Inulin/PVA biomaterials using thiamine as an alternative plasticizer

Preparation of niacinamide imprinted starch-based biomaterials for treating of hyperpigmentation

The aim of this study was to prepare niacinamide (NA) imprinted biomaterials for treating hyperpigmentation using mungbean starch (MS), PVA, and plasticizers (glycerol (GL) and citric acid (CA)). Biomaterials and NA were characterized by FE-SEM, FT-IR, and ¹H NMR. To evaluate the applicability of the NA imprinted biomaterials for a transdermal drug delivery system (TDDS), NA release experiment was conducted in different pH and temperature conditions. Results of NA release properties indicated that NA was released about 99 % rapidly in the initial 10 min. NA release in low pH and high temperature was also higher than that in high pH and low temperature. The determination of experimental conditions and the analysis of NA release results were achieved using response surface methodology (RSM). Results of NA release using artificial skin indicated that NA release from NA imprinted biomaterials was increased at a relatively steady rate for 90 min. To verify for treating hyperpigmentation of the prepared biomaterials, tyrosinase inhibitory and antioxidant inhibitory were performed. Results indicated that NA imprinted biomaterials with the addition of CA exhibited 55.8 % of tyrosinase inhibitory and 73.0 % of antioxidant inhibitory. In addition, their ability to inhibit melanin synthesis in B16F10 cells was evaluated.

Effect of Plasticization on Stretching Stability of Poly(Vinyl Alcohol) Films: A Case Study Using Glycerol and Water

Adding small molecular plasticizers is the most common route to tailor the stretchability of poly(vinyl alcohol) (PVA). However, how the plasticization along with the nature of the plasticizer governs the structural homogeneity during stretching remains an open question to answer. Herein, two representative plasticizers, glycerol (GLY) and water, are chosen to endow the PVA films with ductility. It is found that large strain cavitations cause obvious stress whitening in the PVA/H₂ O films; on the contrary, most of the PVA/GLY films maintain transparent undergoing tensile deformation. Through a combination of experimental inspections and molecular dynamic simulation, it is revealed that partial water molecules that behave as free water will aggregate into microdomains, which serve as mechanical defects responsible for yielding voids. Whereas, the GLY plasticizer homogeneously disperses at a molecular level and interacts with PVA chains through strong hydrogen bonds. More interestingly, it is illustrated that the dispersion and bound states of plasticizers are closely related to the mechanical character of the plasticized PVA films. These findings offer new insight into the working mechanism of plasticization on the structural stability during stretching, and guide the design of PVA/plasticizer system to obtain excellent comprehensive mechanics.

Hydrogen-bond-dominated mechanical stretchability in PVA films: from phenomenological to numerical insights

Hydrogen bonds (H-bonds) in poly(vinyl alcohol) (PVA) play a crucial role in macroscopic mechanical properties, particularly for stretchability. However, there is still some ambiguity about the quantitative dependence of H-bond interactions on the mechanical performance, mainly attributed to the difficulty in the discrimination of various H-bond types. Herein, small molecular chemicals as plasticizers were incorporated into the PVA matrix to tailor the H-bonding interactions. By altering the PVA molecular weight, plasticizer type and loading, both the stretchability and H-bond content were regulated on a large scale. By a combination of DMA, IR spectroscopy, MD simulation and solid-state ¹³C-NMR, every sort of H-bond in PVA was assigned, and their relative fractions were ascertained quantitatively. After correlating the elongation ratio with the relative fraction of the different types of H-bonding interaction, it was found that all the pairs of elongation vs. intermolecular H-bond content derived from different series of PVA/plasticizer films could be plotted into a master curve and exhibited good linearity, indicating that intermolecular H-bonds dominate the mechanical stretchability in PVA films. Our efforts contribute towards an in-depth understanding of performance optimization induced by H-bond manipulation from empirical, phenomenological aspects to intrinsic, numerical insights.

Preparation and evaluation of functional allopurinol imprinted starch based biomaterials for transdermal drug delivery

This study focuses on the synthesis of functional allopurinol (ALP) imprinted biomaterials for a transdermal drug delivery using mung bean starch (MBS), polyvinyl alcohol (PVA), sodium benzoate (SB) as a crosslinking agent, and poloxamer (PX) as a thermo-sensitive polymer. Prepared functional biomaterials were characterized and evaluated by SEM, FT-IR analysis, and physical properties. Results of ALP recognition properties indicated that adsorbed amounts (Q) of ALP on functional ALP imprinted biomaterials were 3.8 to 4.9-fold higher than that of non-ALP imprinted biomaterial. Results of ALP release revealed that the ALP release rate for PX added biomaterials was 1.10 (36.5 °C) or 1.30 (45 °C) times faster than that at 25 °C. These results indicate that functional ALP imprinted biomaterials have thermo-sensitive properties due to the addition of PX. Results of ALP release using artificial skin indicated that ALP release was increased at a relatively steady-state rate for 3 h and that the ALP release behavior followed the non-Fickian diffusion mechanism.

Ferric Ions Modified Polyvinyl Alcohol for Enhanced Molecular Structure and Mechanical Performance

The highly crystallized molecular structure of polyvinyl alcohol (PVA) makes the polymer with poor performance in mechanical strength and water resistance. To modify the molecular structure of PVA and to diminish the complicated procedures and environmental impacts, ferric ions (in ion composite form) have been used to set the interactions with the molecule chains of PVA. The crystallinity, chemical groups change, and mechanical performance of the polymer has been confirmed by X-ray diffraction (XRD), Fourier transform infrared spectroscope (FTIR), and the bonding/membrane tensile strength test. The crystallinity of PVA is reduced from 41.6% to 7.7% with the addition of 2.0% of ferric ions. The tensile strength of the modified PVA membrane is increased by 240%. Moreover, with tougher structure and improved fluidity, the strength of ferric ions modified PVA bonded wood samples is increased by 157%. The modification of PVA with ion composite may have vast applications in many fields, such as paper industry, wood adhesives, functional materials, and polymer structure design.