Moldable Gel Research Articles

Exploration of proper heating protocol for injectable horizontal platelet-rich fibrin gel

PurposePlatelet-rich fibrin (PRF) has been proposed as promising biomaterials with the advantages of host accumulation of platelets and leukocytes with entrapment of growth factors and fibrin scaffold. However, limitations including fast resorption rate (~ 2 weeks) restricts its clinical application. Recent studies have demonstrated heating treatment can prolong PRF degradation. Current published articles used the method of 75 °C for 10 min to obtain longer degradation, while few studies investigated the most suitable temperature for heating horizontal PRF. Our present study was to discover and confirm the optimum temperature for heat treatment before obtaining H-PRF gels by investigating their structure, mechanical properties, and bioactivity of the H-PRF gels after heating treatment.MethodsIn the present study, 2-mL upper layer of horizontal PRF was collected and heated at 45 °C, 60 °C, 75 °C, and 90 °C to heat 2-mL upper layer of horizontal PRF for 10 min before mixing with the 2-mL lower layer horizontal PRF. The weight, solidification time and the degradation properties were subsequently recorded. Scanning electron microscopy (SEM) and rheologic tests were carried out to investigate the microstructure and rheologic properties of each H-PRF gel. The biological activity of each H-PRF gel was also evaluated using live/dead staining.ResultsH-PRF gel prepared at 75 °C for 10 min had the fast solidification period (over a tenfold increase than control) as well as the best resistance to degradation. The number of living cells in H-PRF gel is greater than 90%. SEM showed that H-PRF gel becomes denser as the heating temperature increases, and rheologic tests also revealed that the heat treatment improved the mechanical properties of H-PRF gels when compared to non-heated control group. Future clinical studies are needed to further support the clinical application of H-PRF gels in tissue regeneration procedures.ConclusionsOur results demonstrated that the H-PRF gel obtained at 75 °C for 10 min could produce a uniform, moldable gel with a short time for solidification time, great rheologic behavior and, high percent of live cells in PRF gel. A promising use of the commonly utilized PRF gel was achieved facilitating tissue regeneration and preventing degradation.

Hexacatenars Exhibiting π-π Driven Supergelation, Aggregation Induced Blue Light Emission and Thermochromism

Two series of five ring polycatenars, which vary from each other with respect to the position of connection to the central benzene ring are reported. The overall shape of the molecule plays a major role than the number of flexible tails in the periphery in dictating the self-assembly (liquid crystallinity and gelation) and the photophysical behavior. Tetracatenars were crystalline and meta-substituted compounds exhibited reduced tendency to stabilize the mesophase. In the para-substituted series, all the hexacatenars exhibited columar hexagonal phase. p-Substituted hexacatenar with n-dodecyloxy tails exhibited thermochromism, with the highly emissive Colh phase and non-emissive soft crystal phase. Three p-substituted compounds exhibited supergelation exclusively promoted by π-π interactions. Besides the capability to form self-standing, moldable gel, one of the compounds exhibited technologically important aggregation-induced blue light emission. The columnar order and emissive nature in the aggregated state makes these molecules promising for the application in emissive displays.

A moldable gel that can heal itself

A moldable gel that can heal itself

Use of Silk Protein, Sericin, as a Sustained-Release Material in the Form of a Gel, Sponge and Film

To evaluate the usability of silk protein (sericin, SC) as a sustained-release material, the physicochemical properties of SC and the release profiles of model drugs from SC gel, sponge and film were studied. Heat aids the dissolution of SC. The molecular weight of SC tended to decrease as the heating temperature and heating time increased. The gel and sponge formed by SC were moldable and consisted of high molecular weight SC polymers (250 kDa and about 400 kDa). SC film was easily broken and exhibited elastic distortion. The addition of moisture-retaining plasticizer (glycerin and sorbitol) improved the film-forming characteristics of SC. The results suggested that SC is practical as a moldable gel and sponge, and as a tensible film. To evaluate the release profiles of small molecules, fluorescein isothiocyanate-dextran ((1) FD4, 4 kDa and (2) FD70, 70 kDa) were used as two model drugs with significantly different molecular weights, and fluorescein isothiocyanate-albumin ((3) FA, 66 kDa) was used as a charged drug. Each was formulated in SC gel, sponge and film. In each preparation, the release rate of the model drugs tended to be FA<FD70<FD4. FA, which has a large molecular weight and negative charge, was released for the longest period of time (≥1 week) from each preparation. The results suggest that SC is usable as an aqueous sustained-release material for high molecular weight drugs. Furthermore, if the drug is charged, its release can be sustained for an extended time.