Aptamer Conjugated Indium Phosphide Quantum Dots with a Zinc Sulphide Shell as Photoluminescent Labels for Acinetobacter baumannii.

Acinetobacter baumannii is a remarkable microorganism known for its diversity of habitat and its multi-drug resistance, resulting in hard-to-treat infections. Thus, a sensitive method for the identification and detection of Acinetobacter baumannii is vital. However, current methods used for the detection of pathogens have not improved in the past decades and suffer from long process times and low detection limits. A cheap, quick, and easy detection mechanism is needed. In this work, we successfully prepared indium phosphide quantum dots with a zinc sulphide shell, conjugated to a targeting aptamer ligand, to specifically label Acinetobacter baumannii. The system retained both the photophysical properties of the quantum dots and the folded structure and molecular recognition function of the aptamer, therefore successfully targeting Acinetobacter baumannii. Confocal microscopy and transmission electron microscopy showed the fluorescent quantum dots surrounding the Acinetobacter baumannii cells confirming the specificity of the aptamer conjugated to indium phosphide quantum dots with a zinc sulphide shell. Controls were undertaken with a different bacteria species, showing no binding of the aptamer conjugated quantum dots. Our strategy offers a novel method to detect bacteria and engineer a scalable platform for fluorescence detection, therefore improving current methods and allowing for better treatment.

Cadmium-Free Quantum Dots as Fluorescent Labels for Exosomes.

Quantum dots are attractive alternatives to organic fluorophores for the purposes of fluorescent labeling and the detection of biomarkers. They can also be made to specifically target a protein of interest by conjugating biomolecules, such as antibodies. However, the majority of the fluorescent labeling using quantum dots is done using toxic materials such as cadmium or lead due to the well-established synthetic processes for these quantum dots. Here, we demonstrate the use of indium phosphide quantum dots with a zinc sulfide shell for the purposes of labeling and the detection of exosomes derived from the THP-1 cell line (monocyte cell line). Exosomes are nano-sized vesicles that have the potential to be used as biomarkers due to their involvement in complex cell processes. However, the lack of standardized methodology around the detection and analysis of exosomes has made it difficult to detect these membrane-containing vesicles. We targeted a protein that is known to exist on the surface of the exosomes (CD63) using a CD63 antibody. The antibody was conjugated to the quantum dots that were first made water-soluble using a ligand-exchange method. The conjugation was done using carbodiimide coupling, and was confirmed using a range of different methods such as dynamic light scattering, surface plasmon resonance, fluorescent microscopy, and Fourier transform infrared spectroscopy. The conjugation of the quantum dot antibody to the exosomes was further confirmed using similar methods. This demonstrates the potential for the use of a non-toxic conjugate to target nano-sized biomarkers that could be further used for the detection of different diseases.

Expression of the human TRIM14 and its mutant form (P207L) promotes apoptosis in transgenic loaches.

The tripartite-motif (TRIM)14 protein, one of the TRIM family members, was shown to participate in the antiviral and antibacterial defence. Besides, it appears to play an essential role in the processes of oncogenesis. In some types of human tumour cells, TRIM14 has been shown to inhibit apoptosis, while in others-the overexpression of TRIM14 promotes apoptosis. However, whether TRIM14 mediates apoptosis in the normal cells remains unknown. In the present study, we investigated the possible participation of the human TRIM14 gene and its mutant form (620C > T) in the induction of apoptosis in the transgenic larvae loach Misgurnus fossilis L. We observed that the expression of both forms of TRIM14 gene was accompanied by the increase of the frequency of pyknotic nuclei in fish embryos compared to control groups. Accordingly, using the TUNEL assay, the enhanced apoptosis was revealed upon expression of both forms of TRIM14 gene. The transcription of proapoptotic genes (bax, tp53, and casp9) was significantly increased in transgenic loaches expressing human wild-type TRIM14, but remained unchanged upon expression of its mutant form. In addition, the transcription of c-myc was upregulated in transgenic loaches expressing both forms. Thus, it can be assumed that during embryonic development TRIM14 has a proapoptotic effect on the cells via the activation of c-myc, tp53, and bax genes. Apparently, the mutant TRIM14 directs apoptosis via c-myc by p53-independent mechanism.