AIE-active polysiloxane-based fluorescent probe for identifying cancer cells by locating lipid drops.

Comparing with normal cells, Lipid droplets (LDs) of cancer cells show lower polarity and less quantity, which can be utilized as a marker for cancer diagnosis. However, the investigation of LDs in living cancer cells is restricted by the lack of effective molecular tools. Herein, we first reported a novel polysiloxane-based polymer fluorescent polar probe TR-1 with AIE properties, which realized the possibilities for locating LDs. It can aggregate in the LDs of cancer cells and show a stronger fluorescent signal to conduct cancer diagnosis. Moreover, the excellent photostability of TR-1 enable stable fluorescence to exhibit in cancer cells during effective time.

Binding Reaction Sites to Polysiloxanes: Unique Fluorescent Probe for Reversible Detection of ClO-/GSH Pair and the in Situ Imaging in Live Cells and Zebrafish.

PDMS is biocompatible, economically viable, transparent, and facile to handle and thus is suitable for fluorescent microscopy and biological research. However, there has been no report about polysiloxane-based fluorescent probes applied in bioimaging. In this report, a two-photon polysiloxane-based reversible luminescent probe (P1) was fabricated for the first time. P1 is a powerful tool for detecting the ClO-/GSH cycle in situ both in live cells and in zebrafish. This work demonstrates the potential of polysiloxane-based fluorescent probes for versatile in vivo or in vitro applications in the future.

Poly(silsesquioxanes) and poly(siloxanes) grafted with N-acetylcysteine for eradicating mature bacterial biofilms in water environment.

Bacteria adapt to their living environment forming organised biofilms. The survival strategy makes them more resistant to disinfectants, which results in acute biofilm-caused infections, secondary water pollution by biofilm metabolites and bio-corrosion. New, efficient and environmentally friendly strategies must be developed to solve this problem. Water soluble N-acetyl derivative of L-cysteine (NAC) is a non-toxic compound of mucolytic and bacteriostatic properties that can interfere with the formation of biofilms. However, it can also be a source of C and N for undesired microorganisms, as well as a reason for some adverse human health effects. Consequently, novel procedures are required, that would decrease the take-up of NAC but not reduce its antibacterial properties. We have grafted N-acetyl-l-cysteine onto linear poly(vinylsilsesquioxanes) and poly(methylvinylsiloxanes) via thiol-ene addition. Antibacterial activity of the obtained hybrid materials (respectively, NAC-Si-1 and NAC-Si-2) was determined against Escherichia coli, Pseudomonas aeruginosa and Staphylococcus aureus strains. Native NAC inhibited growth of planktonic cells for the tested bacteria at concentration 0.25% w/v. Inhibition with equivalent solutions of the polymer derivatives was less effective due to the lack of SH groups. However, the tested polymers proved to be quite effective in eradication of mature biofilms. Treatment with 1% w/v emulsions of the hybrid polymers resulted in a significant reduction of viable cells in biofilm matrix despite the absence of thiol moieties. The effect was most pronounced for mature biofilms of S. aureus eradicated with NAC-Si-2.

Electroactive polyurethane/siloxane derived from castor oil as a versatile cardiac patch, part I: Synthesis, characterization, and myoblast proliferation and differentiation.

Tissue-engineered cardiac patch aims at regenerating an infarcted heart by improving cardiac function and providing mechanical support to the diseased myocardium. In order to take advantages of electroactivity, a new synthetic method was developed for the introduction of an electroactive oligoaniline into the backbone of prepared patches. For this purpose, a series of electroactive polyurethane/siloxane films containing aniline tetramer (AT) was prepared through sol-gel reaction of trimethoxysilane functional intermediate polyurethane prepolymers made from castor oil and poly(ethylene glycol). Physicochemical, mechanical, and electrical conductivity of samples were evaluated and the recorded results were correlated to their structural characteristics. The optimized films were proved to be biodegradable and have tensile properties suitable for cardiac patch application. The embedded AT moieties in the backbone of the prepared samples preserved their electroactivity with the electrical conductivity in the range of 10-4 S/cm. The prepared films were compatible with proliferation of C2C12 and had potential for enhancing myotube formation even without external electrical stimulation. © 2015 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 104A: 775-787, 2016.

Preparation of polyhedral oligomeric silsesquioxane-based hybrid monolith by ring-opening polymerization and post-functionalization via thiol-ene click reaction.

A polyhedral oligomeric silsesquioxane (POSS) hybrid monolith was simply prepared by using octaglycidyldimethylsilyl POSS (POSS-epoxy) and cystamine dihydrochloride as monomers via ring-opening polymerization. The effects of composition of prepolymerization solution and polycondensation temperature on the morphology and permeability of monolithic column were investigated in detail. The obtained POSS hybrid monolithic column showed 3D skeleton morphology and exhibited high column efficiency of ∼71,000 plates per meter in reversed-phase mechanism. Owing to this POSS hybrid monolith essentially possessing a great number of disulfide bonds, the monolith surface would expose thiol groups after reduction with dithiothreitol (DTT), which supplied active sites to functionalize with various alkene monomers via thiol-ene click reaction. The results indicated that the reduction with DTT could not destroy the 3D skeleton of hybrid monolith. Both stearyl methylacrylate (SMA) and benzyl methacrylate (BMA) were selected to functionalize the hybrid monolithic columns for reversed-phase liquid chromatography (RPLC), while [2-(methacryloyloxy)ethyl]-dimethyl-(3-sulfopropyl)-ammonium hydroxide (MSA) was used to modify the hybrid monolithic column in hydrophilic interaction chromatography (HILIC). These modified hybrid monolithic columns could be successfully applied for separation of small molecules with high efficiency. It is demonstrated that thiol-ene click reaction supplies a facile way to introduce various functional groups to the hybrid monolith possessing thiol groups. Furthermore, due to good permeability of the resulting hybrid monoliths, we also prepared long hybrid monolithic columns in narrow-bore capillaries. The highest column efficiency reached to ∼70,000 plates using a 1-m-long column of 75µm i.d. with a peak capacity of 147 for isocratic chromatography, indicating potential application in separation and analysis of complex biosamples.

Poly(N-vinylpyrrolidone)-poly(dimethylsiloxane)-based polymersome nanoreactors for laccase-catalyzed biotransformations.

Laccases (Lac) are oxidizing enzymes with a broad range of applications, for example, in soil remediation, as bleaching agent in the textile industry, and for cosmetics. Protecting the enzyme against degradation and inhibition is of great importance for many of these applications. Polymer vesicles (polymersomes) from poly(N-vinylpyrrolidone)-block-poly(dimethylsiloxane)-block-poly(N-vinylpyrrolidone) (PNVP-b-PDMS-b-PNVP) triblock copolymers were prepared and investigated as intrinsically semipermeable nanoreactors for Lac. The block copolymers allow oxygen to enter and reactive oxygen species (ROS) to leave the polymersomes. EPR spectroscopy proved that Lac can generate ROS. They could diffuse out of the polymersome and oxidize an aromatic substrate outside the vesicles. Michaelis-Menten constants Km between 60 and 143 µM and turn over numbers kcat of 0.11 to 0.18 s(-1) were determined for Lac in the nanoreactors. The molecular weight and the PDMS-to-PNVP ratio of the block copolymers influenced these apparent Michaelis-Menten parameters. Encapsulation of Lac in the polymersomes significantly protected the enzyme against enzymatic degradation and against small inhibitors: proteinase K caused 90% less degradation and the inhibitor sodium azide did not affect the enzyme's activity. Therefore, these polymer nanoreactors are an effective means to stabilize laccase.

Enhanced in-vitro transfection and biocompatibility of L-arginine modified oligo (-alkylaminosiloxanes)-graft-polyethylenimine.

Branched poly ethylene imine (PEI) has been considered as the most efficient non-viral gene transfection agent. However, its clinical application is confined due to cytotoxicity. In the present study, we tried to enhance transfection efficiency and reduce toxicity of PEI by conjugating it with arginine modified oligo(-alkylaminosiloxane) [P(SiDAAr)n]. These derivatives were complexed with plasmid DNA and the resulting nanoparticles were characterised by dynamic light scattering (DLS), Atomic force microscopy (AFM), transmission electron microscopy (TEM), gel retardation and DNase I interaction to determine surface charge, particle size, morphology, complex formation and protection of DNA respectively. Among the four P(SiDAAr)n derivatives, nanoparticles of the P(SiDAAr)5/pDNA was found to exhibit 98% cell viability and around 150% more gene transfection than branched PEI in KB cell lines. Studies performed on transfection mechanism, using inhibitor study, clearly stated that the enhancement in transfection is due to the multiple pathways for cellular uptake which offered by the presence of uniformly spaced arginine moiety by oligo(-alkylaminosiloxane) arms. The nuclear localisation ability of the arginine residue was also established by using FITC stained nanoparticles on Hoechst 33342 stained nucleus.

Enantiomeric separation of alcohols and amines on a proline chiral stationary phase by gas chromatography.

A new chiral stationary phase for gas chromatography was prepared by covalently attaching a diproline chiral selector that has proven to be effective in liquid chromatography to a methylhydrosiloxane-dimethylsiloxane copolymer. With this new chiral stationary phase for GC, racemic aromatic alcohols could be resolved without derivatization. Racemic aromatic and aliphatic amines could also be resolved after derivatization of the amino groups with trifluoroacetic anhydride or isopropyl isocyanate. On this stationary phase, the isopropyl isocyanate derivatives of amines showed higher enantioselectivity than the trifluoroacetic anhydride derivatives. In both the enantiomeric separations of alcohols and derivatized amines, the aromatic racemic analytes showed higher enantioselectivities than their aliphatic analogs. Some of the alpha-amino and alpha-hydroxy aromatic acids could also be separated after derivatization to N-trifluoroacetyl methyl esters for amino acids or O-trifluoroacetyl methyl esters for hydroxyl acids.

Preparation and characterization of poly(methyltetradecylsiloxane) stationary phases immobilized by gamma radiation onto zirconized silica.

The preparation of stationary phases with enhanced chemical stability in alkaline eluents has been the principal objective of many chromatographers. New and improved silica substrates and advanced chemical modification methods are among the possibilities being investigated to reach this objective. The present work has evaluated these two possibilities for new stationary phases. First, the silica surface was modified by reaction with zirconium tetrabutoxide to produce zirconized silica particles having about 21% (w/w) of zirconium. Then poly(methyltetradecylsiloxane) (PMTDS) was immobilized onto this surface using different doses (50-120 kGy) of gamma radiation. These new phases were characterized using elemental analysis and infrared and solid-state (29)Si-nuclear magnetic resonance (NMR) spectroscopies. These new stationary phases presented column efficiencies of about 68,000 plates m(-1), symmetric peaks for apolar compounds and retention factors that depend on the irradiation dose and show improved stability in high pH mobile phases. The separation of several pharmaceuticals at pH 11 is presented.

Preparation and evaluation of a new class of gene transfer reagents: poly(-alkylaminosiloxanes).

We report the evaluation of poly(-alkylaminosiloxane) as a novel class of polycationic DNA carriers. Controlled hydrolysis of mono- and di-aminoalkylmethyldimethoxysilane provided a wide range of defined oligomeric mixtures. Basic hydrolysis conditions yielded mixtures composed mainly of cyclic and long linear oligomers, while under acidic conditions mainly short-linear oligomers were derived. They all efficiently interacted with plasmid DNA as revealed by electron microscopy and DNA retardation assays. However, only diamine-based oligomers prepared under basic conditions were able to mediate substantial levels of DNA transfection in human HeLa cells. SiDA1b, prepared by basic hydrolysis of 3-(2-aminoethylamino)propyl-methyl-dimethoxysilane, was found to be at least as efficient as the frequently used cationic transfection agents DOTAP and polyethylenimine (PEI). The transfection activity was sensitive to bafilomycin A1, suggesting a mechanism that depends on proton capture during the acidification process associated with endocytosis.

A modular synthetic approach toward exhaustively stereodiversified ligand libraries.

[structure] This report describes a modular approach to the synthesis of stereodiversified natural product-like libraries. Monomers 2 and 3 were coupled in parallel by silyl-tethered olefin metathesis to generate all 16 stereoisomers of cis-enediols 1. All 16 stereoisomers were incorporated into chimerae having flanking peptidic segments. These chimerae exhibited a broad range of hydrophobicities, raising the possibility that stereochemical variation might be used to tune the pharmacologic properties of small molecules.

Synthesis and characteristics of [60]fullerene polysiloxane stationary phase for capillary gas chromatography.

A new type of fullerene-containing polysiloxane was synthesized by reacting [60]fullerene with azidopropyl polysiloxane directly. The polysiloxanes have been used successfully as stationary phases for capillary gas chromatography. They displayed high column efficiency, wide operational temperature and high thermostability, and exhibited unique selectivity for many organic substances, such as alkanes, alcohols, ketones and aromatic compounds. The stationary phase was especially suitable for separation of high boiling-point compounds like polycyclic aromatic hydrocarbons and phthalic esters, etc. It was also found that some alcoholic or aromatic positional isomers could be well separated on the column. The influence of the fullerene content on the separation was also investigated.

New biomaterials through surface segregation phenomenon: new quaternary ammonium compounds as antibacterial agents.

Five new trisiloxane quaternary ammonium compounds were synthesized from hydrotrisiloxane with allyl glycidyl ether to yield the epoxy function. Various amines were then reacted to yield trisiloxane amines which were further reacted to methyl substitute or oxidize the beta-carbons in order to provide thermal stability. These new compounds were employed as melt additives in a nonwoven polypropylene fiber extrusion process to produce, through surface segregation, a new biomaterial with antibacterial properties.

Synthesis and characterization of poly(dimethylsiloxane)-poly(ethylene oxide)-heparin CBABC type block copolymers.

Heparin and poly(ethylene oxide) were coupled to a central anchoring block of poly(dimethylsiloxane) in order to investigate its blood compatible properties. Diamino telechelic poly(dimethylsiloxane) (PDMS-(NH2)2, Mw = 20,000) was first modified to isocyanate functionalities using toluene 2,4-diisocyanate. This modified PDMS was then coupled to diamino-telechelic poly(ethylene oxide) (PEO-(NH2)2, Mw = 2000, 4000, 6000) to create BAB type copolymers having terminal free amino groups. These amino groups were covalently coupled to heparin containing terminal aldehyde groups using sodium cyanoborohydride to yield a bioactive, CBABC type block copolymer. The physical characterization of these copolymers was performed with IR, NMR, sulphur elemental analysis, Wilhelmy plate contact angle, and differential scanning calorimetry (DSC). CBABC block copolymer surfaces demonstrated heparin bioactivity in in vitro evaluation, and improved nonthrombogenic properties during ex vivo A-A shunt experiments.

Poly(dimethylsiloxane)-poly(ethylene oxide)-heparin block copolymers. I. Synthesis and characterization.

Amphiphilic block copolymers containing poly(dimethylsiloxane), poly(ethylene oxide), and heparin (PDMS-PEO-Hep) have been prepared via a series of coupling reactions using functionalized prepolymers, diisocyanates, and derivatized heparins. All intermediate steps of the synthesis yield quantifiable products with reactive end-groups, while the final products demonstrate bioactive, covalently bound heparin moieties. Due to the solvent systems required, commercial sodium heparin was converted to its benzyltrimethyl ammonium salt to enhance its solubility. The same procedure was applied to heparin degraded by nitrous acid in order to covalently couple it in solutions with the semitelechelic copolymers. As might be expected, this derivatization reduces the apparent bioactivity of the heparin. However, preliminary findings suggest that the bioactivity can be restored by reforming the heparin sodium salt.