A dual action electrochemical molecularly imprinted aptasensor for ultra-trace detection of carbendazim

Carbendazim is often used in agriculture to prevent crop diseases, even though it has been associated with health concerns. To ensure the safety of food products and comply with environmental regulations, an ultrasensitive method for carbendazim determination must be developed. In this study, a new electrochemical molecularly imprinted polymer-aptasensor based on hemin-Al-metal organic framework@gold nanoparticles (H-Al-MOF@AuNPs) was developed for sensitive and selective carbendazim detection. Hemin linked to the surface of the Al-metal organic framework also possesses outstanding peroxidase-like qualities that can electrocatalyse the reduction of H2O2. Thus, H-Al-MOF functions as an in-situ probe. Additionally, AuNPs offer many binding sites to load carbendazim aptamers and create an imprinted polymer-aptasensing interface. Dopamine is the chemical functional monomer in the electropolymerised film, while carbendazim is the template molecule. Thus, compared to the molecularly imprinted polymer or aptasensor alone, the molecularly imprinted polymer-aptasensor showed greater selectivity due to the synergistic action of the polymer and carbendazim aptamer towards carbendazim. A decrease in peak current was observed by differential pulse voltammetry (DPV) and chronoamperometry (CA) as the concentration of carbendazim increased. This possibly resulted from carbendazim connecting to the carbendazim aptamer and simultaneously blocking the imprinted polymer cavities on the surface of the modified electrode, which reduced the transfer of electrons. Signals were observed for hemin DPV and H2O2 catalytic reduction CA. DPV and CA showed that the linear ranges for carbendazim were 0.3 fmol L-1-10 pmol L-1 and 0.7 fmol L-1-10 pmol L-1, respectively, with limits of detection of 80 and 300 amol L-1. Satisfactory recoveries were obtained with tap water, apple juice, and tomato juice samples, demonstrating that the proposed sensor has potential for food and environmental analysis.

Water Quality Carbon Nanotube-Based Sensors Technological Barriers and Late Research Trends: A Bibliometric Analysis

Water is the key element that defines and individualizes our planet. Relative to body weight, water represents 70% or more for the majority of all species on Earth. Taking care of water as a whole is equivalent with taking care of the entire biodiversity or the whole of humanity itself. Water quality is becoming an increasingly important component of terrestrial life, hence intensive work is being conducted to develop sensors for detecting contaminants and assessing water quality and characteristics. Our bibliometric analysis is focused on water quality sensors based on carbon nanotubes and highlights the most important objectives and achievements of researchers in recent years. Due to important measurement characteristics such as sensitivity and selectivity, or low detection limit and linearity, up to the ability to measure water properties, including detection of heavy metal content or the presence of persistent organic compounds, carbon nanotube (CNT) sensors, taking advantage of available nanotechnologies, are becoming increasingly attractive. The conducted bibliometric analysis creates a visual, more efficient keystones mapping. CNT sensors can be integrated into an inexpensive real-time monitoring data acquisition system as an alternative for classical expensive and time-consuming offline water quality monitoring. The conducted bibliometric analysis reveals all connections and maps all the results in this water quality CNT sensors research field and gives a perspective on the approached methods on this specific type of sensor. Finally, challenges related to integration of other trends that have been used and proven to be valuable in the field of other sensor types and capable to contribute to the development (and outlook) for future new configurations that will undoubtedly emerge are presented.

Biomimetic electrochemical sensors: New horizons and challenges in biosensing applications

The urge to meet the ever-growing needs of sensing technology has spurred research to look for new alternatives to traditional analytical methods. In this scenario, the glucometer is the flagship of commercial electrochemical sensing platforms, combining selectivity, reliability and portability. However, other types of enzyme-based biosensors seldom achieve the market, in spite of the large and increasing number of publications. The reasons behind their commercial limitations concern enzyme denaturation, and the high costs associated with procedures for their extraction and purification. In this sense, biomimetic materials that seek to imitate the desired properties of natural enzymes and biological systems have come out as an appealing path for robust and sensitive electrochemical biosensors. We herein portray the historical background of these biomimicking materials, covering from their beginnings until the most impactful applications in the field of electrochemical sensing platforms. Throughout the discussion, we present and critically appraise the major benefits and the most significant drawbacks offered by the bioinspired systems categorized as Nanozymes, Synzymes, Molecularly Imprinted Polymers (MIPs), Nanochannels, and Metal Complexes. Innovative strategies of fabrication and challenging applications are further reviewed and evaluated. In the end, we ponder over the prospects of this emerging field, assessing the most critical issues that shall be faced in the coming decade.

Nanomaterials with enzyme-like characteristics (nanozymes): next-generation artificial enzymes (II)

An updated comprehensive review to help researchers understand nanozymes better and in turn to advance the field.

Study on the performance of micro-flow injection preconcentration method on-line coupled to thermospray flame furnace AAS using MWCNTs wrapped with polyvinylpyridine nanocomposites as adsorbent

An adsorbent nanocomposite based on multi-walled carbon nanotubes and polyvinylpyridine is used in the development of a micro-flow injection preconcentration method coupled to TS-FF-AAS for the determination of very low levels of Cd.

Creating BHb-imprinted magnetic nanoparticles with multiple binding sites

A kind of protein imprinted over magnetic Fe₃O₄@Au multifunctional nanoparticles (NPs) with multiple binding sites was synthesized and investigated.

Molecularly Imprinted Membranes: Past, Present, and Future

More than 80 years ago, artificial materials with molecular recognition sites emerged. The application of molecular imprinting to membrane separation has been studied since 1962. Especially after 1990, such research has been intensively conducted by membranologists and molecular imprinters to understand the advantages of each technique with the aim of constructing an ideal membrane, which is still an active area of research. The present review aims to be a substantial, comprehensive, authoritative, critical, and general-interest review, placed at the cross section of two broad, interconnected, practical, and extremely dynamic fields, namely, the fields of membrane separation and molecularly imprinted polymers. This review describes the recent discoveries that appeared after repeated and fertile collisions between these two fields in the past three years, to which are added the worthy acknowledgments of pioneering discoveries and a look into the future of molecularly imprinted membranes. The review begins with a general introduction in membrane separation, followed by a short theoretical section regarding the basic principles of mass transport through a membrane. Following these general aspects on membrane separation, two principles of obtaining polymeric materials with molecular recognition properties are reviewed, namely, molecular imprinting and alternative molecular imprinting, followed the methods of obtaining and practical applications for the particular case of molecularly imprinted membranes. The review continues with insights into molecularly imprinted nanofiber membranes as a promising, highly optimized type of membrane that could provide a relatively high throughput without a simultaneous unwanted reduction in permselectivity. Finally, potential applications of molecularly imprinted membranes in a variety of fields are highlighted, and a look into the future of membrane separations is offered.

Synthesis of Water-Dispersible Molecularly Imprinted Electroactive Nanoparticles for the Sensitive and Selective Paracetamol Detection

A novel kind of water-dispersible molecularly imprinted electroactive nanoparticles was prepared combining macromolecular self-assembly with molecularly imprinting technique employing paracetamol (PCM) as template molecule. An amphiphilic electroactive copolymer (P(NVC-EHA-AA), PNEA) containing carbazole group was first synthesized through a one-pot free radical copolymerization. The coassembly of the electroactive copolymers with the template molecules (PCM) in aqueous solution generated nanoparticles embedded with PCM, leading to the formation of molecularly imprinted electroactive nanoparticles (MIENPs). A robust MIP film was formed on the surface of electrode by electrodeposition of MIENPs and subsequent electropolymerization of the carbazole units in MIENPs. After the extraction of PCM molecules, a MIP sensor was successfully constructed. It should be noted that electropolymerization of the electroactive units in MIENPs creates cross-conjugated polymer network, which not only locks the recognition sites but also significantly accelerates the electron transfer and thus enhances the response signal of the MIP sensor. These advantages endowed the MIP sensor with good selectivity and high sensitivity for PCM detection. The MIP sensor could recognize PCM from its possible interfering substances with good selectivity. Under the optimal conditions, two linear ranges from 1 μM to 0.1 mM and 0.1 to 10 mM with a detection limit of 0.3 μM were obtained for PCM detection. The MIP sensor also showed good stability and repeatability, which has been successfully used to analyze PCM in tablets and human urine samples with satisfactory results.