Direct deposition of chitosan macromolecules on a substrate from solutions in supercritical carbon dioxide: Solubility and conformational analysis

Universal scaling of the osmotic pressure for dense, quasi-two-dimensionally confined polymer melts reveals transitions between fractal dimensions

A scaling law for the osmotic pressure of quasi-two-dimensional polymer melts as a function of concentration is obtained, which shows fractal characteristics. Structural properties such as the chains' contour length and their inner-monomer pair distribution function display fractal scaling properties as well. These predictions are confirmed with mesoscale numerical simulations. The chains are swollen and highly entangled, yet Flory's exponent is always ν = 1/2. The melt can be considered a fluid of "blobs" whose size becomes renormalized in terms of the contour's length while the fractal dimension df increases monotonically between 5/4 and 2, as the monomer concentration is increased. The semidilute scaling of the pressure is recovered when df = 1. Our results agree with recent experiments and with numerical reports on quasi-2d melts. This work provides a new paradigm to study and interpret thermodynamic and structural data in low-dimensional polymer melts, namely as fractal macromolecular objects.

Novel Span-PEG Multifunctional Ultrasound Contrast Agent Based on CNTs as a Magnetic Targeting Factor and a Drug Carrier

Based on the targeting of ferroferric oxide (Fe3O4) and the drug-loading property of carbon nanotubes (CNTs), a novel Span-PEG-composited Fe3O4-CNTs-DOX multifunctional ultrasound contrast agent was designed and applied to tumor lesions. In situ liquid phase synthesis was employed to prepare the Fe3O4-CNTs magnetic targeting complex, and the physical method was used to obtain the Fe3O4-CNTs-DOX complex by loading doxorubicin (DOX) onto Fe3O4-CNTs. The targeted drug-loading complex Fe3O4-CNTs-DOX was combined with the membrane material of Span-PEG by the acoustic vibration cavitation method. The maximum tolerance for Span-PEG-composited Fe3O4-CNTs-DOX microbubbles was 450 times higher, which has good safety. The loading rate of DOX in the obtained composite microbubbles was 17.02%. The proliferation inhibition rate of Span-PEG-composited Fe3O4-CNTs-DOX microbubbles on liver cancer SMMC-7721 cells reached 48.3%. Span-PEG-composited Fe3O4-CNTs-DOX microbubbles could significantly enhance ultrasonic imaging and enrich at a specific location under an external magnetic field, and the extended imaging time could ensure the effective observation and diagnosis of lesions.