This study was aimed at establishing a novel visual detection method for SARS-CoV-2 based on magnetic beads(MBs)enrichment and Au@Pt nanoparticles(Au@PtNPs)enzyme catalysis.According to the double-antibody sandwich method,MBs conjugated with SARS-CoV-2 antibody 1 enriched SARS-CoV-2 antigen in samples.After magnetic adsorption,separation,and washing,the enriched antigen reacted with Au@PtNPs labeled with SARS-CoV-2 antibody 2,thereby forming an immune com-plex.After another round of magnetic adsorption and washing,the color change was catalyzed by Au@PtNPs in the chromogenic solu-tion,and the results were determined through comparison of color changes:a blue color change indicated a positive result,whereas no obvious color change indicated a negative result.The sensitivity and specificity of this method were evaluated.This study successfully established a visual detection method based on MBs enrichment and Au@PtNPs enzyme catalysis for targeting SARS-CoV-2 antigens.The method was able to detect SARS-CoV-2 antigens within 30 minutes and SARS-CoV-2nucleocapsid protein samples with antigen concentrations above 3.125 ng/mL.The method showed no cross-reactivity with seasonal influenza(H1N1)or influenza B virus nu-cleoprotein.The visual detection method established in this study,based on Au@PtNPs enzyme catalysis and MBs enrichment,has high specificity and sensitivity,is simple and quick to operate,and provides a new approach for rapid viral detection.

Hemoglobin A1c (HbA1c) has a unique structure that makes monoclonal antibody (mAb) preparation challenging. This study aims to develop a method for preparing HbA1c mAbs and establish a fluorescent immunochromatographic assay (FICA) for rapid detection of HbA1c. Three glycosylated peptides were synthesized and used to prepare complete antigens, which were identified by dot enzyme-linked immunosorbent assay (Dot-ELISA) and ultraviolet absorption spectroscopy. The complete antigens and natural HbA1c were used for cross-immunization of mice, and the optimal complete antigen was selected. The mouse with the highest serum titer was chosen for mAb preparation. The purity and specificity of the mAbs were verified, and a FICA method was developed. The optimal complete antigen, with a titer of 1:512 000, was successfully prepared and selected. Fusion with splenocytes resulted in four specific HbA1c antibodies (purity > 90%). The best antibody exhibited a binding constant (Ka) of 1.67×10¹⁰ L/mol with the antigen. Based on this antibody, a FICA method was successfully established, capable of producing results within 15 min. The method demonstrated a good linear range (3%-13% HbA1c, y=0.071 3x+0.005 6, R²=0.993 7), recovery rates of 98%-102%, precision < 10.00%, and no nonspecific reactions. Clinical testing of 210 samples showed positive agreement of 96.36%, negative agreement of 97.00%, and overall agreement of 96.68%. The receiver operating characteristic (ROC) curve analysis yielded an area under curve (AUC) of 0.980 9 [95% confidence interval (CI): 0.961 0-1.000 0], with high consistency verified in multicenter studies. We successfully developed a key technique for preparing HbA1c monoclonal antibodies and established a FICA method for rapid detection of HbA1c. It will provide an efficient and convenient detection method for the early diagnosis and long-term management of diabetes and its complications.
Antibodies, Monoclonal/biosynthesis* ; Animals ; Mice ; Glycated Hemoglobin/immunology* ; Mice, Inbred BALB C ; Humans ; Antibody Specificity ; Chromatography, Affinity/methods* ; Enzyme-Linked Immunosorbent Assay/methods* ; Female

This study was aimed at establishing a novel visual detection method for SARS-CoV-2 based on magnetic beads(MBs)enrichment and Au@Pt nanoparticles(Au@PtNPs)enzyme catalysis.According to the double-antibody sandwich method,MBs conjugated with SARS-CoV-2 antibody 1 enriched SARS-CoV-2 antigen in samples.After magnetic adsorption,separation,and washing,the enriched antigen reacted with Au@PtNPs labeled with SARS-CoV-2 antibody 2,thereby forming an immune com-plex.After another round of magnetic adsorption and washing,the color change was catalyzed by Au@PtNPs in the chromogenic solu-tion,and the results were determined through comparison of color changes:a blue color change indicated a positive result,whereas no obvious color change indicated a negative result.The sensitivity and specificity of this method were evaluated.This study successfully established a visual detection method based on MBs enrichment and Au@PtNPs enzyme catalysis for targeting SARS-CoV-2 antigens.The method was able to detect SARS-CoV-2 antigens within 30 minutes and SARS-CoV-2nucleocapsid protein samples with antigen concentrations above 3.125 ng/mL.The method showed no cross-reactivity with seasonal influenza(H1N1)or influenza B virus nu-cleoprotein.The visual detection method established in this study,based on Au@PtNPs enzyme catalysis and MBs enrichment,has high specificity and sensitivity,is simple and quick to operate,and provides a new approach for rapid viral detection.

Objective To develop engineered bacterial membrane biomimetic nanoparticles,Angiopep-2 E.coli membrane(ANG-2 EM)@PDA-PEI-CpG(ANG-2 EM@PPC),for efficient targeted drug delivery in the treatment of glioma,and to provide theoretical and technical support for targeted glioma therapy.Methods The expression of inaX-N-angiopep-2 engineered bacteria was constructed in the laboratory,and ANG-2 EM was obtained through lysozyme treatment and ultrafiltration centrifugation.ANG-2 EM@PPC was prepared by ultrasonication of bacterial membranes.Western blotting,agarose gel electrophoresis,and transmission electron microscopy(TEM)were used to verify the preparation.Particle size and Zeta potential were measured to investigate the stability of ANG-2 EM@PPC.Regarding cell experiments,CCK-8 assay was performed to determine the effect of ANG-2 EM@PPC on the survival rate of neutrophils.A flow chamber model was designed and constructed,and the uptake efficiency of neutrophils was measured by flow cytometry to investigate the hitchhiking efficiency of ANG 2 EM@PPC on neutrophils in inflammatory environment.Neutrophil death patterns were characterized by fluorescence microscopy,and flow cytometry and Western blotting were performed to examine neutrophil apoptotic bodies and the proportion of apoptotic bodies produced.Regarding animal experiments,a mouse model of in situ glioma was established and the inflammatory environment of tumor tissue was verified.The tumor model mice were divided into three groups,including DiR group,EM@PPC group,and ANG-2 EM@PPC group(all n=3),which were injected with DiR,ANG-2 EM@PDA-PEI-CpG,and EM@PDA-PEI-CpG via the tail vein,respectively(all at 10 mg/kg).Fluorescence images of organs and the brain were used to examine the distribution of the three formulations in vivo and in the brain.The tumor model mice were further divided into PBS group,PDA group,PC group,PPC group,EM@PPC group,and ANG-2 EM@PPC group(all n=4),which were injected with PBS,PDA,PC,PPC,EM@PPC,and ANG-2 EM@PPC injected via the tail vein,respectively(all at 10 mg/kg).Imaging was performed in vivo to observe tumor regression,and the survival rate and body mass of mice were measured to evaluate in vivo pharmacodynamics.TUNEL staining(brain tissue)and HE staining(brain,heart,liver,spleen,lung and kidney tissues)were performed to evaluate the therapeutic effect.Results The results of TEM showed successful preparation of engineered bacterial membrane biomimetic nanoparticles,with PPC exhibiting a distinct shell-core structure and a shell thickness of about 8.2 nm.Due to the coating of ANG-2 EM,the shell thickness of ANG-2 EM@PPC increased to about 9.6 nm,with a clear bacterial membrane layer on the surface.Stability was maintained for at least one week.ANG-2 EM@PPC had no significant effect on the activity of neutrophils according to the findings from the CCK-8 assay.Flow cytometry showed that ANG-2 EM@PPC uptake is enhanced in activated neutrophils and hitchhiking on neutrophils was more efficient in the stationary state than that in the flowing condition.Compared with the EM@PPC group,the neutrophil hitchhiking ability of the ANG-2 EM@PPC group was enhanced(uptake efficiency 24.9%vs.31.1%).Fluorescence microscopy showed that ANG-2 EM@PPC changed the death pathway of neutrophils from neutrophil extracellular traps-osis(NETosis)to apoptosis.Western blot confirmed the production of neutrophil apoptotic bodies,and flow cytometry showed that the production rate was as high as 77.7%.Animal experiments showed that there was no significant difference in the distribution of engineered bacterial membrane biomimetic nanoparticles in the organs(heart,liver,spleen,lungs,and kidney)in the DiR group,the EM@PPC gropu,and the ANG-2 EM@PPC group(P＞0.05),but there was higher distribution in the brain tissue in EM@PPC and ANG-2 EM@PPC groups compared to the DiR group(P＜0.05).Engineered bacterial membrane biomimetic nanoparticles crossed the blood-brain barrier(BBB),and exhibited high affinity to and internalization by neutrophils located in brain tumors.Compared with PBS,PDA,PC,and PPC groups,the survival rate and body mass of mice in the EM@PPC group were improved,tumor fluorescence intensity was weakened,and apoptotic cells were increased.These trends were even more prominent in the ANG-2 EM@PPC group.No abnormality was found in the HE staining of any group.Conclusion An ANG-2 EM@PPC nanodelivery system with inflammation response characteristics was successfully prepared,capable of crossing BBB and targeting the tumor inflammatory microenvironment to improve the anti-glioma efficacy.This study provides a new drug delivery strategy for glioma treatment and offers a new idea for targeted drug delivery in the non-invasive inflammatory microenvironments in other central nervous system diseases.

This study aims to establish a time-resolved fluorescence immunochromatography method for simultaneous determination of human papillomavirus (HPV) type 16 E6 and L1 protein concentrations. The amount of lanthanide microsphere-labeled antibodies, the concentration of coated antibodies, and the reaction time were optimized, and then a test strip for the simultaneous determination of the protein concentrations was prepared. The performance of the detection method was evaluated based on the concordance of the results from clinical practice. The optimal conditions were 8 μg and 10 μg of HPV16 L1 and E6-labeled antibodies, respectively, 1.5 mg/mL coated antibodies, and reaction for 10 min. The detection with the established method for L1 and E6 proteins showed the linear ranges of 5-320 ng/mL and 2-64 ng/mL and the lowest limits of detection of 1.78 ng/mL and 1.09 ng/mL, respectively. There was no cross reaction with human immunodeficiency virus (HIV), treponema pallidum (TP), or HPV18 E6 and L1 proteins. The average recovery rate of the established method was between 97% and 107%. The test strip prepared in this study showed the sensitivity, specificity, and diagnostic accuracy of 97.46%, 90.57%, and 95.32%, respectively, in distinguishing patients with cervical cancer and precancerous lesions from healthy subjects, with the area under the curve (AUC) of 0.980 1 and 95% Confidence Interval (CI) of 0.956 5 to 1.000 0. The time-resolved fluorescence immunochromatography combined with the test strips prepared in this study showed high sensitivity, high accuracy, simple operation, and rapid reaction in the quantitation of HPV16 E6 and L1 proteins. It thus can be used as an auxiliary method for the diagnosis and early screening of cervical cancer and precancerous lesions and the assessment of disease course.
Oncogene Proteins, Viral/immunology* ; Humans ; Chromatography, Affinity/methods* ; Female ; Human papillomavirus 16 ; Repressor Proteins/immunology* ; Capsid Proteins/immunology* ; Papillomavirus Infections/diagnosis* ; Fluorescence ; Uterine Cervical Neoplasms/virology*

A fusion protein containing a tetanus toxin peptide, a tuftsin peptide and a SARS-CoV-2S protein receptor-binding domain (RBD) was prepared to investigate the effect of intramolecular adjuvant on humoral and cellular immunity of RBD protein. The tetanus toxin peptide, tuftsin peptide and S protein RBD region were connected by a flexible polypeptide, and a recombinant vector was constructed after codon optimization. The recombinant S-TT-tuftsin protein was prepared by prokaryotic expression and purification. BALB/c mice were immunized after mixed with aluminum adjuvant, and the humoral and cellular immune effects were evaluated. The recombinant S-TT-tuftsin protein was expressed as an inclusion body, and was purified by ion exchange chromatography and renaturated by gradient dialysis. The renaturated protein was identified by Dot blotting and reacted with serum of descendants immunized with SARS-CoV-2 subunit vaccine. The results showed that the antibody level reached a plateau after 35 days of immunization, and the serum antibody ELISA titer of mice immunized with recombinant protein containing intramolecular adjuvant was up to 1:66 240, which was significantly higher than that of mice immunized with S-RBD protein (P < 0.05). At the same time, the recombinant protein containing intramolecular adjuvant stimulated mice to produce a stronger lymphocyte proliferation ability. The stimulation index was 4.71±0.15, which was significantly different from that of the S-RBD protein (1.83±0.09) (P < 0.000 1). Intramolecular adjuvant tetanus toxin peptide and tuftsin peptide significantly enhanced the humoral and cellular immune effect of the SARS-CoV-2 S protein RBD domain, which provideda theoretical basis for the development of subunit vaccines for SARS-CoV-2 and other viruses.
Adjuvants, Immunologic ; Aluminum ; Animals ; Antibodies, Neutralizing ; Antibodies, Viral ; COVID-19/prevention & control* ; COVID-19 Vaccines/genetics* ; Humans ; Mice ; Mice, Inbred BALB C ; Recombinant Proteins/genetics* ; SARS-CoV-2/genetics* ; Spike Glycoprotein, Coronavirus/genetics* ; Tetanus Toxin ; Tuftsin ; Vaccines, Subunit ; Viral Vaccines

Objective:To explore the biological effects of the targeted nanocomposite on breast cancer 4T1 cells with hepatitis B virus-like particles (HBc-RGD-VLPs) as a carrier for the delivery of anti-cancer drugs, and to provide a new theoretical basis for reducing the toxicity of doxorubicin (DOX) anti-tumor drugs and changing the path of administration.Methods:The hepatitis B pseudoviral particles prepared in the early stage of this laboratory enveloped DOX to form a target nanocomposite HBc-RGD-VLPs/DOX. The homogeneity and morphology of particles were detected by transmission electron microscopy and granular size analyzer, and applied to 4T1 cells for in vitro bioactivity exploration.Results:The structure of the target nanocomposite HBc-RGD-VLPs/DOX was detected by means of a transmission electron microscope, in a homogenous form, and the particle size distribution was 30-35 nm. In vitro cell experiments showed that the safety of target vector HBc-RGD-VLPs was better, the cell survival rate was more than 80%, and the HBc-RGD-VLPs/DOX after encapsulation had a significant inhibitory effect on the growth of 4T1 cells, and the effective inhibitory concentration (IC50) for half of 4T1 tumor cells was 1.445 g/ml. Fluorescence microscopy showed that HBc-RGD-VLP/DOX can be specifically targeted to tumor cells relative to the isolated DOX.Conclusions:The safety of target vector HBc-RGD-VLPs is better, HBc-RGD-VLPs/DOX showed good proliferation inhibitory effect and certain tumor-targeting effect on tumor cells.

Different fragments of SARS-CoV-2 nucleocapsid (N) protein were expressed and purified, and a fluorescence immunochromatography method for detection of SARS-CoV-2 total antibody was established. The effect of different protein fragments on the performance of the method was evaluated. The N protein sequence was analyzed by bioinformatics technology, expressed in prokaryotic cell and purified by metal ion affinity chromatography column. Different N protein fragments were prepared for comparison. EDC reaction was used to label fluorescence microsphere on the synthesized antigen to construct sandwich fluorescence chromatography antibody detection assay, and the performance was systemically evaluated. Among the 4 prepared N protein fragments, the full-length N protein (N419) was selected as the optimized coating antigen, N412 with 0.5 mol/L NaCl was used as the optimal combination; deleting 91-120 amino acids from the N-terminal of N412 reduced non-specific signal by 87.5%. the linear range of detection was 0.312-80 U/L, the limit of detection was 0.165 U/L, and the accuracy was more than 95%. A fluorescence immunochromatographic detection method for analysis of SARS-CoV-2 total antibody was established by pairing N protein fragments. The detection result achieved 98% concordance with the commercially available Guangzhou Wanfu test strip, which is expected to be used as a supplementary approach for detection of SARS-CoV-2. The assay could also provide experimental reference for improving the performance of COVID-19 antibody detection reagents.
Antibodies, Viral ; COVID-19 ; Chromatography, Affinity ; Fluorescent Antibody Technique ; Humans ; Microspheres ; SARS-CoV-2 ; Sensitivity and Specificity

A rapid and simple method to detect tumor markers in liver cancer was established by combining immunochromatography technique with fluorescent microsphere labeling. According to the principle of double antibody sandwich, the cytoskeleton-associated protein 4 (CKAP4) paired antibody was used as the labeled and coated antibody, and the goat anti-rabbit polyclonal antibody was used as the quality control line coated antibody in the preparation of the CKAP4 fluorescent immunochromatographic test strips. After the preparation, the test strips were evaluated on various performance indicators, such as linearity, precision and stability. The CKAP4 immunochromatographic strip prepared by time-resolved fluorescent microspheres had high sensitivity, and good specificity. Its precision was within 15%, recovery between 85% and 115%, and linear range between 25 and 1 000 pg/mL. The test strip could be kept stable at 37 °C for 20 days, and it correlated well with commercial ELISA kits. The CKAP4 fluorescence immunochromatography method can quantitatively detect the content of CKAP4 in serum. Furthermore, it is rapid, sensitive, simple, economical and single-person operation. This method has the potential of becoming a new method for the diagnosis and treatment of liver cancer.
Animals ; Antibodies ; metabolism ; Chromatography, Affinity ; Fluorescence ; Humans ; Liver Neoplasms ; diagnosis ; Membrane Proteins ; isolation & purification ; Molecular Diagnostic Techniques ; instrumentation ; methods ; Sensitivity and Specificity

To establish a time-resolved fluorescence immunochromatographic assay for quantitative determination of carbohydrate antigen 19-9 (CA19-9) in serum, we prepared CA19-9 test strips by integrating double-antibody sandwich method and fluorescence immunochromatography technique. Carboxy fluorescent microspheres and nitrocellulose membrane were used as carriers for labeling and coating CA19-9 pairing antibodies. We optimized the process by adjusting the amount of labeling and coating antibody. According to the linear range, lowest detection limit and precision, We evaluated the time-resolved fluorescence immunochromatographic assay of CA19-9. When the amount of labeled antibody was 80 μg for 20 μL fluorescent microspheres, and the concentration of coated antibody on the test line was 1.5 mg/mL, the optimal reaction time was 15 minutes. Assay linear range was 12.5 to 800 U/mL and the minimum detection limit was 6.32 U/mL. The Within-run and between-run coefficient of variation were less than 15%. Average recovery rate was 101%. By detecting 50 clinical samples in parallel with Roche electrochemical luminescence detection kit, correlation coefficient was 0.980 6. The experiment, initially established a fluorescence immunochromatographic detection method to quantitative detection of serum CA19-9, which has a good clinical application prospect.