Madalina Georgiana Albu

Collagen Wound Dressings with Anti-Inflammatory Activity

The aim of this study was to develop modern wound dressings such as controlled drug delivery systems. These systems consist in collagen as release support and niflumic acid as drug. The scaffolds were prepared by lyophilization in order to obtain porous structures and were evaluated by release profile of niflumic acid, water absorption, collagenase degradation and biocompatibility with fibroblast cells. The collagen scaffold with 0.75% niflumic acid solved in laurel oil was optimal in terms of biodegradability, absorbability and fibroblast cells biocompatibility. Thus, the obtained collagen scaffolds could be used as wound dressings with absorbent, antibacterial and anti-inflammatory properties.

Doxycycline Delivery From Collagen Matrices Crosslinked With Tannic Acid

Collagen-doxycycline matrices crosslinked with a natural polyphenol – tannic acid for the treatment of infected wounds were obtained by the freeze-drying of the corresponding gels. FT-IR spectra show that the triple helical structure of collagen is preserved in all the matrices, doxycycline produce collagen crosslinking and the degree of crosslinking increases with tannic acid concentration. Digestion of matrices using collagenase confirms the crosslinking effect of doxycycline and tannic acid and the increasing of the crosslinking degree with the amount of acid. The release of doxycycline from the matrices crosslinked with tannic acid is slower than that from the uncrossliked one and decreases with increasing of acid concentration, according to FT-IR and digestion results, and follows the power law model, with a release exponent of about 0.4, which indicates an anomalous transport. The matrices containing doxycycline, tannic acid and their combination do not develop gram-positive (Staphylococcus aureus) or gram-negative (Escherichia coli, Pseudomonas aeruginosa) bacteria, fungi or leavens.

The effect of the hydration degree on the hydrothermal and thermo-oxidative stability of some collageneous matrices

The methods of the thermal analysis (TG, DTG and DTA) were used in order to investigate the effect of the hydration degree on the thermal behaviour of some collageneous matrices. It was pointed out that the degradation of hydrated collagen in the temperature range 20-400°C occurs through two successive processes accompanied by mass losses. The first process, consisting in the collagen dehydration, is endothermic and takes place in the temperature range ≈25 - ≈125°C. The second process is exothermic and consists in the decomposition and/or thermo-oxidation of dry collagen. The thermal parameters of both processes depend on the hydration degree of collagen. The observed dependencies show that the hydrothermal and thermo-oxidative stability of collagen are strongly correlated with its water content.

Composite scaffolds based on silver nanoparticles for biomedical applications

This paper presents the synthesis, characterisation, and in vitro testing of homogenous and heterogeneous materials containing silver nanoparticles (nanoAg). Three types of antiseptic materials based on collagen (COLL), hydroxyapatite (HA), and collagen/hydroxyapatite (COLL/HA) composite materials were obtained. The synthesis of silver nanoparticles was realized by chemical reaction as well as plasma sputtering deposition. The use of chemical reduction allows the synthesis of homogenous materials while the plasma sputtering deposition can be easily used for the synthesis of homogeneous and heterogeneous support. Based on the in vitro assays clear antiseptic activity against Escherichia coli was relieved even at low content of nanoAg (10 ppm).

In Vitro Biocompatibility of Human Endothelial Cells with Collagen-Doxycycline Matrices

The aim of this study was to test the biocompatibility between collagen-doxycycline matrices with various porosities and human endothelial cells. Collagen matrices were prepared by freeze-drying process. The crosslinking degree of collagen matrices was evaluated by FT-IR spectroscopy, the matrices morphology by SEM microscopy. The biocompatibility of collagen matrices with endothelial cells was monitored byfluorescence and transmission electron microscopy. We found that the three-dimensional structures of matrix with 1.2% collagen, 0.2% doxycycline crosslinked with 0.25% glutaraldehyde was optimal in terms of biodegradability, morphology and endothelial cells biocompatibility indicating the use of these scaffolds in tissueengineering.

Natural Polymer-Cell Bioconstructs for Bone Tissue Engineering

The major goal of bone tissue engineering is to develop bioconstructs which substitute the functionality of damaged natural bone structures as much as possible if critical-sized defects occur. Scaffolds that mimic the structure and composition of bone tissue and cells play a pivotal role in bone tissue engineering applications. First, composition, properties and in vivo synthesis of bone tissue are presented for the understanding of bone formation. Second, potential sources of osteoprogenitor cells have been investigated for their capacity to induce bone repair and regeneration. Third, taking into account that the main property to qualify one scaffold as a future bioconstruct for bone tissue engineering is the biocompatibility, the assessments which prove it are reviewed in this paper. Forth, various types of natural polymer- based scaffolds consisting in proteins, polysaccharides, minerals, growth factors etc, are discussed, and interaction between scaffolds and cells which proved bone tissue engineering concept are highlighted. Finally, the future perspectives of natural polymer-based scaffolds for bone tissue engineering are considered.

Antitumoral materials with regenerative function obtained using a layer-by-layer technique

A layer-by layer technique was successfully used to obtain collagen/hydroxyapatite-magnetite-cisplatin (COLL/HAn-Fe3O4-CisPt, n=1–7) composite materials with a variable content of hydroxyapatite intended for use in the treatment of bone cancer. The main advantages of this system are the possibility of controlling the rate of delivery of cytostatic agents, the presence of collagen and hydroxyapatite to ensure more rapid healing of the injured bone tissue, and the potential for magnetite to be a passive antitumoral component that can be activated when an appropriate external electromagnetic field is applied. In vitro cytotoxicity assays performed on the COLL/HAn-Fe3O4-CisPt materials obtained using a layer-by layer method confirmed their antitumoral activity. Samples with a higher content of hydroxyapatite had more antitumoral activity because of their better absorption of cisplatin and consequently a higher amount of cisplatin being present in the matrices.

Collagen—Dexamethasone and Collagen-D3 Scaffolds for Bone Tissue Engineering

The aim of the study was to test the biocompatibility and osteoinductive potential of collagen with dexamethasone (Dex) and collagen with 1, 25 dihydroxycholecalciferol (D3) scaffolds on two human osteoblast cell lines, MG63 and hFOB1.19. The cell morphology was examined by SEM, the scaffolds colonization was monitored by fluorescence microscopy, viability by MTT assay and cells differentiation by PCR. The two utilized scaffolds sustained biointegration/proliferation of human osteoblast cells. However, collagen-Dex and collagen-D3 scaffolds promoted osteogenic activity of MG63 cells incresing the gene expression of osteonectine, osteocalcin and BSP II whereas no osteoinductive effect on hFOB1.19 cells was detected.

Advances in the field of soft tissue engineering: From pure regenerative to integrative solutions

Abstract The aim of this chapter is to discuss the advances in the field of soft tissue engineering highlighting the advantages of the use of drug delivery systems instead of pure, regenerative grafts. Tissue engineering evolved dramatically, from natural occurring materials to cell-seeded and drug-loaded engineered materials, from macro- to micro- and nanoscale. It is most important to mention the evolution from the last century because this is the period when, based on scientific approaches, the outcomes became exponential. From an evolutionary point of view, both pure regenerative as well as the drug-loaded systems are now studied, in preclinical and clinical phases. In fact, these two general classes of systems should be studied together because the properties of the drug-loaded systems are strongly dependent on the support characteristics. In the field of soft tissue engineering, some materials are intensively studied: chitosan and its derived materials; collagen and gelatin, polyvinyl alcohol, polycaprolactone, etc. The recent advances in this field are related to the active components which are used for loading these materials in order to improve or even induce new properties/functionalities. Special attention over recent decades has been devoted to the faster healing, antimicrobial and antitumoral activity of these materials and, consequently, this chapter is mainly devoted to these aspects.

New Scaffold Structure Based on Collagen. Fabrication and Biocompatibility Evaluation

Development of bioactive material template for in vitro and in vivo synthesis of osteoinductive and biodegradable bone material was intensevely studied over the last decade and the research in the field of partial substitution of bone tissue, use a very large range of natural and synthetic polymers, inorganic components and their composites. Despite of composites collagen hydroxiapatite with a mimetic osseous composition until now was not defined a scaffold model suitable to biofunctionality of native osseous structure. The goal of the article is fabrication of a new scaffold structure, based on collagen fibrils with length 1–1.5 cm, thikness 0.1–0.3 and having a shroud structure. Collagen crosslinking was performed with aldehides in such way that aminic groups became bloked and carboxylic groups remain free in order to involve hydroxiapatite and biocompatible synthetic polymer (polyvinil alchol, polilactide) coupling. Crosslinking temperature for collagen fibrils is 70°C being a suitable temperature for resistance to “in vivo” resorbtion. Infrared spectra was performed and the amount of the hidroxyl bonds was correlated with hydrophilic [2] balance estimated from contact angle measurements. The morphology and the surface composition were determined with an Environmental Scanning Electron Microscope FEI/Phillips XL30 ESEM and all physical chemical properties especially surface features were used as basic factors in future cell growth and proliferation process. The main aim of biocompatibility tests is to multiply and to differentiate cells in vitro in osteoblasts from marrow. The environment of culture was supplemented with specific media containing Na β glicerofosfat and the cell was differentiated in osteoblasts. As arguments for differentiation were proposed the evidence of specific markers: osteonectine, sialoproteines and osteocalcine. Osteoprogenitors cells culture were tested on various samples of scaffold. Cell cultures were tested for alkaline phosphatase at a week after culture. The technique uses p-nitrophenole which is going to be change by alkaline phosphatase in dinitro-phenole.