Multiplex Immunochips for High-Accuracy Detection of AFP-L3% Based on Surface-Enhanced Raman Scattering: Implications for Early Liver Cancer Diagnosis

Dual-reporter fluorescent probe for precise identification of liver cancer by sequentially responding to carboxylesterase and polarity

Early treatment significantly improves the survival rate of liver cancer patients, so the development of early diagnostic methods for liver cancer is urgent. Liver cancer can develop from viral hepatitis, alcoholic liver, and fatty liver, thus making the above diseases share common features such as elevated viscosity, reactive oxygen species, and reactive nitrogen species. Therefore, accurate differentiation between other liver diseases and liver cancer is both a paramount practical need and challenging. Numerous fluorescent probes have been reported for the diagnosis of liver cancer by detecting a single biomarker, but these probes lack specificity for liver cancer in complex biological systems. Obviously, using multiple liver cancer biomarkers as the basis for judgment can dramatically improve diagnostic accuracy. Herein, we report the first fluorescent probe, LD-TCE, that sequentially detects carboxylesterase (CE) and lipid droplet polarity in liver cancer cells with high sensitivity and selectivity, with linear detection of CE in the range of 0-6 U/mL and a 65-fold fluorescence enhancement in response to polarity. The probe first reacts with CE and releases weak fluorescence, which is then dramatically enhanced due to the decrease in lipid droplet polarity in liver cancer cells. This approach allows the probe to enable specific imaging of liver cancer with higher contrast and accuracy. The probe successfully achieved the screening of liver cancer cells and the precise identification of liver cancer in mice. More importantly, it is not disturbed by liver fibrosis, which is a common pathological feature of many liver diseases. We believe that the LD-TCE is expected to be a powerful tool for early diagnosis of liver cancer.

Ultrasensitive Detection of Cancer Biomarkers Using Photonic-Crystal-Enhanced Single-Molecule Imaging

The rapid and sensitive quantification of low-abundance protein markers holds immense significance in early disease diagnosis and treatment. Single-molecule fluorescence imaging exhibits very high detection sensitivity and thus has great application potential in this area. The single-molecule signal, however, is often susceptible to interference from background noise due to its inherently weak intensity. A variety of signal amplification techniques based on cascading reactions have been developed to improve the signal-to-noise ratio of single-molecule imaging. Nevertheless, the operation of these methods is typically complicated and time-consuming, which limits the clinical application. Herein, we introduce an enzyme-free, photonic-crystal-based single-molecule (PC-SM) biochip for cost-effective, time-efficient, and ultrasensitive detection of disease markers. The PC-SM biochip can enhance the signal-to-noise ratio of single molecules by nearly 3-fold compared with unamplified samples, through coupling of the single-molecule photon energy with the optical band gap of the photonic crystal. We used the PC-SM biochip to detect the low-abundance leukemia inhibitory factor in the blood of pancreatic cancer patients and healthy people and achieved a detection limit of 2.0 pg/L and an AUC of 0.9067. The method exhibits exceptional sensitivity and specificity, showing great application potential in various clinical settings.

Surface-Enhanced Raman Spectroscopy: Current Understanding, Challenges, and Opportunities

While surface-enhanced Raman spectroscopy (SERS) has experienced substantial advancements since its discovery in the 1970s, it is an opportunity to celebrate achievements, consider ongoing endeavors, and anticipate the future trajectory of SERS. In this perspective, we encapsulate the latest breakthroughs in comprehending the electromagnetic enhancement mechanisms of SERS, and revisit CT mechanisms of semiconductors. We then summarize the strategies to improve sensitivity, selectivity, and reliability. After addressing experimental advancements, we comprehensively survey the progress on spectrum-structure correlation of SERS showcasing their important role in promoting SERS development. Finally, we anticipate forthcoming directions and opportunities, especially in deepening our insights into chemical or biological processes and establishing a clear spectrum-structure correlation.

Two Birds with one Stone: Dual-mode immunoassay constructed using a novel emitter ethylene glycol-induced perylene diimide and a multifunctional ANS probe

Perylene diimide (PDI) is a readily reducible electron-deficient dye that exhibits strong photoluminescent properties, providing new opportunities for synthesizing novel electrochemiluminescence (ECL) emitters. In this study, ethylene glycol (EG) was used to induce the self-assembly of PDI supramolecules for the preparation of ultrathin EG-PDI nanosheets characterized by low crystallinity and weak stacking interaction. Notably, EG-PDI integrates luminescent and catalytic functions into one device, accelerating the interfacial electron transfer and the faster charge transfer kinetics of EG-PDI with K2S2O8. Furthermore, the narrow band gap of EG-PDI facilitates its excitation at an ultra-low potential (-0.3 V). To improve the efficiency of tumor marker analysis, multifunctional Au nanostars (ANS) was introduced both as an energy acceptor of the ECL system and a probe for the photothermal system. Dual-mode immunoassay have demonstrated superior analytical performance in detecting alpha-fetoprotein (AFP), meeting the requirements of modern clinical diagnostics in resource-limited environments.

Alpha-fetoprotein: Past, present, and future

Alpha-fetoprotein (AFP) is a glycoprotein that plays an important role in immune regulation with critical involvement in early human development and maintaining the immune balance during pregnancy. Postfetal development, the regulatory mechanisms controlling AFP undergo a shift and AFP gene transcription is suppressed. Instead, these enhancers refocus their activity to maintain albumin gene transcription throughout adulthood. During the postnatal period, AFP expression can increase in the setting of hepatocyte injury, regeneration, and malignant transformation. It is the first oncoprotein discovered and is routinely used as part of a screening strategy for HCC. AFP has been shown to be a powerful prognostic biomarker, and multiple HCC prognosis models confirmed the independent prognostic utility of AFP. AFP is also a useful predictive biomarker for monitoring the treatment response of HCC. In addition to its role as a biomarker, AFP plays important roles in immune modulation to promote tumorigenesis and thus has been investigated as a therapeutic target in HCC. In this review article, we aim to provide an overview of AFP, encompassing the discovery, biological role, and utility as an HCC biomarker in combination with other biomarkers and how it impacts clinical practice and future direction.

Frequency shift Raman-based sensing of serum MicroRNA for ultrasensitive cervical cancer diagnosis

Cervical cancer is the most common gynaecological tumor. The development of a sensor for the ultrasensitive detection of cervical cancer is significant in guaranteeing its prognosis. Herein, we proposed a novel surface-enhanced Raman scattering (SERS) analysis platform using a frequency shifts-based sensing model for rapid and ultrasensitive microRNA (miRNA) assay. During the analysis process, miR-21 can be captured by the single-stranded DNA (ssDNA) modified on the platform which is complementary pairing with miR-21. The connection of miR-21 can lead to the variation of the molecular weight and result in the deformation extent of the Raman report molecule 6Thioguanine (6TG); thus, the peak at 1301 cm-1 due to the ring C-N stretches of 6TG shifts to lower frequency. The detection limit (LOD) of the proposed SERS analysis platform is as low as 8.32 aM. Moreover, the platform also has excellent specificity and repeatability, with the relative standard deviation (RSD) value of 6.53 %. Serum samples of cervical cancer patients and healthy subjects were analyzed via the platform and the accuracy of the detection results was verified by qRT-PCR, revealing that SERS results and qRT-PCR results have high homogeneity. Thus, the platform can serve as a potential tool for clinical diagnosis of cervical cancer.

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

BACKGROUND

Cancer 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.

RESULTS

A 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.

SIGNIFICANCE

This 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.

Application of microfluidic technology based on surface-enhanced Raman scattering in cancer biomarker detection: A review

With the continuous discovery and research of predictive cancer-related biomarkers, liquid biopsy shows great potential in cancer diagnosis. Surface-enhanced Raman scattering (SERS) and microfluidic technology have received much attention among the various cancer biomarker detection methods. The former has ultrahigh detection sensitivity and can provide a unique fingerprint. In contrast, the latter has the characteristics of miniaturization and integration, which can realize accurate control of the detection samples and high-throughput detection through design. Both have the potential for point-of-care testing (POCT), and their combination (lab-on-a-chip SERS (LoC-SERS)) shows good compatibility. In this paper, the basic situation of circulating proteins, circulating tumor cells, exosomes, circulating tumor DNA (ctDNA), and microRNA (miRNA) in the diagnosis of various cancers is reviewed, and the detection research of these biomarkers by the LoC-SERS platform in recent years is described in detail. At the same time, the challenges and future development of the platform are discussed at the end of the review. Summarizing the current technology is expected to provide a reference for scholars engaged in related work and interested in this field.

Intramolecular fluorescence resonance energy transfer strategy for accurate detection of AFP-L3% and improved diagnosis of hepatocellular carcinoma

Early and accurate diagnosis of hepatocellular carcinoma (HCC) is of significant importance for improving the survival rate and quality of life for HCC patients. The combined detection of alpha-fetoprotein (AFP) and alpha-fetoprotein-L3 (AFP-L3), namely AFP-L3%, can greatly improve the accuracy of HCC diagnosis compared with AFP detection. Herein, we developed a novel intramolecular fluorescence resonance energy transfer (FRET) strategy for sequential detection of AFP and AFP-specific core fucose to improve the diagnosis accuracy of HCC. Firstly, fluorescence-labeled AFP aptamer (AFP Apt-FAM) was used to specifically recognize all AFP isoforms, and total AFP was quantitatively determined using fluorescence intensity of FAM. Then, 4-((4-(dimethylamino)phenyl)azo)benzoic acid (Dabcyl) labeled lectins (PhoSL-Dabcyl) were used to specifically recognize the core fucose expressed on AFP-L3 that does not bind to other AFP isoforms. The combination of FAM and Dabcyl on the same AFP molecule could generate FRET effect, thereby quenching the fluorescence signal of FAM and quantitatively determining AFP-L3. After that, AFP-L3% was calculated according to the ratio of AFP-L3 to AFP. With this strategy, the concentration of total AFP, AFP-L3 isoform as well as the AFP-L3% were sensitively detected. Detection limits of 0.66 and 0.186 ng/mL were obtained for AFP and AFP-L3 in human serum, respectively. Clinical human serum test results showed that AFP- L3 % test was more accurate than AFP assay to distinguish healthy people, HCC patients and benign liver disease patients. Therefore, the proposed strategy is simple, sensitive and selective, which can improve the accuracy of early diagnosis of HCC, and has good clinical application potential.

Flexible SERS Biosensor Based on Core-Shell Nanotags for Sensitive and Multiple Detection of T1DM Biomarkers

Sensitive and multiple detection of the biomarkers of type 1 diabetes mellitus (T1DM) is vital to the early diagnosis and clinical treatment of T1DM. Herein, we developed a SERS-based biosensor using polyvinylidene fluoride (PVDF) membranes as a flexible support for the detection of glutamic acid decarboxylase antibodies (GADA) and insulin autoantibodies (IAA). Two kinds of silver-gold core-shell nanotags embedded with Raman probes and attached with GADA or IAA antibodies were synthesized to capture the targets, enabling highly sensitive and highly selective detection of GADA and IAA. The embedded Raman probes sandwiched between silver and gold layers guaranteed spectral stability and reliability. Moreover, the utilization of two Raman probes enables simultaneous and multiplexing detection of both GADA and IAA, improving the detection accuracy for T1DM. The proposed SERS-based method has been proven feasible for clinical sample detection, demonstrating its great potential in sensitive, reliable, and rapid diagnosis of T1DM.

Nanozyme-Catalyzed Metasurface Plasmon Sensor-Based Portable Ultrasensitive Optical Quantification Platform for Cancer Biomarker Screening

Developing plasmonic biosensors that are low-cost, portable, and relatively simple to operate remains challenging. Herein, a novel metasurface plasmon-etch immunosensor is described, namely a nanozyme-linked immunosorbent surface plasmon resonance biosensor, for the ultrasensitive and specific detection of cancer biomarkers. Gold-silver composite nano cup array metasurface plasmon resonance chip and artificial nanozyme-labeled antibody are used in two-way sandwich analyte detection. Changes in the biosensor's absorption spectrum are measured before and after chip surface etching, which can be applied to immunoassays without requiring separation or amplification. The device achieved a limit of alpha-fetoprotein (AFP) detection < 21.74 fM, three orders of magnitude lower than that of commercial enzyme-linked immunosorbent assay kits. Additionally, carcinoembryonic antigen (CEA) and carbohydrate antigen 125 (CA125) are used for quantitative detection to verify the universality of the platform. More importantly, the accuracy of the platform is verified using 60 clinical samples; compared with the hospital results, the three biomarkers achieve high sensitivity (CEA: 95.7%; CA125: 90.9%; AFP: 86.7%) and specificity (CEA: 97.3%; CA125: 93.9%; AFP: 97.8%). Due to its rapidity, ease of use, and high throughput, the platform has the potential for high-throughput rapid detection to facilitate cancer screening or early diagnostic testing in biosensing.

SERS immuno- and apta-assays in biosensing/bio-detection: Performance comparison, clinical applications, challenges

Surface Enhanced Raman Spectroscopy is increasingly used as a sensitive bioanalytical tool for detection of variety of analytes ranging from viruses and bacteria to cancer biomarkers and toxins, etc. This comprehensive review describes principles of operation and compares the performance of immunoassays and aptamer assays with Surface Enhanced Raman scattering (SERS) detection to each other and to some other bioassay methods, including ELISA and fluorescence assays. Both immuno- and aptamer-based assays are categorized into assay on solid substrates, assays with magnetic nanoparticles and assays in laminar flow or/and strip assays. The best performing and recent examples of assays in each category are described in the text and illustrated in the figures. The average performance, particularly, limit of detection (LOD) for each of those methods reflected in 9 tables of the manuscript and average LODs are calculated and compared. We found out that, on average, there is some advantage in terms of LOD for SERS immunoassays (0.5 pM median LOD of 88 papers) vs SERS aptamer-based assays (1.7 pM median LOD of 51 papers). We also tabulated and analyzed the clinical performance of SERS immune and aptamer assays, where selectivity, specificity, and accuracy are reported, we summarized the best examples. We also reviewed challenges to SERS bioassay performance and real-life application, including non-specific protein binding, nanoparticle aggregation, limited nanotag stability, sometimes, relatively long time to results, etc. The proposed solutions to those challenges are also discussed in the review. Overall, this review may be interesting not only to bioanalytical chemist, but to medical and life science researchers who are interested in improvement of bioanalyte detection and diagnostics.

Vertically-Ordered Mesoporous Silica Film Based Electrochemical Aptasensor for Highly Sensitive Detection of Alpha-Fetoprotein in Human Serum

Convenient and rapid detection of alpha fetoprotein (AFP) is vital for early diagnosis of hepatocellular carcinoma. In this work, low-cost (0.22 USD for single sensor) and stable (during 6 days) electrochemical aptasensor was developed for highly sensitive and direct detection of AFP in human serum with the assist of vertically-ordered mesoporous silica films (VMSF). VMSF has silanol groups on the surface and regularly ordered nanopores, which could provide binding sites for further functionalization of recognition aptamer and also confer the sensor with excellent anti-biofouling capacity. The sensing mechanism relies on the target AFP-controlled diffusion of Fe(CN)₆^3-/4- redox electrochemical probe through the nanochannels of VMSF. The resulting reduced electrochemical responses are related to the AFP concentration, allowing the linear determination of AFP with a wide dynamic linear range and a low limit of detection. Accuracy and potential of the developed aptasensor were also demonstrated in human serum by standard addition method.

Precision diagnosis of hepatocellular carcinoma

ABSTRACT

Hepatocellular carcinoma (HCC) is the most common type of primary hepatocellular carcinoma (PHC). Early diagnosis of HCC remains the key to improve the prognosis. In recent years, with the promotion of the concept of precision medicine and more in-depth analysis of the biological mechanism underlying HCC, new diagnostic methods, including emerging serum markers, liquid biopsies, molecular diagnosis, and advances in imaging (novel contrast agents and radiomics), have emerged one after another. Herein, we reviewed and analyzed scientific advances in the early diagnosis of HCC and discussed their application and shortcomings. This review aimed to provide a reference for scientific research and clinical practice of HCC.

SERS Immunosensors for Cancer Markers Detection

Early diagnosis and monitoring are essential for the effective treatment and survival of patients with different types of malignancy. To this end, the accurate and sensitive determination of substances in human biological fluids related to cancer diagnosis and/or prognosis, i.e., cancer biomarkers, is of ultimate importance. Advancements in the field of immunodetection and nanomaterials have enabled the application of new transduction approaches for the sensitive detection of single or multiple cancer biomarkers in biological fluids. Immunosensors based on surface-enhanced Raman spectroscopy (SERS) are examples where the special properties of nanostructured materials and immunoreagents are combined to develop analytical tools that hold promise for point-of-care applications. In this frame, the subject of this review article is to present the advancements made so far regarding the immunochemical determination of cancer biomarkers by SERS. Thus, after a short introduction about the principles of both immunoassays and SERS, an extended presentation of up-to-date works regarding both single and multi-analyte determination of cancer biomarkers is presented. Finally, future perspectives on the field of SERS immunosensors for cancer markers detection are briefly discussed.

SERS-based biosensor for detection of f-PSA%: Implications for the diagnosis of prostate cancer

In diagnosing prostate cancer and distinguishing it from other prostate diseases, the ratio of the concentration of free prostate-specific antigen (f-PSA) to total prostate-specific antigen (t-PSA), i.e., (f-PSA%) is more accurate than the concentration of t-PSA alone. Immunoassay based on surface-enhanced Raman scattering (SERS) frequency shift has been proven to be particularly suitable for detecting large biomolecules with high reproducibility. Along similar lines, the present study developed a SERS-based biosensor that simultaneously detects t-PSA and f-PSA. The 4-mercaptobenzoic acid (MBA) on the immunocapture substrate is coupled to the t-PSA antibody through the carboxyl group, and the combination of t-PSA induces the Raman frequency shifts of MBA. The immunocolloidal gold attached with f-PSA antibodies selectively capture the f-PSA that immobilized on the MBA-modified SERS substrates, allowing for f-PSA quantification according to the SERS intensities of the 5, 5'-Dithiobis (succinimidyl-2-nitrobenzoate) (DSNB) probe. The results show that f-PSA and t-PSA have good linear response in the concentration scale of 0.1-20 ng/mL, and 1-200 ng/mL, respectively. The biosensor combines Raman frequency shifts and intensities, which greatly simplifies traditional procedures for f-PSA% detection. All the results demonstrated the great potential of the proposed biosensor in highly reproducible and accurate diagnosis of prostate cancers.

Construction of a competitive electrochemical immunosensor based on sacrifice of Prussian blue and its ultrasensitive detection of alpha-fetoprotein

Effective signal amplification is a prerequisite for ultrasensitive detection by electrochemical immunosensors. For quantitative and ultrasensitive detection of alpha-fetoprotein (AFP), we designed a competitive electrochemical immunosensor and transferred the immunoreactivity from the electrode surface to the cuvette. AFP antigen was captured using AFP primary antibody (Ab₁) immobilized on magnetic nanobeads (MBs), and ZIF-8 nanomaterials attached to secondary antibody (Ab₂) were used as probes. MBs helped retain the sandwich structure in the test tube through incubation and washing steps. Then, an appropriately fixed excess of sodium ethylenediaminetetraacetic acid (EDTA) solution was added to the cuvettes, resulting in etching of Zn ions from ZIF-8 and formation of Zn-EDTA complexes. After magnetic separation, a certain amount of supernatant is added dropwise to the Prussian blue (PB)-modified electrode (GCE), and Fe ions (from PB) complex with the remaining EDTA in the supernatant, thus reducing the signal response value of PB. The higher the AFP concentration, the lower the amount of free EDTA in the supernatant, the less the destruction of PB, and therefore the higher the current. Under optimal conditions, the immunosensor achieved ultra-sensitive detection of AFP in the range of 10^-4 ng/mL-100 ng/mL with a limit of detection (LOD) as low as 0.032 pg/mL (S/N = 3). The excellent performance provides an important tool for the early screening and detection of AFP.

Screening of hepatocellular carcinoma via machine learning based on atmospheric pressure glow discharge mass spectrometry

Hepatocellular carcinoma (HCC) is one of the most common malignant tumors with a high mortality rate. The diagnosis of HCC is currently based on alpha-fetoprotein detection, imaging examinations, and liver biopsy, which are expensive or invasive. Here, we developed a cost-effective, time-saving, and painless method for the screening of HCC via machine learning based on atmospheric pressure glow discharge mass spectrometry (APGD-MS). Ninety urine samples from HCC patients and healthy control (HC) participants were analyzed. The relative quantification data were utilized to train machine learning models. Neural network was chosen as the best classifier with a classification accuracy of 94%. Besides, the levels of eleven urinary carbonyl metabolites were found to be significantly different between HCC and HC, including glycolic acid, pyroglutamic acid, acetic acid, etc. The possible reasons for the regulation were tentatively proposed. This method realizes the screening of HCC via potential urine metabolic biomarkers based on APGD-MS, bringing a hopeful point-of-care diagnosis of HCC in a patient-friendly manner.

Dual-mode electrochemiluminescence and electrochemical sensor for alpha-fetoprotein detection in human serum based on vertically ordered mesoporous silica films

In this study, we demonstrated the highly sensitive detection of alpha-fetoprotein (AFP) by electrochemiluminescence (ECL) and electrochemistry (EC) based on the gated transport of the bifunctional probe (tris(1,10-phenanthroline) ruthenium (II) chloride, Ru (phen)₃Cl₂) into the nanochannels of vertically ordered mesoporous silica films (VMSFs). Due to the negatively charged surface and ultrasmall pore size, VMSF displays a signal amplification effect on Ru (phen)₃Cl₂ and is suitable for the construction of sensors with excellent sensitivity. With the linkage of (3-glycidyloxypropyl) trimethoxysilane, the anti-AFP antibody could covalently bind to the external surface of VMSF, generating a highly specific recognized sensing interface toward AFP. When AFP is presented, the formed immunocomplex hinders the diffusion of Ru (phen)₃Cl₂ to the underlying electrode surface, resulting in a decreased ECL or EC response. The dual-mode detection of AFP is achieved with a relatively low limit of detection (0.56 fg/ml for ECL and 4.5 pg/ml for EC) and a wide linear range (10 fg/ml∼1 μg/ml for ECL and 10 pg/ml∼1 μg/ml for EC). Moreover, owing to the inherent anti-fouling property of VMSF, satisfactory results in the analysis of human serum were obtained, showing the great potential of the designed strategy in clinical diagnosis.

Electrochemically Controlled Atom Transfer Radical Polymerization for Electrochemical Aptasensing of Tumor Biomarkers

Tumor biomarkers are of great value in the liquid biopsy of malignant tumors. In this work, a simple and cost-friendly electrochemical aptasensor was presented for the highly sensitive and selective detection of glycoprotein tumor biomarkers. The DNA aptamer-modified electrode was used as the sensing interface to specifically capture the target glycoprotein tumor biomarkers, to which the alkyl halide initiators for atom transfer radical polymerization (ATRP) were then attached via the esterification crosslinking between the boronic acid group and the cis-dihydroxyl sites of the conjugated oligosaccharide chains on glycoprotein tumor biomarkers followed by the growth of long-chain polymers through electrochemically controlled ATRP (eATRP) to efficiently recruit the ferrocene detection tags. As there are tens to hundreds of cis-dihydroxyl sites on a glycoprotein tumor biomarker for attaching ATRP initiators while each long-chain polymer can recruit hundreds to thousands of ferrocene detection tags, a significantly high current signal can be generated even in the presence of ultralow-abundance targets. Hence, the eATRP-based electrochemical aptasensor is capable of sensitively and selectively detecting glycoprotein tumor biomarkers. Using alpha-fetoprotein as the model target, the limit of detection was demonstrated to be 0.32 pg/mL. Moreover, the aptasensor has been successfully applied to detect glycoprotein tumor biomarkers in human serum samples. In view of its high sensitivity and selectivity, simple operation, and cost-friendliness, the eATRP-based electrochemical aptasensor shows great promise in the glycoprotein-based liquid biopsy of malignant tumors, even at the early stage of development.

A Glycoform-Resolved Dual-Modal Ratiometric Immunoassay Improves the Diagnostic Precision for Hepatocellular Carcinoma

The glycosylation pattern of alpha fetoprotein (AFP) paves the basis for precise early diagnosis of hepatocellular carcinoma (HCC). However, existing analytical methods ignore the contribution of terminal sialic acid, which has been reported to be highly connected with HCC. Besides, the development of diagnostic assays is severely hindered by the preparation of anti-glycans antibodies. Molecularly imprinted polymers (MIPs), as synthetic antibody mimics, provide unique strengths to address these issues. Herein, we report a MIPs-based dual-modal ratiometric immunoassay for precise HCC diagnosis. Using a "pit one against ten" MIP to recognize a subset of glycans containing sialic acid and/or core fucose, we demonstrated our assay exhibited improved precision as compared with ELISA. This assay provided not only a glycoform-resolved method for precise HCC diagnosis, but also a new paradigm for developing antibody mimics via molecular imprinting towards challenging biomedical applications.

Recent Advances in Sandwich SERS Immunosensors for Cancer Detection

Cancer has been one of the most prevalent diseases around the world for many years. Its biomarkers are biological molecules found in the blood or other body fluids of people with cancer diseases. These biomarkers play a crucial role not only in the diagnosis of cancer diseases, but also in risk assessment, selection of treatment methods, and tracking its progress. Therefore, highly sensitive and selective detection and determination of cancer biomarkers are essential from the perspective of oncological diagnostics and planning the treatment process. Immunosensors are special types of biosensors that are based on the recognition of an analyte (antigen) by an antibody. Sandwich immunosensors apply two antibodies: a capture antibody and a detection antibody, with the antigen ‘sandwiched’ between them. Immunosensors’ advantages include not only high sensitivity and selectivity, but also flexible application and reusability. Surface-enhanced Raman spectroscopy, known also as the sensitive and selective method, uses the enhancement of light scattering by analyte molecules adsorbed on a nanostructured surface. The combination of immunosensors with the SERS technique further improves their analytical parameters. In this article, we followed the recent achievements in the field of sandwich SERS immunosensors for cancer biomarker detection and/or determination.

Surface-enhanced Raman scattering from an electromagnetic induced transparency substrate for the determination of hepatocellular carcinoma

Surface-enhanced Raman scattering (SERS) is a powerful analytical method that is especially suitable for the detection of protein molecules. Detection sensitivity of SERS is directly related to the enhancement factor of the substrate, which is dependent on the strength of a local surface electric field generated by surface plasmonic resonance from substrate. In this study, an electromagnetic induced transparency like (EIT-like) metamaterial was used as the SERS substrate. The corresponding plasmonic resonance structure not only produces stronger optical near field but also reduces the spectral line broadening due to radiation damping. This is very beneficial for SERS process, which is strongly dependent on electric field intensity, to improve the sensitivity of SERS detection. Compared with the single resonance mode substrate, the enhancement factor for SERS with the double-mode substrate was increased by an order of magnitude. The obtained EIT-like substrate was used as a SERS-active substrate to detect Lens culinaris agglutinin (LCA)-reactive fraction of AFP (AFP-L3), a hepatocellular carcinoma (HCC)-specific maker. Experimental results are in good agreement with the clinical diagnosis, which demonstrates the potential application of metamaterials in the SERS-based diagnosis and biosensing.

Gold nanoparticle-based optical nanosensors for food and health safety monitoring: recent advances and future perspectives

Modern society has been facing serious health-related problems including food safety, diseases and illness. Hence, it is urgent to develop analysis methods for the detection and control of food contaminants, disease biomarkers and pathogens. As the traditional instrumental methods have several disadvantages, including being time consuming, and having high cost and laborious procedures, optical nanosensors have emerged as promising alternative or complementary approaches to those traditional ones. With the advantages of simple preparation, high surface-to-volume ratio, excellent biocompatibility, and especially, unique optical properties, gold nanoparticles (AuNPs) have been demonstrated as excellent transducers for optical sensing systems. Herein, we provide an overview of the synthesis of AuNPs and their excellent optical properties that are ideal for the development of optical nanosensors based on local surface plasmon resonance (LSPR), colorimetry, fluorescence resonance energy transfer (FRET), and surface-enhanced Raman scattering (SERS) phenomena. We also review the sensing strategies and their mechanisms, as well as summarizing the recent advances in the monitoring of food contaminants, disease biomarkers and pathogens using developed AuNP-based optical nanosensors in the past seven years (2015-now). Furthermore, trends and challenges in the application of these nanosensors in the determination of those analytes are discussed to suggest possible directions for future developments.

Expression of CD28 in Hepatocellular Carcinoma and Its Prognostic Value

Background: CD28 expression is correlated with malignancy development in long-term survivors after liver transplantation. Immune cell activation is mediated by the interaction of CD28 with CD4 and CD8. Objectives: In this study, we attempted to investigate the expression level and prognostic value of CD28 in hepatocellular carcinoma (HCC). Methods: A total of 54 HCC patients with complete clinical information were examined. The expression level of CD28 in HCC tissues was detected by immunohistochemistry. The correlations of CD28 expression with clinical characteristics, CD4+/CD8+ T-cells, and prognosis in HCC were analyzed. The expression profile of CD28 and survival time of HCC patients were retrieved from the TCGA database, followed by survival analysis. Results: The positive expression rate of CD28 in HCC tissues was 70.73%. The CD28 expression was significantly higher in the positive expression group (area: 659174.9 ± 670060, IOD: 123348.3 ± 106348.6) than in the negative expression group (area: 8405.7 ± 9983.3, IOD: 1959.6 ± 2117.7) (P < 0.01). The CD4+ and CD8+ cell counts were 526.13 ± 258.17 cells/µL and 383.93 ± 223.39 cells/µL, respectively. The expression level of CD28 was significantly related to the degree of differentiation and the number of CD4+ and CD8+ T-cells (P < 0.05). The survival time of patients was longer in the positive CD28 expression group than in the negative expression group. Based on the CD28 expression profiles of 406 HCC patients retrieved from the TCGA database, patients with high CD28 expression showed a better prognosis than those with low expression (P < 0.05). Conclusions: CD28 may play a vital role in the occurrence, development, and prognosis of HCC by interacting with CD4+ and CD8+ T-cells. Thus, CD28 could be suggested as the immune checkpoint target for HCC treatment.

AFP-L3 for the diagnosis of early hepatocellular carcinoma: A meta-analysis

BACKGROUND

The present study aimed to systematically evaluate the diagnostic value of an isoform of alpha-fetoprotein (AFP), AFP-L3, for early hepatocellular carcinoma (HCC) by a meta-analysis.

METHODS

Diagnostic reports of AFP-L3% in early HCC were searched in the PubMed, Web of Science, Cochrane Library, and Embase databases up to December 2019. The retrieved literature was reviewed, and eligible articles were selected. Data were extracted from the eligible articles, and the risk of bias was evaluated according to the Quality Assessment of Diagnostic Accuracy Studies scale. Statistical analyses were conducted by MetaDiSc1.4 and RevMan5.3 software. The sensitivities, specificities, and diagnostic odds ratios were pooled. The summary receiver operating characteristic curve was drawn, and the area under the curve was calculated.

RESULTS

Six studies with acceptable quality were included in the meta-analysis involving 2447 patients. No threshold effect was observed among the 6 studies, but there was obvious heterogeneity. The pooled sensitivity, specificity, and positive and negative likelihood ratios of AFP-L3% for the diagnosis of early HCC were 0.34 (95% CI 0.30-0.39, P < .0001), 0.92 (95% CI 0.91-0.93, P < .0001), 4.46 (95% CI 2.94-6.77, P = .0033), and 0.71 (95% CI 0.61-0.82, P = .0004), respectively. The diagnostic odds ratio was 6.78 (95% CI 4.02-11.44, P = .0074). The the area under the curve of the summary receiver operating characteristic was 0.755 (95% CI 0.57-0.94).

CONCLUSION

AFP-L3% has high specificity but low sensitivity for diagnose early HCC, suggesting that AFP-L3% is more valuable for excluding HCC in conditions with elevated AFP than for diagnosing early HCC. In addition, a hypersensitive detection method can improve the diagnostic accuracy of AFP-L3% for early HCC.

Frequency Shift Surface-Enhanced Raman Spectroscopy Sensing: An Ultrasensitive Multiplex Assay for Biomarkers in Human Health

The sensitive and selective detection of biomarkers for human health remains one of the grand challenges of the analytical sciences. Compared to established methods (colorimetric, (chemi) luminescent), surface-enhanced Raman spectroscopy (SERS) is an emerging alternative with enormous potential for ultrasensitive biological detection. Indeed even attomolar (10^-18 M) detection limits are possible for SERS due to an orders-of-magnitude boosting of Raman signals at the surface of metallic nanostructures by surface plasmons. However, challenges remain for SERS assays of large biomolecules, as the largest enhancements require the biomarker to enter a "hot spot" nanogap between metal nanostructures. The frequency-shift SERS method has gained popularity in recent years as an alternative assay that overcomes this drawback. It measures frequency shifts in intense SERS peaks of a Raman reporter during binding events on biomolecules (protein coupling, DNA hybridization, etc.) driven by mechanical transduction, charge transfer, or local electric field effects. As such, it retains the excellent multiplexing capability of SERS, with multiple analytes being identifiable by a spectral fingerprint in a single read-out. Meanwhile, like refractive index surface plasmon resonance methods, frequency-shift SERS measures the shift of an intense signal rather than resolving a peak above noise, easing spectroscopic resolution requirements. SERS frequency-shift assays have proved particularly suitable for sensing large, highly charged biomolecules that alter hydrogen-bonding networks upon specific binding. Herein we discuss the frequency-shift SERS method and promising applications in (multiplex) biomarker sensing as well as extensions to ion and gas sensing and much more.

An ultrasensitive disposable sandwich-configuration electrochemical immunosensor based on OMC@AuNPs composites and AuPt-MB for alpha-fetoprotein detection

Early finding and diagnosis are critical for prevention and treatment of hepatocellular carcinoma (HCC). Alpha-fetoprotein (AFP) is a typical biomarker of HCC. Since AFP level can reflect the severity of HCC, it is essential to ensure the accurate detection of AFP. In this study, through a combination of the advantages exhibited by ordered mesoporous carbon (OMC)@gold nanoparticles (AuNPs) composites and AuPt-methylene blue (AuPt-MB), a disposable ultrasensitive sandwich-configuration electrochemical immunosensor for determination of AFP was designed. Characterized by excellent conductivity, highly ordered pore distribution and great surface area, OMC can be effective in promoting electron transfer and loading a large number of AuNPs. In the meantime, AuNPs can also immobilize AFP-Ab₁ through Au-N bonds. As a new redox-active species, rod-like AuPt-MB demonstrates high conductivity, uniform morphology and excellent biocompatibility, which makes it capable not only to fix AFP-Ab₂, but also to release electrochemical signals. A wide linearity of 10 fg mL^-1-100 ng mL^-1 and a low detection limit of 3.33 fg mL^-1 (S/N = 3) were obtained. Moreover, the proposed immunosensor exhibited acceptable selectivity, high stability and reproducibility. The excellent performance in detecting serum samples endows the proposed immunosensor with broad prospects of extensive application in the detection of disease biomarkers.

Sunflower-Like Nanostructure with Built-In Hotspots for Alpha-Fetoprotein Detection

In the present study, a sunflower-like nanostructure array composed of a series of synaptic nanoparticles and nanospheres was manufactured through an efficient and low-cost colloidal lithography technique. The primary electromagnetic field contribution generated by the synaptic nanoparticles of the surface array structures was also determined by a finite-difference time-domain software to simulate the hotspots. This structure exhibited high repeatability and excellent sensitivity; hence, it was used as a surface-enhanced Raman spectroscopy (SERS) active substrate to achieve a rapid detection of ultra-low concentrations of Alpha-fetoprotein (AFP). This study demonstrates the design of a plasmonic structure with strong electromagnetic coupling, which can be used for the rapid detection of AFP concentration in clinical medicine.

Biomarkers Determination Based on Surface-Enhanced Raman Scattering

An overview of noteworthy new methods of biomarker determination based on surface-enhanced Raman scattering (SERS) is presented. Biomarkers can be used to identify the occurrence and development of diseases, which furthers the understanding of biological processes in the body. Accurate detection of a disease-specific biomarker is helpful for the identification, early diagnosis and prevention of a disease and for monitoring during treatment. The search for and discovery of valuable biomarkers have become important research hotspots. Different diseases have different biomarkers, some of which are involved in metabolic processes. Therefore, the fingerprint characteristics and band intensities in SERS spectra have been used to identify metabolites and analyze markers. As a promising technique, SERS has been widely used for the quantitative and qualitative determination of different types of biomarkers for different diseases. SERS techniques provide new technologies for the diagnosis of disease-related markers and determining the basis for clinical treatment. Herein, several SERS-based methods with excellent sensitivity and selectivity for the determination of biomarkers for tumors, viruses, Alzheimer’s disease, cardiac muscle tissue injury, and cell activity are highlighted.

Applications of surface-enhanced Raman spectroscopy in detection fields

Surface-enhanced Raman spectroscopy (SERS) is a Raman spectroscopy technique that has been widely used in food safety, environmental monitoring, medical diagnosis and treatment and drug monitoring because of its high selectivity, sensitivity, rapidness, simplicity and specificity in identifying molecular structures. This review introduces the detection mechanism of SERS and summarizes the most recent progress concerning the use of SERS for the detection and characterization of molecules, providing references for the later research of SERS in detection fields.

SERS Immunosensor of Array Units Surrounded by Particles: A Platform for Auxiliary Diagnosis of Hepatocellular Carcinoma

Hepatocellular carcinoma (HCC) is one of the diseases with high mortality worldwide, so its early diagnosis and treatment have attracted much attention. Due to the advantages of the high sensitivity of surface-enhanced Raman scattering (SERS) detection, SERS has excellent application value in the diagnosis of HCC. In this paper, silver nanoparticles (AgNPs) are modified by magnetron sputtering on the surface of polystyrene (PS) templates with spheres of two different diameters. The array of units surrounded by particles is successfully prepared and the SERS performance is characterized. The effect of the gap between AgNPs on plasmon coupling and hot spot distribution is discussed. Finite-difference time domain (FDTD) simulation is used to verify the electric fields and hot spot distribution of the array. The differences in the concentrations of HCC markers are analyzed by using the change of SERS signal intensity of the array. The whole process proves that the preparation of structures with a strong local electric field to provide highly sensitive SERS signals is a key link in the detection of HCC markers, which is conducive to the diagnosis of HCC and has potential application value in clinical diagnosis.

Secretory Clusterin as a Novel Molecular-targeted Therapy for Inhibiting Hepatocellular Carcinoma Growth

BACKGROUND

Although secretory clusterin (sCLU) plays a crucial role in Hepatocellular Carcinoma (HCC) cells proliferation, Multiple Drug Resistance (MDR), metastasis and so on, its targeted effects and exact mechanism are still unknown. This review summarizes some new progress in sCLU as a molecular-targeted therapy in the treatment of HCC.

METHODS

A systematic review of the published English-language literature about sCLU and HCC has been performed using the PubMed and bibliographic databases. Some valuable studies on sCLU in HCC progression were searched for relevant articles with the keywords: HCC, diagnosis, MDR, as molecular-targeted in treatment, and so on.

RESULTS

The incidence of the positive rate of sCLU was significantly higher in HCC tissues as compared to the surrounding tissues at mRNA or protein level, gradually increasing with tumor-nodemetastasis staging (P<0.05). Also, the abnormal level of sCLU was related to poor differentiation degree, and considered as a useful marker for HCC diagnosis or independent prognosis for patients. Hepatic sCLU could be silenced at mRNA level by specific sCLU-shRNA or by OGX-011 to inhibit cancer cell proliferation with an increase in apoptosis, cell cycle arrest, reversal MDR, alteration of cell migration or invasion behaviors, and a decrease in GSK-3β or AKT phosphorylation in vitro, as well as significant suppression of the xenograft growth by down-regulating β-catenin, p-GSK3β, and cyclinD1 expression in vivo.

CONCLUSION

Abnormal hepatic sCLU expression should not only be a new diagnostic biomarker but also a novel promising target for inhibiting HCC growth.

Analysis of the clinical efficacy of liver resection combined with adjuvant microwave coagulation for patients with hepatocellular carcinoma

Background

Liver resection has been widely applied as a curative measure in the treatment of hepatocellular carcinoma (HCC) patients. However, the high rate of postoperative recurrence observed following liver resection proposes a problem, the solution for which is yet to be well established. Microwave coagulation is a therapy that was recently proposed as an adjuvant tool. In this study, we intended to evaluate the effectiveness of microwave coagulation as an auxiliary therapeutic method for patients undergoing liver resection.

Methods

A total of 236 consecutive patients classified as Barcelona Clinic Liver Cancer (BCLC) stage A who had only one tumor were enrolled in this retrospective study, regardless of tumor size. Survival analyses were performed using the Kaplan-Meier method, and the statistical differences between patients who underwent liver resection with and without adjuvant microwave coagulation were examined by the log-rank test. To investigate the prognostic factors for OS, we carried out univariate and multivariate Cox regression analyses.

Results

Based on the Kaplan-Meier curves, patients who underwent surgical resection with intraoperative adjuvant microwave coagulator had prolonged recurrence-free survival time and showed better overall survival (OS) than those who underwent surgical resection alone, with OS at 1, 3, and 5 years of 77.8%, 33.2%, 12.6% vs. 58.2%, 15.5%, 9.7%, respectively (log-rank P<0.001). The univariate and multivariate analyses demonstrated that tumor size, albumin, bilirubin, Child-Pugh score, and treatment method had significant prognostic power for both PFS and OS. According to the subgroup analyses based on the tumor size, there were significant differences in PFS and OS among overall subsets between the liver resection with adjuvant microwave coagulator and liver resection only groups.

Conclusions

Liver resection combined with intraoperative adjuvant microwave coagulation had a better prognostic performance than treatment with liver resection alone. Adjuvant microwave coagulation should be suggested as an alternative treatment modality for BCLC stage A patients with a single tumor, regardless of its size.

Decreased IL-37 expression in hepatocellular carcinoma tissues and liver cancer cell lines

The role of IL-37 in cancer is currently largely unknown. The present study aimed to investigate IL-37 expression in hepatocellular carcinoma (HCC), paracancerous tissues (PT) and liver cancer cell lines, and their associations between IL-37 and NF-κB. A total of 65 HCC and 65 PT tissues were collected. The expression of IL-37 and NF-κB in tissues was detected by immunohistochemistry (IHC) and the data was analyzed using SPSS software. In the in vitro studies, IL-37 gene was transfected into HepG2 and MHCC97H cell lines with Lipofectamine 3000, and the protein regulation of NF-κB by IL-37 was verified by immunofluorescence (IF) and western blotting. In HCC, the positive expression rates of IL-37 and NF-kB were 21.5 and 95.4%, respectively. In PT, strong positive staining of IL-37and weak positive staining of NF-κB were observed. The normal expression levels of IL-37 and NF-κB, the increased IL-37 and decreased NF-κB induced by IL-37 gene transfection were observed through IF in cell lines. In terms of clinical significance, the difference in IL-37 expression between HCC and PT was statistically significant (χ²=55.05; P<0.001). IL-37 expression in HCC but not PT was negatively associated with serum AFP (χ²=6.522; P=0.039). IL-37 expression in PT was associated with sex (χ²=13.12; P=0.003) and tumor size (χ²=7.996; P=0.045). NF-κB expression in PT was associated with age, sex and BCLC stage. Notably, there was a negative correlation between IL-37 and NF-κB in HCC (r=-0.277; P=0.029) but not in PT (P>0.05). IL-37 overexpression downregulated the NF-κB protein by 56.50% in HepG2 cells (P<0.05) and 30.52% in MHCC97H cells (P<0.05). In conclusion, the expression of IL-37 in HCC and PT was specifically associated with serum AFP and tumor size, respectively. IL-37 expression was negatively correlated with NF-κB protein expression in HCC tissues and liver cancer cell lines.

Preparation of Aptamer Responsive DNA Functionalized Hydrogels for the Sensitive Detection of α-Fetoprotein Using SERS Method

Hepatocellular carcinoma (HCC), which is one of the three major cancers, has attracted growing attention due to its high mortality, health care cost, and circumscribed therapeutic methods. Hence, the development of a fast, accurate, and flexible method to detect α-fetoprotein (AFP), the specific marker of HCC, is significant for diagnosis and treatment of cancer. Here, we constructed a novel SERS biosensing platform combining the target-responsive DNA hydrogel for the sensitive detection of AFP. The linker strand in DNA hydrogel is an aptamer that can specifically recognize AFP and accurately control the release of immunoglobulin G (IgG) encapsulated in hydrogel. In the presence of AFP, the hydrogels were disentangled and the IgG was released. Thereafter, the released IgG was captured by SERS probes and biofunctional magnetic beads through formation of sandwich-like structures, resulting in the signal of Raman tags decreasing in the supernatant after magnetic separation. Due to the ultrahigh sensitivity of the SERS biosensor, the proposed method has a wide detection linear range (50 pg/mL to 0.5 μg/mL) and a detection limit down to 50 pg/mL. Moreover, the sequence of the linker strand in the DNA hydrogel can be specifically encoded into a new aptamer that responds to other cancer markers. This convenient and inexpensive detection method provides a new strategy for the detection of tumor markers.

Nanohoneycomb Surface-Enhanced Raman Spectroscopy-Active Chip for the Determination of Biomarkers of Hepatocellular Carcinoma

Overexpression of the Lens culinaris agglutinin-reactive fraction of alpha-fetoprotein (AFP-L3) is an essential biomarker for early diagnosis of hepatocellular carcinoma (HCC). In this study, we designed a new surface-enhanced Raman spectroscopy active chip for the detection of AFP with high sensitivity and excellent repeatability. This chip was composed of a honeycomb gold nanostructure array with strong electromagnetic field coupling due to the special cavity geometric characteristics of the honeycomb structure. The honeycomb structure exhibited extraordinary performance for the specific detection of AFP in the range of 0.003-3 ng/mL and also determined the proportion of AFP-L3 with a high degree of accuracy, which has shown great potential for application in the clinical diagnosis of HCC.

Derivation and external validation of a model to predict 2-year mortality risk of patients with advanced schistosomiasis after discharge

To date, no risk prediction tools have been developed to identify high mortality risk of patients with advanced schistosomiasis within 2 years after discharge. We aim to derive and validate a risk prediction model to be applied in clinical practice. The risk prediction model was derived from 1487 patients from Jingzhou and externally validated by 723 patients of Huangshi, two prefecture-level cities in Hubei province, China (from September 2014 to January 2015, with follow-up to January 2017). The baseline variables were collected. The mean age [SD] was 62.89 [10.38] years for the derivation cohort and 62.95 [12.22] years for the external validation cohort. The females accounted for 36.3% and 43.7% of the derivation and validation cohorts, respectively. 8.27% patients (123/1487) in the derivation cohort and 7.75% patients (56/723) in the external validation cohort died within 2 years after discharge. We constructed 4 models based on the 7 selected variables: age, clinical classification, serum direct bilirubin (DBil), aspartate aminotransferase (AST), alkaline phosphatase (ALP), hepatitis B surface antigen (HBsAg), alpha fetoprotein (AFP) at admission. In the external validation cohort, the multivariate model including 7 variables had a C statistic of 0.717 (95% CI, 0.646–0.788) and improved integrated discrimination improvement (IDI) value and net reclassification improvement (NRI) value compared to the other reduced models.

Therefore, a multivariate model was developed to predict the 2-year mortality risk for patients with advanced schistosomiasis after discharge. It could also help guide follow-up, aid prognostic assessment and inform resource allocation.