Electrochemical immunosensor with nanocellulose-Au composite assisted multiple signal amplification for detection of avian leukosis virus subgroup J

Progress in Electrochemical Immunosensors with Alkaline Phosphatase as the Signal Label

Electrochemical immunosensors have shown great potential in clinical diagnosis, food safety, environmental protection, and other fields. The feasible and innovative combination of enzyme catalysis and other signal-amplified elements has yielded exciting progress in the development of electrochemical immunosensors. Alkaline phosphatase (ALP) is one of the most popularly used enzyme reporters in bioassays. It has been widely utilized to design electrochemical immunosensors owing to its significant advantages (e.g., high catalytic activity, high turnover number, and excellent substrate specificity). In this work, we summarized the achievements of electrochemical immunosensors with ALP as the signal reporter. We mainly focused on detection principles and signal amplification strategies and briefly discussed the challenges regarding how to further improve the performance of ALP-based immunoassays.

Preparation and Biochemical Characteristics of a New IgG-Type Monoclonal Antibody against K Subgroup Avian Leukosis Virus

This study focused on preparing a new IgG-type monoclonal antibody (MAb) against subgroup K avian leukosis virus (ALV-K) and identifying its biochemical characteristics. A specific gene fragment of ALV-K was amplified by polymerase chain reaction and expressed in E. coli. The purified expressed products were inoculated into BALB/c mice to prepare antibody-secreting spleen lymphocytes, and hybridoma cells were obtained after cell fusion of spleen lymphocytes and myeloma cells. A new hybridoma cell line named 30B9, which stably secreted IgG2b-antibody against ALV-K, was screened and contained 98 chromosomes. The MAb secreted by the 30B9 cells could recognize the ALV-K strain but not the ALV-A/B/J strains in an indirect immunofluorescence assay. Seventeen overlapping truncated ALV-K gp85 protein fragments were expressed, and eight peptides were artificially synthesized to analyze the MAb's antigen epitope by Western blot or enzyme-linked immunosorbent assay, and the results showed that the linear epitope was located on the ^217-RRNYT^-221 of ALV-K gp85 protein. A bioinformatics analysis showed that the epitope has a high antigenicity index, hydrophilicity, and surface accessibility and forms a unique linear spatial structure. Its five amino acids are highly conserved in all published ALV-K strains but are very low in ALV-A/B/J/C/D/E strains. This study provides a new biomaterial for developing specific detection methods against ALV-K.

Nanostructured Carbons: towards Soft-Bioelectronics, Biosensing and Theraputic Applications

Recently, nanostructured carbon-based soft bioelectronics and biosensors have received tremendous attention due to their outstanding physical and chemical properties. The ultrahigh specific surface area, high flexibility, lightweight, high electrical conductivity, and biocompatibility of 1D and 2D nanocarbons, such as carbon nanotubes (CNT) and graphene, are advantageous for bioelectronics applications. These materials improve human life by delivering therapeutic advancements in gene, tumor, chemo, photothermal, immune, radio, and precision therapies. They are also utilized in biosensing platforms, including optical and electrochemical biosensors to detect cholesterol, glucose, pathogenic bacteria (e. g., coronavirus), and avian leucosis virus. This review summarizes the most recent advancements in bioelectronics and biosensors by exploiting the outstanding characteristics of nanocarbon materials. The synthesis and biocompatibility of nanocarbon materials are briefly discussed. In the following sections, applications of graphene and CNTs for different therapies and biosensing are elaborated. Finally, the key challenges and future perspectives of nanocarbon materials for biomedical applications are highlighted.

Antibody mounting capability of 1D/2D carbonaceous nanomaterials toward rapid-specific detection of SARS-CoV-2

Carbonaceous immunosensors are ideal nanoplatforms for developing rapid, precise, and ultra-specific diagnostic kits capable of early detection of viral infectious illnesses such as COVID-19. However, developing a proper carbonic immunosensor requires stepwise protocols to find optimum operating conditions to minimize drawbacks. Herein, for the first time and through a stepwise protocol, activation, and monoclonal IgG antibody mounting capability of multi-walled carbon nanotubes (MWCNTs) at two diverse outer diameters (ODs), viz., 20–30 nm and 50–80 nm, and graphene deriv atives (graphene oxide (GO) and reduced graphene oxide (rGO)) were examined and compared with each other toward finding the prime carbonaceous nanomaterial(s) for maximized antibody loading efficiency along with an ideal detection limit (DL) and sensitivity. Next, the effect of common amplifying agents, i.e., Au nanostars (Au NSs) and Ag nanowires (Ag NWs), on the total performance of the best carbonaceous structure was carefully assessed, and the responsible detection mechanism is investigated in detail. Next, the developed carbonaceous immunosensors were assessed via voltammetric and impedance assays, and their performances toward specific detection of SARS-CoV-2 antigen through immunoreaction were examined in detail. The study's outcome showed the superior performance of conjugated rGO-based immunosensor with Au NSs toward specific and quick (1 min) detection of SARS-CoV-2 antigen in biological fluids compared with other 1D/2D carbonaceous nanomaterials.

A Review on the Role and Performance of Cellulose Nanomaterials in Sensors

Sensors and biosensors play a key role as an analytical tool for the rapid, reliable, and early diagnosis of human diseases. Such devices can also be employed for monitoring environmental pollutants in air and water in an expedited way. More recently, nanomaterials have been proposed as an alternative in sensor fabrication to achieve gains in performance in terms of sensitivity, selectivity, and portability. In this direction, the use of cellulose nanomaterials (CNM), such as cellulose nanofibrils (CNF), cellulose nanocrystals (CNC), and bacterial cellulose (BC), has experienced rapid growth in the fabrication of varied types of sensors. The advantageous properties are related to the supramolecular structures that form the distinct CNM, their biocompatibility, and highly reactive functional groups that enable surface functionalization. The CNM can be applied as hydrogels and xerogels, thin films, nanopapers and other structures interesting for sensor design. Besides, CNM can be combined with other materials (e.g., nanoparticles, enzymes, carbon nanomaterials, etc.) and varied substrates to advanced sensors and biosensors fabrication. This review explores recent advances on CNM and composites applied in the fabrication of optical, electrical, electrochemical, and piezoelectric sensors for detecting analytes ranging from environmental pollutants to human physiological parameters. Emphasis is given to how cellulose nanomaterials can contribute to enhance the performance of varied sensors as well as expand novel sensing applications, which could not be easily achieved using standard materials. Finally, challenges and future trends on the use of cellulose-based materials in sensors and biosensors are also discussed.

Preparation of a novel monoclonal antibody against Avian leukosis virus subgroup J Gp85 protein and identification of its epitope

Avian leukosis virus subgroup J (ALV-J) is an avian oncogenic retrovirus that has caused huge economic losses in the poultry industry due to its great pathogenicity and transmission ability. However, the continuous emergence of new strains would bring challenges to diagnosis and control of ALV-J. .This study focuses on preparing the monoclonal antibody (MAb) against ALV-J Gp85 and identifying its epitope. The truncated ALV-J gp85 gene fragment was amplified and then cloned into expression vectors. Purified GST-Gp85 was used to immune mice and His-Gp85 was used to screen MAb. Finally, a hybridoma cell line named J16 that produced specific MAb against the ALV-J. Immunofluorescence assay showed that MAb J16 specifically recognized ALV-J rather than ALV-A or ALV-K infected DF-1 cells. To identify the epitope recognized by MAb J16, fourteen partially overlapping ALV-J Gp85 fragments were prepared and tested by Western blot. The results indicated that peptide 150-LIRPYVNQ-157 was the minimal epitope of ALV-J Gp85 recognized by MAb J16. Alignment analysis of Gp85 from different ALV subgroups showed that the epitope keep high conservation among 36 ALV-J strains, but significant different from that of ALV subgroup A, B, C, D, E and K. Overall, we prepared a MAb specific against ALV-J and identified peptide 150-LIRPYVNQ-157 as a novel specific epitope of ALV-J Gp85, which may assist in laying the foundation for specific ALV-J detection methods.

Metal Nanoparticle and Quantum Dot Tags for Signal Amplification in Electrochemical Immunosensors for Biomarker Detection

With the increasing importance of healthcare and clinical diagnosis, as well as the growing demand for highly sensitive analytical instruments, immunosensors have received considerable attention. In this review, electrochemical immunosensor signal amplification strategies using metal nanoparticles (MNPs) and quantum dots (Qdots) as tags are overviewed, focusing on recent developments in the ultrasensitive detection of biomarkers. MNPs and Qdots can be used separately or in combination with other nanostructures, while performing the function of nanocarriers, electroactive labels, or catalysts. Thus, different functions of MNPs and Qdots as well as recent advances in electrochemical signal amplification are discussed. Additionally, the methods most often used for antibody immobilization on nanoparticles, immunoassay formats, and electrochemical methods for indirect biomarker detection are overviewed.

Biosensing strategies for the electrochemical detection of viruses and viral diseases - A review

Viruses are the causing agents for many relevant diseases, including influenza, Ebola, HIV/AIDS, and COVID-19. Its rapid replication and high transmissibility can lead to serious consequences not only to the individual but also to collective health, causing deep economic impacts. In this scenario, diagnosis tools are of significant importance, allowing the rapid, precise, and low-cost testing of a substantial number of individuals. Currently, PCR-based techniques are the gold standard for the diagnosis of viral diseases. Although these allow the diagnosis of different illnesses with high precision, they still present significant drawbacks. Their main disadvantages include long periods for obtaining results and the need for specialized professionals and equipment, requiring the tests to be performed in research centers. In this scenario, biosensors have been presented as promising alternatives for the rapid, precise, low-cost, and on-site diagnosis of viral diseases. This critical review article describes the advancements achieved in the last five years regarding electrochemical biosensors for the diagnosis of viral infections. First, genosensors and aptasensors for the detection of virus and the diagnosis of viral diseases are presented in detail regarding probe immobilization approaches, detection methods (label-free and sandwich), and amplification strategies. Following, immunosensors are highlighted, including many different construction strategies such as label-free, sandwich, competitive, and lateral-flow assays. Then, biosensors for the detection of viral-diseases-related biomarkers are presented and discussed, as well as point of care systems and their advantages when compared to traditional techniques. Last, the difficulties of commercializing electrochemical devices are critically discussed in conjunction with future trends such as lab-on-a-chip and flexible sensors.

Plasmonic nano-antimicrobials: properties, mechanisms and applications in microbe inactivation and sensing

Bacterial, viral and fungal infections pose serious threats to human health and well-being. The continuous emergence of acute infectious diseases caused by pathogenic microbes and the rapid development of resistances against conventional antimicrobial drugs necessitates the development of new and effective strategies for the safe elimination of microbes in water, food or on surfaces, as well as for the inactivation of pathogenic microbes in human hosts. The need for new antimicrobials has triggered the development of plasmonic nano-antimicrobials that facilitate both light-dependent and -independent microbe inactivation mechanisms. This review introduces the relevant photophysical mechanisms underlying these plasmonic nano-antimicrobials, and provides an overview of how the photoresponses and materials properties of plasmonic nanostructures can be applied in microbial pathogen inactivation and sensing applications. Through a systematic analysis of the inactivation efficacies of different plasmonic nanostructures, this review outlines the current state-of-the-art in plasmonic nano-antimicrobials and defines the application space for different microbial inactivation strategies. The advantageous optical properties of plasmonic nano-antimicrobials also enhance microbial detection and sensing modalities and thus help to avoid exposure to microbial pathogens. Sensitive and fast plasmonic microbial sensing modalities and their theranostic and targeted therapeutic applications are discussed.

Recombinant subgroup B avian leukosis virus combined with the subgroup J env gene significantly increases its pathogenicity

The differences among different sub-groups of the avian leukosis virus (ALV) genome are mainly concentrated in the env gene, which binds to cell-specific receptors and determines the characteristics of viral tropism and pathogenicity. In this study, two rescued viruses rGX15MM6-2 (ALV of subgroup J, ALV-J) and rGX14FF03 (ALV of subgroup B, ALV-B) and a recombinant virus rALV-B-Jenv (ALV-B's backbone with ALV-J's env) were generated and tested utilizing both in vitro and in vivo experiments. The results showed that the replication ability of the viruses released in DF-1 cell cultures was listed in order as rGX15MM6-2 > rALV-B-Jenv > rGX14FF03. rGX15MM6-2 caused the most serious suppression of body weight gain, exhibited a significant negative effect on the development of immune organs (P < 0.05) and lower antibody responses to vaccinations with the commercial oil-emulsion vaccines (OEVs) (P<0.05) in the challenged chickens. The viral detection showed that the positive rate in blood from the birds infected with rALV-B-Jenv were respectively higher than those from the birds infected with rGX14FF03 (P < 0.05). At 25 wpi, similar tumors were found in the abdominal cavity of the birds in rGX15MM6-2 and rALV-B-Jenv groups. The results demonstrated that the ALV-J env gene significantly increases the pathogenicity of the recombinant ALV-B. With the increasing incidence of co-infections of different subgroups of ALV in the field, the possibility of viral recombination is increasing and demands further study.

A Novel NiFe2O4/Paper-Based Magnetoelastic Biosensor to Detect Human Serum Albumin

For the first time, a novel NiFe2O4/paper-based magnetoelastic (ME) biosensor was developed for rapid, sensitive, and portable detection of human serum albumin (HSA). Due to the uniquely magnetoelastic effect of NiFe2O4 nanoparticles and the excellent mechanical properties of the paper, the paper-based ME biosensor transforms the surface stress signal induced by the specific binding of HSA and antibody modified on the paper into the electromagnetic signal. The accumulated binding complex generates a compressive stress on the biosensor surface, resulting in a decrease in the biosensor's static magnetic permeability, which correlates to the HSA concentrations. To improve the sensitivity of the biosensor, the concentration of NiFe2O4 nanofluid and the impregnated numbers of the NiFe2O4 nanofluid-impregnated papers were optimized. The experimental results demonstrated that the biosensor exhibited a linear response to HSA concentrations ranging from 10 μg∙mL-1 to 200 μg∙mL-1, with a detection limit of 0.43 μg∙mL-1, which is significantly lower than the minimal diagnosis limit of microalbuminuria. The NiFe2O4/paper-based ME biosensor is easy to fabricate, and allows the rapid, highly-sensitive, and selective detection of HSA, providing a valuable analytical device for early monitoring and clinical diagnosis of microalbuminuria and nephropathy. This study shows the successful integration of the paper-based biosensor and the ME sensing analytical method will be a highly-sensitive, easy-to-use, disposable, and portable alternative for point-of-care monitoring.

Applications of Nanocellulose/Nanocarbon Composites: Focus on Biotechnology and Medicine

Nanocellulose/nanocarbon composites are newly emerging smart hybrid materials containing cellulose nanoparticles, such as nanofibrils and nanocrystals, and carbon nanoparticles, such as "classical" carbon allotropes (fullerenes, graphene, nanotubes and nanodiamonds), or other carbon nanostructures (carbon nanofibers, carbon quantum dots, activated carbon and carbon black). The nanocellulose component acts as a dispersing agent and homogeneously distributes the carbon nanoparticles in an aqueous environment. Nanocellulose/nanocarbon composites can be prepared with many advantageous properties, such as high mechanical strength, flexibility, stretchability, tunable thermal and electrical conductivity, tunable optical transparency, photodynamic and photothermal activity, nanoporous character and high adsorption capacity. They are therefore promising for a wide range of industrial applications, such as energy generation, storage and conversion, water purification, food packaging, construction of fire retardants and shape memory devices. They also hold great promise for biomedical applications, such as radical scavenging, photodynamic and photothermal therapy of tumors and microbial infections, drug delivery, biosensorics, isolation of various biomolecules, electrical stimulation of damaged tissues (e.g., cardiac, neural), neural and bone tissue engineering, engineering of blood vessels and advanced wound dressing, e.g., with antimicrobial and antitumor activity. However, the potential cytotoxicity and immunogenicity of the composites and their components must also be taken into account.

Electrochemical virus detections with nanobiosensors

Infectious diseases are caused from pathogens, which need a reliable and fast diagnosis. Today, expert personnel and centralized laboratories are needed to afford much time in diagnosing diseases caused from pathogens.

Recent progress in electrochemical studies shows that biosensors are very simple, accurate, precise, and cheap at virus detection, for which researchers find great interest in this field. The clinical levels of these pathogens can be easily analyzed with proposed biosensors. Their working principle is based on affinity between antibody and antigen in body fluids. The progress still continues on these biosensors for accurate, rapid, reliable sensors in future.

Significant enhancement in the electrochemical determination of 4-aminophenol from nanoporous gold by decorating with a Pd@CeO2 composite film

An electrode based on Pd@CeO₂ nanocomposite-decorated nanoporous gold on a carbon fiber paper was achieved, which demonstrated excellent performance in 4-aminophenol determination.

Bio-/Nanoimmobilization Platform Based on Bioinspired Fibrin-Bone@Polydopamine-Shell Adhesive Composites for Biosensing

Inspired by blood coagulation and mussel adhesion, we report novel adhesive fibrin-bone@polydopamine (PDA)-shell composite matrix as highly efficient immobilization platform for biomacromolecules and nanomaterials. Fibrin, as a bioglue, and PDA, as a chemical adhesive, are integrated in a one-pot simultaneous polymerization consisting of biopolymerization of fibrinogen and chemical polymerization of dopamine. Fibrin fibers act as adhesive bones to construct scaffold, while PDA coat on the scaffold to form adhesive shell, generating 3D porous composite matrix with unique bone@shell structure. Two types of enzymes (glucose oxidase and acetylcholinesterase) and Au nanoparticles were adopted as respective model biomolecules and nanomaterials to investigate the immobilization capability of the matrix. The bionanocomposites showed high efficiency in capturing nanoparticles and enzymes, as well as significant mass-transfer and biocatalysis efficiencies. Therefore, the bionanocomposites exhibited significant potential in biosensing of glucose and paraoxon with limits of detection down to 5.2 μM and 4 ppt, respectively. The biological-chemical-combined polymerization strategy and composite platform with high immobilization capacity and mass-transfer efficiency open up a novel way for the preparation of high-performance bionanocomposites for various applications, in particular, biosensing.

Preparation of a new monoclonal antibody against subgroup A of avian leukosis virus and identifying its antigenic epitope

This study focuses on preparing the monoclonal antibody (MAb) against subgroup A of avian leukosis virus (ALV-A) and identifying its antigenic epitope. The ALV-A gp85 gene with a size of 1005bp was amplified and expressed into a recombinant protein with a size of 46KD in E.coli. The products expressed after purification were inoculated into BALB/c mice for preparing antibody-secreting splenic lymphocytes and further obtaining hybridoma cells. Finally, one new hybridoma cell (A18GH) secreting MAb against ALV-A was screened, and the MAb was able to detect ALV-A/K strains in an indirect immunofluorescence assay (IFA), but not ALV-B/J strains. A total of 14 overlapping truncated ALV-A gp85 protein segments were expressed and eight peptides containing different antigenic amino acids were artificially synthesized for analyzing the antigenic epitope of the MAb using a western blot or an ELISA, and the results indicate that the antigenic epitope consists of seven amino acids within the ^146-ATRFLLR ^-152 region of the ALV-A gp85 protein. A biological information analysis shows that the antigenic epitope has a high antigenic index and develops a curved linear spatial structure. Further, its 7 amino acids are completely within the 17 representative ALV-A strains, 4 are within the 11 ALV-K strains, and fewer are within the ALV-B/J/E strains. This study will significantly assist in a further understanding of the protein structure and function of ALV-A, and in the establishment of specific ALV-A detection methods.

The antiviral property of Sargassum fusiforme polysaccharide for avian leukosis virus subgroup J in vitro and in vivo

Avian Leukosis Virus Subgroup J (ALV-J) is an oncogenic retrovirus, mainly spread by vertical and horizontal transmission, which have caused severe losses in world poultry industry. Sargassum fusiforme polysaccharide (SFP), a marine algae sulfated polysaccharide, has attracted more attention due to its variously biological activities. In this study, the anti-ALV-J property of SFP was assessed in vivo and in vitro. The results demonstrated that different Mw of SFPs showed virustatic activity to ALV-J in vitro by combining with the virus when ALV-J adsorbed onto the host cells. When treated with SFPs, the ALV-J gene and protein expression reduced clearly and SFP-3 (Molecular weight 9 kDa) had the best antiviral effect. Results in vivo showed that the immunosuppression of the ALV-J infected chickens were relieved by SFP-3. Moreover, SFP-3 obviously inhibit the viral shedding and alleviated the organs damage caused by ALV-J. This study offered a new method for ALV-J treatment and enriched the potential application of SFP.

A Label-Free Electrochemical Immunosensor for Detection of the Tumor Marker CA242 Based on Reduced Graphene Oxide-Gold-Palladium Nanocomposite

As a tumor marker, carbohydrate antigen 24-2 (CA242) is a highly accurate and specific diagnostic indicator for monitoring pancreatic and colorectal cancers. The goal of this study was to create a novel label-free electrochemical immunosensor using a nanocomposite glassy carbon electrode for the detection of CA242. Graphene oxide (GO) and polyvinyl pyrrolidone were chosen as the dopants for the preparation of a high-performance reduced-GO-gold-palladium (rGO-Au-Pd) nanocomposite. RGO-Au-Pd was characterized using X-ray diffraction and transmission electron microscopy, revealing that the material exhibited superior electrochemical redox activity and electron transfer ability. The effects of the synthesis method, material concentration, reduction cycle, and pH were investigated to optimize the performance of the immunosensor. As a result of the catalytic activity and biocompatibility of rGO-Au-Pd, the prepared CA242 immunosensor displayed a wide linear range of detection from 0.001 U/mL to 10,000 U/mL with a detection limit of 1.54 × 10⁻³ U/mL and a sensitivity of 4.24 μA (log₁₀C_CA242)⁻¹. More importantly, the immunosensor exhibited satisfactory reproducibility and selectivity when detected CA242 in PBS or human serum. The results of our study provide a platform for the development of novel bioassays for use in early cancer diagnosis and promote the application of biosensing technology in the medical field.

Versatile Application of Nanocellulose: From Industry to Skin Tissue Engineering and Wound Healing

Nanocellulose is cellulose in the form of nanostructures, i.e., features not exceeding 100 nm at least in one dimension. These nanostructures include nanofibrils, found in bacterial cellulose; nanofibers, present particularly in electrospun matrices; and nanowhiskers, nanocrystals, nanorods, and nanoballs. These structures can be further assembled into bigger two-dimensional (2D) and three-dimensional (3D) nano-, micro-, and macro-structures, such as nanoplatelets, membranes, films, microparticles, and porous macroscopic matrices. There are four main sources of nanocellulose: bacteria (Gluconacetobacter), plants (trees, shrubs, herbs), algae (Cladophora), and animals (Tunicata). Nanocellulose has emerged for a wide range of industrial, technology, and biomedical applications, namely for adsorption, ultrafiltration, packaging, conservation of historical artifacts, thermal insulation and fire retardation, energy extraction and storage, acoustics, sensorics, controlled drug delivery, and particularly for tissue engineering. Nanocellulose is promising for use in scaffolds for engineering of blood vessels, neural tissue, bone, cartilage, liver, adipose tissue, urethra and dura mater, for repairing connective tissue and congenital heart defects, and for constructing contact lenses and protective barriers. This review is focused on applications of nanocellulose in skin tissue engineering and wound healing as a scaffold for cell growth, for delivering cells into wounds, and as a material for advanced wound dressings coupled with drug delivery, transparency and sensorics. Potential cytotoxicity and immunogenicity of nanocellulose are also discussed.

Antiviral Activity against Avian Leucosis Virus Subgroup J of Degraded Polysaccharides from Ulva pertusa

Avian Leukosis Virus Subgroup J (ALV-J), a retrovirus of avian, has caused enormous economics losses to poultry industry around the world. Polysaccharides from marine algae are featured diversity bioactivities. To find the potential effect to prevent ALV-J spread, in this study, polysaccharides from Ulva pertusa (UPPs) and four low molecular weight (Mw) U. pertusa polysaccharides (LUPPs) were prepared and their functions on ALV-J were investigated. Firstly, LUPPs were obtained by hydrogen peroxide (H2O2) oxidative degradation. The effects of degradation conditions on Mw of the UPP were also investigated. Results showed that the H2O2 oxidative degradation method could degrade UPP effectively, and the degradation was positively related to H2O2 concentration and temperature and negatively to pH. The chemical characteristics of UPP and LUPPs were also determined. Afterwards, the anti-ALV-J activity of the polysaccharides were carried out in vitro. Results showed that UPP and LUPPs could inhibit ALV-J and LUPP-3 and Mw of 4.3 kDa exerted the strongest suppression. The action phase assay showed that LUPP-3 could bind with the viral particles and prevented ALV-J adsorption onto the host cells. And the ALV-J relative gene and gp85 protein expression were significantly suppressed after being administration with LUPP-3. Therefore, the low Mw polysaccharides from U. pertusa have great potential as an anti-ALV-J drug alternative.

A new electrochemical immunosensor for sensitive detection of prion based on Prussian blue analogue

Based on Co-Co Prussian blue analogue (Co-Co PBA), a novel immunosensor has been developed for sensitive detection of prion protein (PrP^C). Gold nanoparticles (AuNPs)-modified Co-Co PBA nanocubes (PBA-AuNPs) worked as a support of the antibody (Ab2) of PrP^C to obtain Ab2-PBA-AuNPs composite and also as the signal source for PrP^C assay. When PrP^C existed, Ab2-PBA-AuNPs could be introduced to the surface of another antibody of PrP^C (Ab1) modified AuNPs/GC electrode (the gold nanoparticles-modified glassy carbon electrode) through specific antigen-antibody interaction between PrP^C and its antibodies to form the Ab1-PrP^C-Ab2 sandwich structure. With the help of KOH aqueous solution, PBA generated a large DPV response. The response peak currents were linear with the logarithmic values of the concentration of PrP^C in the range from 0.075pgmL^-1 to 100pgmL^-1 with the detection limit of 0.014pgmL^-1. Also, the immunosensor showed good selectivity and reproducibility. Based on the simple sensing structure and good analytical performance, the developed immunosensor may have promising applications in practical assay of infectious isoform of prion (PrP^Sc) and other proteins by simply changing the related antibody.

Degradation of Polysaccharides from Grateloupia filicina and Their Antiviral Activity to Avian Leucosis Virus Subgroup J

In this study, polysaccharides from Grateloupia filicinia (GFP) were extracted and several low molecular weight (Mw) G. filicina polysaccharides (LGFPs) were prepared by the hydrogen peroxide (H₂O₂) oxidation method. Additionally, the effect of different experimental conditions on the degradation of GFP was determined. Results showed that the GFP degradation rate was positively related to H₂O₂ concentration and temperature, and negatively related to pH. Chemical analysis and Fourier transform infrared spectra (FT-IR) of GFP and LGFPs showed that the degradation caused a slight decrease of total sugar and sulfate content. However, there was no obvious change for monosaccharide contents. Then, the anti-ALV-J activity of GFP and LGFPs were determined in vitro. Results revealed that all of the samples could significantly inhibit ALV-J and lower Mw LGFPs exhibited a stronger suppression, and that the fraction LGFP-3 with Mw 8.7 kDa had the best effect. In addition, the reaction phase assays showed that the inhibition effect was mainly because of the blocking virus adsorption to host cells. Moreover, real-time PCR, western-blot, and IFA were further applied to evaluate the blocking effects of LGFP-3. Results showed that the gene relative expression and gp85 protein for LGFPS-3 groups were all reduced. Data from IFA showed that there was less virus infected cells for 1000 and 200 μg/mL LGFPS-3 groups when compared to virus control. Therefore, lower Mw polysaccharides from G. filicina might supply a good choice for ALV-J prevention and treatment.