Z7-7169 — Final report
1.
Microstructured and degradable bacterial cellulose-gelatin composite membranes: mineralization aspects and biomedical relevance

Bacterial cellulose (BC)–gelatin (GEL) membranes were processed by successive periodate oxidation and a freeze-thawing/carbodiimide crosslinking procedure, first facilitating a Schiff-base reaction among respective aldehyde and hydroxyl groups, and later GEL stabilization and microstructuring. The formation of highly microporous structures within the GEL portion, with significant differences between bottom and top, was elucidated, and pores in the 27.6 ± 3 µm–108 ± 5 µm range were generated, exceeding the threshold value of ~10 µm. During a relatively short (6 h) exhaustion procedure in supersaturated simulated body fluid solution, the membranes accommodated the combination of biologically relevant minerals, i.e., flake-like octacalcium phosphate (OCP) and (amorphous) apatite, onto their surface, forming a membrane with intensive swelling (650–1650%) and up to 90% weight loss in a 4-week period. The membranes´ 6-day eluates did not evoke any cytotoxic effects toward human fibroblast, MRC-5 cells. The same type of cells retained their morphology in direct contact with the membrane, attaching to the GEL porous site, while not attaching to the GEL thin-coated BC side, most probably due to combined, ablation effect of dominant ß-sheet conformation and carbodiimide crosslinking. Together with arrested proliferation through the BC side, the membranes demonstrated beneficial properties for potential guided tissue regeneration (GTR) applications.

COBISS.SI-ID: 22161942
2.
Autofluorescence-aided assessment of integration and [mu]-structuring in chitosan/gelatin bilayer membranes with rapidly mineralized interface in relevance to guided tissue regeneration

Beyond providing barrier function, the advanced materials in guided tissue regeneration (GTR) concept are further prompt to foster regeneration of distinct interfacing tissues. Herein we develop chitosan (CHT)/gelatin (GEL) bilayer membranes via successive solvent– and freeze–casting procedures and genipin (GEN) cross-linking chemistry. By utilizing the autofluorescence signal from GEN cross-linking products, the Confocal Fluorescent Microscopy (CFM) identifies the chemical linking as well as physical integration between interface layers. The presence of non- and highly µ-porous and poreinterconnecting regions is demonstrated within cross-sections of membranes with (by weight) prevalent GEL contribution in contrast to the sheet-like organization in membrane with equal presence of components. The constant processing conditions on variable compositions did not significantly affect the pore size distributions (in 1–230 µm range), while pore wall thickness increase up to 220 µm with GEL increase, which also improves the yield stress at compression (from 10 kPa to 19 kPa) and elastic modulus(from 26 kPa to 34 kPa). The rapid mineralization procedure resulted in deposition of non-regular to spherical minerals, containing nonstoichiometric carbonated apatite with Ca/P ration in 1.7–2 range, which demonstrates formation of osseointegrative interface. The fast and high (up to 580%), composition-dependent swelling, as well as 67% to 100% weight loss in 4 weeks in vitro degradation experiment point on membranes' relevance in GTR.

COBISS.SI-ID: 21605910
3.
Processing of biopolymers-based, efficiently integrated bilayer membranes for use in guided tissue regeneration procedures

Periodontitis is a chronic inflammatory disease affecting the tooth supporting structures - the alveolar bone in particular, to extent of eventual tooth loss. Among others, the guided tissue regeneration (GTR) procedure including placement of occlusive barrier membrane is very promising approach. Herein we develop chitosan (CHT) / gelatin (GEL) bilayer membranes via successive solvent– and freeze-casting procedures and genipin (GEN)-mediated cross-linking chemistry. By utilizing the auto-fluorescence signal from GEN cross-linking products (i.e. the secondary CHT (GEL) amines and GEN esters), the Confocal Fluorescent Microscopy (CFM) identifies the chemical as well as physical integration between layers´ interfaces, supported also by Scanning Electron Microscopy (SEM) data. The presence of non- and highly µ-porous and pore-interconnecting regions is demonstrated within cross-sections of GEL-prevalent membranes in contrast to the sheet-like organization in membrane with equal components presence. The constant processing conditions onto variable compositions did not significantly affect the pore size distributions (in 1-230 µm range), while pore wall thickness increases up to 220 µm with GEL increase, which also improves the yield stress at compression from 10 to 19 kPa and elastic modulus from 26 to 34 kPa. The further applied rapid mineralization resulted in deposition of non-regular to spherical minerals, containing nonstoichiometric carbonated apatite with Ca/P ration in 1.7-2 range, which demonstrates formation of osseointegrative interface. The intensive, composition-dependent swelling (up to 580%), as well as 67% to 100% weigh loss in 4 weeks in vitro degradation experiment imply on bilayer membranes GTR relevance.

COBISS.SI-ID: 22005014
4.
Preparative methods and devices of bioinspired materials in drug-delivery systems

The recent developments of self- and site-specific delivery drugs place biomimetics as an emerging science field, already proved as feasible both from a design, as well as engineering/ processing standpoint. The preparation of super hydrophobic surfaces, protein- (or self-) growing carriers and layer-by-layer assembling are some of the preparative tools within a bioinspired platform involved in the newly introduced concept-extension of nanotechnology in drug-delivery systems technology-the bioinspired nanoarchitectonics. This highly challenging concept expands its applicability to traditional biological materials design, from liposomes (polymeric) micelles, microemulsions, dendrimers and conjugates containing cell-penetrating peptides, to inorganics (mesoporous or layered silica particles). Besides the technological variety offered in biomimetic materials processing, the future biomimetic-based development will be involved also in mechanisms of triggering drug release, from independent, to pH or temperature dependent, up to advanced, mechanically induced pressure/stretching induced release. By elucidating the principles underlying the mentioned preparation tools, this chapter will also outline the already available bioinspired nanomaterial designs.

COBISS.SI-ID: 19929366
5.
Textile-based biomaterials for surgical applications

Medical textiles (MedTech), as the cross-point of (bio)polymer chemistry, textile technology, and medical science, represent the most emerging technical textile area, evidencing innovations far beyond the “classical.” In that frame, a state of the art is presented for implantable MedTech products as the most demanding (by functionality and safety) among health care and hygiene materials, extracorporeal devices, and nonimplantable materials. Innovative processing and finishing technologies in combination with (bio)polymers and high standards applied for medium-to-high risk medical devices for soft and hard tissue regeneration, cardiovascular implants, or sutures are overviwed. Particular accent is given on authors’ research topics, that is, hernia repair composites, vascular grafts, and orthopedic implants with emphasis on their acceptance from biomedical aspects: cells’ adherence/growth, cytotoxicity, biocompatibility with the host, hemocompatibility, and biodegradation kinetic. Finally, recent regulations within directives are presented, covering the quality, safety, and reliability of medical devices. The adaption of textile manufacturing/finishing processes for development of smart and personalized textile implants are foreseen as future MedTech perspective.

COBISS.SI-ID: 21298454