Efficient Quantification by X-ray Photoelectron Spectroscopy and Thermogravimetric Analyses of the One-Pot Grafting of Two Molecules on the Surface of Iron Oxide Nanoparticles.

In this study, Superparamagnetic iron oxide nanoparticles (SPION) were functionalized in one pot with two organic molecules. Firstly, polyethylene glycol (PEG) was mixed for 46 hours to improve steric stability and then, two hours before the end of the reaction, dimercaptosuccinic acid (DMSA) was added to provide negative charges and thiol groups for post-functionalization. Three different molecular weights of PEG were used (550, 2000 and 5000 g mol-1). The main goal of this study was to characterize and quantify accurately the surface of SPION functionalized with two organic molecules. We demonstrated the advantages of coupling thermogravimetric and X-ray photoelectron spectrometry analyses to distinguish accurately the covering of SPION's surface. Thanks to the combination of these two techniques we were able to distinguish the amount of DMSA and PEG on SPION regarding the length of the polymer. We also showed that the length of the PEG influenced the quantity of DMSA adsorbed. With the smallest PEG (550 g mol-1) the presence of DMSA is almost ten times higher than with the two other PEG used proving that long polymers prevent the adsorption of small molecules on the surface of SPION.

Nanomaterial Based Biosensors for Detection of Viruses Including SARS-CoV-2: A Review.

The COVID-19 outbreak led to an uncontrollable situation and was later declared a global pandemic. RT-PCR is one of the reliable methods for the detection of COVID-19, but it requires transporting samples to sophisticated laboratories and takes a significant amount of time to amplify the viral genome. Therefore, there is an urgent need for a large-scale, rapid, specific, and portable detection kit. Nowadays nanomaterials-based detection technology has been developed and it showed advancement over the conventional methods in selectivity and sensitivity. This review aims at summarising some of the most promising nanomaterial-based sensing technologies for detecting SARS-CoV-2. Nanomaterials possess unique physical, chemical, electrical and optical properties, which can be exploited for the application in biosensors. Furthermore, nanomaterials work on the same scale as biological processes and can be easily functionalized with substrates of interest. These devices do not require extraordinary sophistication and are suitable for use by common individuals without high-tech laboratories. Electrochemical and colorimetric methods similar to glucometer and pregnancy test kits are discussed and reviewed as potential diagnostic devices for COVID-19. Other devices working on the principle of immune response and microarrays are also discussed as possible candidates. Nanomaterials such as metal nanoparticles, graphene, quantum dots, and CNTs enhance the limit of detection and accuracy of the biosensors to give spontaneous results. The challenges of industrial-scale production of these devices are also discussed. If mass production is successfully developed, these sensors can ramp up the testing to provide the accurate number of people affected by the virus, which is extremely critical in today's scenario.

Influence of TAT-peptide polymerization on properties and transfection activity of TAT/DNA polyplexes.

Use of bioactive cationic peptides as gene carriers is limited by instability of their DNA complexes in vivo and by the loss of their biological activity due to undesired interactions of their bioactive parts with the DNA. To overcome the two major limitations, biodegradable high-molecular-weight form of TAT peptide (POLYTAT) sensitive to cellular redox-potential gradients was synthesized in this study by oxidative polycondensation. Physicochemical and transfection properties of DNA polyplexes based on POLYTAT were investigated and compared with polyplexes based on TAT polymer prepared by in situ template-assisted polymerization. Physicochemical properties of TAT-based polyplexes were affected by the molecular weight and method of polymerization of the TAT peptide. All TAT-based DNA polyplexes exhibited reduced cytotoxicity when compared with control polyethylenimine (PEI) polyplexes. Polyplexes based on both high-molecular-weight TAT polypeptides exhibited increased transfection efficiency compared to control TAT peptide but lower than that of PEI polyplexes. The evidence shows that transfection activity of TAT-based polyplexes is strongly dependent on the presence of chloroquine and therefore suggests that TAT polyplexes are internalized by an endocytosis. Overall, high-molecular-weight reducible polycations based on bioactive peptides has the potential as versatile carriers of nucleic acids that display low cytotoxicity and can prove to be especially beneficial in cases that require surface presentation of membrane-active or cell-specific targeting peptides.

Stimulus-controlled delivery of drugs and genes.

Macromolecular and colloidal systems used for the systemic delivery of drugs and genes promise to improve the way we treat and prevent numerous diseases. New generations of drug and gene delivery systems (DGDS) are being designed to enhance further efficiency by using a range of endogenous and external stimuli. This review focuses on three qualitatively distinct ways a stimulus can improve the efficiency of DGDS; namely, by selectively triggering release of the therapeutic agent from the DGDS, by modulating physical properties of DGDS and by favourably altering physiological properties of tissues to enhance DGDS transport. Recent developments in these areas are discussed to illustrate the potential of stimulus-controlled DGDS in the development of new generations of therapeutics.

Dispersion of titanate nanotubes for nanomedicine: comparison of PEI and PEG nanohybrids.

In the present study, we report the dispersion of titanate nanotubes (TiONts) via polymer grafting (PolyEthylene Glycol, PEG) or polymer adsorption (polyethylene imine, PEI) where different TiONts/polymer ratios have been investigated. The TiONts/PEI and TiONts/PEG nanohybrids were characterized by scanning and transmission electron microscopy as well as by zeta potential measurements in order to determine both their dispersion state and stability in water (at different pH for zetametry). The nature of the chemical bonds at the surface of these nanohybrids was investigated by Fourier-transformed infrared (FTIR) spectroscopy while the grafting densities of PEG on the nanotubes were quantified by thermogravimetric analyses (TGA). The nanohybrids reported here are promising tools for biotechnology applications due to their tubular morphology, their very good dispersion in water and the reactivity of their surface.

Temperature-reversible ultrathin films of N-isopropylacrylamide terpolymer adsorbed at the solid-liquid interface.

This article describes the stability and reversibility of ultrathin films of N-isopropylacrylamide (NIPA)-vinylimidazole (VI)-poly(ethylene glycol) (PEG) graft terpolymer adsorbed at the solid-liquid interface upon temperature cycling from below to above its phase transition temperature. The coil-to-globule and globule-to-coil phase transitions were captured by in situ fluid tapping atomic force microscopy (AFM). The film thickness of 1 nm was determined by AFM, X-ray photoelectron spectroscopy, and X-ray reflectivity. The concentration required to reach full coverage was found to be higher when adsorption occurred below the phase transition temperature. From 23 to 42 degrees C, the adsorbed NIPA terpolymer film was observed to be molecularly smooth, corresponding to the close-packed structure of flexible polymer coils. Particles containing between one and a few globules appeared abruptly at the interface at 42-43 degrees C, the same temperature as the solution phase transition temperature, which was determined by dynamic light scattering. The size of the particles did not change with temperature, whereas the number of particles increased with increasing temperature up to 60 degrees C. The particles correspond to the collapsed and associated state of the globules. The film morphological changes were found to be reversible upon temperature cycling. Subtle differences were observed between dip-coated and spin-coated films that are consistent with a higher degree of molecular freedom for spin-coated films. The study contributes to the fundamental understanding and applications of smart ultrathin films and coatings.

Temperature-controlled properties of DNA complexes with poly(ethylenimine)-graft-poly(N-isopropylacrylamide).

End-functionalized poly(N-isopropylacrylamide) (PNIPA) was synthesized by living free radical polymerization and conventional free radical polymerization and was used to prepare graft copolymers with poly(ethylenimine) (PEI). The copolymers exhibited lower critical solution temperature (LCST) behavior between 30 and 32 degrees C and formed complexes with plasmid DNA. The LCST of the copolymers in the DNA complexes increased slightly to approximately 34-35 degrees C. Cytotoxicity of the copolymers was evaluated by measuring lactate dehydrogenase (LDH) release from cells. The copolymers exhibited temperature-dependent toxicity, with higher levels of LDH release observed at temperatures above the LCST. Cellular uptake and transfection activity of the DNA complexes with the PEI-g-PNIPA copolymers were lower than those of the control PEI/DNA complexes at temperature below the LCST but increased to the PEI/DNA levels at temperatures above the LCST.