A poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate)-based electrochemical sensor for tert.-butylhydroquinone

Aptasensor based on high surface area covalent organic framework for simple and ultrasensitive detection of sarcosine in the diagnosis of prostate cancer

In this study, an electrochemical aptasensor was developed for the specific detection of sarcosine using a covalent organic framework (COF). The imine-based two-dimensional COF was synthesized through a solvothermal process using terephthaldehyde and melamine. This resulted in the formation of a structure that is highly porous and has a unique surface area of 908 m2/g. The produced biosensor demonstrated a significant linear relationship between charge transfer resistance (Rct) and various concentrations of sarcosine in blood serum samples. The aptasensor had two linear ranges, spanning from 0.5 fM to 700 fM and 10 pM to 0.12 nM, respectively, with a detection limit of 0.15 fM. The incorporation of high surface area COFs in the aptasensor design offers a promising combination of sensitivity, stability, and specificity. This combination creates a valuable device for diagnosing and monitoring of prostate cancer and potentially other diseases.

Co-MOF@MWCNTs/GCE for the sensitive detection of TBHQ in food samples

tert-Butylhydroquinone (TBHQ) is a novel synthetic antioxidant with a higher safety profile and antioxidant effect that is more excellent than other synthetic antioxidants and is internationally recognized as one of the best food antioxidants. However, its excessive use in food can have unfavorable effects on the human body. Thus, it is critical to establish a rapid method for the detection of TBHQ in food samples. In this study, a cobalt-based metal-organic framework (Co-MOF) was fabricated by a one-pot hydrothermal method and embedded in multi-walled carbon nanotubes (MWCNTs) to construct an economical and sensitive electrochemical sensor for TBHQ. The results showed that this sensor possessed a wide linear range (0.004-20 μM and 20-300 μM), a low limit of detection (LOD = 2.5 nM, S/N = 3) as well as an ultra-high sensitivity (43.19 μA μM-1 cm-2). Moreover, the sensor also has superior selectivity, repeatability, reproducibility and anti-interference ability and can be successfully applied for the detection of TBHQ in samples of instant noodles and potato chips.

Fabrication of an electrochemical aptasensor for the determination of sarcosine based on synthesized CuCo2O4 nanosheets

Sarcosine (SRN) detection in body fluids is related to the diagnosis of prostate cancer. However, the development of SRN biosensors has been limited due to the low concentration of SRN in body fluids. Here, a new electrochemical strategy for selective and accurate determination of SRN in urine samples is reported. CuCo2O4 nanosheets (CuCo2O4 NSs) have been synthesized and used as a new platform in the design of efficient electrochemical aptasensors for prostate cancer diagnosis. As far as we know, CuCo2O4 NSs have not been used so far in electrochemical aptasensor design. The presence of CuCo2O4 NSs on the electrode surface as a platform improves the conductivity and surface area. Therefore, it can be very effective in improving the diagnostic performance of the electrochemical aptasensor. The linear concentration range and limit of detection (LOD) for this strategy were calculated to be 1 pM- 8 μM and 350 fM, respectively.

Flower-like core-shell nanostructures based on natural asphalt coated with Ni-LDH nanosheets as an electrochemical platform for prostate cancer biomarker sensing

Flower-like core-shell nanostructures based on natural asphalt (NA) coated with nickel-layered double hydroxide nanosheets (Ni-LDH NSs) were synthesized for the first time. The synthetic nanostructures were successfully used as an efficient platform in the design of sarcosine (SAR) electrochemical aptasensor. SAR is considered an efficient biomarker for prostate cancer (PCa) diagnosis. However, the low concentration of SAR in urine, plasma, and tissue cells has limited the growth of SAR biosensors. The performance of the presented SAR aptasensor is very promising in being applied as a portable device in the identification of PCa. After drawing the calibration curve, the linear concentration range was obtained in two ranges from 5 pM to 100 nM and 100 nM to 7.9 μM, and the limit of detection (LOD) was calculated to be 1.6 pM. This study can provide a basis for wider research in various programs such as developing PCa diagnostic aptasensors and investigating the use of NA nanostructures in other electrochemical applications such as electrocatalysis and energy storage.

In Situ Synthesis of MnMgFe-LDH on Biochar for Electrochemical Detection and Removal of Cd2+ in Aqueous Solution

Herein, MnMgFe-layered double hydroxides/biochar (MnMgFe-LDHs/BC) composite was fabricated by immobilizing MnMgFe-LDHs on BC via the coprecipitation method, which was employed as an effective material for the detection and removal of Cd²⁺ from aqueous media. A lamellar structure of MnMgFe-LDHs with abundant surface-hydroxyl groups and various interlayer anions inside present a greater chance of trapping Cd²⁺. Meanwhile, the conductive BC with a porous structure provides numerous channels for the adsorption of Cd²⁺. Using the MnMgFe-LDHs/BC-based sensor, Cd²⁺ can be detected with a low limit of detection down to 0.03 ng/L. The feasibility of detecting Cd²⁺ in paddy water was also carried out, with satisfactory recoveries ranging from 97.3 to 102.3%. In addition, the MnMgFe-LDHs/BC material as an adsorbent was applied to remove Cd²⁺ from water with adsorption capacity of 118 mg/g, and the removal efficiency can reach 91%. These results suggest that the as-prepared MnMgFe-LDHs/BC can serve as a favorable platform for efficient determination and removal of Cd²⁺ in water.

Rapid and sensitive detection of tert-butylhydroquinone in soybean oil using a gold-based paper sensor

tert-Butylhydroquinone (TBHQ) residues in foods pose a threat to human health. Therefore, it is necessary to develop a rapid method for TBHQ detection. In this study, a sensitive monoclonal antibody 5C3 (IgG2a subclass) against TBHQ was produced. It possessed a half maximal inhibitory concentration of 7.43 ng mL^-1. A gold nanoparticle-based immunochromatographic assay (ICA) was established for the rapid and sensitive screening of TBHQ in soybean oil. Qualitative analysis results were obtained within 10 min and observed with the naked eye. The visual limit of detection (LOD) was 50 ng g^-1 and the cut-off value was 1000 ng g^-1. A hand-held strip reader was used for quantitative analysis, in which the calculated LOD was defined as 18.68 ng g^-1. The average recoveries of TBHQ ranged from 89.55% ± 2.70% to 100.66% ± 3.02% for soybean oil, with a coefficient of variation of 2.89%-7.05%. Therefore, our developed ICA is a useful tool for the rapid and on-site detection of TBHQ in real food samples.

Application of PEDOT:PSS and Its Composites in Electrochemical and Electronic Chemosensors

Poly(3,4-ethylenedioxythiophene):polystyrene sulfonate (PEDOT:PSS) is a highly important and attractive conducting polymer as well as commercially available in organic electronics, including electrochemical and electronic chemosensors, due to its unique features such as excellent solution-fabrication capability and miscibility, high and controllable conductivity, excellent chemical and electrochemical stability, good optical transparency and biocompatibility. In this review, we present a comprehensive overview of the recent research progress of PEDOT:PSS and its composites, and the application in electrochemical and electronic sensors for detecting liquid-phase or gaseous chemical analytes, including inorganic or organic ions, pH, humidity, hydrogen peroxide (H2O2), ammonia (NH3), CO, CO2, NO2, and organic solvent vapors like methanol, acetone, etc. We will discuss in detail the structural, architectural and morphological optimization of PEDOT:PSS and its composites with other additives, as well as the fabrication technology of diverse sensor systems in response to a wide range of analytes in varying environments. At the end of the review will be given a perspective summary covering both the key challenges and potential solutions in the future research of PEDOT:PSS-based chemosensors, especially those in a flexible or wearable format.

Ultrasensitive detection of cytotoxic food preservative tert-butylhydroquinone using 3D cupric oxide nanoflowers embedded functionalized carbon nanotubes

Accurate detection of cytotoxic food preservative tert-butylhydroquinone (TBHQ) has significant importance in maintaining food quality and safety. TBHQ is a chronic hazard to aquatic life and its use in applications involving direct human exposure and frequent release to environment makes its quantification critical to maintain safety. Hence, we report development of a sensitive electrochemical sensor for TBHQ determination at nanomolar level in commonly used edible oils and water sample. Novel cupric oxide (CuO) decorated amine functionalized carbon nanotubes (NH₂-CNTs) were prepared for development of TBHQ sensor. 3D CuO nanoflowers and NH₂-CNTs were synthesized using hydrothermal and ultrasound-assisted method respectively. Techniques such as SEM, elemental mapping, XRD, FTIR, micro Raman, XPS, EIS, and UV-Visible spectroscopy were taken to affirm significant characterizations of synthesized materials. We have observed outstanding electrocatalytic activity towards TBHQ detection using the sonochemically prepared nanocomposite modified screen printed carbon electrode (SPCE). The proposed sensor exhibited ultra-low detection limit at 3 nM and exceptional sensitivity at 37.7 μA μM^-1 cm^-2. Furthermore, TBHQ sensor showcased outstanding anti-interference, stability, reproducibility, and repeatability. The practical feasibility of TBHQ detection was validated using real sample analysis resulting in excellent recovery in the range 95.90-104.87% and a maximum RSD of mere 2.71%.

Simple synthesis of a clew-like tungsten carbide nanocomposite decorated with gold nanoparticles for the ultrasensitive detection of tert-butylhydroquinone

The excessive use of food additives in manufactured food products negatively affects their quality and potentially impacts human health. In the present study, a composite consisting of gold nanoparticles decorated on tungsten carbide (AuNP-WC) was successfully fabricated using a facile and cost-effective ultrasonication technique. Compared to a bare glassy carbon electrode (GCE), AuNP-GCE, and WC-GCE, the AuNP-WC-GCE demonstrated excellent sensing performance for tert-butylhydroquinone (TBHQ) when used as an electrocatalyst in 0.05 M phosphate buffer solution (PBS), with a low working potential and a high peak current. In particular, the composite was able to detect the oxidation of TBHQ within a linear concentration range of 5 to 75 nM, with an extremely low detection limit of 0.20 nM. The practicability of the sensor was also assessed in the analysis of TBHQ in real samples of soybean oil, blended oil, and red wine, with satisfactory recovery rates obtained.