Tumor-Targeted Fluorescence Imaging and Mechanisms of Tumor Cell-Derived Carbon Nanodots

An ideal cancer diagnostic probe should possess precise tumor-targeted accumulation with negligible sojourn in normal tissues. Herein, tumor cell-derived carbon nanodots (C-CNDU87 and C-CNDHepG2) about 3~7 nm were prepared by a solvothermal method with stable fluorescence and negligible cytotoxicity. More interestingly, due to the differences in gene expression of cancers, C-CND structurally mimicked the corresponding precursors during carbonization in which carbon nanodots were functionalized with α-amino and carboxyl groups with different densities on their edges. With inherent homology and homing effect, C-CND were highly enriched in precursor tumor tissues. Mechanistic studies showed that under the mediation of the original configuration of α-amino and carboxyl groups, C-CND specifically bound to the large neutral amino acid transporter 1 (LAT1, overexpressed in cancer cells), achieving specific tumor fluorescence imaging. This work provided a new vision about tumor cell architecture-mimicked carbon nanodots for tumor-targeted fluorescence imaging.

Plasma Co-Polymerization of HMDSO and Limonene with an Atmospheric Pressure Plasma Jet

Plasma co-polymers (co-p) were deposited with an atmospheric pressure plasma jet (APPJ) using a precursor mixture containing hexamethyldisiloxane (HMDSO) and limonene. A coating with fragments from both precursors and with siloxane, carbonyl and nitrogen functional groups was deposited. The flow rate of limonene was found to be an important parameter for plasma co-polymerization to tune the formation and structure of the functional groups. The FTIR and XPS analysis indicates that with increasing flow rate of limonene a higher proportion of carbon is bound to silicon. This is related to a stronger incorporation of fragments from limonene into the siloxane network and a weaker fragmentation of HMDSO. The formation mechanism of the nitroxide and carboxyl groups can be mainly differentiated into in-plasma and post-plasma reactions, respectively.

Preparation of multiple-reactive-site and flexible crosslinking agent with transaconitic acid and acrylic acid and its application for three-dimensional crosslinking of cellulose

A novel multiple-reactive-site crosslinking agent, P(TAA‒AA), was developed from transaconitic acid and acrylic acid in this study. Cotton fabrics with durable wrinkle-resistant properties were obtained by crosslinking with P(TAA‒AA), which benefited from the multifunctional carboxyl groups of crosslinking agents and the three-dimensional crosslinking inside cotton fibers. The wrinkle-resistant properties of P(TAA‒AA)-modified fabrics were evaluated and compared with those of other polycarboxylic acid-treated fabrics, and the P(TAA‒AA)-modified fabrics showed a wrinkle recovery angle of 262° as high as the 1,2,3,4-butanetetracarboxylic acid-modified fabrics while maintaining nearly two-fold higher tearing strength retention (62.9%), and they showed a much higher value of whiteness index than the citric acid-modified fabrics. This demonstrated that the obtained P(TAA‒AA) is an ideal polycarboxylic acid already known to date simultaneously to realize the high wrinkle recovery angle and high tearing strength retention for treated cotton fabrics. The Raman depth mapping images and the scanning electron microscope images of P(TAA‒AA)-modified samples indicated that P(TAA‒AA) molecules can diffuse into the amorphous regions of the cellulose fibers and form crosslinking bridges between cellulose chains. The multiple reactive carboxyl groups in P(TAA‒AA) may form three or more ester bonds between the P(TAA‒AA) molecule and different cellulose chains, which were regarded as the main contribution to the high crosslinking effectiveness of the P(TAA‒AA)-modified fabrics.

INVESTIGATION OF THE POSSIBILITY OF USING THE METHOD OF DIFFERENTIAL SPECTROPHOTOMETRY FOR THE ANALYSIS OF OVERLAPPING ABSORPTION BANDS OF TRITERPENE SAPONINS CHROMOPHORES AND THEIR QUANTITATIVE DETERMINATION IN AQUEOUS SOLUTIONS

A detailed analysis of the absorption spectra of mono- and bidesmoside triterpene glycosides was performed. It is suggested that the maximum in the region of 198–208 nm is attributed to the absorption of the double bond in the cyclohexene ring of the aglycone. The second less seen maximum at a wavelength of 280 nm is observed in the spectrum of saponin Quillaja Saponaria and is almost completely absent in the spectrum of saponin Mukorossi Sapindus. Identification of this maximum is extremely difficult, since its presence can be due to both the aldehyde group in the aglycone and the hydroxyl and carboxyl groups in the carbohydrate molecules. Using the method of differential spectrophotometry, a method for decomposing the UV spectrum of saponins into its constituent components is proposed and justified. A spectral analysis was performed, including the assignment of the absorption bands to the functional groups of the studied compounds. The possibility of estimating changes in the spectral properties of glycoside solutions with changes in the acidity of the medium is considered. The possibility of a bathochromic shift of the maximum absorption of the aglyconic part of saponin depending on the microenvironment (the structure of the carbohydrate part) and changes in the pH of the solution is established. It is shown that the bands at 274, 280.5 nm correspond to n-π* transitions of carbonyl and carboxyl groups and are determined only in the regions of high concentrations in Quillaja Saponaria saponin solutions. Based on the results obtained, calibration models for the quantitative determination of saponins in solutions are proposed. The regression analysis of the calibration equations is carried out, the main statistical indicators are calculated.

Selective Aerobic Oxidation of P-Methoxytoluene by Co(II)-Promoted NHPI Incorporated into Cross-Linked Copolymer Structure

A wide series of copolymer materials with various contents of 4-vinyl-diisopropyl-phtalate ester (10–90 mol%), divinylbenzene (1–11 mol%) and styrene, as monomers, were obtained by radical copolymerization. In the last steps of the synthesis, diisopropyl ester functionalities were converted into the form of N-hydroxyphthalimide (NHPI) rings. The obtained materials with the NHPI groups immobilized in the copolymer structure were studied by various physicochemical techniques, including FT-IR, UV-Vis-DR, XPS, elemental analysis, and tested as catalysts in aerobic oxidation of p-methoxytoluene in the presence of Co(II) acetate co-catalyst. Conversion of the aromatic substrate was correlated with the NHPI content and cross-linking degree. The best catalytic performance (conversions higher than 23%) was achieved for the copolymer catalysts containing 60% and 30% of 4-vinyl-diisopropyl-phtalate ester. At too high concentrations of NHPI and DVB, some of the NHPI groups were transformed into inactive (C=O)-N=O species or not available due to embedding inside the copolymer structure. The mechanism of the process involving both NHPI centers, forming phthalimide N-oxyl (PINO) radicals, and Co(II) cations was discussed. Stability of the developed catalysts was also tested. The opening of imide rings took place during the catalytic process, resulting in the formation of carboxyl groups and the release of hydroxylamine molecules. The deactivated catalyst could be easily regenerated by repeating two last steps of closing imide ring.

Computational Investigations of a pH-Induced Structural Transition in a CTAB Solution with Toluic Acid

In this work, molecular dynamics simulations were performed to study the pH-induced structural transitions for a CTAB/p-toluic acid solution. Spherical and cylindrical micelles were obtained for aqueous surfactants at pH 2 and 7, respectively, which agrees well with the experimental observations. The structural properties of two different micelles were analyzed through the density distributions of components and the molecular orientations of CTA+ and toluic acid inside the micelles. It was found that the bonding interactions between CTA+ and toluic in spherical and cylindrical micelles are very different. Almost all the ionized toluic acid (PTA−) in the solution at pH 7 was solubilized into the micelles, and it was located in the CTA+ headgroups region. Additionally, the bonding between surfactant CTA+ and PTA− was very tight due to the electrostatic interactions. The PTA− that penetrated into the micelles effectively screened the electrostatic repulsion among the cationic headgroups, which is considered to be crucial for maintaining the cylindrical micellar shape. As the pH decreased, the carboxyl groups were protonated. The hydration ability of neutral carboxyl groups weakened, resulting in deeper penetration into the micelles. Meanwhile, their bonding interactions with surfactant headgroups also weakened. Accompanied by the strengthen of electrostatic repulsion among the positive headgroups, the cylindrical micelle was broken into spherical micelles. Our work provided an atomic-level insights into the mechanism of pH-induced structural transitions of a CTAB/p-toluic solution, which is expected to be useful for further understanding the aggregate behavior of mixed cationic surfactants and aromatic acids.

Glycidyl methacrylate-crosslinked fish swim bladder as a novel cardiovascular biomaterial with improved antithrombotic and anticalcification properties

At present, commercial artificial biological valves are mostly prepared by crosslinking bovine or porcine pericardia with glutaraldehyde. Swim bladder has similar components and lower immunogenicity compared to bovine or porcine pericardium. In this study, we used a glycidyl methacrylate (GMA)–based radical polymerization method to crosslink decellularized swim bladders. Amino and carboxyl groups in the swim bladder were reacted with epoxy groups on GMA to introduce carbon–carbon double bonds to the swim bladder. The results showed that the platelet adhesion of GMA-crosslinked swim bladders (GMA-SBs) decreased by 35%, as compared to that of glutaraldehyde-crosslinked swim bladders (GLUT-SBs). Moreover, the superior anticoagulant property was further verified by the ex vivo arteriovenous shunt assay. Meanwhile, the subcutaneous implantation in rats showed that GMA-SBs were able to effectively inhibit the calcification compared with GLUT-SBs. In conclusion, GMA-SBs showed improved antithrombotic and anticalcification properties compared to GLUT-SBs.