Inclusion Of Functional Groups Research Articles

DNA-Based Nanomaterials as Drug Delivery Platforms for Increasing the Effect of Drugs in Tumors

DNA nanotechnology has significantly advanced and might be used in biomedical applications, drug delivery, and cancer treatment during the past few decades. DNA nanomaterials are widely used in biomedical research involving biosensing, bioimaging, and drug delivery since they are remarkably addressable and biocompatible. Gradually, modified nucleic acids have begun to be employed to construct multifunctional DNA nanostructures with a variety of architectural designs. Aptamers are single-stranded nucleic acids (both DNAs and RNAs) capable of self-pairing to acquire secondary structure and of specifically binding with the target. Diagnosis and tumor therapy are prospective fields in which aptamers can be applied. Many DNA nanomaterials with three-dimensional structures have been studied as drug delivery systems for different anticancer medications or gene therapy agents. Different chemical alterations can be employed to construct a wide range of modified DNA nanostructures. Chemically altered DNA-based nanomaterials are useful for drug delivery because of their improved stability and inclusion of functional groups. In this work, the most common oligonucleotide nanomaterials were reviewed as modern drug delivery systems in tumor cells.

Effect of Electron Donating/Withdrawing Groups on Molecular Photoswitching of Functionalized Hemithioindigo Derivatives: a Computational Multireference Study

AbstractHemithioindigos are a versatile group of molecules with the ability to undergo double bond isomerisation upon light excitation. Using electronic structure theory, a detailed description of the photoisomerisation of hemithioindigo and five of its functionalized derivatives is reported. We use a combination of Density Functional Theory (DFT), approximate second order Coupled Cluster (CC2), and multireference methods such as the complete active space self‐consistent field (CASSCF) method to probe how isomerisation capabilities of functionalized hemithioindigo derivatives are affected by functionalisation with both electron donating and withdrawing groups. We demonstrate that important properties such as the thermal barrier, electronic absorption spectra and, to an extent, the mechanism can all show pronounced differences compared to the parent hemithioindigo molecule. Our results demonstrate how the inclusion of functional groups can have important effects on its photoisomerisation capabilities, which in turn, can influence the fate of these molecules upon light excitation and their utility as molecular switches.

On-surface formation of metal–organic coordination networks with C⋯Ag⋯C and C=O⋯Ag interactions assisted by precursor self-assembly

Surface-bound reactions are commonly employed to develop nanoarchitectures through bottom-up assembly. Precursor molecules are carefully designed, and surfaces are chosen with the intention to fabricate low-dimensional extended networks, which can include one-dimensional and two-dimensional structures. The inclusion of functional groups can offer the opportunity to utilize unique chemistry to further tune the bottom-up method or form novel nanostructures. Specifically, carbonyl groups open up new avenues for on-surface coordination chemistry. Here, the self-assembly and formation of an organometallic species via the thermally induced reaction of 3,6-dibromo-9,10-phenanthrenequinone (DBPQ) molecules were studied on Ag(100) and Ag(110). Low-temperature ultrahigh vacuum scanning tunneling microscopy revealed the room temperature formation of self-assemblies defined by hydrogen and halogen bonds on Ag(100). Following a thermal anneal to 300 °C, DBPQ on Ag(100) was found to form metal-organic coordination networks composed of a combination of organometallic species characteristics of Ullmann-like coupling reactions and carbonyl complexes. On Ag(110), the C-Br bonds were found to readily dissociate at room temperature, resulting in the formation of disordered organometallic species.

Influence of fiber–matrix adhesion and operating parameters on sliding wear performance of carbon fabric polyethersulphone composites

Abstract Carbon fabric (CF) reinforced polyethersulphone (PES) composites were fabricated using solution impregnation technique. Cold remote nitrogen–oxygen plasma (CRNOP) treatment to the CF was done to enhance the fiber–matrix adhesion. The developed composites based on treated and untreated CF were evaluated for tribological properties in sliding/adhesive wear mode under various operating conditions such as load, temperature and humidity. The composite with treated fabric excelled in all tribo-properties such as low coefficient of friction; high wear resistance and high limiting load. The fiber surface analysis was done with FESEM at higher resolution and lot of perforations on the treated surface was found to be one of the causes for enhanced fiber–matrix adhesion apart from inclusion of functional groups (Fourier transform infra red spectroscopy). Worn surface analysis was done by using SEM and EDAX technique to understand wear mechanism and investigate the fiber–matrix adhesion.

Gamma radiation treatment of carbon fabric to improve the fiber–matrix adhesion and tribo-performance of composites

Abstract Fiber–matrix interfacial bonding plays a critical role in controlling performance properties of the composites. Carbon fibers have major constraint of chemical inertness with the matrix and need surface treatment to improve the adhesion with the matrix. In this work, gamma irradiation technique with varying doses (100–300 kGy) was employed to carbon fabric (CF) to develop composites with polyetherimide (PEI) matrix based on impregnation method followed by compression molding. Composites were characterized for interlaminar shear strength (ILSS) and adhesive wear studies against mild steel disc under various loads. Improvement in the friction and wear properties was correlated with the improvement in ILSS as a result of CF treatment. Higher the dosing, higher was the enhancement in ILSS and tribo-performance of composites. Fourier transform infrared spectroscopy (FTIR) indicated inclusion of functional groups (mainly carbonyl). SEM studies on fibers indicated roughening of the surface as a consequence of treatment. Both these factors were thought to be responsible for enhancing the fiber–matrix interface. For in depth analysis, various techniques such as fiber tension test, adhesion test and Raman spectroscopy analysis of CF were also exploited.

Polyetherimide composites with gamma irradiated carbon fabric: Studies on abrasive wear

Abstract Interfacial adhesion between matrix and fiber is an important aspect in controlling performance properties of the composites. Carbon fibers are known for chemical inertness and hence limited wettability with the matrix and need prior surface treatment to improve its adhesion with the matrix. In this work, γ (gamma) irradiation technique with varying doses (0–300 kGy) was employed to the twill weave carbon fabric (CF) to develop composites with polyetherimide (PEI) matrix based on impregnation method followed by compression molding. Composites were characterized for interlaminar shear strength (ILSS) and abrasive wear performance. Improvement in the friction and wear properties was correlated with the improvement in ILSS as a result of CF treatment. Higher the treatment dose, higher was the ILSS and better was the tribo-performance. SEM studies on fibers indicated increased roughness of the surface as a consequence of treatment and dose. Fourier Transform Infrared Spectroscopy in Attenuated Total Reflectance (FTIR-ATR) mode indicated inclusion of functional groups (mainly carbonyl). Both these factors were responsible for enhancing the fiber–matrix interface. Various techniques such as adhesion test, fiber tension test and Raman spectroscopic analysis of CF were also exploited to analyze the influence of γ irradiation on CF.