Synthesis of PDA-Mediated Magnetic Bimetallic Nanozyme and Its Application in Immunochromatographic Assay.

Immunochromatographic assay (ICA) is widely applied in various fields. However, severe matrix interference and weak signal output present major challenges in achieving accurate and ultrasensitive detection in ICA. Here, a polydopamine (PDA)-mediated magnetic bimetallic nanozyme (Fe3O4@PDA@Pd/Pt) with peroxidase-like activity was synthesized and used as a probe in ICA. The magnetic property of Fe3O4@PDA@Pd/Pt enabled effective magnetic enrichment of targets, thereby reducing the matrix interference in the sample. PDA coating on the magnetic bimetallic nanozyme was employed as a mediator and a stabilizer. It improved the catalytic ability and stability of the magnetic bimetallic nanozyme by providing more coordination sites for Pd/Pt growth and functional groups (-NH and -OH). In addition, the Pd/Pt bimetallic synergistic effect could further enhance the catalytic ability of the nanozyme. A method was developed by integrating Fe3O4, PDA, and Pd/Pt into Fe3O4@PDA@Pd/Pt as a probe in ICA. With the proposed method, human chorionic gonadotropin and Escherichia coli O157:H7 were successfully detected to be as low as 0.0094 mIU/mL in human blood serum and 9 × 101 CFU/mL in the milk sample, respectively. This method may be readily adapted for accurate and ultrasensitive detection of other biomolecules in various fields.

Human chorionic gonadotropin-mediated modulation of pregnancy-compatible peripheral blood natural killer cells in frozen embryo transfer cycles.

PROBLEM: To evaluate pregnancy-compatible phenotypic and functional changes in peripheral blood natural killer (pNK) cells during frozen embryo transfer (FET) cycles. METHOD OF STUDY: Peripheral blood was collected from patients undergoing frozen embryo transfer cycles at three separate time points in the cycle. pNK cell phenotype was analyzed by flow cytometry. Impact of pregnancy status on pNK cell cytotoxicity was characterized by two methods: (1) a three-dimensional endovascular tube formation approach and (2) a NK cell-specific K562 cell kill assay. RESULTS: A total of 35 patients were enrolled, 15 with clinical pregnancies and 20 with negative serum ß-hCG levels. Overall percentage of CD45+ CD3- CD56+ pNK cell did not change during the FET cycle. Pregnancy resulted in an increase in CD45+ CD3- CD56+ pNK cell population on the day of serum ß-hCG. pNK cells from non-pregnant patients caused significant tube disruption when compared to pregnant patients. Addition of serum from pregnant women reduced the tube disruption by pNK cells from non-pregnant patients. pNK cells from pregnant patients showed significantly lower cytotoxicity toward K562 cells in serum-free conditions. The addition of pregnancy serum decreased non-pregnant pNK cell cytotoxicity. Pregnancy status had no impact on VEGF-A and VEGF-C serum levels. Recombinant hCG added to non-pregnant serum resulted in a significant reduction in non-pregnant pNK cell-mediated K562 cell kill. CONCLUSION: There was no difference in pNK cell populations based on timing of the FET cycle. However, pregnancy increased the percentage of CD45+ CD3- CD56+ pNK cells. Additionally, pNK cells from pregnant women have reduced cytotoxicity and this is possibly mediated by hCG.

El efecto de la vitamina D3 y su relación. con el nivel de glóbulos blancos en las mujeres con aborto espontáneo, inyección intracitoplasmática de espermatozoides (ICSI) técnicao / The effect of vitamin D3 and its relationship with the level of white blood cells in women spontaneous miscarriage undergoing intracytoplasmic sperm injection (ICSI) technique

Women were studied undergoing ICSI for 84 who suffer non-pregnancy at the Fertility Center, Al-Sadr Medical Hospital in Najaf Governorate, Period between January 2019 and March 2020. WBC, Vitamin D3 and ß-hCG were measured, The pregnant women was divided into (Pregnancy Group, and spontaneous miscarriage) and then demonstrate the immunological effect on pregnancy of women after ICSI technique. Current resultsstudy showed a significant increase (p<0.05) in hormone level ß-hCG is evidence of the presence of high success rates for pregnancy in women who performed operations IVF, where the success rate at the beginning of the matter reached 61.9%, after which it decreased to 33.3% after the first three months due to the occurrence of spontaneous miscarriage of pregnant women due to various immunological and physiological reasons, a positive correlation between the level of ß-hCG and other parameters in the study (Vitamin D3 -WBC).Also The current resultsshowed a significant decrease in a groups (pregnancy failure) and the group (spontaneous miscarriage) compared with the control group (continued pregnancy) in relation to the level of vitamin D3 Also, The current results showed a significant increasein (pregnancy failure) and (spontaneous miscarriage) compared with control groups (continuation of pregnancy) in relation WBC numbers, and the present study founds a negative relationship between the level of vitamin D3 and WBC.

Intrauterine administration of autologous hCG- activated peripheral blood mononuclear cells improves pregnancy outcomes in patients with recurrent implantation failure; A double-blind, randomized control trial study.

We aimed to investigate the effect of intrauterine administration of autologous hCG-activated PBMCs in RIF women with low Th-17/Treg cell ratio. 248 women with a history of implantation failure volunteered to receive PBMC-therapy. After immunologic consultation and doing flow cytometry analysis, 100 women with at least three IVF/ET failure who had low Th-17/Treg ratio in comparison with healthy control were enrolled in this study. These 100 patients were randomly divided into two groups as PBMC receiving (n = 50) and controls (n = 50). Then PBMCs were obtained from patients and treated with hCG for 48 h. Afterward, PBMCs were administered into the uterine cavity of the patient in the study group, two days before ET. The concentration of inflammatory cytokines was examined in the supernatant of cultured PBMCs after 2, 24, and 48 h of incubation using the ELISA method. The frequency of Th-17, Treg, and the Th-17/Treg ratio was significantly lower in RIF women than the healthy controls (P < 0.0001). The secretion of inflammatory cytokines was significantly higher after 48 h compared to 2 and 24 h (P < 0.0001). The pregnancy and live birth rate were significantly increased in women undergoing the PBMC-therapy compared to control (PBS-injecting) group (P = 0.032 and P = 0.047, respectively). The miscarriage rate was considerably lower in PBMC-therapy group (P = 0.029). Our findings suggest that intrauterine administration of autologous in vitro hCG-activated PBMCs improves pregnancy outcomes in patients with at least three IVF/ET failures.

Electrochemiluminescence immunoassay of human chorionic gonadotropin using silver carbon quantum dots and functionalized polymer nanospheres.

A composite, reduced graphene oxide (rGO) doped with silver nanoparticles (Ag NPs), was prepared by using binary reductants of sodium citrate and hydrazine hydrate. Carbon quantum dots (CQDs) synthesized by papaya peel combined with silver ions to form a CQDs-loaded silver nanoparticle (AgCQDs) nanocomposite. Polymer nanospheres (PNS) were generated via the infinite coordination polymer of ferrocene dicarboxylic acid and employed as carriers to load AgCQDs. The prepared AgCQDs@PNS-PEI has good biocompatibility and electrical conductivity and can be used as a matrix for the immobilization of a secondary antibody (Ab2). A sandwich-type electrochemiluminescence (ECL) immunosensor using AgCQDs@PNS-PEI nanocomposite as probe has been developed for the detection of human chorionic gonadotropin (HCG). The proposed immunosensor exhibits a linear range from 0.00100 to 500 mIU mL-1 and the detection limit is 0.33 µIU mL-1 (S/N = 3) under optimal conditions. The sensor exhibits excellent selectivity, good reproducibility, and high stability. These features demonstrate that the proposed method has promising potential for clinical protein detection and displays a new strategy to fabricate an immunosensor. Graphical abstract.

Human Chorionic Gonadotrophin: New Pleiotropic Functions for an "Old" Hormone During Pregnancy.

Human chorionic gonadotrophin (hCG) is the first specific molecule synthesized by the embryo. hCG RNA is transcribed as early as the eight-cell stage, and the blastocyst produces the protein before its implantation. hCG in the uterine microenvironment binds with its cognate receptor, luteinizing hormone/choriogonadotropin receptor (LHCGR), on the endometrial surface. This binding stimulates leukemia inhibitory factor (LIF) production and inhibits interleukin-6 (IL-6) production by epithelial cells of the endometrium. These effects ensure essential help in the preparation of the endometrium for initial embryo implantation. hCG also effects angiogenic and immunomodulatory actions as reported in many articles by our laboratories and other ones. By stimulating angiogenesis and vasculogenesis, hCG provides the placenta with an adequate maternal blood supply and optimal embryo nutrition during the invasion of the uterine endometrium. The immunomodulatory properties of hCG are numerous and important for programming maternal immune tolerance toward the embryo. The reported effects of hCG on uterine NK, Treg, and B cells, three major cell populations for the maintenance of pregnancy, demonstrate the role of this embryonic signal as a crucial immune regulator in the course of pregnancy. Human embryo rejection for hCG-related immunological reasons has been studied in different ways, and a sufficient dose of hCG seems to be necessary to maintain maternal tolerance. Different teams have studied the addition of hCG in patients suffering from recurrent miscarriages or implantation failures. hCG could also have a beneficial or a negative impact on autoimmune diseases during pregnancy. In this review, we will discuss the immunological impacts of hCG during pregnancy and if this hormone might be used therapeutically.

Human Chorionic Gonadotropin modulates CXCL10 Expression through Histone Methylation in human decidua.

The process of implantation, trophoblast invasion and placentation demand continuous adaptation and modifications between the trophoblast (embryonic) and the decidua (maternal). Within the decidua, the maternal immune system undergoes continued changes, as the pregnancy progress, in terms of the cell population, phenotype and production of immune factors, cytokines and chemokines. Human chorionic gonadotropin (hCG) is one of the earliest hormones produced by the blastocyst and has potent immune modulatory effects, especially in relation to T cells. We hypothesized that trophoblast-derived hCG modulates the immune population present at the maternal fetal interface by modifying the cytokine profile produced by the stromal/decidual cells. Using in vitro models from decidual samples we demonstrate that hCG inhibits CXCL10 expression by inducing H3K27me3 histone methylation, which binds to Region 4 of the CXCL10 promoter, thereby suppressing its expression. hCG-induced histone methylation is mediated through EZH2, a functional member of the PRC2 complex. Regulation of CXCL10 expression has a major impact on the capacity of endometrial stromal cells to recruit CD8 cells. We demonstrate the existence of a cross talk between the placenta (hCG) and the decidua (CXCL10) in the control of immune cell recruitment. Alterations in this immune regulatory function, such as during infection, will have detrimental effects on the success of the pregnancy.

Comparison of three sample addition methods in competitive and sandwich colloidal gold immunochromatographic assay.

Immunochromatographic assays (ICAs) are mainstream point-of-care diagnostic tools in disease control, food safety, and environmental monitoring. However, the important issue pertaining to the influence of sample addition methods on the detection performance of ICAs has not been addressed, and related information is still lacking. Herein, we selected the well-accepted gold nanoparticles (AuNPs) as visual labels. AuNP-based ICA was then used to explore the effects of three sample addition methods (i.e., dry, wet, and insert) on the analytical performance of ICAs by using competitive and sandwich models. Under optimized conditions, the competitive ICA with clenbuterol as an analyte showed a negligible difference (p > 0.05) in the detection performance of the three methods in ideal phosphate buffered saline solution. However, the wet method demonstrated the worst performance in pork samples (p < 0.05). The sandwich ICA strip with human chorionic gonadotropin as an analyte revealed the significantly different analytical performances of the three approaches in phosphate buffer (PB) solution and spiked serum (p < 0.05). Two independent linear correlations were observed with the increase in target concentration. However, for the wet method in the PB solution and serum, the first linear correlation was at a relatively narrow target concentration range, and the second linear correlation was at a wider concentration range compared with those for the dry and insert methods. Our findings demonstrated that sample addition methods slightly influence competitive ICAs (p > 0.05) but remarkably affect sandwich ICAs (p < 0.05). We believe that this study can further explain the differences in detection results for the same target analyte in actual ICA detection. The results may serve as a reference in the rational selection of the appropriate sample addition method for succeeding ICA works.

All-in-one paper-based sampling chip for targeted protein analysis.

A novel all-in-one paper-based sampling concept for mass spectrometric bottom-up protein analysis is here demonstrated in a chip format integrating instant immunocapture, protein reduction, - alkylation and tryptic digestion all in-device. Conventional laboratory grade filter paper was coated with the polymer 2-hydroxyethyl methacrylate-co-2-vinyl-4,4-dimethyl azlactone (pHEMA-VDM) with a subsequent covalent immobilization of the monoclonal antibody E27 targeting the biomarker human chorionic gonadotropin (hCG). In-device protein reduction and alkylation was optimized with regards to reagent concentration and reaction pH. The sampling concept showed a high degree of performance between 10 and 1000 ng/mL (R2 > 0.99) by a five-point calibration curve sampled with hCG spiked to human serum samples and freshly collected whole blood samples, respectively. LOD (experimentally obtained at 100 pg/mL (2.64 pM/0.9 IU/L)) was demonstrated to be up to ten times lower with more than six times faster sample preparation than what has previously been reported for on-paper analysis of hCG in human serum samples.

Colorimetric immunoassay for human chorionic gonadotropin by using peroxidase-mimicking MnO2 nanorods immobilized in microplate wells.

A colorimetric immunoassay is described for the pregnancy marker human chorionic gonadotropin (HCG). The assay is based on the use of MnO2 nanorods acting as a peroxidase mimic. The nanorods were prepared by a hydrothermal method using EDTA as a template. They exhibit excellent peroxidase-like activity and stability. The nanorods were immobilized in a chitosan matrix in the wells of a BSA-modified microplate which then were further modified with streptavidin and biotinylated capture antibodies. The specific recognition between HCG and the antibodies in wells inhibit the peroxidase-like activity of the nanorods. Hence, the substrate 3,3',5,5'-tetramethylbenzidine is less efficiently catalytically oxidized by H2O2 to form a blue colored product. This results in a decrease in the absorbance at 652 nm. Response is linear in the 0.5 to 400 mIU·mL-1 HCG concentration range, and the detection limit is 0.36 mIU·mL-1 under optimized conditions. The method is highly specific, acceptably reproducible and stable. It was applied to the determination of HCG concentration in serum samples, and results were in good agreement with data obtained by the reference method." Graphical abstract Schematic presentation of colorimetric immunoassay for human chorionic gonadotropin (HCG) by using MnO2 nanorods with peroxidase-like activity immobilized in microplate wells. The specific recognition between HCG and the antibodies in wells inhibits the peroxidase-like activity of the nanorods. TMB: 3,3',5,5'-tetramethylbenzidine.

Human chorionic gonadotropin suspected heterophile interference investigations in immunoassays: a recommended approach.

Background Heterophile antibody (HAb) interferences in immunoassays can cause falsely elevated hCG concentrations leading to incorrect diagnosis and treatments options. When results are not consistent with the clinical findings, hCG HAb interference investigation may be requested by the physician. A retrospective evaluation of the frequency of HAb interference was performed among cases of physician-requested investigations and the effectiveness of commercially available blocking reagents to detect HAb interference in two immunoassay systems was evaluated. Methods One hundred and thirteen physician requests for hCG HAb investigation from 2008 to 2017 were reviewed. The primary method used to measure hCG was the Beckman Coulter Access Total ßhCG (2008-2010) and the Roche Elecsys HCG+ß (2014-2017). HAb investigation included measurement by two immunoassays before and after treatment of samples with heterophile blocking reagents and serial dilution studies. Results Five cases of HAb and HAb-like interference were identified. The interference frequency was 6.7% for the Beckman assay and 2.9% for the Roche assay. The presence of HAb was detected using heterophile blocking reagents and an alternative method in three cases. The other two cases were detected due to discrepant results with an alternative method and non-linear serial dilutions (HAb-like). Conclusions HAb interference was observed in the Beckman and the Roche assays. The heterophile blocking reagents failed to detect 40% of interference cases. Blocking reagents should not solely be used for these investigations. Multiple strategies including the use of serial dilutions and using an alternative platform are critical when troubleshooting interferences in hCG immunoassays.

Paper-based immunocapture for targeted protein analysis.

A novel sampling concept for mass spectrometric bottom-up targeted protein analysis is here demonstrated with polymeric sampling spots integrated with instant immunocapture for analysis of dried matrix spots. The polymers 2-hydroxyethyl methacrylate-co-2-vinyl-4,4-dimethyl azlactone (pHEMA-VDM) and pHEMA-Tosyl for covalent attachment of antibodies where investigated alongside with adsorption on non-treated filter paper. From performance characterization, the pHEMA-VDM had the best performance. The sampling spots demonstrated fast and easy sampling and preparation of human serum spiked with the biomarker human chorionic gonadotropin. The sampling spots enabled a detection limit of 1 ng/mL (26.4 pM) within a five point concentration curve from 1 ng/mL to 20 ng/mL (R2 = 0.97). The detection limit was demonstrated to be two times lower than previously demonstrated with standard DMPK-C sampling cards. A five point concentration curve from 100 ng/mL to 2000 ng/mL was also investigated (R2 = 0.998). Intra day precision was within 16% and 23% for concentration range 1 ng/mL to 20 ng/mL and 100 ng/mL to 2000 ng/mL, respectively. Inter day precision was within 20%. Accuracy was determined to 10% and 11% for 2.5 ng/mL and 20 ng/mL, respectively. The sampling spots were also demonstrated in a realistic setting where serum samples from two confirmed patients with testicular germ cell cancer were analyzed. These analyses confirmed an elevated hCG content in the sera of 418.5 ±â€¯4.2 ng/mL and 21 ±â€¯0.02 ng/mL hCG for patient one and two respectively.

Yeast Surface Display in Combination with Fluorescence-activated Cell Sorting Enables the Rapid Isolation of Antibody Fragments Derived from Immunized Chickens.

Yeast surface display emerged as a viable tool for the generation of human and murine monoclonal antibodies. This platform technology enables the careful definition of selection conditions, the potential for high-throughput screening, as well as the isolation of antibodies recognizing predefined epitopes. In this study, the applicability of yeast surface display in combination with fluorescence-activated cell sorting (FACS) for the isolation of antigen-specific chicken-derived antibodies is demonstrated. To this end, yeast-displayed recombinant antibody libraries from splenic mRNA of chickens immunized with epidermal growth factor receptor (EGFR) and human chorionic gonadotropin (hCG) were constructed as single chain variable fragments (scFv) by overlap extension polymerase chain reaction. A large number of antigen binding scFvs were readily isolated in a convenient screening process. Target-specific scFv-Fc molecules were produced as soluble proteins and more extensively characterized by confirming specificity, thermostability and high affinity. Essentially, we demonstrated the biotechnological applicability of binders directed against both antigens via specific cellular binding for EGFR and in the context of a lateral flow test by utilizing hCG-binding scFvs as capturing antibodies for pregnancy detection. Altogether, the described strategy using yeast surface display expands the repertoire of display methods for the isolation of antibodies resulting from chicken immunization campaigns.

Intrauterine infusion of human chorionic gonadotropin before embryo transfer in IVF/ET cycle: The critical review.

Intrauterine infusion of human chorionic gonadotropin (IUI-hCG) has been proposed to improve the outcome of in vitro fertilization-embryo transfer (IVF-ET), since it plays a critical role in synchronizing endometrial and fetal development. As the early mediator from embryo, hCG promotes the decidualization, angiogenesis, maternal immune tolerance, and trophoblast invasion, favoring successful implantation of embryo. Although multiple clinical trials have been conducted to verify the efficacy of IUI-hCG on IVF-ET outcome in recent years, the findings remained controversial. The difference in study design and population might be the cause to the different consequences after administration of hCG. More importantly, the endometrial receptivity, which might affect the efficacy of IUI-hCG, has not been assessed in women receiving this intervention. Selecting the right population suitable for IUI-hCG based on known etiology would be crucial in enhancing its efficacy and minimize any possible complications. Investigation of optimal indications for IUI-hCG should be highlighted in the future.

"Application of the ultra micro analytical system (SUMA) technology for the detection of urinary hCG in antidoping control".

The Ultra Micro Analytical System (SUMA) is an ELISA-based analytical platform, developed andmanufactured by the Cuban Immunoassay Center (IC), which is primarily used in clinical medicine applications. In this article, we describe the validation of the UMELISA HCG kits, which are based on SUMA, as a pre-screening procedure for the detection of human Chorionic Gonadotrophin (hCG) in urine for anti-doping purposes. Validation of assay performance parameters showed satisfactory results, in accordance with the criteria established by the World Anti-Doping Agency (WADA): intra-assay repeatability (6.7-9.7%), inter-assay reproducibility (7.8-10.5%), accuracy (91-98%), limit of detection (2.7 IU/L), and linearity. Relative sensitivity and specificity and Predictive Positive and Negative Values were used to evaluate the Efficacy showing a value of 97.6%. A Kappa Index analysis was applied to check agreement with the commercially available, reference assay COBASe411 (Roche), which is often applied in WADA-accredited anti-doping laboratories for measurement of intact (heterodimeric) hCG in urine. UMELISA HCG kits are considered as fit for anti-doping control purposes.

The re-awakening of hCG expression. Its role in the diagnosis of cervical squamous cell carcinoma.

OBJECTIVES: To compare immunohistochemical detection of Human chorionic gonadotropin (hCG) expression in paraffin embedded tissue of squamous cell carcinomas (SCC) and high grade squamous intraepithelial lesions (HSIL). METHODS: The samples in this retrospective study were obtained from the archives of the Pathology Department at Gaziantep University, Gaziantep, Turkey, over the period from January 2012 to September 2016. The study group consisted of 55 cases of SCC and 45 cases of HSIL. Tissue expression of hCG was detected by specific binding of anti-hCG antibody using an automated immunohistochemistry staining device. The categorical variables of intensity and coverage were analyzed statistically using Pearson Chi-Square test. RESULTS: High grade squamous cell lesions cases showed weak (84.4%, n=38/45) to no (15.6%, n=7/45) staining for hCG. None of the HSIL cases showed strong positivity. Strong positivity for hCG was detected in 90.9% (n=50/55) of SCC cases. CONCLUSION: Our study supports the association of ectopic hCG expression in cancer pathogenesis by demonstrating strong hCG immunoreactivity only in SCC cases. This finding can be helpful in supporting the diagnosis of invasive carcinoma in small or fragmented biopsies, which can on their own be confusing for the pathologists.

Enhancement of monoclonal antibody production after single and combination treatment of the hybridoma cells with all-trans retinoic acid and docosahexaenoic acid: An in vitro and in vivo study.

Murine hybridoma cells can produce monoclonal antibody (MAb) and the production of these antibodies in culture and peritoneum can be affected by different factors, including stimulants, inhibitors and supplements. Among these factors, the impact of micronutrients on the production of MAbs by mouse hybridoma cells has not fully been explored. In this study the murine hybridoma cells, M3C5, were cultured and treated with different concentrations of ATRA and DHA, alone, in combinations, and at different time of exposure. Then, changes in the production of MAb in culture medium were evaluated using ELISA. The hybridoma cells after single and combined treatment with ATRA, DHA and vehicles were IP injected to Balb/c mice and the changes in production of MAb in ascites were determined by ELISA. The results showed that single and combined treatment of ATRA and DHA elevated the production of MAb by hybridoma cells in both in vivo and in vitro. The production of MAb following in vitro single treatment with 1 µM of ATRA and 10 µM of DHA for 2 days was significantly increased. The in vitro effects of ATRA on increase of MAb production was obtained more than DHA. The MAb productions in combined treatment with 0.5 µΜ of ATRA plus 5 µΜ of DHA were significantly increased in in vivo and in vitro. However, the effect of DHA was obtained more significant in in vivo conditions. The results of this study showed for the first time that in vitro and in vivo treatments of ATRA and DHA could increase the production of MAb in mouse M3C5 hybridoma cells.

[Preparation of anti-hCG single domain antibody by antibody grafting technique using an antigen-binding peptide].

We used the antibody grafting technology to prepare anti-hCG single-domain antibodies on the basis of antigen-binding peptide to simplify the single-domain antibody preparation process and improving the biochemical stability of peptide. By using a universal single-domain antibody backbone (cAbBCII10), CDR1 or CDR3 was replaced by the hCG-binding peptide, and the grafted antibody gene sequences were synthesized and cloned into the prokaryotic expression vector pET30a(+) in fusion with a C-terminal sfGFP gene, i.e. pET30a-(His6)-cAbBCII10-CDR1/hCGBP1-sfGFP and pET30a-(His6)-cAbBCII10-CDR3/hCGBP3-sfGFP. The recombinant plasmids were transformed into E. coli BL21(DE3), and the fusion proteins were induced by IPTG. Highly soluble recombinant fusion proteins were obtained and purified by Ni-NTA affinity column. SDS-PAGE confirmed the purified protein as the target protein. The antigen-antibody binding assay showed that both the CDR1 and CDR3 grafted antibodies have hCG-binding activities. While the titers of the two grafted antibodies were similar, the binding affinity of CDR3 grafted antibody was higher than that of CDR1 grafted protein (about 2-3 times). The grafted antibodies retained the relatively high biochemical stability of the single-domain antibody backbone and were relatively thermostable and alkaline tolerant. The obtained antibodies also had a relatively high antigen-binding specificity to hCG. This study provided a reliable experimental basis for further optimization of anti-hCG single domain antibody by antibody grafting technology using antigen-binding peptide.

Enhancement of lateral flow assay performance by electromagnetic relocation of reporter particles.

Lateral flow assays (LFAs) are a widely-used point-of care diagnostic format, but suffer from limited analytical sensitivity, especially when read by eye. It has recently been reported that LFA performance can be improved by using magnetic reporter particles and an external magnetic field applied at the test line. The mechanism of sensitivity/performance enhancement was suggested to be concentration/retardation of reporter particles at the test line. Here we demonstrate an additional mechanism of particle relocation where reporter particles from the lower depths of the translucent LFA strip relocate to more-visible locations nearer to the top surface, producing a more visible signal. With a magnetic field we observed an improvement in sensitivity of human chorionic gonadotropin (hCG) detection from 1.25 ng/mL to 0.31 ng/mL. We also observed an increase of the color intensity per particle in test lines when the magnetic field was present.