Latest Advances in Determination of Bisphenols with Nanomaterials, Molecularly Imprinted Polymers and Aptamer Based Electrochemical Sensors

Selective apigenin assay in plant extracts and herbal supplement with molecularly imprinted polymer-based electrochemical sensor

This study is the first successful application of a nanomaterial-supported molecularly imprinted polymer (MIP)-based electrochemical sensor for the sensitive and selective determination of apigenin (API), which is a naturally occurring product of the flavone class that is an aglycone of several glycosides. Secondary metabolites are biologically active substances produced by plants in response to various environmental factors. The levels of these compounds can vary depending on factors such as climate, soil conditions and the season in which the plants are grown. Therefore, the analysis of these compounds is essential to properly understand the biological effects of plant extracts and to ensure their safe use. To increase the glassy carbon electrode (GCE) surface's active surface area and porosity, zinc oxide nanoparticles (ZnO NPs) were integrated into the MIP-based electrochemical sensor design. Tryptophan methacrylate (TrpMA) was selected as the functional monomer along with other MIP components such as 2-hydroxyethyl methacrylate (HEMA, basic monomer), 2-hydroxy-2-methylpropiophenone (initiator), and ethylene glycol dimethacrylate (EGDMA, crosslinking agent). The morphological and electrochemical characterizations of the developed API/ZnO NPs/TrpMA@MIP-GCE sensor were performed with scanning electron microscopy (SEM), energy dispersive X-ray analysis (EDX), cyclic voltammetry (CV), and electrochemical impedance spectroscopy (EIS). The indirect measurement approach via 5.0 mM [Fe(CN)6]3-/4- solution was utilized to determine API in the linear range of 1.0x10-13 M - 1.0x10-12 M. The limit of detection (LOD) and limit of quantification (LOQ) for standard solutions were found to be 2.47x10-14 and 8.23x10-14 M, respectively. In addition, the extraction processes were carried out using ultrasound-assisted extraction (UAE) and maceration (MCR) procedures. For Apium graveolens L., Petroselinum crispum (Mill.) Fuss and herbal supplement, the API recoveries varied from 98.79 % to 102.71 %, with average relative standard deviations (RSD) less than 2.25 % in all three cases. The sensor's successful performance in the presence of components with chemical structures similar to the API was also demonstrated, revealing its unique selectivity.

Designing a molecularly imprinted polymer-based electrochemical sensor for the sensitive and selective detection of the antimalarial chloroquine phosphate

For the first time an electrochemical sensor based on nanomaterial-supported molecularly imprinted polymers (MIPs) is applied to the sensitive and specific determination of chloroquine phosphate (CHL). The sensor was produced using an electropolymerization (EP) approach, and it was formed on a glassy carbon electrode (GCE) using CHL as a template and 2-acrylamido-2-methyl-1-propane sulfonic acid (AMPS) and aniline (ANI) as functional monomers. Incorporating Prussian blue polyethyleneglycol-amine nanoparticles (PB@PEG-NH2) in the MIP-based electrochemical sensor increased the active surface area and porosity. The developed CHL/AMPS-PANI/PB@PEG-NH2/MIP-GCE sensor was characterized morphologically and electrochemically using electrochemical impedance spectroscopy (EIS), cyclic voltammetry (CV), and scanning electron microscopy (SEM). The indirect measurement of CHL was accomplished in 5.0 mmol L-1 [Fe(CN)6]-3/-4 solution using differential pulse voltammetry, displaying linear response between 1.75 × 10-12 and 2.50 × 10-13 M, and limits of detection (LOD) and quantitation (LOQ) of 6.68 × 10-14 M and 2.23 × 10-13 M, respectively, in standard solutions. CHL recoveries in spiked serum and tablet form ranged from 99.13 to 101.51%, while the relative standard deviations (RSD%) were below 2.41% in both types of samples. In addition, the sensor's excellent selectivity was successfully demonstrated in the presence of components with a chemical structure similar to CHL.

Simultaneous determination of bisphenol A and bisphenol AF using a carbon nanocages and CuO nanochains-based sensitive voltammetric sensor

A new and highly sensitive voltammetric technique was described in this study for the concurrent detection of endocrine disruptors bisphenol A (BPA) and bisphenol AF (BPAF) based on carbon nanocages (CNCs) and copper oxide nanochains (CuONCs). The CNCs was prepared by the solvothermal method and characterized using various techniques. Utilizing the nanocomposite of CNCs and CuONCs, the voltammetric sensor demonstrated outstanding performance in detecting BPA and BPAF simultaneously with distinct oxidation peaks and increased current peaks. The voltammetric signals have linear relationships with the two bisphenols ranging from 0.500 μM to 100 μM with a detection limit of 0.16 µM for BPA and 0.14 µM for BPAF. The newly designed sensor showed reliable consistency, long-term durability and anti-interference ability, and performed well in analyzing real water samples, indicating great potential for environmental monitoring.

A molecularly imprinted polymer-based detection platform confirmed through molecular modeling for the highly sensitive and selective analysis of ipratropium bromide

This study presented a new method to design a MIP-based electrochemical sensor that could improve the selective and sensitive detection of ipratropium bromide (IPR). The polymeric film was designed using 2-hydroxyethyl methacrylate (HEMA) as the basic monomer, 2-hydroxy-2-methylpropiophenone as the initiator, ethylene glycol dimethacrylate (EGDMA) as the crosslinking agent, and N-methacryloyl-L-aspartic acid (MAAsp) as the functional monomer. The presence of MAAsp results in the functional groups in imprinting binding sites, while the presence of poly(vinyl alcohol) (PVA) allows the generation of porous materials not only for sensitive sensing but also for avoiding electron transport limitations. Electrochemical characterizations of the changes at each stage of the MIP preparation process were confirmed using cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). In addition, morphological characterizations of the developed sensor were performed using scanning electron microscopy (SEM), attenuated total reflectance-Fourier transform infrared spectroscopy (ATR-FTIR), and contact angle measurements. Theoretical calculations were also performed to explain/confirm the experimental results better. It was found that the results of the calculations using the DFT approach agreed with the experimental data. The MAAsp-IPR@MIP/GCE sensor was developed using the photopolymerization method, and the sensor surface was obtained by exposure to UV lamp radiation at 365 nm. The improved MIP-based electrochemical sensor demonstrated the ability to measure IPR for standard solutions in the linear operating range of 1.0 × 10-12-1.0 × 10-11 M under optimized conditions. For standard solutions, the limit of detection (LOD) and limit of quantification (LOQ) were obtained as 2.78 × 10-13 and 9.27 × 10-13 M, respectively. The IPR recovery values for the inhalation form were calculated as 101.70 % and 100.34 %, and the mean relative standard deviations (RSD) were less than 0.76 % in both cases. In addition, the proposed modified sensor demonstrated remarkable sensitivity and selectivity for rapid assessment of IPR in inhalation forms. The sensor's unique selectivity is demonstrated by its successful performance even in the presence of IPR impurities.

The Evaluation of Clinical Applications for the Detection of the Alzheimer's Disease Biomarker GFAP

One of the most prevalent neurodegenerative diseases is Alzheimer's disease (AD). The hallmarks of AD include the accumulation of amyloid plaques and neurofibrillary tangles, which cause related secondary diseases, progressive neurodegeneration, and ultimately death. The most prevalent cell type in the human central nervous system, astrocytes, are crucial for controlling neuronal function. Glial fibrillary acidic protein (GFAP) is released from tissue into the bloodstream due to astrocyte breakdown in neurological diseases. Increased levels of GFAP in the serum can function as blood markers and be an effective prognostic indicator to help diagnose neurological conditions early on, from stroke to neurodegenerative diseases. The human central nervous system (CNS) is greatly affected by diseases associated with blood GFAP levels. These include multiple sclerosis, intracerebral hemorrhage, glioblastoma multiforme, traumatic brain injuries, and neuromyelitis optica. GFAP demonstrates a strong diagnostic capacity for projecting outcomes following an injury. Furthermore, the increased ability to identify GFAP protein fragments helps facilitate treatment, as it allows continuous screening of CNS injuries and early identification of potential recurrences. GFAP has recently gained attention due to data showing that the plasma biomarker is effective in identifying AD pathology. AD accounts for 60-70% of the approximately 50 million people with dementia worldwide. It is critical to develop molecular markers for AD, whose number is expected to increase to about 3 times and affect humans by 2050, and to investigate possible targets to confirm their effectiveness in the early diagnosis of AD. In addition, most diagnostic methods currently used are image-based and do not detect early disease, i.e. before symptoms appear; thus, treatment options and outcomes are limited. Therefore, recently developed methods such as point-of-care (POC), on-site applications, and enzyme-linked immunosorbent assay-polymerase chain reaction (ELISA-PCR) that provide both faster and more accurate results are gaining importance. This systematic review summarizes published studies with different approaches such as immunosensor, lateral flow, POC, ELISA-PCR, and molecularly imprinted polymer using GFAP, a potential blood biomarker to detect neurological disorders. Here, we also provide an overview of current approaches, analysis methods, and different future detection strategies for GFAP, the most popular biosensing field.

Micro and nanoplastics pollution: Sources, distribution, uptake in plants, toxicological effects, and innovative remediation strategies for environmental sustainability

Microplastics and nanoplastics (MNPs), are minute particles resulting from plastic fragmentation, have raised concerns due to their widespread presence in the environment. This study investigates sources and distribution of MNPs and their impact on plants, elucidating the intricate mechanisms of toxicity. Through a comprehensive analysis, it reveals that these tiny plastic particles infiltrate plant tissues, disrupting vital physiological processes. Micro and nanoplastics impair root development, hinder water and nutrient uptake, photosynthesis, and induce oxidative stress and cyto-genotoxicity leading to stunted growth and diminished crop yields. Moreover, they interfere with plant-microbe interactions essential for nutrient cycling and soil health. The research also explores the translocation of these particles within plants, raising concerns about their potential entry into the food chain and subsequent human health risks. The study underscores the urgency of understanding MNPs toxicity on plants, emphasizing the need for innovative remediation strategies such as bioremediation by algae, fungi, bacteria, and plants and eco-friendly plastic alternatives. Addressing this issue is pivotal not only for environmental conservation but also for ensuring sustainable agriculture and global food security in the face of escalating plastic pollution.

Recent Advancements in Molecularly Imprinted Polymers Based Aptasensors: Critical Role of Nanomaterials for the Efficient Food Safety Analysis

Biosensors are being studied extensively for their ability to detect and analyze molecules. There has been a growing interest in combining molecular imprinted polymers (MIPs) and aptamers to create hybrid recognition elements that offer advantages such as target binding, sensitivity, selectivity, and stability. These hybrid elements have been successfully used in identifying a wide range of analytes in food samples. However, the application of MIP-based aptasensors in different sensing approaches is still challenging due to the low conductivity of MIPs-aptamers and limited adsorption capacity of MIPs. To address these limitations, researchers have been exploring the use of nanomaterials (NMs) to design efficient multiple-recognition systems that exploit the synergies between aptamers and MIPs. These hybrid systems can enhance the sensitivity and selectivity of MIP-based aptasensors in quantifying analytical samples. This review provides a comprehensive overview of recent advancements in the field of MIP-based aptasensors. It also introduces technologies that combine MIPs and aptamers to achieve higher sensitivity and selectivity in quantifying analytical samples. The review also highlights potential future trends and practical approaches that can be employed to address the limitations of MIP-based aptasensors, including the use of new NMs, the development of new fabrication techniques, and the integration of MIP-based aptasensors with other analytical tools.

A comparative study of electropolymerization and photopolymerization for the determination of molnupiravir and their application in an electrochemical sensor via computationally designed molecularly imprinted polymers

A comparative analysis of molecularly imprinted polymers based on different synthesis techniques was performed for the recognition of molnupiravir (MOL). The polymerizations were performed with 3-thienyl boronic acid (3-TBA) as a functional monomer by electropolymerization (EP) and with guanine methacrylate (GuaM) as a functional monomer by photopolymerization (PP). Morphological and electrochemical characterizations of the developed sensors were investigated to verify the constructed sensors. Moreover, quantum chemical calculations were used to evaluate changes on the electrode surface at the molecular and electronic levels. The dynamic linear range of both designed sensors under optimized experimental conditions was found to be 7.5 × 10-12-2.5 × 10-10 M and 7.5 × 10-13-2.5 × 10-11 M for EP and PP, respectively. The effect of various interfering agents on MOL peak current was assessed for the selectivity of the study. In the presence of 100 times more interfering agents, the RSD and recovery values were determined. The RSD values of GuaM/MOL@MIP/GCE and poly(Py-co-3-PBA)/MOL@MIP/GCE sensors were found to be 1.99% and 1.72%, respectively. Furthermore, the recovery values of the MIP-based sensors were 98.18-102.69% and 98.05-103.72%, respectively. In addition, the relative selectivity coefficient (k') of the proposed sensor was evaluated, and it exhibited good selectivity for MOL with respect to the NIP sensor. The prepared sensor was successfully applied to determine MOL in commercial serum samples and capsule form. In conclusion, the developed sensors provided excellent reproducibility, repeatability, high sensitivity, and selectivity against the MOL molecule.

Simultaneous determination of environmental endocrine disruptors bisphenol A and 4-nitrophenol bleached from food-contacting materials using the spin-ladder compound La2Cu2O5 modified glassy carbon electrode

Environmental endocrine-disrupting chemicals, Bisphenol A (BPA) and 4-Nitrophenol (4-NP), pose significant risks to reproductive health in both animals and humans. Here, we introduce the first utilization of the 4-leg spin ladder compound La2Cu2O5 as an electrode material for electrochemical sensor. Nanostructured La2Cu2O5 was synthesized via a straightforward Sol-Gel method and thoroughly characterized using X-ray photoelectron spectroscopy, high-resolution transmission electron microscopy, and powder X-ray diffraction. La2Cu2O5 nanoparticles modified glassy carbon electrode (GCE) exhibited a significant electrocatalytic activity towards the oxidation of BPA and 4-NP in phosphate buffer saline (pH 7.0). Square wave voltammetry studies revealed lowest detection limits of 3 nM for BPA and 2.6 nM for 4-NP over a wider concentration range of 0.01-500 μM. Notably, this study marks the first utilization of La2Cu2O5 for simultaneous electrochemical detection of BPA and 4-NP, demonstrating its potential in this field. Furthermore, the sensor exhibited good sensitivity, reproducibility, and selectivity towards BPA and 4-NP, even in the presence of similar potential organic and inorganic interferents. Additionally, the newly developed sensor enabled simultaneous quantification of BPA and 4-NP in real samples such as packaged milk, river water, and plastic bottles, achieving recovery rates above 95%. Importantly, our results underscore the leaching of BPA into water from thin and thick plastics at elevated temperatures (40 °C-80 °C), emphasizing the utility of the proposed sensor for rapid and simultaneous detection of BPA and 4-NP in environmental and food matrices.

The Effect of Polymerization Techniques on the Creation of Molecularly Imprinted Polymer Sensors and Their Application on Pharmaceutical Compounds

Molecularly imprinted polymers (MIPs) have become more prevalent in fabricating sensor applications, particularly in medicine, pharmaceuticals, food quality monitoring, and the environment. The ease of their preparation, adaptability of templates, superior affinity and specificity, improved stability, and the possibility for downsizing are only a few benefits of these sensors. Moreover, from a medical perspective, monitoring therapeutic medications and determining pharmaceutical compounds in their pharmaceutical forms and biological systems is very important. Additionally, because medications are hazardous to the environment, effective, quick, and affordable determination in the surrounding environment is of major importance. Concerning a variety of performance criteria, including sensitivity, specificity, low detection limits, and affordability, MIP sensors outperform other published technologies for analyzing pharmaceutical drugs. MIP sensors have, therefore, been widely used as one of the most crucial techniques for analyzing pharmaceuticals. The first part of this review provides a detailed explanation of the many polymerization techniques that were employed to create high-performing MIP sensors. In the subsequent section of the review, the utilization of MIP-based sensors for quantifying the drugs in their pharmaceutical preparation, biological specimens, and environmental samples are covered in depth. Finally, a critical evaluation of the potential future research paths for MIP-based sensors clarifies the use of MIP in pharmaceutical fields.

Advances in optical and electrochemical sensing of bisphenol a (BPA) utilizing microfluidic Technology: A mini perspective

Continuous exposure to toxic pollutants highlights the need for sensitive detection technologies that can be rapidly applied in the current world for quick screening of real samples. Bisphenol A (BPA) is one of the most common environmental contaminants, and it has the potential to harm both the environment and human health, notably causing reproductive disorders, cancer, heart disease, infertility, mental disorders, etc. Thus, significant attention has been paid to the detection of BPA and microplastics to promote food safety, environmental health, and human health on a sustainable earth. Among the current technologies, microfluidic based systems have garnered a lot of interest as future diagnostic tools for healthcare applications. Microfluidic devices can be deployed for quick screening and real-time monitoring, with inherent advantages like portability, miniaturisation, highly sensing tool and ease of integration with various detection systems. Optical and electrochemical sensors are two major analytical tools found in almost all microfluidic-based devices for ultrasensitive BPA and microplastics determination. In this review, we have evaluated and discussed microfluidic-based detection methods for BPA and microplastics.

A porous molecularly imprinted electrochemical sensor for specific determination of bisphenol S from human serum and bottled water samples in femtomolar level

In this study, a porous molecularly imprinted electrochemical sensor was successfully fabricated for the selective assay of bisphenol S (BPS) by introducing N-methacryloyl-L tyrosine functional monomer. The molecularly imprinted polymer (MIP)-based sensor (MA-Tyr@MIP/GCE) was prepared via photopolymerization on the glassy carbon electrode and subsequently characterized by using cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), scanning electron microscopy (SEM), and Fourier-transform infrared spectroscopy (FTIR). The analytical performance of the sensor was evaluated via CV and differential pulse voltammetry (DPV) measurements. Under the optimized conditions, the rebinding experiment demonstrated that the peak current of the porous MIP-based sensor obviously decreased with the increase of BPS concentration in the concentration range of 1-10 fM. Therefore, the detection limit was determined as 0.171 fM. It should be underlined that MA-Tyr@MIP/GCE exhibited high sensitivity and excellent selectivity because MA-TyrMA-Tyr@MIP/GCE sensor has a higher imprinting factor (IF) toward BPS in respect to competitive analogs, i.e., bisphenol A, bisphenol B, and bisphenol F. The practical application of the sensor also showed good reproducibility and stability for the detection of BPS in human serum and water samples. These results showed MA-Tyr@MIP/GCE successfully applied for the selective recognition of BPS in biological and water samples with high sensitivity and excellent selectivity.