查找使用阿拉丁产品的科研文献

A simple and sensitive electrochemical immunosensor based on thiol aromatic aldehyde as a substrate for the antibody immobilization

Youming Shen,Youyu Zhang,Meiling Liu,Xiaoyin Liu,Huan Guo,Xiangyang Zhang,Chunxiang Zhang,Haitao Li,Shouzhuo Yao

In this work, a novel sulfur-containing compound with aldehyde groups was synthesized, which was used to immobilize antibodies through the covalent bonding of the aldehyde groups with amino groups, in which no additional chemical cross-linker is required. Human IgG was used as a model analyte to fabricate the electrochemical immunosensor. Using the proposed immunosensor, IgG was detected within the range from 0.01 to 25   ng   mL −1 with a detection limit of 0.003   ng   mL −1 obtained by 3 S/N. The simple electrochemical immunosensor had a good specificity, stability and reproducibility.

A Fluidic Biosensor Based on a Phase-Sensitive Low-Coherence Spectral-Domain Interferometer

Cuixia Guo,Xiaojie Yang,Zhiyuan Shen,Jian-Ping Wu,Suyi Zhong,Yonghong He,Tian Guan,Fangyi Chen

A phase-sensitive fluidic biosensor based on a spectral-domain low-coherence interferometer is presented in this paper. With a fiber optic probe employing the common-path interferometric configuration, subnanometric changes in thickness of the molecular layers can be detected through phase analysis of the acquired interference signal from the sensor surface. Advantages of this biosensor include its picometer-scale thickness sensitivity, 13.9-ms time response, and tolerance to the fluctuation in concentration of the target solution. The capabilities of this biosensor in monitoring specific molecular binding and recognizing specific molecular was successfully demonstrated by using the reactions between the molecules of protein A and IgG. The calculated minimum detectable concentration of IgG is 0.11 µg/mL.Keywords:phase-sensitive;low-coherence spectral-domain interferometer;fluidic;immunoassays

Lateral flow immunoassay of Fe3O4@PMAA@IgG nanoprobe for quick detection of SARS-CoV-2 based on natural color

Fangjun Wu,Juan Sun,Zheng Nie,Fujie Lai,Xudong Yang,Shaoyang Chen,Yang Wang

In the context of the ongoing normalisation of the SARS-CoV-2, the number of patients infected with the new coronavirus remains high on an annual basis. It is therefore imperative that individuals have access to rapid and cost-effective diagnostic tests. Conventional diagnostic tests,such as Reverse Transcription-Quantitative Polymerase Chain Reaction(RT-QPCR), Enzyme-Linked Immunosorbent Assay(ELISA) are costly and cumbersome, impeding their application in single-sample detection. This study has developed a cost-effective lateral flow immunoassay that rivals the sensitivity and simplicity of ELISA and colloidal gold tests, facilitating rapid and affordable detection of SARS-CoV-2 antigen. The synthesis of Fe 3 O 4 particles with a diameter of approximately 150 nm was initially conducted via a solvothermal method. Subsequently, the preparation of Fe 3 O 4 @PMAA particles with carboxyl groups, was undertaken through a reflux precipitation polymerization. Finally, the above particles were coupled with mouse anti-coronavirus SARS-CoV-2 N protein IgG by standard NHS/EDC methods to obtain Fe 3 O 4 @PMAA@IgG nanoprobe. This nanoprobe was then used as an immunoconjugate pad for the detection of the SARS-CoV-2 nucleoprotein. The nanoprobe-based method demonstrated significant advantages in cost-effectiveness and timeliness (with an assay duration of only 1 min), costing approximately $0.13 per sample. When used for SARS-CoV-2 antigen detection, this cost represents only 0.02% of that of RT-QPCR and 0.05% of that of ELISA.The detection limit of the lateral flow immunoassay is (0. 5 ng/mL).

Adsorption of IgG and BSA on Two Chromatographic Resins—Poly(ethylenimine)-4FF Resin and Tetrapeptide-poly(ethylenimine)-4FF Resin

Yu-Ming Fang,Dong-Qiang Lin,Shan-Jing Yao

Poly(ethylenimine) (PEI) as a long flexible chain has been well used in protein chromatography with the advantages of high spatial utilization and “chain delivery” effect. In this work, two resins, i.e., poly(ethylenimine)-4FF resin (PEI-4FF resin) and Ac-YFRH-PEI-4FF resin by grafting tetrapeptide to PEI-4FF resin, were prepared for the protein adsorption and chromatographic separation. The pH-dependent adsorption properties of PEI-4FF resin and Ac-YFRH-PEI-4FF resin were discovered by getting the data of adsorption capacities of bovine serum albumin (BSA) and immunoglobulin G (IgG) under different pH conditions and buffer systems. The results showed high binding capacities of BSA on PEI-4FF resins across a range of pH values (5.0–8.9) with almost very little adsorption of IgG over a pH range from 5.0 to 8.0, indicating that IgG could be separated by flow-through method using PEI-4FF resin. Since PEI has the advantage of having many flexible branched chains and Ac-YFRH (Ac-Try-Phe-Arg-His) as a peptide ligand has the advantages of comparatively high stability and low immunogenicity for antibody adsorption, Ac-YFRH-PEI-4FF resins were prepared by using PEI as the spacer arm and Ac-YFRH as the peptide ligand. The isotherm adsorption of the Ac-YFRH-PEI-4FF resin showed that the maximum binding capacity of IgG (qm = 123.6 mg/g resin, Kd = 0.10 mg/mL) was far more than that of BSA (qm = 62.0 mg/g resin, Kd = 0.25 mg/mL) at pH 8.0. Meanwhile, this tetrapeptide resin also showed high binding capacity of BSA (qm = 131.0 mg/g resin, Kd = 0.05 mg/mL) and low binding capacity of IgG (qm = 2.0 mg/g resin, Kd = 0.01 mg/mL) at pH 5.0, indicating that the separation of BSA and IgG could be achieved with the big differences in adsorption behaviors.

Effects of Interfacial Properties of a Surface Modified Surface Plasmon Resonance Chip on Protein Immobilization Performance

Juan WU,Yanbin JIANG,Lishi WANG,Qiang ZENG

In order to confirm the correlation between interfacial properties of modified surface plasmon resonance (SPR) chips and their SPR responses to immobilized anti-IgG, SPR chips were modified by mercaptoundecanoic acid, poly(ethylene glycol) diacrylate (PEG), PEG-based copolymer and cyclodextrin coupled PEG using self-assembled or radical polymerization methods. The resulting interfacial properties such as film thickness and hydrophilicity were characterized by AFM, elliptic polarization scanners and contact angle meter. Immobilization of human IgG on the modified chips was achieved by EDC/NHS activation through an amide bond. The association between fixed IgG and free anti-IgG was reflected by the variation of SPR responses and the binding ability was evaluated by Langmuir isotherms. As observed, the adsorption between IgG and anti-IgG was affected by the interfacial properties of different modifiers, such that a chip with a thinner and more hydrophilic layer may result in a higher SPR response, producing a larger adsorption equilibrium constant for protein interaction.

Establishing a high sensitivity detection method for SARS-CoV-2 IgM/IgG and developing a clinical application of this method

Chunyan Zhang,Lei Zhou,Hao Liu,Sibing Zhang,Yaping Tian,Junli Huo,Fei Li,Yao Zhang,Bo Wei,Dan Xu,Jinwei Hu,Jiayi Wang,Yuxuan Cheng,Wenjie Shi,Xiuli Xu,Jianping Zhou,Peipei Sang,Xudong Tan,Weiwei Wang,Minjie Zhang,Bin Wang,Yujun Zhou,Kan Zhang,Kunlun He

Liposomal Co-Delivery of Antigenic Glycan LDNF and α-GalCer Elicits Potent IgG Responses with Potential for Anti-Helminth Immunity

Qianghui Tang,Qiang Chao,Jianfeng Zhang,Bei Wang,Song Zhao,Kun Yang

Introduction Parasitic worms (helminths) express unique antigenic glycans such as LDN and LDNF, which are absent in mammalian hosts and represent promising vaccine targets. However, free glycans typically elicit weak immune responses and require multivalent delivery and adjuvants to enhance immunogenicity and promote antibody class-switching.Methods Two cetyl-modified glycan antigens (LDN-C16 and LDNF-C16) were chemo-enzymatically synthesized and incorporated into liposomes, either with or without the invariant natural killer T cell agonist α-GalCer as an adjuvant. C57BL/6 mice were immunized subcutaneously. Humoral immune responses were evaluated by ELISA using glycan-BSA conjugates. Cytokine levels were measured in sera from immunized mice. Additionally, the ability of immune sera to recognize native helminth proteins was assessed by Western blotting using protein extracts from adult Schistosoma japonicum worms.Results Liposomal delivery of LDNF, but not LDN, induced potent glycan-specific antibody responses. Adding α-GalCer slightly reduced total antibody titers but enhanced response quality by shifting IgM to IgG, increasing IgG1 and decreasing IgG2b. Liposomal LDNF with α-GalCer also boosted in vivo cytokine responses, increasing IL-4 and IL-10 while maintaining IFN-γ. The induced antibodies showed high specificity for LDNF and effective recognition of native schistosome worm proteins.Conclusion Liposomal presentation of the LDNF epitope strongly enhances immunogenicity. Co-delivery with α-GalCer effectively promotes class-switched IgG responses, modulates cytokine profiles, and improves recognition of native parasite antigens. This liposomal glycan-antigen delivery strategy represents a promising approach for the development of anti-helminth vaccines targeting glycan epitopes.

Highly sensitive fluorescent lateral flow immunoassay based on core–shell PS@Dip@SiO2 microspheres for SARS-CoV-2 IgG detection

Sun Juan,Nie Zheng,Wu Fangjun,Lai Fujie,Chen Shaoyang,Wang Yang,Jiang Yong

A highly sensitive fluorescent lateral flow immunoassay (LFIA) was developed for SARS‑CoV‑2 IgG detection. Polystyrene (PS) microspheres were synthesized via emulsion polymerization, doped with dipyridamole (Dip), and coated with a protective silica (SiO 2 ) shell through a sol–gel process. After amine functionalization, the SARS‑CoV‑2 nucleocapsid (N) protein was covalently immobilized onto the microsphere surface using EDC/NHS chemistry, yielding PS@Dip@SiO 2 –N fluorescent probes. The LFIA strip enabled one‑step detection within 15 min. Under optimized conditions (N protein conjugation concentration of 40 µg/mL), the strip showed excellent specificity with no cross‑reactivity against other human coronaviruses (NL63, OC43, 229E). Quantitative determination based on the T/C grayscale ratio fitted the Hill equation (R² = 0.9782). The detection limit for SARS‑CoV‑2 IgG was 10 ng/mL, approximately two orders of magnitude lower than that of a commercial colloidal gold‑based LFIA strip. This platform provides a rapid, sensitive, and low‑cost solution for point‑of‑care serological screening of COVID‑19. Graphical abstract

Dual-recognition fluorescent immunochromatographic strip based on IgG and antibiotic for smartphone-assisted detection of Staphylococcus aureus in food samples

Kai-Xin Qin,Rui-Ting Bai,Xiao-Xue Zhao,Yang Yang,Xian-Hua Wang,Linyi Dong

Staphylococcus aureus (S. aureus), a bacterium ubiquitously distributed in natural environments and commonly colonizing human skin and mucous membranes, is a highly pathogenic agent that poses significant threats to human health. Consequently, the development of accurate and efficient detection methods for S. aureus is of utmost importance in clinical and public health contexts. Flow chromatography is widely used for the detection of S. aureus because of its short detection time and low demand for labor and material resources. Herein, we fabricated test strip sensors with dual recognition of IgG and cefradine (CE) for S. aureus detection, achieving a high degree of specificity and a low detection limit (102 CFU·mL⁻¹). Meanwhile, by capturing images of the T-line with a smartphone to quantify its fluorescence intensity, this method enabled both qualitative and quantitative detection of S. aureus. The detection process was simple, which required no personnel training, and takes only 40 minutes, offering fast and convenient analysis. To prove the practicability, we applied the test strip sensors to orange juice , milk and beef, and they were highly sensitive (orange juice: 102 CFU·mL-1, milk: 104 CFU·mL-1, beef: 104 CFU·mL-1), reproducible (RSD<5.4%) .Therefore, we believe the test strip sensors have a bright application prospect in the field of rapid detection of S. aureus.

A PDA/AuNPs/PDANPs sandwich structure modified fiber optic SPR biosensor for high precision and specific detection of Rabbit IgG

Tengfei Yang,Pengxiang Chang,Ailing Zhang,Fei Liu,Honggang Pan,Junfeng Wang,Guangxiao Cao,Mingxuan Zheng,Zhao Zhang

A PDA/AuNPs/PDANPs sandwich structure modified optical fiber surface plasmon resonance (SPR) biosensor for specific detecting of rabbit IgG were proposed in this paper. On the proposed sensor, polydopamine (PDA), gold nanoparticles (AuNPs) and polydopamine nanoparticles (PDANPs) were sequentially deposited to form a multilayer hybrid structure. The refractive index (RI) sensitivity of the sensor has been significantly enhanced through the strong coupling effects of SPR and localized surface plasmon resonance. The sensor achieves an RI sensitivity of3009.58 nm/RIU, representing a 3-fold increase compared to the original SPR sensor. In addition, due to the high surface activity and large specific surface area of PDANPs, the biosensitivity of the sensor has been enhanced. The sensor demonstrated specific detection of Rabbit IgG with a biosensitivity of 0.9157 nm/(μg/mL) and limit of detection (LOD) of 22 ng/mL. These findings indicate that the prepared sensor can specifically detect Rabbit IgG with high precision and a low LOD. Therefore, this PDA/AuNPs/PDANPs sandwich structure modified biosensor has great potential in clinical detection and other bio-detection fields.

The development of an electrochemical immunosensor using a thiol aromatic aldehyde and PAMAM-functionalized Fe3O4@Au nanoparticles

Chunxiang Zhang,Guangyu Shen,Youming Shen,Xiangyang Zhang

In this work, a novel thiol aromatic aldehyde was synthesized. It can be used as a substrate to directly immobilize antibodies on a gold electrode, for which no additional chemical cross-linker is required. It was also applied as a linker to prepare Fe 3 O 4 @Au/PAMAM/Ab 2 –horseradish peroxidase bioconjugates , which introduced multiple enzymes onto a sensing interface owing to the high surface-to-volume ratio of Fe 3 O 4 @Au nanoparticles and many functional groups of the poly(amidoamine) dendrimer (PAMAM). The introduced multiple enzymes greatly improved the detection signal. Under optimal conditions, the proposed electrochemical immunosensor exhibited desirable performance for detection of IgG in the range 0.005–50   ng   ml −1 with a detection limit of 3   pg   ml −1 based on a signal-to-noise ratio of 3. It has great potential application in the area of clinical analysis.

Microshell Arrays Enhanced Sensitivity in Detection of Specific Antibody for Reduced Graphene Oxide Optical Sensor

Wen-Shuai Jiang,Wei Xin,Shao-Nan Chen,Cun-Bo Li,Xiao-Guang Gao,Lei-Ting Pan,Zhi-Bo Liu,Jian-Guo Tian

Protein-protein interactions play an important role in the investigation of biomolecules. In this paper, we reported on the use of a reduced graphene oxide microshell (RGOM)-based optical biosensor for the determination of goat anti-rabbit IgG. The biosensor was prepared through a self-assembly of monolayers of monodisperse polystyrene microspheres, combined with a high-temperature reduction, in order to decorate the RGOM with rabbit IgG. The periodic microshells allowed a simpler functionalization and modification of RGOM with bioreceptor units, than reduced graphene oxide (RGO). With additional antibody-antigen binding, the RGOM-based biosensor achieved better real-time and label-free detection. The RGOM-based biosensor presented a more satisfactory response to goat anti-rabbit IgG than the RGO-based biosensor. This method is promising for immobilizing biomolecules on graphene surfaces and for the fabrication of biosensors with enhanced sensitivity.Keywords:reduced graphene oxide;microshells;optical sensor;goat anti-rabbit IgG;real-time;label-free