Sol-Gel-Derived TiO2 and TiO2/Cu Nanoparticles: Synthesis, Characterization, and Antibacterial Efficacy.

This study reports on the antibacterial efficacy of both the TiO2 and TiO2/Cu nanoparticles prepared through the sol-gel method. The materials were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy-dispersive X-ray spectroscopy (EDS), X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), thermogravimetric analysis (TGA), and Brunauer-Emmett-Teller (BET) analysis. The SEM and TEM showed the spherical morphology of the nanoparticles, while EDX and XPS confirmed the incorporation of Cu into the TiO2 nanoparticles. The XRD confirmed the formation of the tetragonal anatase phase of TiO2/Cu while the FTIR revealed the functional groups linked to the doped TiO2 nanoparticles. The thermal stability of TiO2/Cu was found to be lower than pure TiO2. Moreover, TiO2 and the doped TiO2 nanoparticles were notably effective against Bacillus subtilis(B. subtilis) andEscherichia coli(E. coli); however, the addition of Cu to TiO2 did not have any effect on the antibacterial activity probably due to the lower weight content in the composites. Interestingly, the antibacterial efficiency was determined to be 90 and 80% against B. subtilis and E. coli, respectively.

Antibacterial Activity and Cytotoxicity Screening of Acyldepsipeptide-1 Analogues Conjugated to Silver/Indium/Sulphide Quantum Dots.

The continuous rise in bacterial infections and antibiotic resistance is the driving force behind the search for new antibacterial agents with novel modes of action. Antimicrobial peptides (AMPs) have recently gained attention as promising antibiotic agents with the potential to treat drug-resistant infections. Several AMPs have shown a lower propensity towards developing resistance compared to conventional antibiotics. However, these peptides, especially acyldepsipeptides (ADEPs) present with unfavorable pharmacokinetic properties, such as high toxicity and low bioavailability. Different ways to improve these peptides to be drug-like molecules have been explored, and these include using biocompatible nano-carriers. ADEP1 analogues (SC005-8) conjugated to gelatin-capped Silver/Indium/Sulfide (AgInS2) quantum dots (QDs) improved the antibacterial activity against Gram-negative (Escherichia coli and Pseudomonas aeruginosa), and Gram-positive (Bacillus subtilis, Staphylococcus aureus and Methicillin-resistant Staphylococcus aureus) bacteria. The ADEP1 analogues exhibited minimum inhibition concentrations (MIC) between 63 and 500 µM, and minimum bactericidal concentrations (MBC) values between 125 and 750 µM. The AgInS2-ADEP1 analogue conjugates showed enhanced antibacterial activity as evident from the MIC and MBC values, i.e., 1.6-25 µM and 6.3-100 µM, respectively. The AgInS2-ADEP1 analogue conjugates were non-toxic against HEK-293 cells at concentrations that showed antibacterial activity. The findings reported herein could be helpful in the development of antibacterial treatment strategies.

Development of a Versatile Half-Strip Lateral Flow Assay toward the Detection of Rift Valley Fever Virus Antibodies.

Rift Valley fever (RVF) is a mosquito-borne zoonotic disease that is caused by the Rift Valley fever virus (RVFV); Bunyaviridae: Phlebovirus. RVF disease can affect several different species, including ruminants, camels and humans and thus present a dual threat to public health and livestock food production in endemic regions. In livestock, the RVFV infection is characterised by an acute hepatitis, abortion and high mortality rates in new-born animals. The current RVF diagnostic techniques have shown good sensitivity. However, they require extensive sample processing and complex instrumentation. Owing to speed, low cost, ease of use, and most importantly, the ability to diagnose diseases at sites where they are managed, lateral flow immunoassays (LFIA) are the most widely used point-of-care (POC) tools for disease diagnosis. In this study, a lateral flow assay (LFA) device that is able to detect antibodies against RVFV, with a minimum detectable concentration of 0.125 mg/mL, was successfully developed. The LFA also successfully detected RVFV antibodies in reference RVFV sera. Protein A (ProA), which has the ability to bind immunoglobulins from different species, was used in the detection probe, giving the developed RVFV LFA potential for multi-species diagnosis.

Recombinant expression, purification, and characterization of full-length human BST-2 from Escherichia coli.

HIV-1 virus release from infected cells is blocked by human BST-2, but HIV-1 Vpu efficiently antagonises BST-2 due to direct transmembrane domain interactions that occur between each protein. Targeting the interaction between these two proteins is seen as viable for HIV-1 antiviral intervention. This study describes the successful over-expression and purification of a recombinant full-length human BST-2 from inclusion bodies using affinity and anion exchange chromatography. Two milligrams of purified full-length BST-2 were produced per litre of BL21 (DE3) T7 Express® pLysY E. coli culture. Far-UV circular dichroism validated the renaturing of the recombinant protein and retention of its secondary structure. Furthermore, through ELISA, a known human BST-2 binding partner, HIV-1 Vpu, was shown to bind to the renatured and purified protein, further validating its folding. To our knowledge this is the first report of the purification of a wild-type, full-length human BST-2 from Escherichia coli.