A signal-enhanced lateral flow strip biosensor for ultrasensitive and on-site detection of bisphenol A

Composite membrane of graphene oxide and gold nanoparticles functionalized S fiber taper aptasensor for highly sensitive bisphenol A detection

The S fiber taper (SFT) aptasensor with a composite sensitive membrane of graphene oxide and gold nanoparticles was proposed for the rapid and highly sensitive detection of bisphenol A (BPA). The SFT was obtained using a fusion splicer; subsequently, the composite film was deposited on its surface, and the specific aptamer was covalently bonded to the surface of gold nanoparticles. The detection mechanism relies on monitoring changes in the external refractive index induced by the specific binding of BPA to the aptamer. The developed SFT aptasensor exhibited a remarkable sensitivity of 15.5 nm/nM and a limit of detection as low as 0.01 nM for BPA. These findings highlight the aptasensor's potential for diverse monitoring applications.

Development of 177Lu-Cetuximab-PAMAM dendrimeric nanosystem: a novel theranostic radioimmunoconjugate

PURPOSE

Epidermal growth factor receptors (EGFRs) are overexpressed in a wide range of tumors and are attractive candidates to target in targeted therapies. This study aimed to introduce a novel radiolabeled compound, 177Lu-cetuximab-PAMAM G4, for the treatment of EGFR-expressing tumors.

METHODS

In this study, the cetuximab mAb was bound to PAMAM G4 and labeled with 177Lu via DTPA-CHX chelator. The synthesized nanosystem was confirmed by different analyses such as DLS, FT-IR, TEM, and RT-LC. Cell viability of the radioimmunoconjugate was assessed over the EGFR-expressing cell line of SW480. The biodistribution of 177Lu-Cetuximab-PAMAMG4 was determined in different intervals after injection of the radiolabeled compound in normal and tumoral nude mice via scarification and SPECT images.

RESULTS

The average size of PAMAM G4 and PAMAM-Cetuximab-DTPA-CHX nanoparticles were 2 and 70 nm, respectively. 177Lu-Cetuximab-PAMAMG4 was prepared with radiochemical purity of more than 98%. The survival rates of SW480 cells at 24, 48, and 72 h post-treatment with177Lu-Cetuximab-PAMAMG4 (500 nM) were 18%, 15%, and 14%, respectively. The biodistribution studies showed a significant accumulation of 177Lu-Cetuximab-PAMAM in the EGFR-expressing tumor.

CONCLUSION

According to the results, this new agent can be considered as an efficient therapeutic complex for tumors expressing EGFR receptors.

An Overview of Aptamer-Based Sensor Platforms for the Detection of Bisphenol-A

Endocrine disruptive compounds are natural or anthropogenic environmental micropollutants that alter the function of the endocrine system ultimately damaging the metabolism. Bisphenol A (BPA) is the most common of these pollutants and it is often used in epoxy coatings and polycarbonates as a plasticizer. Therefore, monitoring BPA levels in different environments is very important and challenging. In recent years, an increasing number of BPA detection methods have been proposed. This article presents a critical review of aptamer-based electrochemical, fluorescence-based, colorimetric, and several other BPA detection platforms published in the last decade. Furthermore, a statistical evaluation has been made using principle component analysis showing analytical performance parameters do not create very different clusters. Comparisons to other BPA detection methods are also presented so that the reader has an overall literature overview.

Design of a Signal-Amplified Aptamer-Based Lateral Flow Test Strip for the Rapid Detection of Ochratoxin A in Red Wine

In order to improve the weak optical performance of gold nanoparticles and realize the signal amplification of lateral flow chromatography test strips, individual gold nanoparticles (AuNPs) were aggregated into gold nanoparticle aggregates through functional groups around polyamidoamine (PAMAM) dendrimers. A signal-amplified aptamer-based lateral flow chromatography test strip was constructed for the rapid determination of ochratoxin A (OTA). Under optimal conditions, the visual detection limit of this test strip was 0.4 ng mL⁻¹ and the semi-quantitative limit of detection (LOD) was 0.04 ng mL⁻¹. Compared with other traditional aptamer lateral flow chromatography test strips, its sensitivity was improved about five times. The whole test could be completed within 15 min. The aptamer-based strip was applied to the detection of OTA in red wine; the average recoveries ranged from 93% to 105.8% with the relative standard deviation (RSD) varying from 3% to 8%, indicating that the test strip may be a potentially effective tool for the on-site detection of OTA.

A nanomaterial-free and thionine labeling-based lateral flow immunoassay for rapid and visual detection of the transgenic CP4-EPSPS protein

Nanomaterial-based lateral flow immunoassays (LFIAs) have been widely used for the on-site detection of genetically modified components. However, the practical applications are often limited by the complex matrix, such as in red samples. In this study, a thionine (Thi) labeling-based LFIA was developed for the first time to detect CP4-EPSPS protein. The optimal labeling concentration of Thi was 0.5 mg/mL, and the antibody could be rapidly coupled to Thi in 10 min. The visual limit of detection (vLOD) levels for transgenic soybean, sugar beet, and cotton containing the CP4-EPSPS protein reached 0.05%, 0.1%, and 0.1%, respectively, and had no interference from other proteins. After storage at 4 °C for three months, the LFIA sensitivity remained unchanged and showed good stability. This method could be used to screen and detect a variety of transgenic crops containing the CP4-EPSPS protein, and the results were consistent with the current standard assay. This study pioneered the development of an immunochromatographic method using Thi as a marker and applied it to the detection of the CP4-EPSPS protein in herbicide-tolerant transgenic crops. This provides a new method for the rapid immunoassay of Thi as a dye and has good prospects for practical application.

Development of a Lateral Flow Immunoassay (LFIA) to Screen for the Release of the Endocrine Disruptor Bisphenol A from Polymer Materials and Products

One of the most important chemicals used in the production of polymer plastics and coatings is bisphenol A. However, despite the large number of studies on the toxicity and hormonal activity of BPA, there are still open questions and thus considerable media attention regarding BPA toxicity. Hence, it is necessary to develop a sensitive, simple, cost-efficient, specific, portable, and rapid method for monitoring bisphenol A and for high sample throughput and on-site screening analysis. Lateral flow immunoassays have potential as rapid tests for on-site screening. To meet sensitivity criteria, they must be carefully optimized. A latex microparticle-based LFIA for detection of BPA was developed. The sensitivity of the assay was improved by non-contact printing of spot grids as the control and test lines with careful parameter optimization. Results of the test could be visually evaluated within 10 min with a visual cut-off of 10 µg/L (vLOD). Alternatively, photographs were taken, and image analysis performed to set up a calibration, which allowed for a calculated limit of detection (cLOD) of 0.14 µg/L. The method was validated for thermal paper samples against ELISA and LC-MS/MS as reference methods, showing good agreement with both methods.

Aptamer-enhanced fluorescence determination of bisphenol A after magnetic solid-phase extraction using Fe3O4@SiO2@aptamer

Bisphenol A (BPA) is used as a stabilizing agent in many food packaging plastics and is a known endocrine-disrupting chemical that can alter the development of mammary glands, affect egg cells, and cause chromosomal defects. However, the pretreatment of traditional assays for detecting BPA is difficult. In this work, a novel aptamer functionalized magnetic adsorbent was developed and combined with magnetic solid-phase extraction (MSPE) for the selective enrichment of BPA. First, magnetic silica-coated Fe₃O₄ microspheres (Fe₃O₄@SiO₂) were synthesized by the sol-gel method, and functional magnetic nanoparticles (Fe₃O₄@SiO₂@Apt) were formed by modifying with nucleic acids. In the presence of BPA in a MSPE system, the nucleic acid aptamer can specifically capture the target BPA. After magnetic separation, the Apt/BPA composite was eluted, and we observed enhanced fluorescence with the Apt/BPA composite that was formed. Our results showed that this method allowed a limit of detection of 0.05 ng mL^-1.

High affinity truncated aptamers for ultra-sensitive colorimetric detection of bisphenol A with label-free aptasensor

The widespread exposure of bisphenol A (BPA) presents a significant risk to human health. A rapid, ultra-sensitive and label-free colorimetric aptasensor using high affinity truncated aptamers was developed for BPA detection. Truncated 38-mer and 12-mer aptamers specific for BPA were obtained through rationally truncation from 63-mer BPA aptamer. The dissociation constants (K_d) of 38-mer and 12-mer aptamers were determined to be 13.17 nM and 27.05 nM. Then, truncated aptamers were used in label-free colorimetric detection assays based on gold nanoparticles (AuNPs). The limit of detections of aptasensors using 38-mer and 12-mer aptamers were 7.60 pM and 14.41 pM, which were 265-fold and 140-fold lower than that of the aptasensor using 63-mer aptamer, respectively. The recovery rates in milk, orange juice and mineralized water samples were 93.88% to 107.30%. Therefore, the developed BPA colorimetric aptasensor using truncated aptamers has great application prospects in food safety control and environmental monitoring.

Rapid and Sensitive Detection of Bisphenol A Based on Self-Assembly

Bisphenol A (BPA) is an endocrine disruptor that may lead to reproductive disorder, heart disease, and diabetes. Infants and young children are likely to be vulnerable to the effects of BPA. At present, the detection methods of BPA are complicated to operate and require expensive instruments. Therefore, it is quite vital to develop a simple, rapid, and highly sensitive method to detect BPA in different samples. In this study, we have designed a rapid and highly sensitive biosensor based on an effective self-assembled monolayer (SAM) and alternating current (AC) electrokinetics capacitive sensing method, which successfully detected BPA at nanomolar levels with only one minute. The developed biosensor demonstrates a detection of BPA ranging from 0.028 μg/mL to 280 μg/mL with a limit of detection (LOD) down to 0.028 μg/mL in the samples. The developed biosensor exhibited great potential as a portable BPA biosensor, and further development of this biosensor may also be useful in the detection of other small biochemical molecules.