Fluorescence sensing strategy based on aptamer recognition and mismatched catalytic hairpin assembly for highly sensitive detection of alpha-fetoprotein

Recent Advances in Biosensor Technology for Early-Stage Detection of Hepatocellular Carcinoma-Specific Biomarkers: An Overview

Hepatocellular carcinoma is currently the most common malignancy of the liver. It typically occurs due to a series of oncogenic mutations that lead to aberrant cell replication. Most commonly, hepatocellular carcinoma (HCC) occurs as a result of pre-occurring liver diseases, such as hepatitis and cirrhosis. Given its aggressive nature and poor prognosis, the early screening and diagnosis of HCC are crucial. However, due to its plethora of underlying risk factors and pathophysiologies, patient presentation often varies in the early stages, with many patients presenting with few, if any, specific symptoms in the early stages. Conventionally, screening and diagnosis are performed through radiological examination, with diagnosis confirmed by biopsy. Imaging modalities tend to be limited by their requirement of large, expensive equipment; time-consuming operation; and a lack of accurate diagnosis, whereas a biopsy's invasive nature makes it unappealing for repetitive use. Recently, biosensors have gained attention for their potential to detect numerous conditions rapidly, cheaply, accurately, and without complex equipment and training. Through their sensing platforms, they aim to detect various biomarkers, such as nucleic acids, proteins, and even whole cells extracted by a liquid biopsy. Numerous biosensors have been developed that may detect HCC in its early stages. We discuss the recent updates in biosensing technology, highlighting its competitive potential compared to conventional methodology and its prospects as a tool for screening and diagnosis.

Tetrahedral DNA-linked aptamer-antibody-based sandwich-type electrochemical sensor with Ag@Au core-shell nanoparticles as a signal amplifier for highly sensitive detection of α-fetoprotein

The conventional electrochemical detection strategy for alpha-fetoprotein (AFP) is limited by the antigen-antibody (Ag-Ab) reactions and suffers from low sensitivity and poor reproducibility due to the inconsistency of Ab-modified electrodes. Herein, we designed and explored a sandwich-type electrochemical sensor for highly sensitive detection of AFP based on aptamer (Apt)-AFP-Ab interaction mode with silver@gold (Ag@Au) core-shell nanoparticles (NPs) as a signal amplifier. AuNPs were electrodeposited onto MXene (Ti3C2TX)-modified glassy carbon electrode (GCE) to get AuNPs/MXene/GCE and further used as the signal amplification substrate. The tetrahedral DNA-linked AFP aptamers were immobilized onto AuNPs/MXene/GCE surface via Au-S bonds and used as the sensing and recognition platform for AFP capturing. Ag@AuNPs with core-shell structures were synthesized, characterized, and bound with Ab as detection elements by catalyzing H2O2 reduction. In the presence of AFP, a stable Apt-AFP-Ab sandwich structure was formed owing to the high affinities of aptamer and Ab toward the target AFP. The catalytic current produced by H2O2 reduction increased linearly with the logarithm of AFP concentration from 5 × 10-4 ng/mL to 1 × 105 ng/mL, accompanied by a low detection limit (1.6 × 10-4 ng/mL). Moreover, the novel sandwich-type electrochemical sensor shows high sensitivity, outstanding selectivity, and promising performance in the analysis of actual samples, displaying a broad application prospect in bioanalysis.

Sensitive fluorescence assay of chloramphenicol coupled with two-level isothermal amplification using a self-powered catalyzed hairpin assembly and entropy-driven circuit

Two levels of nucleic acids-based isothermal amplification normally require a long reaction time due to the low concentration of catalyst, which limits its practical application. A sensitive fluorescence assay of chloramphenicol (CAP) was developed coupled with two-level isothermal amplification using a self-powered catalyzed hairpin assembly (CHA) and entropy-driven circuit (EDC). CAP can bind with its aptamer to open its closed structure. The opened hairpin can initiate self-powered CHA and EDC. The product of CHA can circularly catalyze the CHA with increasing concentration. In principle, the product of CHA plays the role of catalyst and increases with the progression of the reaction. Compared with the normal two levels of amplification, the amplification efficiency of our strategy is much higher due to the self-powered reaction by the CHA product. Thus, the reaction time is shortened to 110 min in this strategy. Moreover, the detection limit for CAP can achieve 0.1 pM and shows promising prospects for practical application.

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.

Fluorometric detection of alpha-fetoprotein based on the use of a novel organic compound with AIE activity and aptamer-modified magnetic microparticles

BACKGROUND

Liver cancer is one of the most common cancers in the world, and it seriously threatens human life and health. Alpha-fetoprotein (AFP), as a carcinogenic glycoprotein, is an important serum marker for detecting liver cancer. Therefore, the accurate and sensitive determination of AFP is crucial for the early diagnosis and treatment of liver cancer. To this end, a label-free fluorescence aptasensor for detecting AFP based on the use of a novel organic Compound D with an aggregation-induced emission activity and aptamer-modified magnetic microparticles was constructed.

RESULTS

Compound D could combine with the complementary short chain of the aptamer (CSC-Apt) of AFP to form the D/CSC-Apt complex and realize the fluorescence enhancement of Compound D. Then, magnetic particles modified by the Apt of AFP (Apt-Fe3O4) were prepared. When AFP (or nontarget substance) and D/CSC-Apt were successively added to the Apt-Fe3O4 solution, Apt-Fe3O4 selectively bound to AFP or the D/CSC-Apt complex. Magnetic separation technology showed the changes in the fluorescence intensity of the supernatant. The research results revealed a good linear relationship between the changes in the fluorescence intensity of the supernatant and concentration of AFP within the concentration range of 10-10000 pg mL-1. The proposed aptasensor could achieve high-sensitivity and high-specificity detection of AFP, and its limit of detection was 3 pg mL-1 (S/N = 3).

SIGNIFICANCE AND NOVELTY

The sensor combines the advantages of high selectivity of Apt, high sensitivity of fluorescence analysis, AIE effect and good water solubility of Compound D, and rapid separation using magnetic separation technology. And it can be directly used for the detection of AFP in actual serum samples with high accuracy, whereas most of the methods reported in the literature can only detect AFP in spiked serum samples.

A new portable toluidine blue/aptamer complex-on-polyethyleneimine-coated gold nanoparticles-based sensor for label-free electrochemical detection of alpha-fetoprotein

The quantification of alpha-fetoprotein (AFP) as a potential liver cancer biomarker which is generally found in ultratrace level is of significance in biomedical diagnostics. Therefore, it is challenging to find a strategy to fabricate a highly sensitive electrochemical device towards AFP detection through electrode modification for signal generation and amplification. This work shows the construction of a simple, reliable, highly sensitive, and label-free aptasensor based on polyethyleneimine-coated gold nanoparticles (PEI-AuNPs). A disposable ItalSens screen-printed electrode (SPE) is employed for fabricating the sensor by successive modifying with PEI-AuNPs, aptamer, bovine serum albumin (BSA), and toluidine blue (TB), respectively. The AFP assay is easily performed when the electrode is inserted into a small Sensit/Smart potentiostat connected to a smartphone. The readout signal of the aptasensor derives from the electrochemical response of TB intercalating into the aptamer-modified electrode after binding with the target. The decrease in current response of the proposed sensor is proportional to the AFP concentration due to the restriction of the electron transfer pathway of TB by a number of insulating AFP/aptamer complexes on the electrode surface. PEI-AuNPs improve SPE's reactivity and provide a large surface area for aptamer immobilization whereas aptamer provides selectivity to the target AFP. Consequently, this electrochemical biosensor is highly sensitive and selective for AFP analysis. The developed assay reveals a linear range of detection from 10 to 50000 pg mL^-1 with R ² = 0.9977 and provided a limit of detection (LOD) of 9.5 pg mL^-1 in human serum. With its simplicity and robustness, it is anticipated that this electrochemical-based aptasensor will be a benefit for the clinical diagnosis of liver cancer and further developed for other biomarkers analysis.

Recent advances in optical aptasensors for biomarkers in early diagnosis and prognosis monitoring of hepatocellular carcinoma

Hepatocellular carcinoma (HCC) accounts for approximately 90% of all primary liver cancers and is one of the main malignant tumor types globally. It is essential to develop rapid, ultrasensitive, and accurate strategies for the diagnosis and surveillance of HCC. In recent years, aptasensors have attracted particular attention owing to their high sensitivity, excellent selectivity, and low production costs. Optical analysis, as a potential analytical tool, offers the advantages of a wide range of targets, rapid response, and simple instrumentation. In this review, recent progress in several types of optical aptasensors for biomarkers in early diagnosis and prognosis monitoring of HCC is summarized. Furthermore, we evaluate the strengths and limitations of these sensors and discuss the challenges and future perspectives for their use in HCC diagnosis and surveillance.

A photoelectrochemical immunosensing platform for ultrasensitive detection of alpha-fetoprotein based on a signal amplification strategy

For the first time, a PEC immunosensor based on a signal amplification strategy is successfully constructed to quantitatively detect alpha-fetoprotein in serum sample. Three favorable factors explain the ultra-high sensitivity of this method. Firstly, compared with pure BiPO₄, the BiPO₄/BiOBr heterojunction has a narrower band gap, which expands the light absorption range and enables the light energy to be fully utilized. Secondly, the separation of photogenerated electrons and hole pairs during PEC detection is due to the efficient matching of energy levels among BiPO₄, BiOBr and CdS, inhibiting the recombination of photogenerated electrons, which improves the performance of PEC immunosensor. Thirdly, due to the presence of CdS, the light absorption capability of the sensor is enhanced, more electron-hole pairs are generated, and the photocurrent signal is increase. Under the optimal conditions, the PEC immunosensor shows a wide linear range of 0.001-1000 ng/mL for AFP and a low detection limit of 0.82 pg/mL. The PEC immunosensor developed in this experiment has excellent reproducibility, stability and high sensitivity, and also achieves satisfactory results in the analysis of human serum samples, establishing a new analytical method for biomarker detection.

Recent Trends in Biosensing and Diagnostic Methods for Novel Cancer Biomarkers

Cancer is one of the major public health issues in the world. It has become the second leading cause of death, with approximately 75% of cancer deaths transpiring in low- or middle-income countries. It causes a heavy global economic cost estimated at more than a trillion dollars per year. The most common cancers are breast, colon, rectum, prostate, and lung cancers. Many of these cancers can be treated effectively and cured if detected at the primary stage. Nowadays, around 50% of cancers are detected at late stages, leading to serious health complications and death. Early diagnosis of cancer diseases substantially increases the efficient treatment and high chances of survival. Biosensors are one of the potential screening methodologies useful in the early screening of cancer biomarkers. This review summarizes the recent findings about novel cancer biomarkers and their advantages over traditional biomarkers, and novel biosensing and diagnostic methods for them; thus, this review may be helpful in the early recognition and monitoring of treatment response of various human cancers.

Functional Micro-/Nanostructures in Agrofood Science: Precise Inspection, Hazard Elimination, and Potential Health Risks

Nanotechnology, biotechniques, and chemical engineering have arisen as new trends with significant impacts on agrofood science development. Advanced analytical techniques with high sensitivity, specificity, and automation based on micro-/nanomaterials for food hazard elimination have become leading research hotspots in agrofood science. Research progress in micro-/nanomaterials has provided a solid theoretical basis and technical support to solve problems in the industry. However, the rapid development of micro-/nanostructures has also raised concerns regarding potential risks to human health. This review presents the latest advances in the precise inspection and elimination of food hazards from micro-/nanomaterials and discusses the potential threats to human health posed by nanomaterials. The theoretical reference was provided for the application trend of micro-/nanomaterials in the field of agrofood science in the future.

2D MXene-Based Biosensing: A Review

MXene emerged as decent 2D material and has been exploited for numerous applications in the last decade. The remunerations of the ideal metallic conductivity, optical absorbance, mechanical stability, higher heterogeneous electron transfer rate, and good redox capability have made MXene a potential candidate for biosensing applications. The hydrophilic nature, biocompatibility, antifouling, and anti-toxicity properties have opened avenues for MXene to perform in vitro and in vivo analysis. In this review, the concept, operating principle, detailed mechanism, and characteristic properties are comprehensively assessed and compiled along with breakthroughs in MXene fabrication and conjugation strategies for the development of unique electrochemical and optical biosensors. Further, the current challenges are summarized and suggested future aspects. This review article is believed to shed some light on the development of MXene for biosensing and will open new opportunities for the future advanced translational application of MXene bioassays.

A facile aptamer-based sensing strategy for dopamine detection through the fluorescence energy transfer between dye and single-wall carbon nanohorns

Dopamine (DBA) as an important biomarker, plays a crucial role in disease diagnosis. In this study, we have developed a fast and simple aptamer-based fluorescence strategy which used single-wall carbon nanohorns (SWCNHs) as a quencher for dopamine detection. SWCNHs were negatively charged after pretreated, which improved its dispersion in solution. 5-carboxy-fluorescein (FAM) was used to label dopamine aptamer. In the absence of dopamine, FAM-modified aptamer could be absorbed onto the SWCNHs surface due to π-π interaction, resulting in the fluorescence intensity decreased. Dopamine could specifically bind with FAM-DNA to form G-quadruplex, which could not be absorbed onto the surface of SWCNHs. Hence, the fluorescence of FAM-DNA recovered, and the fluorescent intensity as a function of different concentrations of dopamine was measured. We obtained a detection limit of 5 μM for this detection system with a linear detection range of 0.02-2.20 mM. Furthermore, the feasibility of the innovative detection system has been verified by detecting dopamine in spiked serum samples.

Optical and Electrochemical Aptasensors Developed for the Detection of Alpha-Fetoprotein

Early diagnosis of hepatocellular carcinoma (HCC), a leading cause of cancer mortality, is decisive for successful treatment of this type of cancer and increasing the patients' survival rate. Alpha-fetoprotein (AFP) is a glycoprotein that has been currently employed as a potential serological biomarker for determination of HCC and several other cancers. Achieving highly sensitive and specific detection of this biomarker is an effective strategy to inhibit developing issues caused by the cancer. Though, traditional procedures cannot meet the requirements due to the technical drawbacks. Recently, growing number of aptamer-based biosensors (aptasensors) attracted important attention as superior diagnostic tools because of their unique properties such as high stability, target versatility and remarkable affinity and selectivity. Nanomaterials, which broadly employed in the structure of these aptasensors, can considerably enhance the detection limit and sensitivity of analytes determination. Therefore, this review selectively investigated the recent progresses in several different optical and electrochemical aptasensors and nano-aptasensors designed for AFP assay.

Applications of Smartphone-Based Aptasensor for Diverse Targets Detection

Aptamers are a particular class of functional recognition ligands with high specificity and affinity to their targets. As the candidate recognition layer of biosensors, aptamers can be used to sense biomolecules. Aptasensors, aptamer-based biosensors, have been demonstrated to be specific, sensitive, and cost-effective. Furthermore, smartphone-based devices have shown their advantages in binding to aptasensors for point-of-care testing (POCT), which offers an immediate or spontaneous responding time for biological testing. This review describes smartphone-based aptasensors to detect various targets such as metal ions, nucleic acids, proteins, and cells. Additionally, the focus is also on aptasensors-related technologies and configurations.

Recent advances of catalytic hairpin assembly and its application in bioimaging and biomedicine

Catalytic hairpin assembly (CHA) appears to be a particularly appealing nucleic acid circuit because of its powerful amplification capability, simple protocols, and enzyme-free and isothermal conditions, and can combine with various signal output modes for the biosensing of various analytes. Especially in the last five years, vast CHA related studies have sprung up. With the deep exploration of the CHA mechanism, some novel and excellent CHA strategies have been proposed; meanwhile the CHA cascade strategies with various amplification techniques further improve the analysis performance. Furthermore, diverse CHA based biosensors have been tactfully engineered and extensively employed in imaging applications in living cells and in vivo ascribed to its gentle reaction, efficient amplification and universality. Hence, we present a comprehensive and systematic summary of the progress in CHA and its application in bioimaging and biomedicine to date. At first, we introduced the mechanism and diversification of CHA in detail, including the newly developed CHA and its ingenious combination with a variety of other technologies. Concurrently, we summarized the latest application progress of different CHA strategies in bioimaging and biomedicine, highlighting the merits and drawbacks of representative approaches. Finally, we put forward some views on the challenges and prospects of CHA in bioimaging and biomedicine in the future.

Ratiometric fluorescence enzyme-linked immunosorbent assay based on carbon dots@SiO2@CdTe quantum dots with dual functionalities for alpha-fetoprotein

Molecular tags such as fluorophores are increasingly being replaced with nanoparticles thanks to their superior optical properties, substantial chemical stability, and stability against photobleaching. Herein, we innovatively constructed a new ratiometric fluorescence enzyme-linked immunosorbent assay (RF-ELISA) for the screening of alpha-fetoprotein (AFP) in early hepatocellular carcinoma in vitro diagnostics using carbon dots@SiO₂@CdTe quantum dots (CDs@SiO₂@CdTe QDs). Carbon dots with blue fluorescence were initially encapsulated into SiO₂ nanospheres through the typical Stöber method. Thereafter, CdTe QDs with red fluorescence were modified onto the surface of CDs@SiO₂ nanospheres. Dual-emission nanotags with blue and red fluorescent signals were utilized to design a RF-ELISA method for the determination of AFP on the anti-AFP capture antibody-coated microplate using glucose oxidase (GOx)-labeled anti-AFP secondary antibody. After the formation of the sandwiched immunocomplex, GOx catalyzed glucose to generate hydrogen peroxide (H₂O₂), which could quench the red fluorescence of CdTe QDs on the surface of nanotags. Meanwhile, the encapsulated carbon dots in the nanotags could still maintain the initial blue fluorescence intensity. The ratio between red fluorescence intensity and blue-emission intensity could be used for the quantitative monitoring of AFP concentration under optimum conditions. The experimental results indicated that CDs@SiO₂@CdTe QDs-based RF-ELISA could exhibit a good fluorescence signal with a dynamic linear range of 0.05-60 ng mL^-1 at a low detection limit of 8.7 pg mL^-1. Moreover, the fluorescence color of the solution including CDs@SiO₂@CdTe QDs changed from pink to purple to blue with the increasing AFP level when viewed by the naked eye. Good reproducibility, high specificity, and acceptable stability were achieved for the analysis of target AFP. Importantly, the accuracy of ratiometric fluorescence immunoassay was evaluated to determine human serum samples, giving well-matched results relative to commercially usable human AFP ELISA method.

A chemiluminescence aptasensor for sensitive detection of alpha-fetoprotein based on hemin@ZIF-67

In this work, hemin@ZIF-67 composites were prepared and were used to construct a chemiluminescence (CL) aptasensor for alpha-fetoprotein (AFP) detection. Hemin is a catalytic porphyrin with two carboxylate groups that can covalently bond to metal ions. A hemin/ZIF-67 composite was prepared via covalent bonding between the carboxyl groups of hemin and the cobalt ion of ZIF-67, and these materials were characterized by scanning electron microscopy (SEM), infrared spectroscopy (IR), and X-ray diffraction (XRD). Hemin@ZIF-67 was used as the peroxidase material, and the aptamer of alpha-fetoprotein was modified on its surface by electrostatic adsorption. Then a simple CL aptasensor was constructed based on the CL system of luminol-H₂O₂-NaOH. Under the optimal conditions, the CL intensity value was linearly proportional to the concentration of AFP in the range of 4 × 10^-10 to 200 × 10^-10 mg/mL. The detection limit was 1.3 × 10^-10 mg/mL. Thus the aptasensor enables highly sensitive and selective detection of AFP.

Next-Generation Intelligent MXene-Based Electrochemical Aptasensors for Point-of-Care Cancer Diagnostics

Delayed diagnosis of cancer using conventional diagnostic modalities needs to be addressed to reduce the mortality rate of cancer. Recently, 2D nanomaterial-enabled advanced biosensors have shown potential towards the early diagnosis of cancer. The high surface area, surface functional groups availability, and excellent electrical conductivity of MXene make it the 2D material of choice for the fabrication of advanced electrochemical biosensors for disease diagnostics. MXene-enabled electrochemical aptasensors have shown great promise for the detection of cancer biomarkers with a femtomolar limit of detection. Additionally, the stability, ease of synthesis, good reproducibility, and high specificity offered by MXene-enabled aptasensors hold promise to be the mainstream diagnostic approach. In this review, the design and fabrication of MXene-based electrochemical aptasensors for the detection of cancer biomarkers have been discussed. Besides, various synthetic processes and useful properties of MXenes which can be tuned and optimized easily and efficiently to fabricate sensitive biosensors have been elucidated. Further, futuristic sensing applications along with challenges will be deliberated herein.

Fluorescence detection of milk allergen β-lactoglobulin based on aptamers and WS2 nanosheets

β-Lactoglobulin (β-Lg), a food allergen, can easily cause allergic reactions in infants and young children. Therefore, it is necessary to develop a rapid, sensitive, and selective detection method to protect individuals prone to allergies. In this paper, a fluorescence assay based on WS₂ nanosheets and a fluorescent dye (FAM)-labeled β-Lg aptamer was designed to detect β-Lg rapidly with high sensitivity. In the sensing platform, the β-Lg aptamer is adsorbed on the WS₂ nanosheet surface by van der Waals forces, which trigger the phenomenon of fluorescence resonance energy transfer (FRET) and suppress the fluorescence signal in the system. When β-Lg is present, the conformation of the aptamer specifically bound to β-Lg changes. Therefore, the aptamer is separated from the WS₂ nanosheet surface, and the fluorescence signal is recovered. This method combines the high quenching efficiency of WS₂ nanosheets and good specificity of the β-Lg aptamer. The detection range of this method for β-Lg is 0.1-100 μg mL^-1. The detection limit is 20.4 ng mL^-1. This method exhibits high sensitivity, selectivity and good reproducibility, and it can be used for β-Lg detection in actual samples.

Ti3C2 MXene anchors CuAu-LDH multifunctional two-dimensional nanomaterials for dual-mode detection of CEA in electrochemical immunosensors

Electrochemical immunoassays are commonly used to detect biomarkers and Ti₃C₂ MXene anchored CuAu-LDH two-dimensional hydroxide heterojunctions for dual-mode electrochemical immunosensors were fabricated in this work. Layered double hydroxides have a large surface area, high chemical stability, tunable metal composition and interchangeable anions, however, the insulating nature of LDH further limits its catalytic performance. For this reason, Ti₃C₂ Mxenes were introduced to improve this problem. 2D layers of Ti₃C₂ Mxenes with large specific surface area and excellent conductivity have been well proven and widely used. And the surface of Ti₃C₂ Mxenes (due to the presence of abundant surface functional groups), will facilitate the anchoring of metal ions and the nucleation of LDH. In addition, its excellent electrical conductivity will facilitate the electron transfer between Cu²⁺ and Cu⁺. The immunosensor not only showed a heavy square wave voltammetry (SWV) signal. It also exhibited high electrocatalytic activity for H₂O₂ redox reactions and improves the sensitivity of the Ampere Current (i-t) detection. The CEA immunosensor developed in this study showed a wide linear response (0.0001-80 ng/mL) and the lowest detection limits (SWV: 33.6 fg/mL and i-t: 45.4 fg/mL S/N = 3). The results confirmed the excellent analytical capability of the immunosensor.

A dual-rotator fluorescent probe for analyzing the viscosity of mitochondria and blood

A novel mitochondria-targeting molecular rotator FD was designed to visualize changes in viscosity under hypoxic conditions in vitro and in vivo. Importantly, FD can be used to detect changes in the blood viscosity of liver cancer and liver cirrhosis patients, and also rehabilitation of liver disease.