A novel immunoassay for residual bovine serum albumin (BSA) in vaccines using laser-induced fluorescence millimeter sensor array detection platform

A compact microfluidic laser-induced fluorescence immunoassay system using avalanche photodiode for rapid detection of alpha-fetoprotein

Alpha-fetoprotein (AFP), commonly employed for early diagnosis of liver cancer, serves as a biomarker for cancer screening and diagnosis. Combining the high sensitivity and specificity of fluorescence immunoassay (FIA), developing a low-cost and efficient immunoassay system for AFP detection holds significant importance in disease diagnosis. In this work, we developed a miniaturized oblique laser-induced fluorescence (LIF) immunoassay system, coupled with a microfluidic PMMA/paper hybrid chip, for rapid detection of AFP. The system employed an avalanche photodiode (APD) as the detector, and implemented multi-level filtering in the excitation light channel using the dichroic mirror and optical trap. At first, we employed the Savitzky-Golay filter and baseline off-set elimination methods to denoise and normalize the original data. Then the cutoff frequency of the low-pass filter and the reverse voltage of the APD were optimized to enhance the detection sensitivity of the system. Furthermore, the effect of laser power on the fluorescence excitation efficiency was investigated, and the sampling time during the scanning process was optimized. Finally, a four-parameter logistic (4PL) model was utilized to establish the concentration-response equation for AFP. The system was capable of detecting concentrations of AFP standard solution within the range of 1-500 ng/mL, with a detection limit of 0.8 ng/mL. The entire immunoassay process could be completed within 15 min. It has an excellent potential for applications in low-cost portable diagnostic instruments for the rapid detection of biomarkers.

Developing novel oenological tannins from 44 plants sources by assessing astringency and color in model wine

BACKGROUND

Oenological tannins are commercial natural products extracted from different botanical sources, which were widely reported as prominent contributors to wine quality. Research on wine quality affected by tannins extracts promoted the development of new oenological products with low cost and high accessibility. In the present study, the structure and concentration of tannin in polyphenol extracts, as well as their correlation with astringency and the color of model wine, was investigated by UV spectrophotometer, HPLC, fluorescence quenching, sodium dodecylsulfate-polyacrylamide gel electrophoresis, colorimeter and sensory evaluation.

RESULTS

Resource extracts from 16 of 44 plants were screened as wine oenological tannins, according to the total polyphenol and total flavanol, as well as the intensity of astringency and bitterness. Polyphenols extracted from grape seeds and green tea were more effective in increasing the wine astringency compared to other plant tannins.

CONCLUSION

Total flavanol content and tannin activity showed a strong correlation with wine astringency. Condensed tannins with mean degree of polymerization also exhibited strong color stability, and the concentrations of (-)-epigallocatechin were associated with the a* value, a negative qualitative factor for wine color. The present study provides new clues regarding the development of low-cost and highly accessible sources of polyphenol extracts and lays a theoretical foundation for the development of the oenological product. © 2022 Society of Chemical Industry.

Ultrasensitive, highly selective, and real-time detection of protein using functionalized CNTs as MIP platform for FOSPR-based biosensor

A facile approach is presented for the detection of bovine serum albumin (BSA), based on fiber optic surface plasmon resonance (FOSPR) combined with molecular imprinting (MI). The probe is fabricated by exploiting the plasmonic property of silver thin film and vinyl-functionalised carbon nanotube-based MIP platform. BSA template molecules are imprinted on the MIP layer coated over multi-walled carbon nanotubes to ensure high specificity of the probe in the interfering environments. In addition, FOSPR endorses the sensor capability of real-time and remote sensing along with very high sensitivity due to the use of nanostructured MI platform. The response of the probe is considered in terms of the absorbance spectrum recorded for various concentrations of BSA. The sensor shows a wide dynamic range of 0-350 ng l^-1 with a considerably linear response up to 100 ng l^-1 in the peak absorbance wavelength with BSA concentration. A highest sensitivity of 0.862 nm per ng l^-1 is achieved for the lowest concentration of BSA and it decreases with the increase in BSA concentration. The performance of the present sensor is compared with those reported in the literature in terms of the limit of detection. It is found that the probe possesses a lowest LOD of 0.386 ng l^-1 in addition to other advantages such as real-time online monitoring, high sensitivity, high specificity, and remote sensing.

Ring-Oven Washing Technique Integrated Paper-based Immunodevice for Sensitive Detection of Cancer Biomarker

A paper-based microfluidic immunodevice has recently attracted considerable interest for point-of-care testing (POCT) and a washing procedure was used as a standard procedure in immunoassay to eliminate the nonspecific binding protein from a paper surface. However, the traditional washing method cannot get rid of the nonspecific binding protein more completely to get a lower background. In this work, a novel washing strategy with a ring-oven technique integrated on a paper-based immunodevice was presented, which can effectively wash a nonspecific binding protein and enable a low background for sensitive detection of the carcinoembryonic antigen (CEA). By immobilizing the antibody on the detection area and incorporating the temperature-controlled ring-oven under the paper-based device, the continuous washing solution can carry the nonspecific binding protein to the waste area freely by capillary force and then the waste area dried quickly by heating. The paper device, which is matched to the size of the ring-oven, is composed of eight microfluidic channels by the simple and rapid paper-cutting fabrication method. With the HRP-catalyzed 3,3',5,5'-tetramethylbenzidine (TMB)-H2O2 colorimetric detection method, a lower detection limit of 0.03 ng/mL CEA can be obtained by enzyme-linked immunosorbent assay (ELISA). The washing efficiency for the nonspecific binding protein was improved a lot compared to the traditional washing methods, and the established paper-based device can be used in the determination of CEA in human serum with high sensitivity. The paper-based device provides a new washing strategy for sensitive immunoassay and point-of-care diagnostics.

Establishment of indirect enzyme-linked immunosorbent assay for artificial musk

Anti-inflammatory component (AIC) known as an important constituent of artificial musk exhibits bioactive effects on many pharmacological models. This study describes an immunochemical assay for the quality control of artificial musk in traditional Chinese medicine using an enzyme-linked immunosorbent assay. A polyclonal antibody against AIC was produced by rabbit. The method, at an effective measuring range of 3.13-200 ng/ml of AIC, 3 ng/ml limit of detection, and no cross-reaction with natural musk, successfully detected artificial musk in many traditional Chinese prescriptions containing artificial musk. The results demonstrated that a novel and reliable assay system for detection of artificial musk was generated.

Development of an ELISA for evaluation of swab recovery efficiencies of bovine serum albumin

After a potential biological incident the sampling strategy and sample analysis are crucial for the outcome of the investigation and identification. In this study, we have developed a simple sandwich ELISA based on commercial components to quantify BSA (used as a surrogate for ricin) with a detection range of 1.32–80 ng/mL. We used the ELISA to evaluate different protein swabbing procedures (swabbing techniques and after-swabbing treatments) for two swab types: a cotton gauze swab and a flocked nylon swab. The optimal swabbing procedure for each swab type was used to obtain recovery efficiencies from different surface materials. The surface recoveries using the optimal swabbing procedure ranged from 0–60% and were significantly higher from nonporous surfaces compared to porous surfaces. In conclusion, this study presents a swabbing procedure evaluation and a simple BSA ELISA based on commercial components, which are easy to perform in a laboratory with basic facilities. The data indicate that different swabbing procedures were optimal for each of the tested swab types, and the particular swab preference depends on the surface material to be swabbed.