Combined Analytical Approaches to Standardize and Characterize Biomaterials Formulations: Application to Chitosan-Gelatin Cross-Linked Hydrogels.

A protocol based on the combination of different analytical methodologies is proposed to standardize the experimental conditions for reproducible formulations of hybrid hydrogels. The final hybrid material, based on the combination of gelatin and chitosan functionalized with methylfuran and cross-linked with 4-arm-PEG-maleimide, is able to mimic role, dynamism, and structural complexity of the extracellular matrix. Physical-chemical properties of starting polymers and finals constructs were characterized exploiting the combination of HP-SEC-TDA, UV, FT-IR, NMR, and TGA.

Design and Synthesis of Chitosan-Gelatin Hybrid Hydrogels for 3D Printable in vitro Models.

The development of 3D printable hydrogels based on the crosslinking between chitosan and gelatin is proposed. Chitosan and gelatin were both functionalized with methyl furan groups. Chemical modification was performed by reductive amination with methyl furfural involving the lysine residues of gelatin and the amino groups of chitosan to generate hydrogels with tailored properties. The methyl furan residues present in both polymers were exploited for efficient crosslinking via Diels-Alder ligation with PEG-Star-maleimide under cell-compatible conditions. The obtained chitosan-gelatin hybrid was employed to formulate hydrogels and 3D printable biopolymers and its processability and biocompatibility were preliminarily investigated.

3D Extracellular Matrix Mimics: Fundamental Concepts and Role of Materials Chemistry to Influence Stem Cell Fate.

Synthetic 3D extracellular matrices (ECMs) find application in cell studies, regenerative medicine, and drug discovery. While cells cultured in a monolayer may exhibit unnatural behavior and develop very different phenotypes and genotypes than in vivo, great efforts in materials chemistry have been devoted to reproducing in vitro behavior in in vivo cell microenvironments. This requires fine-tuning the biochemical and structural actors in synthetic ECMs. This review will present the fundamentals of the ECM, cover the chemical and structural features of the scaffolds used to generate ECM mimics, discuss the nature of the signaling biomolecules required and exploited to generate bioresponsive cell microenvironments able to induce a specific cell fate, and highlight the synthetic strategies involved in creating functional 3D ECM mimics.

Incorporation in Lipid Microparticles of Acid Red 87, a Colorant Used in Tattoo Inks: Effect on Photodegradation Under Simulated Sunlight and Laser Radiation.

Tattoo colorants decompose under solar radiation and when exposed to laser light for their removal, leading to the accumulation in the dermis of toxic products. Aim of this study was to develop lipid microparticles (LMs) loaded with the colorant, Acid Red 87 (C.I. 45380) used in tattoo inks, and to investigate the effect of this system on the photostability of the colorant under simulated sunlight or laser irradiation. LMs loaded with C.I. 45380 were prepared by melt emulsification using tristearin and phosphatidylcholine as excipients. They were characterized by optical microscopy, laser diffraction, X-ray diffraction and release studies. Free C.I. 45380 and the colorant-loaded LMs were irradiated with a solar simulator or a Q-switched laser. Irradiation with a solar simulator demonstrated that photodecomposition of C.I. 45380 was markedly reduced by incorporation of the dye in the LMs, from 20.5 ± 4.6% to 1.3 ± 1.8%. Conversely, the laser-induced degradation of the colorant (30.1 ± 6.6%) was not significantly influenced by encapsulation in the LMs (the encapsulated C.I. 45380 loss was 27.4 ± 5.5%). Incorporation of C.I. 45380 in lipid microparticles enhances the photostability under sunlight of tattoo inks containing this colorant, without affecting its laser-induced degradation and hence laser removal efficiency.