Liquid crystal biosensor based on AuNPs signal amplification for detection of human chorionic gonadotropin

The detection of human chorionic gonadotropin (HCG) allows for the determination of pregnancy and is thus crucial during early pregnancy testing. This study introduces a novel liquid crystal (LC) biosensor that employs Au nanoparticles (AuNPs) for signal amplification, thus enabling the detection of the HCG antigen in a micro, efficient, and cost-effective manner. The sensor design capitalizes on the unique properties of LC to facilitate the detection of HCG. In this research, the surface of the base substrate was first modified with material from DMOAP and APTES, and EDC/sulfo-NHS was used to couple AuNPs and β-hCG to form an AuNP-β-hCG conjugate that improves the coupling rate. The carboxyl group of the antibody was reacted with the aldehyde group of glutaraldehyde, which helps to fix the β-hCG antibody to the surface of the substrate. The HCG sample is immobilized on the surface of the substrate via antigen-antibody immunobinding. As signal amplifiers, the AuNPs can have a significant effect on the topology of the interface and the vertical order of the LC molecules, thus reducing the limit of detection. Finally, the limit of detection was calculated using the SPSS system, and the relationship between grey values and concentrations was also obtained. The detection limit for HCG can be as low as 1.916 × 10-3 mIU·mL-1 under ideal conditions. Compared to other detection methods for HCG, this structure provides a detection pathway with excellent sensitivity, low detection limits, and better specificity, thus offering a new idea for HCG or any other target requiring trace detection.

Black oxidized 3,3',5,5'-tetramethylbenzidine nanowires (oxTMB NWs) for enhancing Pt nanoparticle-based strip immunosensing

It is well known that 3,3',5,5'-tetramethylbenzidine (TMB) can be oxidized into blue or yellow oxidzed TMB (oxTMB) with the catalysis of peroxidase or mimetic enzyme of platinum nanoparticles (Pt NPs). In this work, we found that TMB could be oxidized into very stable black oxTMB with the catalysis of Pt NPs under certain chromogenic reaction conditions. For the first time, the black oxTMB was revealed to consist of nanowires (oxTMB NWs) with lengths of more than 100 μm and diameters of around 100 nm. The black oxTMB NWs showed very strong light absorption ability, thus could be used to greatly amplify the signal of Pt NP-based immunochromatography test strips (ICTSs). The Pt NP-based ICTSs with black oxTMB NW signal amplification have shown much better assay ability (linear response range and limit of detection) than those of gold nanoparticle (Au NP)-based ICTS, Pt NP-based ICTS, and Pt NP-based ICTS with blue or yellow oxTMB signal amplifications. The developed Pt NP-oxTMB NW-based ICTS has been demonstrated to be a new, accurate, sensitive, selective, and rapid immunosensor for quantitative detection of antigens such as human chorionic gonadotropin (HCG).

Pitfalls and tips in the diagnosis of ectopic pregnancy

Women of reproductive age with pelvic pain, vaginal bleeding, and a positive pregnancy test often require evaluation with pelvic ultrasound. In these situations, the primary role of pelvic ultrasound is to differentiate an ectopic pregnancy from either a normal or abnormal intrauterine pregnancy. While an accurately performed and interpreted pelvic ultrasound results in rapid diagnosis and management, numerous diagnostic pitfalls can lead to negative outcomes. Therefore, familiarity with the appropriate laboratory tests, sonographic technique, and imaging features of ectopic pregnancy is essential for all radiologists. We present a review of ectopic pregnancy cases from our institution with attention to common pitfalls and troubleshooting tips for physicians who perform and interpret pelvic ultrasounds. We also present recently published literature to aid in the management of first trimester pregnancy.