Detection Of Alpha-fetoprotein Research Articles

Biosensing of Alpha-Fetoprotein: A Key Direction toward the Early Detection and Management of Hepatocellular Carcinoma.

Hepatocellular carcinoma (HCC) is currently one of the most prevalent cancers worldwide. Associated risk factors include, but are not limited to, cirrhosis and underlying liver diseases, including chronic hepatitis B or C infections, excessive alcohol consumption, nonalcoholic fatty liver disease (NAFLD), and exposure to chemical carcinogens. It is crucial to detect this disease early on before it metastasizes to adjoining parts of the body, worsening the prognosis. Serum biomarkers have proven to be a more accurate diagnostic tool compared to imaging. Among various markers such as nucleic acids, circulating genetic material, proteins, enzymes, and other metabolites, alpha-fetoprotein (AFP) is a protein marker primarily used to diagnose HCC. However, current methods need a large sample and carry a high cost, among other challenges, which can be improved using biosensing technology. Early and accurate detection of AFP can prevent severe progression of the disease and ensure better management of HCC patients. This review sheds light on HCC development in the human body. Afterward, we outline various types of biosensors (optical, electrochemical, and mass-based), as well as the most relevant studies of biosensing modalities for non-invasive monitoring of AFP. The review also explains these sensing platforms, detection substrates, surface modification agents, and fluorescent probes used to develop such biosensors. Finally, the challenges and future trends in routine clinical analysis are discussed to motivate further developments.

Rapid antibody conjugation strategy via instant charge inversion of AuNBPs toward ultrasensitive SERS-LFIA detection of AFP

Alpha-fetoprotein (AFP) is widely utilized as the primary serum marker for diagnosing Hepatocellular carcinoma. Integrating surface-enhanced Raman scattering (SERS) with lateral flow immunoassays (LFIA) displays significant promise for the rapid quantification of AFP. Gold nanobipyramids (AuNBPs) is a kind of SERS probe with high activity showing strong application potential in SERS-LFIA. However, the drastic electrostatic interaction between negative charged antibodies and positive charged AuNBPs will result in uncontrollable aggregation, which poses a challenge for antibody binding and limits its application in SERS-LFIA. Hence, we propose a rapid antibody conjugation strategy with the aid of instant charge inversion of AuNBPs, which enables efficient and expedited antibody coupling onto AuNBPs. The thiol-free fish sperm (FSDNA) was employed to adsorb on the cetyltrimethylammonium bromide (CTAB) coated AuNBPs for immediate charge inversion. The adsorption of FSDNA will cause partial stripping of CTAB from the AuNBPs surface to provide additional active sites for antibodies binding. In this study, approximately average 37 AFP-antibodies were verified bonding on one charge inverted AuNBPs by direct incubation for 30 min. The antibodies modified AuNBPs were further incubated with 4-nitrothiophenol for preparing SERS immune probes, which display excellent colloid stability and specificity. The probes were used to construct SERS-LFIA strips for AFP detection, enabling highly sensitive detection of AFP with the limit of detection (LOD) as low as 0.72 pg·mL−1. The developed SERS-LFIA strip demonstrates excellent stability and accuracy in detecting serum samples, with a recovery rate ranging from 84 % to 114 %. This rapid antibody coupling strategy is applicable to a wide range of positively charged nanoparticles, effectively addressing the challenging issue of utilizing such nanomaterials in LFIA.

A photoelectrochemical platform constructed with C-doped ZnIn2S4 /Bi2S3: Excellent for the visual detection of tumor marker

A photoelectrochemical (PEC) immunosensor based on a novel composite material was proposed for the highly sensitive and selective detection of Alpha-fetoprotein (AFP). C-doped ZnIn2S4/Bi2S3 (ZnIn2S4/Bi2S3/C) nanocomposites were synthesized in one pan by solvothermal method using glucose as carbon precursor and used as photoanode. ZnIn2S4/Bi2S3 displayed efficient visible light utilization and carrier separation efficiency. In addition, the high electrical conductivity of carbon materials also allowed ZnIn2S4/Bi2S3/C to show stronger photocurrent compared to ZnIn2S4/Bi2S3. The PEC sensor was successfully prepared in combination with a selective AFP antibody. The photocurrent decreased with the increase of AFP concentration in the range of 0.001–1000 ng mL−1, with a calculated detection limit of 0.12 ng mL−1. Besides, in order to eliminate the workstation's limitations, a colorimetric device that can display AFP levels nearly simultaneously was constructed by modifying Prussian blue on another FTO electrode and connecting the two electrodes by wires. This work provided a new approach for the instant detection of AFP in serum by developing a visualization device for rapid screening and identification of AFP by introducing the electrochromic principle and integrating the device from the viewpoint of improving the practicality of the sensing method.

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.

A simple, rapid and sensitive sandwich immunoassay based on poly(N-isopropylacrylamide) for the detection of alpha-fetoprotein

Alpha-fetoprotein (AFP), as a tumor marker, plays a vital role in the diagnosis of liver cancer. In this work, a novel sandwich immunoassay based on a thermosensitive polymer, poly(N-isopropylacrylamide) (PNIPAM), was developed for the detection of AFP. This immunoassay could realize one-step rapid reaction within 1 h, and facilitate the separation of the target molecules by incorporating PNIPAM. In this method, a conjugate of PNIPAM and capture antibody (Ab1) was successfully synthesized as a capture probe and the synthetic method of PNIPAM-Ab1 was simple, while the detection antibody (Ab2) was labeled with fluorescein isothiocyanate (FITC) to form a fluorescent detection probe. By employing a sandwich immunoassay, the method achieved quantitative determination of AFP, exhibiting a wide linear range from 5 ng/mL to 200 ng/mL and a low detection limit of 2.44 ng/mL. Furthermore, it was successfully applied to the analysis of spiked human serum samples and the screening of patients with hepatic diseases in clinical samples, indicating its potential application prospect in the diagnosis of liver cancer.

Biosensor Based on Zif-8-905% Metal-organic Nanocomposite and Carbon Nanotubes Associated with Concanavalin a for Detection of Alpha-fetoprotein

Introduction:: Lung carcinoma presents an aggressive evolution, with its carriers having reduced survival. Late diagnosis is one of the main factors of death. In the neoplasia in question, there is an established correlation with increases in Alpha-Fetoprotein (AFP) serum concentrations. Method:: Commonly used diagnostic methods are invasive or inaccessible. Therefore, a low-cost, non-invasive method would be extremely promising, and biomarkers can be used to achieve this goal. Electrochemical biosensors are a promising approach for detecting analytes of clinical interest using innovative bioreceptors. In this work, we obtained an electrochemical biosensor based on a hybrid ligand metal-organic structure (ZIF-8-905%) and functionalized carbon nanotubes (MWCNTs- COOH) in association with the lectin Concanavalin A (ConA), as a biorecognition element for detecting AFP in human serum from patients with lung carcinoma. Cyclic Voltammetry (CV), Square Wave Voltammetry (SWV), and Electrochemical Impedance Spectroscopy (EIS) were used to characterize the development of this biosensor. Microscopic analysis through Atomic Force Microscopy (AFM) revealed the formation of ConA-AFP complexes, pointing out the sensor's ability to identify the target analyte. Result:: The blocking electron transfer effect in the electrode-redox pair interface assessed AFP detection. The ZIF-8-905%/MWCNTs-COOH/ConA platform exhibited a limit of detection (LOD) of 7.98 ng/mL, and a limit of quantification (LOQ) of 23.78ng/mL was also estimated. In addition, the biosensor showed excellent selectivity towards interfering biomolecules. Conclusion:: Therefore, the biosensor represents an efficient form of detection, contributing to research that aims to detect tumor biomarkers and ensure better prognoses.

Clinical analysis of 12 cases of ovarian yolk sac tumor

Objective: To investigate the diagnosis, treatment and prognosis of ovarian yolk sac tumor (OYST). Methods: The clinicopathological data and follow-up data of 12 patients with OYST admitted to the Affiliated Hospital of Qingdao University from January 2013 to December 2020 were retrospectively analyzed, and the diagnosis, treatment and prognosis of OYST patients were summarized. Results: (1) The age of 12 patients with OYST ranged from 11 to 37 years, with a median age of 20 years. At the first visit, all 12 patients had pelvic masses. Reasons for seeing a doctor: 6 cases of abdominal distension and abdominal pain, 4 cases of mass in the lower abdomen, 1 case of vaginal bleeding, and 1 case of appendicitis. International Federation of Obstetrics and Gynecology (FIGO) 2014 staging: 4 cases in stage Ⅰa, 2 cases in stage Ⅰc, 1 case in stage Ⅱc, 4 cases in stage Ⅲc, and 1 case in stage Ⅳb. (2) All 12 patients were examined by color Doppler ultrasound before operation, among which 10 cases showed unilateral adnexal masses and 2 cases bilateral adnexal masses. The median maximum diameter of tumor was 16.5 cm (range: 6.0-28.0 cm). The preoperative levels of alpha fetoprotein (AFP) in 12 patients (all >1 210 μg/L) were significantly higher than normal (<25 μg/L). Among the 11 patients with cancer antigen 125 (CA125) detection results, 9 patients showed elevated serum CA125 levels. (3) Among the 12 patients, 8 young infertile patients who needed to preserve their reproductive function underwent appendectomy, 3 infertile patients underwent staged surgery for ovarian malignant germ cell tumor, and only one bilateral lesion and infertile patient underwent unsatisfactory staged surgery for ovarian malignant germ cell tumor. Of the 12 patients, 11 patients were given combined chemotherapy regimen of bleomycin, cisplatin, and etoposide (BEP) after operation. One patient without chemotherapy developed metastasis 3 months after operation, and was given BEP chemotherapy, and her condition was controlled. (4) The deadline for follow-up was December 31st, 2022, and the median follow-up time was 60 months (range: 25-115 months). All the 12 patients survived without tumor during the follow-up period, and the median disease-free survival time was 84.5 months (range: 25-115 months). Conclusions: OYST mostly occurs in children and young women. Color Doppler ultrasound examination and serum AFP and CA125 detection have diagnostic value for OYST. Surgical treatment after diagnosis of OYST includes surgery to preserve reproductive function and timely and standardized chemotherapy after operation. The prognosis of patients is good regardless of stage.

Research Progress of Optical Biosensing Technology for Alpha-fetoprotein Detection

Alpha-fetoprotein (AFP) is intimately associated with the incidence and progression of liver cancer and various tumors. AFP exhibits elevated concentrations in various tumors, making it a viable positive detection marker for these malignancies. Consequently, the development of precise, ultra-sensitive, and highly selective AFP detection methods is crucial for the early detection and effective monitoring of these life-threatening diseases. Optical biosensors rank among the most efficient detection techniques currently available. These biosensors possess features such as low cost, high sensitivity, real-time monitoring, and non-invasiveness, making them more suitable for AFP detection compared to other methods. This article reviews the role of this novel biosensor in the early detection of AFP, which holds significant implications for cancer diagnosis.

Epitope imprinted electrochemical sensor for highly sensitive detection of alpha-fetoprotein

A selective and sensitive epitope imprinted electrochemical sensor for the precise quantification of alpha-fetoprotein (AFP) was developed through electropolymerization by using the C-terminus of alpha-fetoprotein as the template and o-phenylenediamine as the functional monomer. The prepared epitope molecularly imprinted polymer film was characterized by the scanning electron microscope (SEM), cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). Experimental parameters including the molar ratio of template to functional monomer, electropolymerization cycle, elution time and rebinding time were systemically investigated and optimized. Under optimized conditions, the proposed epitope imprinted electrochemical sensor demonstrated outstanding sensing capabilities within the alpha-fetoprotein concentration range of 0.1 pg mL−1 to 1.0 μg mL−1, with a limit of detection of 0.075 pg mL−1. Furthermore, this electrochemical sensor exhibited exceptional selectivity when tested against other proteins or disease biomarkers, including human serum albumin, bovine serum albumin, prostate-specific antigen and carcinoembryonic antigen. In practical application, it was successfully employed for the analysis of alpha-fetoprotein in human serum samples, yielding a recovery rate ranging from 99.70 % to 108.48 %. This study proposed a straightforward approach for the construction of epitope molecularly imprinted electrochemical sensor tailored for the determination of alpha-fetoprotein.

Multi-omics combined test performance effectiveness on opportunistic screening of high-risk liver cancer population

Objective: To validate the performance of a multi-omics combined test for early screening of high-risk liver cancer populations. Methods: 173 high-risk patients with liver cancer were prospectively screened in a real-world setting, and 164 cases were finally enrolled. B-ultrasound, alpha-fetoprotein (AFP), and HCC screens were conducted in all patients. A multi-omics early screening test was performed for liver cancer in combination with multi-gene methylation, TP53/TERT/CTNNB1 mutations, AFP, and abnormal prothrombin (PIVKA-II). Differences in rates were compared using the chi-square test, adjusted chi-square test, or Fisher's exact probability method for count data. A non-parametric rank test (Mann-Whitney) was used to compare the differences between the two groups of data. Results: The HCCscreen detection had a sensitivity of 100% for liver cancer screening, 93.8% for liver cancer and precancerous diseases, 34.1% for positive predictive value, 99.2% for negative predictive value, and 0.89 for an area under the curve (AUC). Parallel detection of AFP, AFP+B-ultrasound, and methylation+mutation had a sensitivity/specificity and AUC of 31.3%/88.5% (AUC=0.78), 56.3%/88.2% (AUC=0.86), and 81.3%/82.4 % (AUC=0.84). At the same time, the disease severity range was significantly correlated with the methylation+mutation score, HCCscreen score, or positive detection rate (PDR). There was no significant correlation between AFP serum levels and methylation+mutation or HCCscreen scores, while there was a significant linear correlation between methylation+mutation scores and HCCscreen scores (r = 0.73, P < 0.001). Conclusion: In real-world settings, HCCscreen shows high sensitivity for screening opportunistic, high-risk liver cancer populations. Furthermore, it may efficaciously detect liver cancer and precancerous diseases, with superior performance to AFP and AFP+ultrasound. Hence, HCCscreen has the potential to become an effective screening tool that is superior to existing screening methods for high-risk liver cancer populations.

CdS quantum dots sensitized Ti-MOFs as high-performance photocathodic materials for immunoassay of alpha-fetoprotein based on Ag+ exchange strategy

Cathodic photoelectrochemical (PEC) analysis has drawn much attention because of its excellent anti-interference capability toward reductive substances in samples, but the development high-performance photocathodic materials is challenging. We report here CdS quantum dots (QDs) sensitized titanium-based metal–organic frameworks (Ti-MOFs) as high-performance photocathodic materials for ultrasensitive immunoassay of alpha-fetoprotein (AFP) based on Ag+ exchange strategy. Due to the excellent sensitization effect of CdS QDs, the photocathodic current of CdS QDs decorated MIL-125-NH2(Ti) is 25-fold that of MIL-125-NH2(Ti) alone. The photocathodic current of CdS/MIL-125-NH2(Ti) can be quenched after Ag+ exchange, because CdS is partially converted to Ag2S that serves as a charge-recombination center. Based on the PEC response of CdS/MIL-125-NH2(Ti) to Ag+, a cathodic PEC immunoassay platform is constructed for AFP detection by using CdS/MIL-125-NH2(Ti) as the photoactive material and Ag nanoparticles modified SiO2 nanospheres as labels. The linear range for AFP detection is from 1.0 × 10−4 to 1.0 × 102 ng mL−1, and the detection limit is 20 fg mL−1. The constructed PEC immunosensor is successfully used for detecting AFP in human serum samples. In this work, a novel and high-performance photoactive material is developed for cathodic PEC analysis, and a simple and effective PEC immunoassay platform for AFP detection is constructed based on Ag+ exchange strategy.

S-Tapered WaveFlex Biosensor Based on Multimode Fiber and Seven-Core Fiber Composite Structure for Detection of Alpha-Fetoprotein

S-Tapered WaveFlex Biosensor Based on Multimode Fiber and Seven-Core Fiber Composite Structure for Detection of Alpha-Fetoprotein

A novel microfluidic chip integrating with microcolumn array electrodes for rapid and ultrasensitive detection of alpha-fetoprotein

BackgroundCancer posed a serious threat to human health, and early diagnosis of cancer biomarker was extremely important for the treatment and control of cancer. Electrochemistry-based assays were low-cost, responsive and easy to operate, but there were some challenges in terms of accuracy, detection limit, efficiency and portability. The combination of microfluidic devices and electrochemical methods was expected to construct a high-performance sensing platform, but long-time antigen-antibody incubation was still required. Therefore, a novel microfluidic chip needs to be developed, which has the advantages of good portability, short incubation time, high accuracy, low detection limit and great application to point-of-care testing. ResultsA microfluidic sensor based on microcolumn array electrodes was developed, in which microcolumns could create local mixed flow to reduce the incubation time of target molecules and enhance their interaction with the sensing interface. Besides, three dimensional Mxene fibers-gold nanoparticles (3D MF-Au) was modified on the microcolumn array electrodes to increase active sites and provide more electrolyte shuttle holes. The electrolyte turbulence caused by the microcolumn array electrodes could heighten the contact between the target molecules and sensing interface and accelerate the transfer of redox pairs, thus reducing the incubation time of the target molecules and improving the electrochemical responses in synergy with the 3D MF-Au. Herein, the detection of AFP was chosen as a model, and the microfluidic sensor possessed superior performance for analysis of AFP in the range of 0.1 pg mL−1 - 200 ng mL−1 with a low detection limit (LOD) of 0.0648 pg mL−1. SignificanceThis microfluidic chip integrating with microcolumn array electrodes has been successfully implemented to detect AFP in human serum, and the results were consistent with that of electrochemical chemiluminescence method. The microfluidic chip provided a new strategy of portability, shortening incubation time and enhancing electrical signals for antigen detection of real samples, which showed great utilization potentiality in point-of-care testing.

An AgPd NP-based lateral flow immunoassay for simultaneous detection of glycocholic acid and alpha-fetoprotein.

Hepatocellular carcinoma (HCC) remains a leading cause of cancer-related mortality globally, ranking third in cancer deaths. Early diagnosis of HCC markers is imperative for effective prognosis and treatment. This study explores the utility of glycocholic acid (GCA) and alpha-fetoprotein (AFP) as biomarkers for liver diseases, with a specific focus on their simultaneous detection for enhanced diagnostic and prognostic capabilities. Harnessing the benefits of lateral flow immunoassay (LFIA), such as operational simplicity, speed, and accuracy, we engineered AgPd nanocomposites with antibodies targeting GCA and AFP. Under the optimized conditions, the visual detection limit for GCA was established at 50 ng mL-1 and the cut-off value at 104 ng mL-1. And for AFP, the visual detection limit was 0.1 ng mL-1 and the cut-off value was 500 ng mL-1. The accuracy and feasibility of the strips were validated through the detection of 39 actual serum samples. The results highlight the potential of LFIA as a rapid and effective tool for clinical diagnosis. The developed LFIA method not only demonstrates accuracy and feasibility but also presents a promising avenue for the early diagnosis of hepatocellular carcinoma.

Biomineralization–powered integrated immunoprobe and its application in Immunochromatographic assay

Immunochromatographic assay (ICA) has attracted widespread attention owing to its advantages of economy, simplicity, and rapidity. However, the synthesis of immunoprobes is still limited by complicated design ideas and multistep operations from preparing nanoparticles to conjugating monoclonal antibodies (mAb) onto nanoparticles. Inspired by the biomineralization of zeolitic imidazolate framework-8 (ZIF-8), we proposed a strategy for the rapid synthesis of an integrated immunoprobe (ZIF-8@QDs-mAb), achieving a one-step integration with strong fluorescent signal output capability and specific recognition ability. In addition, different fluorescent colors of ZIF-8@QDs-mAb were generated by doping red and green quantum dots (QDs) in various ratios. With a smart detection platform, the developed ZIF-8@QDs-mAb-based multiplex ICA (ZIF-8@QDs-mAb-mICA) achieved the on-site quantitative detection of enrofloxacin, sulfamethazine, and kanamycin in milk within 15 min, with the limit of detection (LOD) of 0.052, 0.186 and 0.216 ng mL−1, which were 5.69, 2.20 and 4.40 times higher than that of gold nanoparticles-based mICA, respectively. The quantitative detection of alpha-fetoprotein and human chorionic gonadotropin was also achieved with LOD of 0.516 ng mL−1 and 0.225 mIU mL−1, respectively, which verified the universality of the strategy. This work provides a novel idea for the design of an efficient integrated immunoprobe and has broad application prospects in ICA.

Aggregation-induced emission luminogen based ELISA for highly sensitive protein detection

Enzyme-linked immunosorbent assay (ELISA), as the most commonly used immunological detection technique, has been widely used in the clinical diagnosis of disease marker proteins. The key of the traditional ELISA is the probe, the horseradish peroxidase (HRP), which influences the sensitivity. However, the application of traditional ELISA in the biomedical field is limited due to low sensitivity. In this work, an aggregation-induced emission luminogen (AIEgen) was designed as a replacement of HRP in ELISA. It was synthesized by functionalizing a tetraphenylethylene (TPE) fluorogen with phosphorylated peptides (TPE-phenylalanine-phenylalanine-tyrosine(H2PO3)-OH, TPE-FFYp). The TPE-FFYp fluoresced weakly in an aqueous solution. Upon addition of the target protein, the phosphate group was hydrolyzed by alkaline phosphatase (ALP) on the immune complex while forming highly emissive AIE aggregates. Utilizing alpha-fetoprotein (AFP) as the model target, this proposed method has a detection limit as low as 0.78 ng/mL. Besides, the detection of AFP with TPE-FFYp was not only uninterrupted by other proteins, but also performed well in human serum. More importantly, it could be used to detect other targets by changing the corresponding antibodies, which further extended the application of AIEgen in bioassays.

A commentary on 'Prothrombin induced by vitamin K Absence-II versus alpha-fetoprotein in detection of both resectable hepatocellular carcinoma and early recurrence after curative liver resection: a retrospective cohort study' ( Int J Surg 2022;105:106843).

aDepartment of General Surgery, Nanjing Drum Tower Hospital, Chinese Academy of Medical Science and Peking Union Medical College, Graduate School of Peking Union Medical College bSchool of Medicine and Holistic Integrative Medicine, Nanjing University of Chinese Medicine cDepartment of Hepatobiliary Surgery, The Affiliated Drum Tower Hospital of Nanjing University Medical School, Nanjing, China Sponsorships or competing interests that may be relevant to content are disclosed at the end of this article. Published online ■ ■ *Corresponding author. Address: Department of Hepatobiliary Surgery, The Affiliated Drum Tower Hospital of Nanjing University Medical School, No. 321, Zhongshan Road, Nanjing 210008, China. Tel: 86-13357851195; fax: 86-25-86560946. E-mail address: [email protected] (X. Xu). This is an open access article distributed under the terms of the Creative Commons Attribution-Non Commercial-No Derivatives License 4.0 (CCBY-NC-ND), where it is permissible to download and share the work provided it is properly cited. The work cannot be changed in any way or used commercially without permission from the journal. http://creativecommons.org/licenses/by-nc-nd/4.0/

ZnO/Au/GaN heterojunction-based self-powered photoelectrochemical Sensor for alpha-fetoprotein detection

In recent years, the development of miniature and portable sensors has been a major focus of research. PEC self-powered sensors have emerged as a potential solution to the power supply issue, eliminating the need for external power supplies and operating without bias voltage. This study developed a ZnO/Au/GaN sensor for highly sensitive detection of alpha-fetoprotein (AFP). The sensor uses GaN substrates with nanogold films to provide an auxiliary bias voltage, promoting high photogenerated current density. Using ZnO/Au/GaN as a photoanode resulted in significantly higher photocurrent generated by the sensor compared to Au/GaN or ZnO/ITO alone. To enable selective detection of AFP, antibody modification of the ZnO nanorod arrays was employed. The linear range of the sensor response to AFP was determined to be 0.080–5.0 ng/mL, with an impressively low detection limit of 0.027 ng/mL (S/N = 3). These results demonstrate the potential of this self-powered sensor for detecting AFP content in human serum samples. Overall, this study presents a novel approach for developing highly sensitive and selective self-powered sensors for biomarker detection, which could facilitate early detection and clinical diagnosis of various types of cancer.

A novel microfluidics PMMA/paper hybrid bioimmunosensor for laser-induced fluorescence detection in the determination of alpha-fetoprotein from serum

Low loss and high capture efficiency of target samples are prerequisites for sensitive detection by fluorescence immunosensors. For quantitative and ultrasensitive detection of alpha-fetoprotein (AFP), we designed a novel microfluidics pump-free PMMA/paper hybrid immunosensor. Here, the 2D planar structure of the detection area of the plastic microfluidic chip is improved to a 3D spatial structure, which increases the number of capture antibodies immobilized and the cross-section area of the “intercept” target protein. PMMA channels efficiently transport target proteins. The paper-based, three-dimensional detection area not only increases the amount of immobilization of the captured antibody but also improves the contact probability between the captured antibody and the target protein. This greatly improves the efficiency of immune binding. A laser-induced fluorescence detector is applied to detect the target protein on the paper-based detecting unit. Under optimal conditions, the immunosensor ensures that the reaction time is 12 min and the residual liquid is only 6.1% of the original volume, achieving ultra-sensitive detection of AFP in the range of 0.01 ng/mL to 100 ng/mL with a limit of quantitation (LOQ) as low as 4.5 pg/mL. The recoveries for AFP ranged from 96.6% to 101.5%, which means the hybrid microfluidics chip is reliable and has great potential for early screening.

Rapid and Label-Free Analysis of Antigen-Antibody Dynamic Binding of Tumor Markers Using Piezoelectric Quartz Crystal Biosensor.

Quantitative biomacromolecular diagnosis is rapidly developing in molecular oncology. In this study, we developed a continuous flow immunoassay device based on a piezoelectric (PZ) quartz crystal biosensor fabricated with whole-electrode occupation for the quantitative molecular diagnosis of tumor markers such as alpha-fetoprotein (AFP). Only one face of the crystal was in contact with the serum sample during the assays. First, the characteristics of AFP and anti-AFP binding kinetics, such as the optimal time for immune response, the average antigen binding rate, the kinetic constants and the optimal standard curve, were investigated. The overall immunoreaction time was only 12 min, the average antigen binding rate of AFP was 45.9 ng/min, the concentration range of AFP detection was 18.8-1100 ng/mL and the association rate constant (kon), dissociation rate constant (koff) and equilibrium dissociation constant (KD) were 5.58×104 M-1s-1,1.79×10-5 s-1 and 3.21×10-10 M, respectively. This sensing system was further validated by detecting AFP values from clinical serum samples, which were obtained from pregnant women, liver and lung cancer patients and those undergoing liver cancer screening. No cross-reactivity with lung cancer markers were found, and the detection results were in good agreement with the radioimmunoassay (RIA) results, with a relative deviation of no more than 3.7% and correlation coefficient r of 0.9998. Therefore, the developed immunoassay device has the potential to be used in large-scale screening for cancers, as well as in novel high-affinity binding drug development.