Determination of DNA Hybridization on Gold Nanoparticle Conjugated Polystyrene Particle Thin Film Using Attenuated Total Reflectance Fourier Transform Infrared Spectroscopy

Effective gene delivery using size dependant nano core-shell in human cervical cancer cell lines by magnetofection

Biocompatible magnetic nanoparticles are effective for gene delivery in vitro and in vivo transfection. These mediators are mainly used to deliver drugs and genes. It can also be used as probes to diagnose and treat various diseases. Magnetic nanoparticles, primarily iron oxide nanoparticles, are used in various biological applications. However, preparing stable and small-size biocompatible core-shell is crucial in site direct gene delivery. In the present study, superparamagnetic iron oxide nanoparticles were synthesized using the chemical co-precipitation method and were functionalized with starch to attain stable particles. These SPIONs were coated with polyethylenimine to give a net positive charge. The fluorescent plasmid DNA bound to the SPIONs were used as a core shell for gene delivery into the HeLa cells via magnetofection. UV-Visible Spectrophotometry analysis showed a peak at 200 nm, which confirms the presence of FeO nanoparticles. The Scanning Electron Microscopy images revealed the formation of spherical-shaped nanoparticles with an average size of 10 nm. X-ray Diffraction also confirmed FeO as a significant constituent element. Vibrating Sample Magnetometry ensures that the nanoparticles are superparamagnetic. Atomic Force Microscopy images show the DNA bound on the surface of the nanoparticles. The gene delivery and transfection efficiency were analyzed by flow cytometry. These nanoparticles could effectively compact the pDNA, allowing efficient gene transfer into the HeLa cell lines.

New insight into the mechanism by which antifreeze peptides regulate the physiological function of Streptococcus thermophilus subjected to freezing stress

INTRODUCTION

Antifreeze peptides regulate the physiological functions of frozen cells and even their apoptosis; however, the mechanisms by which antifreeze peptides regulate these processes remain unclear, although the interactions between cell membranes and ice are well known to be important in this process.

OBJECTIVES

Our study aims to investigate how antifreeze peptides regulate cell physiological functions during the freezing process.

METHODS

We investigated the cryoprotective effect of rsfAFP on the physiological functions of S. thermophilus under freezing stress by measuring cellular metabolism activity, intracellular enzyme activity, cell membrane characterization, and cell apoptosis. The mechanism by which rsfAFP impacts S. thermophilus physiological functions under freezing stress was investigated using multispectral techniques and cryo-TEM.

RESULTS

We show that a recombinant antifreeze peptide (rsfAFP) interacts with the extracellular capsular polysaccharides and peptidoglycan of Streptococcus thermophilus and ice to cover the outer layer of the membrane, forming a dense protective layer that regulates the molecular structure of extracellular ice crystals, which results in reduced extracellular membrane damage, depressed apoptosis and increased intracellular metabolic activity. This interaction mechanism was indicated by the fact that S. thermophilus better maintained its permeability barrier, membrane fluidity, membrane structural integrity, and cytoplasmic membrane potential during freezing stress with rsfAFP treatment.

CONCLUSION

These results provide new insights into the mechanism by which rsfAFP regulates frozen cellphysiological functionsand apoptosis under freezing stress.

Rapid detection of SARS-CoV-2 viral nucleic acids based on surface enhanced infrared absorption spectroscopy

Efficient point-of-care diagnosis of severe acute respiratory syndrome-corovavirus-2 (SARS-CoV-2) is crucial for the early control of novel coronavirus infections. At present, polymerase chain reaction (PCR) is primarily used to detect SARS-CoV-2. Despite the high sensitivity, the PCR process is time-consuming and complex which limits its applicability for rapid testing of large-scale outbreaks. Here, we propose a rapid and easy-to-implement approach for SARS-CoV-2 detection based on surface enhanced infrared absorption (SEIRA) spectroscopy. The evaporated gold nano-island films are used as SEIRA substrates which are functionalized with the single-stranded DNA probes for specific binding to selected SARS-CoV-2 genomic sequences. The infrared absorption spectra are analyzed using the principal component analysis method to identify the key characteristic differences between infected and control samples. The SEIRA-based biosensor demonstrates rapid detection of SARS-CoV-2, completing the detection of 1 μM viral nucleic acids within less than 5 min without any amplification. When combined with the recombinase polymerase amplification treatment, the detection capability of 2.98 copies per μL (5 aM) can be completed within 30 min. This approach provides a simple and economical alternative for COVID-19 diagnosis, which can be potentially useful in monitoring and controlling future pandemics in a timely manner.