Silver nanoparticle incorporation into flexible polyamide 12 membranes

To meet the demands of the market and society, the development of structured polymeric materials for application in the medical field is constantly increasing. Over the last decades, metallic silver nanoparticles have been explored due to their antimicrobial action. Here, we aimed to incorporate metallic silver nanoparticles into polymeric pieces obtained by additive manufacture via a chemical route involving silver nitrate and sodium borohydride. Polyamide 12 membranes were obtained by selective laser sintering, which was followed by washing, pretreatment, and functionalization with the alkoxides tetraethylorthosilicate and 3-aminopropyl tetraethoxysilane. For nanoparticle preparation and incorporation, a chemical route was tested under different conditions. The samples were characterized by techniques, such as X-ray diffraction, ultraviolet-visible spectroscopy, and infrared vibrational spectroscopy. Nanoparticle formation and incorporation into the polyamide 12 membranes were demonstrated by the absorbance band at 420 nm, which indicated that the particles measured between 10 and 50 nm in size; by the X-ray diffraction peaks at 2θ = 38, 44, and 64°, which are typical of crystalline silver; and by vibrational spectroscopy, which evidenced that the nanoparticles interacted with the polyamide 12 nitrogen groups. Polyamide 12 membranes containing metallic silver nanoparticles have promising biomedical applications as antimicrobial wound dressings associated with drug carriers.

Recent Trends and Developments in Conducting Polymer Nanocomposites for Multifunctional Applications

Electrically-conducting polymers (CPs) were first developed as a revolutionary class of organic compounds that possess optical and electrical properties comparable to that of metals as well as inorganic semiconductors and display the commendable properties correlated with traditional polymers, like the ease of manufacture along with resilience in processing. Polymer nanocomposites are designed and manufactured to ensure excellent promising properties for anti-static (electrically conducting), anti-corrosion, actuators, sensors, shape memory alloys, biomedical, flexible electronics, solar cells, fuel cells, supercapacitors, LEDs, and adhesive applications with desired-appealing and cost-effective, functional surface coatings. The distinctive properties of nanocomposite materials involve significantly improved mechanical characteristics, barrier-properties, weight-reduction, and increased, long-lasting performance in terms of heat, wear, and scratch-resistant. Constraint in availability of power due to continuous depletion in the reservoirs of fossil fuels has affected the performance and functioning of electronic and energy storage appliances. For such reasons, efforts to modify the performance of such appliances are under way through blending design engineering with organic electronics. Unlike conventional inorganic semiconductors, organic electronic materials are developed from conducting polymers (CPs), dyes and charge transfer complexes. However, the conductive polymers are perhaps more bio-compatible rather than conventional metals or semi-conductive materials. Such characteristics make it more fascinating for bio-engineering investigators to conduct research on polymers possessing antistatic properties for various applications. An extensive overview of different techniques of synthesis and the applications of polymer bio-nanocomposites in various fields of sensors, actuators, shape memory polymers, flexible electronics, optical limiting, electrical properties (batteries, solar cells, fuel cells, supercapacitors, LEDs), corrosion-protection and biomedical application are well-summarized from the findings all across the world in more than 150 references, exclusively from the past four years. This paper also presents recent advancements in composites of rare-earth oxides based on conducting polymer composites. Across a variety of biological and medical applications, the fact that numerous tissues were receptive to electric fields and stimuli made CPs more enticing.

Adsorption of cisplatin on oxidized graphene nanoribbons for improving the uptake in non-small cell lung carcinoma cell line A549

BACKGROUND

Graphene nanoribbons are nanosized strips of graphene with unique physicochemical properties like higher drug loading capacity and affinity for tumor cells.

OBJECTIVE

The principal objective of this research was to develop oxidized graphene nanoribbons (O-GNRs)-a based delivery system for cisplatin against non-small cell lung carcinoma cell line A549 by selective endocytosis.

METHOD

The O-GNRs prepared using various synthetic steps like oxidative unzipping were evaluated for various parameters like morphology, Fourier Transform Infrared (FTIR) study, % adsorption efficacy, Differential scanning colometric (DSC) study, and in-vitro efficacy studies.

RESULTS

Graphene nanoribbons with the length of 200-250 nm and width of 20-40 nm were obtained. The FTIR spectrum of drug-loaded O-GNRs exhibited a characteristic peak at 1550 cm-1 (-N-H group) of cisplatin. The DSC indicated the presence of sharp endothermic peaks at 59 ºC (PEG), 254 ºC (-C-NH3) and 308.6 ºC (-C-Pt). The % adsorption efficiency was found to be 74.56 ± 0.798% with in-vitro release in controlled manner (63.36 % ± 0.489 %) for 24 h.

CONCLUSION

The nanoformulation showed an average inhibition of 22.72% at a lower dose of cisplatin (> 25%) by passive targeting cell line A549 by DNA alkylation. In the near future, graphene-based systems will establish potential nanosystems in cancer treatment due to the additive effect of graphene with various therapeutic agents.

Nano-Graphene Oxide-supported APTES-Spermine, as Gene Delivery System, for Transfection of pEGFP-p53 into Breast Cancer Cell Lines

PURPOSE

Genetic diseases can be the result of genetic dysfunctions that happen due to some inhibitory and/or environmental risk factors, which are mostly called mutations. One of the most promising treatments for these diseases is correcting the faulty gene. Gene delivery systems are an important issue in improving the gene therapy efficiency. Therefore, the main purpose of this study was modifying graphene oxide nanoparticles by spermine in order to optimize the gene delivery system.

METHODS

Graphene oxide/APTES was modified by spermine (GOAS) and characterized by FT-IR, DLS, SEM and AFM techniques. Then pEGFP-p53 was loaded on GOAS, transfected into cells and evaluated by fluorescent microscopy and gene expression techniques.

RESULTS

FT-IR data approved the GOAS sheet formation. Ninety percent of the particles were less than 56 nm based on DLS analysis. SEM analysis indicated that the sheets were dispersed with no aggregation. AFM results confirmed the dispersed structures with thickness of 1.25±0.87 nm. STA analysis showed that GOAS started to decompose from 400°C and was very unstable during the heating process. The first weight loss up to 200°C was due to the evaporation of absorbed water, the second one observed in the range of 200-550°C was assigned to the decomposition of labile oxygen- and nitrogen-containing functional groups, and the third one above 550°C was attributed to the removal of oxygen functionalities. In vitro release of DNA demonstrated the efficient activity of the new synthesized system. Ninety percent of the cells were transfected and showed the GFP under fluorescence microscopy, and TP53 gene was expressed 51-fold in BT-20 cells compared to β-actin as the reference gene. Flow cytometry analysis confirmed the apoptosis of the cells rather than necrosis.

CONCLUSION

It could be concluded that the new synthesized structure could transfer a high amount of the therapeutic agent into cells with best activity.

Preparation of hydrophobic epoxy-polydimethylsiloxane-graphene oxide nanocomposite coatings for antifouling application

Epoxy-polydimethylsiloxane-graphene oxide (EPG) nanocomposite coatings were successfully developed by loading different wt% of graphene oxide nanosheets (GNs) into an epoxy-hydroxy-terminated-polydimethylsiloxane (EP-hPD) matrix via a facile in situ preparation technique. The inclusion of GNs into EPN led to an increase in modulus of elasticity and tensile strength up to 1570.46 MPa and 31.54 MPa, respectively, in the case of 1 wt% loading of GNs in the EP-hPD matrix. Also, an increase in the water contact angle from 90.1° to 115.2°, 104.5° and 101.7° was discerned at 1, 3 and 5 wt% loadings of GNs respectively. Taber abrasion results demonstrated a decrease in abrasion loss by 33.3% at 1 wt% loading of GNs in comparison to the unreinforced coating. An improvement in the glass transition temperature (T_g) was observed from 63.5 °C for the neat sample to 77.6 °C, 76.3 °C and 71.6 °C for the 1, 3 and 5 wt% EPG nanocomposites, respectively. An inevitable enhancement in the properties of the nanocomposites was affirmed due to the synergistic effect of GNs dispersed within the EP-hPD blend matrix. The prominent findings of this work include a minimum corrosion rate of 0.73 × 10^-2 mm per year and upgradation in the antifouling performance of the nanocomposite coatings in comparison to the neat coating.

Methylene diphenyl diisocyanate (MDI) and toluene diisocyanate (TDI) based polyurethanes: thermal, shape-memory and mechanical behavior

MDI and TDI based polyurethanes with tunable mechanical and shape memory performance.

Multiple shape memory polymers based on laminates formed from thiol-click chemistry based polymerizations

This investigation details the formation of polymer network trilayer laminates formed by thiol-X click chemistries, and their subsequent implementation and evaluation for quadruple shape memory behavior. Thiol-Michael addition and thiol-isocyanate-based crosslinking reactions were employed to fabricate each of the laminate's layers with independent control of the chemistry and properties of each layer and outstanding interlayer adhesion and stability. The characteristic features of step-growth thiol-X reactions, such as excellent network uniformity and narrow thermal transitions as well as their stoichiometric nature, enabled fabrication of trilayer laminates with three distinctly different glass transition temperatures grouped within a narrow range of 100 °C. Through variations in the layer thicknesses, a step-wise modulus drop as a function of temperature was achieved. This behavior allowed multi-step programming and the demonstration and quantification of quadruple shape memory performance. As is critical for this performance, the interface connecting the layers was evaluated in stoichiometric as well as off-stoichiometric systems. It was shown that the laminated structures exhibit strong interfacial binding and hardly suffer any delamination during cyclic material testing and deformation.