detection of harmful residues in foodstuff. In this study, a paper-based boronate affinity metal-organic framework/molecularly imprinted polymer microfluidic chip (FZS-BA@MIP) was constructed based on the in situ construction strategy, which was also designed as a highly specific biomimetic recognition module. Here, the homogeneous zeolitic imidazole framework-8 (ZIF-8) membrane served as a great scaffold and enrichment layer. Besides, the recognition layer of MIP was prepared based on a highly oriented boronate affinity surface imprinting strategy. With the aid of the liquid flow channel, the highly specific enrichment and visual detection for antibiotic residues like kanamycin in actual products were achieved on the paper chip module of an integrated lateral flow platform. The whole analysis process could be accomplished within 30 min. In brief, this study offered a new integrated biomimetic recognition platform for visually detecting harmful veterinary residues containing cis-diols, which demonstrated promising commercial value in point-of-care testing of foodborne hazardous compounds.

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.

Optical Detection of Acetone Using "Turn-Off" Fluorescent Rice Straw Based Cellulose Carbon Dots Imprinted onto Paper Dipstick for Diabetes Monitoring

Persistent bad breath has been reported as a sign of serious diabetes health conditions. If an individual's breath has a strong odor of acetone, it may indicate high levels of ketones in the blood owing to diabetic ketoacidosis. Thus, acetone gas in the breath of patients with diabetes can be detected using the current easy-to-use fluorescent test dipstick. In another vein, rice straw waste is the most well-known solid pollutant worldwide. Thus, finding a simple technique to change rice straw into a valuable material is highly important. A straightforward and environmentally friendly approach for reprocessing rice straw as a starting material for the creation of fluorescent nitrogen-doped carbon dots (NCDs) has been established. The preparation process of NCDs was carried out via one-pot hydrothermal carbonization using NH₄OH as a passivation substance. A testing strip was developed on the basis of cellulose CD nanoparticles (NPs) immobilized onto cellulose paper assay. The NCDs demonstrated a quantum yield of 23.76%. A fluorescence wavelength was detected at 443 nm upon applying an excitation wavelength of 354 nm. NCDs demonstrated remarkable selectivity for acetone gas as their fluorescence was definitely exposed to quenching by acetone as a consequence of the inner filter effect. A linear correlation was observed across the concentration range of 0.5-150 mM. To detect and measure acetone gas, the present cellulose paper strip has a "switch off" fluorescent signal. A readout limit was accomplished for an aqueous solution of acetone as low as 0.5 mM under ambient conditions. The chromogenic fluorescence of the cellulose assay responsiveness depends on the fluorescence quenching characteristic of the cellulose carbon dots in acetone. A thin fluorescent cellulose carbon dot layer was deposited onto the surface of cellulose strips by a simple impregnation process. CDs were made using NP morphology and analyzed using infrared spectroscopy and transmission electron microscopy. The carbon dot distribution on the paper strip was evaluated by scanning electron microscope and energy-dispersive X-ray analysis. The absorption and fluorescence spectral analyses were investigated. The paper sheets' mechanical qualities were also examined.

[Application of novel quantum dot-based molecularly imprinted fluorescence sensor in rapid detection]

A critical need in analytical chemistry is the efficient fabrication of selective and sensitive sensors to detect trace analytes in complicated samples. In recent years, fluorescence analysis has been widely used in environmental research and the life sciences due to its high sensitivity and simple operation. Quantum dots (QDs) are a new type of fluorescent nanomaterials. Owing to the quantum confinement effect, QDs possess excellent optical properties such as strong anti-bleaching ability, a narrow excitation and emission band, and tunable emission wavelength. As a hot labeling material, QDs are suitable for use in surface-modified analytical sensors employed in fields such as analytical chemistry, biology, and medicine. However, QD materials have a notable disadvantage, in that the actual sample matrix may contain some interferents with luminescent responses similar to those of the target; this decreases the selective ability of the fluorescence sensor. The surface modification of QDs via the molecular imprinting technique (MIT) is a promising solution to overcome this drawback. Molecularly imprinted polymers (MIPs) are a kind of "bionic" material that can carry out specific recognition and selective adsorption and hence, possess the unique properties of recognition specificity, structural predictability, good reproducibility, and excellent stability. Accordingly, MIPs have been widely employed in sensors as well as for drug delivery, catalysis, and solid phase extraction. Notably, QD-based molecularly imprinted fluorescence sensors combine the advantages of QDs and the MIT. Owing to their specific selectivity and high sensitivity, such sensors have been extensively developed for environmental monitoring, food detection, and biological analysis. However, there remain challenges associated with the preparation and application of the sensors: (i) single recognition: it is important to develop a composite sensor that can detect multiple target analytes from the actual samples at the same time during practical application; (ii) poor hydrophilicity: the actual sample is usually a liquid matrix; hence, it is imperative to determine an approach for improving the hydrophilicity of the sensor; (iii) the accuracy of fluorescence response and the resolution of visual detection need to be further improved; (iv) imprinting: it remains challenging to imprint biological macromolecules, viruses, and bacteria. Thus far, many researchers have made progress with regard to the preparation and application of the sensors. Accordingly, this work reviews approximately 20 papers published by the American Chemical Society, Elsevier, and other databases in the last five years to highlight progress in novel preparation methods and practical applications of QD-based molecularly imprinted fluorescence sensors for the sensitive analysis and rapid detection of trace substances. First, according to the different numbers of emission peaks in the fluorescence spectrum, three kinds of QD-based molecularly imprinted fluorescence sensors are introduced and the related recognition mechanisms are explained. Second, according to the different substances to be detected, this mini-review summarizes the latest research progress in sensors for the detection of ions, organic small molecules, biological macromolecules, as well as for the analysis of bacteria and viruses. Finally, existing challenges associated with the preparation and application of the sensors, as well as future development trends, are discussed.

The Microbiome Meets Nanotechnology: Opportunities and Challenges in Developing New Diagnostic Devices

Monitoring of the human microbiome is an emerging area of diagnostics for personalized medicine. Here, the potential of different nanomaterials and nanobiosensing technologies is reviewed for the development of novel diagnostic devices for the detection and measurement of microbiome-related biomarkers. Moreover, the current and future landscape of microbiome-based diagnostics is defined by exploring the advantages and disadvantages of current nanotechnology-based approaches, especially in the context of developing point-of-care (PoC) devices that would meet the international guidelines known as REASSURED (Real-time connectivity; Ease of specimen collection; Affordability; Sensitivity; Specificity; User-friendliness; Rapid & robust operation; Equipment-free; and Deliverability). Finally, the strategies of the latest international scientific consortia working in this field are analyzed, the current microbiome diagnostics market are reported and the principal ethical, legal, and societal issues related to microbiome R&D and innovation are discussed.

Nanomaterial-Integrated Cellulose Platforms for Optical Sensing of Trace Metals and Anionic Species in the Environment

The development of disposable sensors that can be easily adapted to every analytical problem is currently a hot topic that is revolutionizing many areas of science and technology. The need for decentralized analytical measurements at real time is increasing for solving problems in areas such as environment pollution, medical diagnostic, food quality assurance, etc., requiring fast action. Despite some current limitations of these devices, such as insufficient detection capability at (ultra)trace level and risk of interferent effects due to matrix, they allow low-cost analysis, portability, low sample consumption, and fast response. In the last years, development of paper-based analytical devices has undergone a dramatic increase for on-site detection of toxic metal ions and other pollutants. Along with the great availability of cellulose substrates, the immobilization of receptors providing enhanced recognition ability, such as a variety of nanomaterials, has driven the design of novel sensing approaches. This review is aimed at describing and discussing the different possibilities arisen with the use of different nanoreceptors (e.g., plasmonic nanoparticles, quantum dots, carbon-based fluorescent nanoparticles, etc.) immobilized onto cellulose-based substrates for trace element detection, their advantages and shortcomings.

Molecularly imprinted polymer-enhanced biomimetic paper-based analytical devices: A review

The popularization of paper-based analytical devices (PADs) in analytical science has fostered research on enhancing their analytical performance for accurate and sensitive assays. With their superb recognition capability and structural stability, molecularly imprinted polymers (MIPs) have been extensively employed as biomimetic receptors for capturing target analytes in various complex matrices. The integration of MIPs as recognition elements with PADs (MIP-PADs) has opened new opportunities for advanced analytical devices with elevated selectivity and sensitivity, as well as a shorter assay time and a lower cost. This review covers recent advances in MIP-PAD fabrication and engineering based on multifarious signal transduction systems such as colorimetry, fluorescence, electrochemistry, photoelectrochemistry, and chemiluminescence. The application of MIP-PADs in the fields of biomedical diagnostics, environmental analysis, and food safety monitoring is also reviewed. Further, the advantages, challenges, and perspectives of MIP-PADs are discussed.

Selective capturing and fluorescence “turn on” detection of dibutyl phthalate using a molecular imprinted nanocomposite

Fluorescence-based selective detection of dibutyl phthalate is achieved via a paper-strip-based approach.

Raposo MM. Optical Fiber Sensors for Biocide Monitoring: Examples, Transduction Materials, and Prospects

Antifouling biocides are toxic to the marine environment impacting negatively on the aquatic ecosystems. These biocides, namely, tributyltin (TBT) and Cu(I) compounds, are used to avoid biofouling; however, their toxicity turns TBT and Cu(I) monitoring an important health issue. Current monitoring methods are expensive and time-consuming. This review provides an overview of the actual state of the art of antifouling paints' biocides, including their impact and toxicity, as well as the reported methods for TBT and Cu(I) detection over the past decade. The principles of optical fiber sensors (OFS) applications, with focus on environmental applications, and the use of organic chemosensors in this type of sensors are debated. The multiplexing ability of OFS and their application on aquatic environments are also discussed.

Recent Advances in Molecularly Imprinted Membranes for Sample Treatment and Separation

This review describes the recent advances from the past five years concerning the development and applications of molecularly imprinted membranes (MIMs) in the field of sample treatment and separation processes. After a short introduction, where the importance of these materials is highlighted, a description of key aspects of membrane separation followed by the strategies of preparation of these materials is described. The review continues with several analytical applications of these MIMs for sample preparation as well as for separation purposes covering pharmaceutical, food, and environmental areas. Finally, a discussion focused on possible future directions of these materials in extraction and separation field is also given.

Fluorometric determination of tyramine by molecularly imprinted upconversion fluorescence test strip

A fluorometric method based on molecularly imprinted upconversion fluorescence test strip was developed for the determination of tyramine. It exploited the green fluorescence of upconversion nanoparticles (UCNPs) and the specific recognition property of molecularly imprinted polymers (MIPs). UCNPs were attached to filter paper with glue, and MIPs were prepared via in situ polymerization on the surface of UCNPs by using tyramine as template, methacrylic acid as functional monomer, and ethylene glycol dimethacrylate as cross-linker. The green fluorescence of the test strip, with excitation/emission wavelength 980/550 nm, was enhanced by tyramine. The test strip was suitable for the determination of tyramine in the linear range 1.0-100.0 mg L^-1, and a relatively low limit of detection (0.2 mg L^-1) was achieved. The test strip also worked well for the quantitation of tyramine in spiked red wine and mature vinegar. Recoveries are ranged from 84.9 to 99.9%. The relative standard deviations are below 5.6%. Graphical abstract.

A simple and fast protocol for the synthesis of 2-amino-4-(4-formylphenyl)-4H-chromene-3-carbonitrile to develop an optical immunoassay for the quantification of botulinum neurotoxin type F

In this study, a novel optical immunoassay platform using (S)-2-amino-4-(4-formylphenyl)-4H-chromene-3-carbonitrile, which was synthesized by an ultra-sonication method, as an optical probe.

Recent advances of molecularly imprinted polymer-based sensors in the detection of food safety hazard factors

With increasing economic globalization, food safety is becoming the most serious concern in the food production and distribution system. Food safety hazard factors (FSHFs) can be categorized into chemical hazards, biological hazards and physical hazards, with the detection of the former two having fascinated interdisciplinary research areas spanning chemistry, material science and biological science. Molecularly imprinted polymer (MIP) -based sensors overcome many limitations of traditional detection methods and provide opportunities for efficient, sensitive and low-cost detection using smart miniaturized equipment. With highly specific molecular recognition capacity and high stability in harsh chemical and physical conditions, MIPs have been used in sensing platforms such as electrochemical, optical and mass-sensitive sensors as promising alternatives to bio-receptors for food analysis. In this systemic review, we summarize recent advances of MIPs and MIP-based sensors, such as popular monomers, usual polymerization strategies, fresh modification materials and advanced sensing mechanisms. The applications of MIP-based sensors in FSHF detection are discussed according to sensing mechanisms, including electrochemistry, optics and mass-sensitivity. Finally, future perspectives and challenges are discussed.