Molecularly imprinted quartz crystal microbalance sensor based on poly(o-aminothiophenol) membrane and Au nanoparticles for ractopamine determination

An electrochemical microbiosensor for serotonin based on surface imprinted layer coordinated bimetal functionalized acupuncture needle

Serotonin (5-hydroxytryptamine, 5-HT) is a pivotal monoamine neurotransmitter, which is widely distributed in human brain for biological, physical and psychopathological processes. The content of 5-HT can support diagnose of various diseases. To selectively detect 5-HT is very important in clinical medicine. Here, a novel microbiosensor for 5-HT is studied on acupuncture needle. Molecularly imprinted film enwrapped 5-HT was electropolymerized onto bimetallic gold/platinum (Au/Pt) nanoparticles on acupuncture needle microelectrode (ANME). Au/Pt nanostructure exhibited active sites to catalyze the oxidation of 5-HT and bind the generated polymer. 5-HT can be enwrapped by the functional monomer of pyrrole (Py) in the process of electropolymerization with suitably electroactive conformation. Comparing with interfaces of single metal or molecularly imprinted layer, synergistic microbiosensor exhibit better performance for 5-HT. 5-HT can be adsorbed and catalytically oxidized by the imprinted cavities. Under optimized conditions, the peak current linearly increases with the concentration of 5-HT from 0.03 to 500 μM, and a detection limit of 0.0106 μM is obtained. The performance of this microbiosensor is competitive with previous studies. Furthermore, the prepared microbiosensor showed effective application to analyze 5-HT in human serum and urine. Interestingly, the microbiosensor expressed the real-time monitoring ability to 5-HT from stimulated PC12 cells by K+. The microbiosensor also exhibited high selectivity, stability and reproducibility, which is promising in view of the low price, fast response and simple operation.

Supramolecular recognition enhanced electrochemical sensing: β-cyclodextrin and Pd nanoparticle co-decorated 3D reduced graphene oxide nanocomposite-modified glassy carbon electrode for the quantification of ractopamine

Ractopamine (RAC) is universally known for improving lean meat percentage in livestock and thus is widely introduced as a feed additive. However, it is difficult to eliminate the RAC residue in animal tissues from the biological system and will inevitably harm human health. Hence, detecting RAC molecules in biological samples is extremely significant. Herein, a novel strategy of supramolecular recognition-enhanced electrochemical sensing is presented. This platform was constructed by coupling β-cyclodextrin (β-CD) with palladium nanoparticles (Pd NPs)-functionalized three-dimensional reduced graphene oxide (3D-rGO) to form a nanocomposite (3D-rGO/Pd/β-CD), which was further used to modify a glassy carbon electrode (GCE) for RAC detection. Benefiting from the attractive electrical conductivity and catalytic activity of 3D-rGO/Pd, as well as the unique small-molecule-recognition ability of β-CD demonstrated by ¹H NMR spectrum, which revealed the 1 : 2 binding mode of RAC with β-CD, increased peak current signals of RAC were observed in the cyclic voltammetry (CV) test. Under optimized conditions, the wide linear concentration range spanned 1-95 μM, along with a relatively low detection limit of 0.12 μM (S/N = 3), as evidenced by the differential pulse voltammetry (DPV) approach. The platform also exhibited satisfactory stability and fine reproducibility, as well as high selectivity and good anti-interference capability. Moreover, this as-obtained sensor was efficiently applied in pork samples with a high recovery rate (96.44-103.99%), which provides a promising view of its electrochemical biosensing ability in practical applications.

Au Nanoparticles Functionalized Covalent-Organic-Framework-Based Electrochemical Sensor for Sensitive Detection of Ractopamine

Ractopamine, as a feed additive, has attracted much attention due to its excessive use, leading to the damage of the human nervous system and physiological function. Therefore, it is of great practical significance to establish a rapid and effective method for the detection of ractopamine in food. Electrochemical sensors served as a promising technique for efficiently sensing food contaminants due to their low cost, sensitive response and simple operation. In this study, an electrochemical sensor for ractopamine detection based on Au nanoparticles functionalized covalent organic frameworks (AuNPs@COFs) was constructed. The AuNPs@COF nanocomposite was synthesized by in situ reduction and was characterized by FTIR spectroscopy, transmission electron microscope and electrochemical methods. The electrochemical sensing performance of AuNPs@COF-modified glassy carbon electrode for ractopamine was investigated using the electrochemical method. The proposed sensor exhibited excellent sensing abilities towards ractopamine and was used for the detection of ractopamine in meat samples. The results showed that this method has high sensitivity and good reliability for the detection of ractopamine. The linear range was 1.2-1600 μmol/L, and the limit of detection (LOD) was 0.12 μmol/L. It is expected that the proposed AuNPs@COF nanocomposites hold great promise for food safety sensing and should be extended for application in other related fields.

A novel metal-organic frameworks composite-based label-free point-of-care quartz crystal microbalance aptasensing platform for tetracycline detection

A novel label-free point-of-care quartz crystal microbalance (QCM) aptasensing platform based on metal-organic frameworks (MOFs) and gold nanoparticles (AuNPs) was fabricated for tetracycline (TC) detection. MOFs (HKUST-1) and AuNPs were modified onto the sensing interface of QCM sensor to enhance the sensing performance of the QCM aptasensor. TC aptamer with sulfhydryl group was fixed through Au-S bond. The recognition performance of the aptasensor was predicted and verified by the computer simulation. At the optimal conditions, the frequency change of the sensor was adopted for quantitative detection of TC. The prepared QCM aptasensor exhibited a wide linear range from 1 × 10^-10 g mL^-1 to 1 × 10^-5 g mL^-1 with low limit of detection (0.8 × 10^-11 g mL^-1). High sensitivity, good selectivity, acceptable recoveries (87.6-91.4%) in real samples were obtained. For the first time, MOFs were utilized in the construction of QCM aptasensing platform, providing a promising application way of MOFs in the QCM sensing.

Bifunctional Magnetic Fe3O4@Cu2O@TiO2 Nanosphere-Mediated Dual-Mode Assay of PTP1B Activity Based on Photocurrent Polarity Switching and Nanozyme-Engineered Biocatalytic Precipitation Strategies

Dysregulation of protein phosphatases is associated with the progression of various human diseases and cancers. Herein, a photoelectrochemical (PEC)-quartz crystal microbalance (QCM) dual-mode sensing platform was developed for protein tyrosine phosphatase 1B (PTP1B) activity assay based on bifunctional magnetic Fe₃O₄@Cu₂O@TiO₂ nanosphere-mediated PEC photocurrent polarity switching and QCM signal amplification strategies. The PTP1B-specific phosphopeptide (P-peptide) with a cysteine end was designed and immobilized onto the QCM Au chip via the Au-S bond. Subsequently, the Fe₃O₄@Cu₂O@TiO₂ nanosphere was connected to the P-peptide via the specific interaction between the phosphate group on the P-peptide and TiO₂. After incubation with PTP1B, the dephosphorylation of the P-peptide occurred, causing some Fe₃O₄@Cu₂O@TiO₂ nanospheres to be released from the chip surface. The released magnetic Fe₃O₄@Cu₂O@TiO₂ nanospheres (labeled as R-Fe₃O₄@Cu₂O@TiO₂) were quickly separated via magnetic separation technology and attached to the Bi₂S₃-decorated magnetic indium-tin oxide (Bi₂S₃/MITO) electrode by magnetic force, inducing the switch of the photocurrent polarity of the electrode from anodic current (the Bi₂S₃/MITO electrode) to cathodic current (the R-Fe₃O₄@Cu₂O@TiO₂/Bi₂S₃/MITO electrode). Also, the nondephosphorylated P-peptide linked Fe₃O₄@Cu₂O@TiO₂ nanospheres as nanozymes with horseradish peroxidase activity to catalyze the formation of precipitation on the surface of the Au chip, leading to a frequency change of the QCM. Thus, the proposed PEC-QCM dual-mode sensing platform achieved accurate and reliable assay of PTP1B activity because of the different mechanisms and independent signal transductions. In addition, this dual-mode sensing platform can be easily extended for other protein phosphatase activity analysis and shows great potential in the early diagnosis of the protein phosphatase-related diseases and the protein phosphatase-targeted drug discovery.

Molecularly Imprinted Affinity Membrane: A Review

A molecularly imprinted affinity membrane (MIAM) can perform separation with high selectivity due to its unique molecular recognition introduced from the molecular-printing technique. In this way, a MIAM is able to separate a specific or targeted molecule from a mixture. In addition, it is possible to achieve high selectivity while maintaining membrane permeability. Various methods have been developed to produce a MIAM with high selectivity and productivity, with their respective advantages and disadvantages. In this paper, the MIAM is reviewed comprehensively, from the fundamentals of the affinity membrane to its applications. First, the development of a MIAM and various preparation methods are presented. Then, applications of MIAMs in sensor, metal ion separation, and organic compound separation are discussed. The last part of the review discusses the outlook of MIAMs for future development.

A novel ratiometric electrochemical sensor based on dual-monomer molecularly imprinted polymer and Pt/Co3O4 for sensitive detection of chlorpromazine hydrochloride

In this work, a novel signal on/off ratiometric electrochemical sensor for the selective detection of chlorpromazine (CPZ) was developed. The sensor was constructed by electrodepositing dual-monomer molecularly imprinted polymer (DMMIP) film on the surface of Pt/Co₃O₄ nanoparticles modified glassy carbon electrode, using CPZ as template molecule, methylene blue and catechol as functional monomers. The copolymerization of two monomers increased the diversity of functional groups for binding template molecules, and enhanced stability. The quantitative detection of CPZ was performed by differential pulse voltammetry, using the peak current of poly (methylene blue) as reference signal and the peak current of CPZ as indicating signal. The results showed that the developed DMMIP sensor not only possessed high selectivity and sensitivity, but also exhibited satisfactory anti-interference ability. Under the optimum conditions, a linear detection range of 0.005-9 μmol L^-1 (R² = 0.9962) was obtained, and the limit of detection was 2.6 nmol L^-1. Moreover, the sensor showed good reproducibility and stability toward CPZ detection. It was applied to detect CPZ in serum and pharmaceutical samples, and satisfactory recoveries (ranging from 95.3% to 108.0%) were achieved.

Recent Advances and Future Trends in the Detection of Contaminants by Molecularly Imprinted Polymers in Food Samples

Drug residues, organic dyes, heavy metals, and other chemical pollutants not only cause environmental pollution, but also have a serious impact on food safety. Timely and systematic summary of the latest scientific advances is of great importance for the development of new detection technologies. In particular, molecularly imprinted polymers (MIPs) can mimic antibodies, enzymes and other biological molecules to recognize, enrich, and separate contaminants, with specific recognition, selective adsorption, high affinity, and strong resistance characteristics. Therefore, MIPs have been widely used in chemical analysis, sensing, and material adsorption. In this review, we first describe the basic principles and production processes of molecularly imprinted polymers. Secondly, an overview of recent applications of molecularly imprinted polymers in sample pre-treatment, sensors, chromatographic separation, and mimetic enzymes is highlighted. Finally, a brief assessment of current technical issues and future trends in molecularly imprinted polymers is also presented.

Quartz crystal microbalance sensor based on 11-mercaptoundecanoic acid self-assembly and amidated nano-titanium film for selective and ultrafast detection of phosphoproteins in food

A novel quartz crystal microbalance (QCM) sensor for trace-phosphoprotein ultrafast detection was constructed based on the bridge interactions between the NH₂-TiO₂ sites enriched on Au-electrode and phosphate groups. Herein, 11-mercaptoundecanoic acid (MUA) modified by Au-S bond acted as carrier for immobilizing NH₂-TiO₂. Functionalized NH₂-TiO₂ to absorb phosphoproteins. Under the optimal conditions, the proposed sensor showed a linear frequency shift to the concentration of α-casein ranging from 1.0 × 10^-3 to 1.0 mg mL^-1 with a low detection limit of 5.3 × 10^-6 mg mL^-1 (S/N = 3), and the limit of quantitation was 0.001 mg mL^-1. Compared with traditional Ti⁴⁺-IMAC/MOAC-system, the analysis process of NH₂-TiO₂/MUA/AuE-QCM sensor was simpler and faster which could complete within 5 min. Additionally, the constructed biosensor was successfully used for the non-fat milk and chicken egg white. This proposed sensor presents a great prospective strategy for the evaluation of the nutrition in different foods.

SERS-Based Molecularly Imprinted Plasmonic Sensor for Highly Sensitive PAH Detection

A novel hybrid plasmonic platform based on the synergetic combination of a molecularly imprinted polymer (MIP) thin film with Au nanoparticle (NPs) assemblies, noted as Au@MIP, was developed for surface-enhanced Raman scattering (SERS) spectroscopy recognition of polycyclic aromatic hydrocarbons (PAHs). While the MIP trapped the PAH close to the Au surface, the plasmonic NPs enhanced the molecule's Raman signal. The Au@MIP fabrication comprises a two-step procedure, first, the layer-by-layer deposition of Au NPs on glass and their further coating with a uniform MIP thin film. Profilometry analysis demonstrated that the thickness and homogeneity of the MIP film could be finely tailored by tuning different parameters such as prepolymerization time or spin-coating rate. Two different PAH molecules, pyrene or fluoranthene, were used as templates for the fabrication of pyrene- or fluoranthene-based Au@MIP substrates. The use of pyrene or fluoranthene, as the template molecule to fabricate the Au@MIP thin films, enabled its ultradetection in the nM regime with a 100-fold improvement compared with the nonimprinted plasmonic sensors (Au@NIPs). The SERS data analysis allowed to estimate the binding constant of the template molecule to the MIP. The selectivity of both pyrene- and fluoranthene-based Au@MIPs was analyzed against three PAHs of different sizes. The results displayed the important role of the template molecule used for the Au@MIPs fabrication in the selectivity of the system. Finally, the practical applicability of pyrene-based Au@MIPs was shown by performing the detection of pyrene in two real samples: creek water and seawater. The design and optimization of this type of plasmonic platform will pave the way for the detection of other relevant (bio)molecules in a broad range of fields such as environmental control, food safety, or biomedicine.

Advances in Molecularly Imprinting Technology for Bioanalytical Applications

In recent years, along with the rapid development of relevant biological fields, there has been a tremendous motivation to combine molecular imprinting technology (MIT) with biosensing. In this situation, bioprobes and biosensors based on molecularly imprinted polymers (MIPs) have emerged as a reliable candidate for a comprehensive range of applications, from biomolecule detection to drug tracking. Unlike their precursors such as classic immunosensors based on antibody binding and natural receptor elements, MIPs create complementary cavities with stronger binding affinity, while their intrinsic artificial polymers facilitate their use in harsh environments. The major objective of this work is to review recent MIP bioprobes and biosensors, especially those used for biomolecules and drugs. In this review, MIP bioprobes and biosensors are categorized by sensing method, including optical sensing, electrochemical sensing, gravimetric sensing and magnetic sensing, respectively. The working mechanism(s) of each sensing method are thoroughly discussed. Moreover, this work aims to present the cutting-edge structures and modifiers offering higher properties and performances, and clearly point out recent efforts dedicated to introduce multi-sensing and multi-functional MIP bioprobes and biosensors applicable to interdisciplinary fields.

Cross-linked chitosan/thiolated graphene quantum dots as a biocompatible polysaccharide towards aptamer immobilization

Chitosan has a number of commercial and possible biomedical uses. Chitosan as a polysaccharide is a bioactive polymer with a variety of applications due to its functional properties such as antibacterial activity, non-toxicity, ease of modification, and biodegradability. In this work, cross-linked chitosan/thiolated graphene quantum dot as a biocompatible polysaccharide was modified by gold nanoparticle and used for immobilization of ractopamine (RAC) aptamer. A highly specific DNA-aptamer (5'-SH-AAAAAGTGCGGGC-3'), selected to RAC was immobilized onto thiolated graphene quantum dots (GQDs)-chitosan (CS) nanocomposite modified by gold nanostructures (Au NSs) and used for quantification of RAC. Different shapes of gold nanostructures with various sizes from zero-dimensional nanoparticles to spherical structures were prepared by one-step template-assistant green electrodeposition method. Fully electrochemical methodology was used to prepare a new transducer on a glassy carbon surface which provided a high surface area to immobilize a high amount of the aptamer. Therefore, a label free electrochemical (EC) apta-assay for ultrasensitive detection of RAC was developed. A special immobilization media consisting of Au NSs/GQDs-CS/Cysteamine (CysA) was utilized to improve conductivity and performance of the biosensor. The RAC aptamer was attached on the Au NSs of the composite membrane via AuS bond. The fabrication process of the EC aptamer based assay was characterized by some electrochemical techniques. The peak currents obtained by differential pulse voltammetry decreased linearly with the increasing of RAC concentrations and the apta-assay responds approximately over a wide dynamic range of RAC concentration from 0.0044 fM to 19.55 μM. The low limit of quantification was 0.0044 fM.

Electrochemical sensors based on molecularly imprinted polymers on Fe3O4/graphene modified by gold nanoparticles for highly selective and sensitive detection of trace ractopamine in water

A novel molecular imprinting polymer (MIP)-based electrochemical senor, consisting of Fe3O4 nanobeads and gold nanoparticles on a reduced graphene oxide (RGO) substrate, was fabricated to detect ractopamine (RAC) in water using the reversible addition fragmentation chain transfer (RAFT) polymerization technique. The Au nanoparticles widely dispersed on RGO can significantly increase the response current for RAC detection in water, which is confirmed by cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS) and theoretical calculations. By means of the differential pulse voltammetry technique, the as-prepared MIP-based electrode shows a dynamic linear range of 0.002 to 0.1 μM with a correlation coefficient of 0.992 and a remarkably low detection limit of 0.02 nM (S/N = 3). Additionally, the sensor exhibits high binding affinity and selectivity towards RAC with excellent reproducibility. Our study demonstrates the potential for the proposed electrochemical sensors in monitoring organic pollutants in water.

Recent Progress of Imprinted Nanomaterials in Analytical Chemistry

Molecularly imprinted polymers (MIPs) are a type of tailor-made materials that have ability to selectively recognize the target compound/s. MIPs have gained significant research interest in solid-phase extraction, catalysis, and sensor applications due to their unique properties such as low cost, robustness, and high selectivity. In addition, MIPs can be prepared as composite nanomaterials using nanoparticles, multiwalled carbon nanotubes (MWCNTs), nanorods, quantum dots (QDs), graphene, and clays. This review paper aims to demonstrate and highlight the recent progress of the applications of imprinted nanocomposite materials in analytical chemistry.

An electrodeposited molecularly imprinted quartz crystal microbalance sensor sensitized with AuNPs and rGO material for highly selective and sensitive detection of amantadine

In the present work, a new amantadine (AM) imprinted quartz crystal microbalance (QCM) sensor sensitized by Au nanoparticles (AuNPs) and reduced graphene oxide (rGO) material was fabricated by electrodeposition in the presence of o-aminothiophenol (o-AT) by cyclic voltammetry scanning. AuNPs and graphene, with the advantages of great chemical stability, electrical conductivity, and large surface area, show exceptionally high sensitivity. The results of different modifications of the QCM sensor fabrication process were characterized using transmission electron microscopy (TEM), scanning electron microscopy (SEM), atomic force microscopy (AFM) and Raman spectroscopy. Under the optimal experimental conditions, the frequency shift of the MIP-QCM sensor showed a linear relationship with the concentration of the AM template in the range of 1.0 × 10⁻⁵ to 1.0 × 10⁻³ mmol L⁻¹ with a limit of detection (LOD) of 5.40 × 10⁻⁶ mmol L⁻¹. The imprinting factor for AM reached 7.1, the selectivity coefficient for the analogues rimantadine (RT), adamantine (AMT) and 1-chloroadamantane (CMT) were 7.3, 5.6, and 6.1, respectively. Here, a highly sensitive, selective and stable QCM sensor prepared via the imprinting approach is reported for the first time for detection of AM from animal-derived food samples.

In the present work, a new amantadine imprinted quartz crystal microbalance sensor sensitized by Au nanoparticles and reduced graphene oxide material was fabricated by electrodeposition of o-aminothiophenol by cyclic voltammetry scanning.

Current Progress of Nanomaterials in Molecularly Imprinted Electrochemical Sensing

Nanomaterials have received much attention during the past decade because of their excellent optical, electronic, and catalytic properties. Nanomaterials possess high chemical reactivity, also high surface energy. Thus, provide a stable immobilization platform for biomolecules, while preserving their reactivity. Due to the conductive and catalytic properties, nanomaterials can also enhance the sensitivity of molecularly imprinted electrochemical sensors by amplifying the electrode surface, increasing the electron transfer, and catalyzing the electrochemical reactions. Molecularly imprinted polymers that contain specific molecular recognition sites can be designed for a particular target analyte. Incorporating nanomaterials into molecularly imprinted polymers is important because nanomaterials can improve the response signal, increase the sensitivity, and decrease the detection limit of the sensors. This study describes the classification of nanomaterials in molecularly imprinted polymers, their analytical properties, and their applications in the electrochemical sensors. The progress of the research on nanomaterials in molecularly imprinted polymers and the application of nanomaterials in molecularly imprinted polymers is also reviewed.

Upconversion Nanophosphor-Involved Molecularly Imprinted Fluorescent Polymers for Sensitive and Specific Recognition of Sterigmatocystin

Originated from the bottom-up synthetic strategy, molecularly imprinted polymers (MIPs) possess the inherent ability of selective and specific recognition and binding of the target analytes, with their structural cavities that can match the target molecules in respect to size, shape, and functional groups. Herein, based on the high selectivity of MIPs and the fluorescence properties of the β-NaYF₄:Yb3+, Er3+ upconversion nanoparticles, MIPs with both specificity and fluorescent signals are fabricated to recognize trace sterigmatocystin (ST) with high selectivity and sensitivity. The structure analogue of ST, 1,8-dihydroxyanthraquinone (DT), was employed as the template molecule, acrylamide as the functional monomer, 3-methacryloyloxypropyltrimethoxysilane as the crosslinking agent, and a new molecular imprinting technique of non-aqueous sol-gel method is used to synthesize a molecularly imprinted material with high selectivity to ST. Under optimal conditions, the fluorescence enhancement of fluorescent MIPs increased as the concentration of ST increased. In the range of 0.05⁻1.0 mg L-1, fluorescence enhancement and the concentration showed a good linear relationship with a detection limit of 0.013 mg L-1. Real sample analysis achieved the recoveries of 83.8⁻88.8% (RSD 5.1%) for rice, 82.1⁻87.5% (RSD 4.6%) for maize, and 80.6⁻89.2% (RSD 3.0%) for soybeans, respectively, revealing the feasibility of the developed method.

State of art of nanotechnology applications in the meat chain: A qualitative synthesis

BACKGROUND

Nanotechnology is a promising area in industry with a broad range of applications including in the agri-food sector. Several studies have investigated the potential benefits deriving from use of nanomaterials in the context of the whole food chain drawing scenarios of benefits but also potential for concerns. Among the agri-food sector, animal production has potential for nanomaterial application but also for safety concerns due to the possibility of nanomaterial accumulation along the farm-to-fork path. Scope and Approach: The aim of this work was to define the state of the art of nanomaterial applications in the animal production sector by assessing data belonging to recently publishes studies. To do this, a qualitative synthesis approach was applied to build a fit-for-purpose framework and to summarise relevant themes in the context of effectiveness, feasibility and health concerns. Key findings and conclusions: Nanomaterials have potential for use in a wide range of applications from feed production and farming to food packaging, including several detection tools designed for the benefit of consumer protection. The current high degree of variability in nanomaterials tested and in study designs impairs external validation of research results. Further research is required to clearly define which safe nanomaterial applications have the potential to reach the market.

Molecular Imprinting Technology in Quartz Crystal Microbalance (QCM) Sensors

Molecularly imprinted polymers (MIPs) as artificial antibodies have received considerable scientific attention in the past years in the field of (bio)sensors since they have unique features that distinguish them from natural antibodies such as robustness, multiple binding sites, low cost, facile preparation and high stability under extreme operation conditions (higher pH and temperature values, etc.). On the other hand, the Quartz Crystal Microbalance (QCM) is an analytical tool based on the measurement of small mass changes on the sensor surface. QCM sensors are practical and convenient monitoring tools because of their specificity, sensitivity, high accuracy, stability and reproducibility. QCM devices are highly suitable for converting the recognition process achieved using MIP-based memories into a sensor signal. Therefore, the combination of a QCM and MIPs as synthetic receptors enhances the sensitivity through MIP process-based multiplexed binding sites using size, 3D-shape and chemical function having molecular memories of the prepared sensor system toward the target compound to be detected. This review aims to highlight and summarize the recent progress and studies in the field of (bio)sensor systems based on QCMs combined with molecular imprinting technology.

Ag–SnO2 nano-heterojunction–reduced graphene oxide by a stepwise photocatalyzed approach and its application in ractopamine determination

Stepwise reduction process for SnO₂–AgNPs–reduced graphene oxide under UV irradiation and its energy-band structure.

Novel ultrasensitive homogeneous electrochemical aptasensor based on dsDNA-templated copper nanoparticles for the detection of ractopamine

Herein, we describe a novel homogenous electrochemical aptasensor for the ultrasensitive detection of ractopamine (RAC) based on the signal amplification of a hairpin DNA cascade amplifier (HDCA) and electrocatalysis of dsDNA-templated copper nanoparticles.

Molecularly Imprinted Polymers Based Electrochemical Sensor for 2,4-Dichlorophenol Determination

A molecularly imprinted polymers based electrochemical sensor was fabricated by electropolymerizing pyrrole on a Fe₃O₄ nanoparticle modified glassy carbon electrode. The sensor showed highly catalytic ability for the oxidation of 2,4-dichlorophenol (2,4-DCP). Square wave voltammetry was used for the determination of 2,4-DCP. The oxidation peak currents were proportional to the concentrations of 2,4-DCP in the range of 0.04 to 2.0 µM, with a detection limit of 0.01 µM. The proposed sensor was successfully applied for the determination of 2,4-DCP in water samples giving satisfactory recoveries.

Molecular imprinting: perspectives and applications

This critical review presents a survey of recent developments in technologies and strategies for the preparation of MIPs, followed by the application of MIPs in sample pretreatment, chromatographic separation and chemical sensing.

Electrochemical detection of ractopamine based on a molecularly imprinted poly-o-phenylenediamine/gold nanoparticle–ionic liquid–graphene film modified glass carbon electrode

An electrochemical sensor for sensitive detection of ractopamine (RAC) was fabricated by using molecularly imprinted polymer (MIP) incorporation with graphene (GR), ionic liquid (IL) and gold nanoparticle (AuNPs) nanocomposites.

Quartz-Crystal Microbalance (QCM) for Public Health: An Overview of Its Applications

Nanobiotechnologies, from the convergence of nanotechnology and molecular biology and postgenomics medicine, play a major role in the field of public health. This overview summarizes the potentiality of piezoelectric sensors, and in particular, of quartz-crystal microbalance (QCM), a physical nanogram-sensitive device. QCM enables the rapid, real time, on-site detection of pathogens with an enormous burden in public health, such as influenza and other respiratory viruses, hepatitis B virus (HBV), and drug-resistant bacteria, among others. Further, it allows to detect food allergens, food-borne pathogens, such as Escherichia coli and Salmonella typhimurium, and food chemical contaminants, as well as water-borne microorganisms and environmental contaminants. Moreover, QCM holds promises in early cancer detection and screening of new antiblastic drugs. Applications for monitoring biohazards, for assuring homeland security, and preventing bioterrorism are also discussed.

Molecularly Imprinted Nanomaterials for Sensor Applications

Molecular imprinting is a well-established technology to mimic antibody-antigen interaction in a synthetic platform. Molecularly imprinted polymers and nanomaterials usually possess outstanding recognition capabilities. Imprinted nanostructured materials are characterized by their small sizes, large reactive surface area and, most importantly, with rapid and specific analysis of analytes due to the formation of template driven recognition cavities within the matrix. The excellent recognition and selectivity offered by this class of materials towards a target analyte have found applications in many areas, such as separation science, analysis of organic pollutants in water, environmental analysis of trace gases, chemical or biological sensors, biochemical assays, fabricating artificial receptors, nanotechnology, etc. We present here a concise overview and recent developments in nanostructured imprinted materials with respect to various sensor systems, e.g., electrochemical, optical and mass sensitive, etc. Finally, in light of recent studies, we conclude the article with future perspectives and foreseen applications of imprinted nanomaterials in chemical sensors.