Fabrication of Reversible Phase Transition Polymer Gels toward Metal Ion Sensing

Modular Fabrication of Intelligent Material-Tissue Interfaces for Bioinspired and Biomimetic Devices

One of the goals of biomaterials science is to reverse engineer aspects of human and nonhuman physiology. Similar to the body's regulatory mechanisms, such devices must transduce changes in the physiological environment or the presence of an external stimulus into a detectable or therapeutic response. This review is a comprehensive evaluation and critical analysis of the design and fabrication of environmentally responsive cell-material constructs for bioinspired machinery and biomimetic devices. In a bottom-up analysis, we begin by reviewing fundamental principles that explain materials' responses to chemical gradients, biomarkers, electromagnetic fields, light, and temperature. Strategies for fabricating highly ordered assemblies of material components at the nano to macro-scales via directed assembly, lithography, 3D printing and 4D printing are also presented. We conclude with an account of contemporary material-tissue interfaces within bioinspired and biomimetic devices for peptide delivery, cancer theranostics, biomonitoring, neuroprosthetics, soft robotics, and biological machines.

A dual synergistic of curcumin and gelatin on thermal-responsive hydrogel based on Chitosan-P123 in wound healing application

This study aimed to fabricate the potential therapeutic scaffold to efficiently and safely fastening skin wound healing. A biocompatible grafting polymer-based thermal sensitive hybrid hydrogel (Chitosan-P123, CP) containing gelatin and curcumin was designed to be suitable stiffness for tissue regeneration. A detailed in the rheological study found that the encapsulated agents induced the change in the stiffness of the hydrogel from the hard to the soft. Especial, the thermally induced phase transition of CP hydrogel was governed by the participant of gelatin rather than curcumin. For example, at 25 wt% gelatin, CP hydrogel exhibited a unique gel-sol-gel transition following the function of temperature. Moreover, in vitro investigation revealed that the hybrid hydrogel provides the capacity of especially induced curcumin release with a sustainable rate as well as the excellent biocompatibility scaffold. Altogether with in vivo study, the hybrid hydrogel highlighted the advance of the dual synergistic of curcumin and gelatin in development of smart scaffold system, which promoted the efficacy in the regeneration of the structure and the barrier's function of damaged skin such as wound or skin cancer.

Dipicolylamine Functionalized Polyfluorene Based Gel with Lower Critical Solution Temperature: Preparation, Characterization, and Application

A thermoresponsive fluorescent polymer gel with lower critical solution temperature (LCST) phase transition has been prepared by cooperating conjugated fluorene homopolymer poly(2,7-(9,9-di(8-di(2-picolyl)aminooctyl))fluorene) (PPAOF) and small organic dye sulforhodamine B (SRB) or its sodium salt (SRB-Na). The sol-gel phase transition originates from the electrostatic interactions between the protonated pyridyl/amino groups in PPAOF and the sulfonic groups in the organic dye molecules, as revealed by FTIR, variable-temperature ¹H NMR spectroscopies, and cyclic voltammetry measurements. Consequently, the LCST value can be finely controlled by simply tuning the component concentrations. Moreover, due to the inefficient energy transfer, the resulting fluorescent polymer gel exhibits two independent emission bands at 440 and 577 nm, assigned to the characteristic emissions from fluorene homopolymer and organic dye, respectively. Furthermore, this fluorescent polymer gel exhibits a reversible electrofluorochromic (EFC) property with high fluorescence contrast when it is assembled in a single-layer supporting electrolyte-free EFC device. Most interestingly, different fluorescence colors can be achieved from the two electrodes of the device. Our findings may present a new way to design conjugated polymer based LCST gels and EFC materials.

Fabrication and Characterization of a Novel Anticancer Drug Delivery System: Salecan/Poly(methacrylic acid) Semi-interpenetrating Polymer Network Hydrogel

Salecan is a novel linear extracellular polysaccharide with a linear backbone of 1-3-linked glucopyranosyl units. Salecan is suitable for preparing hydrogels for biomedical applications due to its prominent physicochemical and biological profiles. In this contribution, a variety of innovative semi-interpenetrating polymer network (semi-IPN) hydrogels consisting of Salecan and poly(methacrylic acid) (PMAA) were developed via free radical polymerization for controlled drug delivery. The successful fabrication of the semi-IPNs was verified by Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), and thermogravimetric (TGA) measurements. Scanning electron microscopy (SEM) and rheology analyses demonstrated that the morphological and mechanical behaviors of the resultant hydrogels were strongly affected by the contents of Salecan and cross-linker N,N'-methylenebis(acrylamide) (BIS). Moreover, the swelling properties of these hydrogels were systematically investigated, and the results indicated that they exhibited pH sensitivity. The drug delivery applications of such fabricated hydrogels were further evaluated from which doxorubicin (Dox) was chosen as a model drug for in vitro release and cell viability studies. It was found that the Dox release from the Dox-loaded hydrogels was significantly accelerated when the pH of the release media decreased from 7.4 to 5.0. Toxicity assays confirmed that the blank hydrogels had negligible toxicity to normal cells, whereas the Dox-loaded hydrogels remained high in cytotoxicity for A549 and HepG2 cancer cells. All of these attributes implied that the new proposed semi-IPNs serve as potential drug delivery platforms for cancer therapy.

pH-dependent and self-healing properties of mussel modified poly(vinyl alcohol) hydrogels in a metal-free environment

We describe a simple strategy towards a DOPA-based PVA hydrogel with pH-dependent and rapid self-healing properties in the absence of metal ions. The hydrogel could self-heal in 270 s which was much quicker than that prepared in the presence of Fe³⁺.

A visual volumetric hydrogel sensor enables quantitative and sensitive detection of copper ions

A volumetric sensor design enables the precise naked-eye readout of hydrogel volume changes for quantitative and sensitive detection of copper ions.

Functionality-oriented molecular gels: synthesis and properties of nitrobenzoxadiazole (NBD)-containing low-molecular mass gelators

Two nitrobenzoxadiazole (NBD)-containing cholesteryl (Chol) derivatives were prepared by introducing d/l-phenylalanine into the linkers between the NBD and Chol units. The compounds were denoted as and , respectively. The gelation behaviors of them were tested in 34 liquids. It was found that the chirality of the linkers shows a great effect on the gelation ability and the gel properties of the two compounds. SEM studies demonstrated that the gelator in the gel of /DMSO aggregated into uniform fibrous structures. FTIR, (1)H NMR and UV-Vis spectroscopy measurements revealed that intermolecular hydrogen bonding and π-π stacking are two main driving forces to promote the gel formation. Interestingly, the /DMSO gel exhibits rapid and reproducible gel-sol phase transition and fluorescence quenching upon introduction of ammonia. Furthermore, both the gel and the fluorescence emission could be fully recovered upon evaporation of the ammonia gas introduced. Spectroscopy and model system studies revealed the association of ammonia with the nitro group of the NBD unit of the compound, which is recognized as the main reason for the chemical responses of the gel system. On the basis of the discovery, an ammonia sensing film had been fabricated and made into a device. Furthermore, a device-based and conceptual "ammonia leaking" monitoring instrument was developed. A preliminary test demonstrated that the performance of the system is exceptionally good, a typical and persuasive example to show the important real-life applications of molecular gels.

A large dipole moment to promote gelation for 4-nitrophenylacrylonitrile derivatives with gelation-induced emission enhancement properties

4-Nitrophenylacrylonitrile derivatives were gelator, but analogues without nitro group were not, indicating that the electron-withdrawing nitro moiety was important for gel formation. Moreover, the organogels exhibited fluorescence enhancement.