Metal-Free Click Modification of Triple Bond-Containing Polyester with Azide-Functionalized Vegetable Oil: Plasticization and Tunable Solvent Adsorption.

Pressure from environmental nongovernmental organizations and the public has accelerated research on the development of innovative and renewable polymers and additives. Recently, biobased "green" plasticizers that can be covalently attached to replace toxic and migratory phthalate-based plasticizers have gained a lot of attention from researchers. In this work, we prepared an azide-functionalized soybean oil derivative (AzSBO) and investigated whether it can be used as a plasticizer. We covalently attached AzSBO to an electron-deficient triple-bond-containing polyester via a metal-free azide-alkyne click reaction. The thermal, mechanical, and solvent absorption behaviors of different amounts of azidated oil-containing polyesters were determined. Moreover, the plasticization efficiency of AzSBO was compared with the commercial plasticizers bis(2-ethylhexyl) phthalate and epoxidized soybean oil. At relatively lower AzSBO ratios, the degree of cross-linking was higher and thus the plasticization was less pronounced but the solvent resistance was significantly improved. As the ratio of AzSBO was increased, the glass transition temperature of the pristine polymer decreased up to 31 °C from 57 °C. Furthermore, the incorporation of AzSBO also improved the thermal properties and 20% AzSBO addition led to a 60 °C increase in the maximum weight loss temperature.

Fmoc-PEG Coated Single-Wall Carbon Nanotube Carriers by Non-covalent Functionalization: An Experimental and Molecular Dynamics Study.

Due to their structural characteristics at the nanoscale level, single-walled carbon nanotubes (SWNTs), hold great promise for applications in biomedicine such as drug delivery systems. Herein, a novel single-walled carbon nanotube (SWNT)-based drug delivery system was developed by conjugation of various Fmoc-amino acid bearing polyethylene glycol (PEG) chains (Mw = 2,000, 5,000, and 12,000). In the first step, full-atom molecular dynamics simulations (MD) were performed to identify the most suitable Fmoc-amino acid for an effective surface coating of SWNT. Fmoc-glycine, Fmoc-tryptophan, and Fmoc-cysteine were selected to attach to the PEG polymer. Here, Fmoc-cysteine and -tryptophan had better average interaction energies with SWNT with a high number of aromatic groups, while Fmoc-glycine provided a non-aromatic control. In the experimental studies, non-covalent modification of SWNTs was achieved by Fmoc-amino acid-bearing PEG chains. The remarkably high amount of Fmoc-glycine-PEG, Fmoc-tryptophan-PEG, and Fmoc-cysteine-PEG complexes adsorbed onto the SWNT surface, as was assessed via thermogravimetric and UV-vis spectroscopy analyses. Furthermore, Fmoc-cysteine-PEG5000 and Fmoc-cysteine-PEG12000 complexes displayed longer suspension time in deionized water, up to 1 and 5 week, respectively, underlying the ability of these surfactants to effectively disperse SWNTs in an aqueous environment. In vitro cell viability assays on human dermal fibroblast cells also showed the low cytotoxicity of these two samples, even at high concentrations. In conclusion, synthesized nanocarriers have a great potential for drug delivery systems, with high loading capacity, and excellent complex stability in water critical for biocompatibility.

Noncovalent Pyrene-Polyethylene Glycol Coatings of Carbon Nanotubes Achieve in Vitro Biocompatibility.

Single-walled carbon nanotubes (SWNTs) have become increasingly exploited in biological applications, such as imaging and drug delivery. The application of SWNTs in biological settings requires the surface chemistry to remain through the low solubility in aqueous media. In this research, a facile approach for the preparation of a polyethylene glycol (PEG)-coated SWNT-based nanocarrier was reported. We focused on the effect of PEG chain length and SWNT size on the cytotoxicity of PEG-coated SWNTs as a superior drug delivery nanovector. First, all-atom molecular dynamics (MD) simulations were employed to explore the stability and behavior of SWNT/pyrene-PEG (SWNT/Pyr-PEG) structures at a molecular level that is not attainable with experiments. The MD studies revealed that (i) π-π stacking interactions between the pyrene bearing PEG molecules and SWNTs are maintained in bulky situations, regardless of PEG molecular weight or SWNT size; (ii) pyrene molecules diffuse over the SWNT surface without detaching; and (iii) both short and long dynamic Pyr-PEG chains have the capability of effectively coating the SWNT surface. In light of the simulations, noncovalent (π-π stacking) assemblies of SWNT/Pyr-PEG with different molecular weights of PEG ( Mw = 2000, 5000, and 12000) were successfully fabricated and characterized. For longer PEG chains, more effective coating of SWNTs was obtained, resulting in more biocompatible SWNT/Pyr-PEG nanomaterials. The number of SWNTs coated by Pyr-PEG was highly dependent on the length of pyrene bearing PEG polymers. Moreover, the short SWNTs showed a higher amount of PEG coating with respect to the long SWNTs. Cell viability results demonstrated a dose-dependent cytotoxicity of coated SWNTs. Short SWNTs coated with longer PEG chains have low cytotoxicity to be used in in vivo studies.

Hand-Held Volatilome Analyzer Based on Elastically Deformable Nanofibers.

This study reports on a hand-held volatilome analyzer for selective determination of clinically relevant biomarkers in exhaled breath. The sensing platform is based on electrospun polymer nanofiber-multiwalled carbon nanotube (MWCNT) sensing microchannels. Polymer nanofibers of poly(vinylidene fluoride) (PVDF), polystyrene (PS), and poly(methyl methacrylate) (PMMA) incorporated with MWCNT exhibits a stable response to interferences of humidity and CO2 and provides selective deformations upon exposure of exhaled breath target volatilomes acetone and toluene, exhibiting correlation to diabetes and lung cancer, respectively. The sensing microchannels "P1" (PVDF-MWCNT), "P2" (PS-MWCNT), and "P3" (PMMA-MWCNT) are integrated with a microfluidic cartridge (µ-card) that facilitates collection and concentration of exhaled breath. The volatilome analyzer consists of a conductivity monitoring unit, signal conditioning circuitries and a low energy display module. A combinatorial operation algorithm was developed for analyzing normalized resistivity changes of the sensing microchannels upon exposure to breath in the concentration ranges between 35 ppb and 3.0 ppm for acetone and 1 ppb and 10 ppm for toluene. Subsequently, responses of volatilomes from individuals in the different risk groups of diabetes were evaluated for validation of the proposed methodology. We foresee that proposed methodology provides an avenue for rapid detection of volatilomes thereby enabling point of care diagnosis in high-risk group individuals.

Synthesis of Poly(vitamin C) through ADMET.

l-Ascorbic acid, commonly known as vitamin C and one of the most important biological compounds, is converted to a α,ω-diene monomer and subsequently polymerized for the first time by acyclic diene metathesis. Various experimental conditions such as polymerization medium, catalyst type, temperature, and monomer/catalyst ratio are studied. The moderate molecular weight polymers are achieved when the polymerizations are conducted under bulk conditions employing the Grubbs first generation (G1) or Hoveyda-Grubbs second generation catalyst (HG-2). In the solution case, on the other hand, low molecular weight polymers are obtained regardless of the catalyst type. Moreover, when the catalyst performances are compared, it is found that G1 produces the higher molecular weight as well as higher yield polymers with respect to the HG-2.