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

Electrochemical sensors based on molecularly imprinted polymers for the detection of chlorophenols as emergent distributing chemicals (EDCs): a review

Environmental pollutants like chlorophenol chemicals and their derivatives are commonplace. These compounds serve as building blocks in the production of medicines, biocides, dyes, and agricultural chemicals. Chlorophenols enter the environment through several different pathways, including the breakdown of complex chlorinated hydrocarbons, industrial waste, herbicides, and insecticides. Chlorophenols are destroyed thermally and chemically, creating dangerous chemicals that pose a threat to public health. Water in particular is affected, and thorough monitoring is required to find this source of pollution because it can pose a major hazard to both human and environmental health. For the detection of chlorophenols, molecularly imprinted polymers (MIPs) have been incorporated into a variety of electrochemical sensing systems and assay formats. Due to their long-term chemical and physical stability as well as their simple and affordable synthesis process, MIPs have become intriguing synthetic alternatives over the past few decades. In this review, we concentrate on the commercial potential of the MIP technology. Additionally, we want to outline the most recent advancements in their incorporation into electrochemical sensors with a high commercial potential for detecting chlorophenols.

Molecularly imprinted polymer-based electrochemical sensors for monitoring the persistent organic pollutants chlorophenols

Because of the serious risks they pose to the environment and public health, chlorophenols (CPs), a typical class of the most persistent organic pollutants, have drawn increasing attention. Monitoring CPs effectively has become a pressing and difficult problem. The rapidly increasing need for onsite and real-time CP detection has led to the consideration of electrochemical sensing as a workable solution. Molecularly imprinted polymer (MIP)-based electrochemical sensing has emerged as a promising area for environmental monitoring in response to this analytical problem. MIPs, in conjunction with miniature electrochemical transducers, provide the opportunity to detect target analytes in situ. These devices have the advantages of great chemical and physical stability, cheap production costs, good selectivity, and quick response times. Most studies suggest that these sensors use nanoparticles to improve their analytical properties, especially sensitivity. Furthermore, these sensors have successfully used real water samples without the need for time-consuming pretreatment procedures. This article provides an overview of electrochemical MIP-based sensors reported to detect CPs in water samples. To obtain the highest sensitivity, special consideration is given to the fabrication of the sensors, which includes the use of various functional monomers, sensing platforms, and materials. Several other parameters are also discussed, including the linear concentration range, limit of detection, and the types of water samples that were examined.

CuO nanoleaf and β-cyclodextrin functionalized reduced graphene oxide: a highly selective and sensitive electrochemical sensor for the simultaneous detection of 2-chlorophenol and 2, 4-dichlorophenol

Chlorophenols are considered priority pollutants and are harmful to humans and the environment; consequently, sensitive, and selective detection of chlorophenols is very significant. In the present article, a glassy carbon electrode was modified by copper oxide nanoleaves, β-cyclodextrin, and reduced graphene oxide through an electrostatic self-assembly method (CuO NLs-β-CD-rGO-GCE) and successfully utilized for the selective and sensitive detection of 2-chlorophenol (2-CP) and 2,4-dichlorophenol (2,4-DCP). The modified electrodes were characterized by using SEM, EDX, ATR-FTIR, CV, and EIS. The electrochemical behaviour of 2-CP and 2,4 DCP on different modified electrodes was investigated by cyclic voltammetry whereas differential pulse voltammetry was used for the quantitative determination of chlorophenols. Under the optimized conditions, the anodic peak current displayed a good linear relationship to concentration in the range of 5 to 50 μM for 2-CP and 5 to 30 μM for 2,4-DCP, with detection limits of 0.22 nM and 0.52 nM, respectively. Moreover the proposed sensor exhibited good reproducibility, high sensitivity, and long term stability. To further study the practical applicability of the newly developed sensor, the modified electrode was successfully used to determine 2-CP and 2,4-DCP in a water sample with good recovery.

A New Nanomaterial Based Biosensor for MUC1 Biomarker Detection in Early Diagnosis, Tumor Progression and Treatment of Cancer

Early detection of cancer disease is vital to the successful treatment, follow-up and survival of patients, therefore sensitive and specific methods are still required. Mucin 1 (MUC1) is a clinically approved biomarker for determining the cancer that is a type I transmembrane protein with a dense glycosylated extracellular domain extending from the cell surface to 200–500 nm. In this study, nanopolymers were designed with a lectin affinity-based recognition system for MUC1 detection as a bioactive layer on electrochemical biosensor electrode surfaces. They were synthesized using a mini emulsion polymerization method and derivatized with triethoxy-3-(2-imidazolin-1-yl) propylsilane (IMEO) and functionalized with Concanavalin a Type IV (Con A) lectin. Advanced characterization studies of nanopolymers were performed. The operating conditions of the sensor system have been optimized. Biosensor validation studies were performed. Real sample blood serum was analyzed and this new method compared with a commercially available medical diagnostic kit (Enzyme-Linked ImmunoSorbent Assay-ELISA). The new generation nanopolymeric material has been shown to be an affordable, sensitive, reliable and rapid device with 0.1–100 U/mL linear range and 20 min response time.

Molecularly Imprinted Polymer-Based Sensors for Priority Pollutants

Globally, there is growing concern about the health risks of water and air pollution. The U.S. Environmental Protection Agency (EPA) has developed a list of priority pollutants containing 129 different chemical compounds. All of these chemicals are of significant interest due to their serious health and safety issues. Permanent exposure to some concentrations of these chemicals can cause severe and irrecoverable health effects, which can be easily prevented by their early identification. Molecularly imprinted polymers (MIPs) offer great potential for selective adsorption of chemicals from water and air samples. These selective artificial bio(mimetic) receptors are promising candidates for modification of sensors, especially disposable sensors, due to their low-cost, long-term stability, ease of engineering, simplicity of production and their applicability for a wide range of targets. Herein, innovative strategies used to develop MIP-based sensors for EPA priority pollutants will be reviewed.

Preparation of Molecularly Imprinted Magnetic Graphene Oxide-Gold Nanocomposite and Its Application to the Design of Electrochemical Sensor for Determination of Epinephrine

In this study, a new molecularly imprinted polymer (MIP) based nanocomposite was synthesized then used to determine epinephrine (EPN) by the use of an electrochemical sensor modified by it. Typical techniques for the synthesis of MIP have disadvantages, such as weak binding sites, low mass transfer and low selectivity. One of the ways to improve electrochemical properties is the use of graphene oxide (GR-Ox) and modification of its surface. For this purpose, GR-Ox was initially magnetized (MGR-Ox), then its surface was coated with a silica layer, and gold nanoparticles (AuNPs) were coated on its surface. Subsequently, copolymerization of methacrylic acid (MAA) and N,N'-methylene-bis-acrylamide (MBA) in the presence of EPN was performed on the MGO-AuNPs surface. Afterwards, a selective carbon paste electrode (CPE) with synthetic nanocomposite was fabricated to detect EPN. Under optimal conditions, a linear range from 10^-8 to 5.0 × 10^-7 M was obtained for the measurement of EPN in urine and blood with a detection limit of 5 × 10^-9 M (S/N = 3).

Optical Fiber Sensors Based on Polymeric Sensitive Coatings

Polymer technology is one of the fastest growing fields of contemporary research due to the possibility of using a wide variety of synthetic chemical routes for obtaining a polymeric network with a well-defined structure, resulting in materials with outstanding macroscopic properties. Surface engineering techniques based on the implementation of polymeric structures can be used as an interesting tool for the design of materials with functional properties. In this sense, the use of fabrication techniques for the design of nanostructured polymeric coatings is showing an important growth due to the intrinsic advantages of controlling the structure at a nanoscale level because physical, chemical, or optical properties can be considerably improved in comparison with the bulk materials. In addition, the presence of these sensitive polymeric coatings on optical fiber is a hot topic in the scientific community for its implementation in different market niches because a wide variety of parameters can be perfectly measured with a high selectivity, sensitivity, and fast response time. In this work, the two main roles that a polymeric sensitive matrix can play on an optical fiber for sensing applications are evaluated. In a first section, the polymers are used as a solid support for the immobilization of specific sensitive element, whereas in the second section the polymeric matrix is used as the chemical transducer itself. Additionally, potential applications of the optical fiber sensors in fields as diverse as biology, chemistry, engineering, environmental, industry or medicine will be presented in concordance with these two main roles of the polymeric sensitive matrices.

The Multi-Template Molecularly Imprinted Polymer Based on SBA-15 for Selective Separation and Determination of Panax notoginseng Saponins Simultaneously in Biological Samples

The feasible, reliable and selective multi-template molecularly imprinted polymers (MT-MIPs) based on SBA-15 (SBA-15@MT-MIPs) for the selective separation and determination of the trace level of ginsenoside Rb₁ (Rb₁), ginsenoside Rg₁ (Rg₁) and notoginsenoside R₁ (R₁) simultaneously from biological samples were developed. The polymers were constructed by SBA-15 as support, Rb₁, Rg₁, R₁ as multi-template, acrylamide (AM) as functional monomer and ethylene glycol dimethacrylate (EGDMA) as cross-linker. The new synthetic SBA-15@MT-MIPs were satisfactorily applied to solid-phase extraction (SPE) coupled with high performance liquid chromatography (HPLC) for the separation and determination of trace Rb₁, Rg₁ and R₁ in plasma samples. Under the optimized conditions, the limits of detection (LODs) and quantitation (LOQs) of the proposed method for Rb₁, Rg₁ and R₁ were in the range of 0.63⁻0.75 ng·mL-1 and 2.1⁻2.5 ng·mL-1, respectively. The recoveries of R₁, Rb₁ and Rg₁ were obtained between 93.4% and 104.3% with relative standard deviations (RSDs) in the range of 3.3⁻4.2%. All results show that the obtained SBA-15@MT-MIPs could be a promising prospect for the practical application in the selective separation and enrichment of trace Panax notoginseng saponins (PNS) in the biological samples.