Tiziana Nardo

Layer-by-layer assembly for biomedical applications in the last decade.

In the past two decades, the design and manufacture of nanostructured materials has been of tremendous interest to the scientific community for their application in the biomedical field. Among the available techniques, layer-by-layer (LBL) assembly has attracted considerable attention as a convenient method to fabricate functional coatings. Nowadays, more than 1000 scientific papers are published every year, tens of patents have been deposited and some commercial products based on LBL technology have become commercially available. LBL presents several advantages, such as (1): a precise control of the coating properties; (2) environmentally friendly, mild conditions and low-cost manufacturing; (3) versatility for coating all available surfaces; (4) obtainment of homogeneous film with controlled thickness; and (5) incorporation and controlled release of biomolecules/drugs. This paper critically reviews the scientific challenge of the last 10 years--functionalizing biomaterials by LBL to obtain appropriate properties for biomedical applications, in particular in tissue engineering (TE). The analysis of the state-of-the-art highlights the current techniques and the innovative materials for scaffold and medical device preparation that are opening the way for the preparation of LBL-functionalized substrates capable of modifying their surface properties for modulating cell interaction to improve substitution, repair or enhancement of tissue function.

Poly(Lactic Acid)-Based Blends With Tailored Physicochemical Properties for Tissue Engineering Applications: A Case Study

Binary blends of poly(L-lactic) acid (PLLA: 201790 Da) and poly(lactide-co-glycolide) (PLGA) (LA:GA = 50:50 mol:mol; 32030 Da) with various compositions were prepared. Physicochemical properties of PLLA/PLGA blends were analyzed. Blends showed a biphasic morphology, with distinct glass transition temperatures, which only slightly approximated compared to pure polymers. Analysis of tensile mechanical properties through the Kerner-Uemura-Takayanagi model showed compatibility for PLLA/PLGA 75/25 blend. Rapid degradation of PLGA phase (2–8 weeks) in PLLA/PLGA 75/25 blend led to porous samples, which appear promising for drug delivery and tissue engineering. A limited inflammatory reaction resulted from subcutaneous implantation of PLLA/PLGA 75/25 in Balb-c mice. GRAPHICAL ABSTRACT

PolyDOPA Mussel-Inspired Coating as a Means for Hydroxyapatite Entrapment on Polytetrafluoroethylene Surface for Application in Periodontal Diseases

Inert polytetrafluoroethylene (PTFE) membranes for periodontal regeneration suffer from weak osteoconductive properties. In this work, a strategy for hydroxyapatite (HAp) coating on PTFE films through an adhesive layer of self-polymerized 3,4-dihydroxy-DL-phenylalanine (polyDOPA) was developed to improve surface properties. Physico-chemical and morphological analysis demonstrated the deposition of polyDOPA and HAp, with an increase in surface roughness and wettability. A discontinuous coating was present after 14 days in PBS and MC3T3-E1 cells proliferation and adhesion were improved. Results confirmed the potential application of polyDOPA/HAp-coated films for periodontal disease treatments.

Bioartificial biomaterials for regenerative medicine applications

Current tissue engineering (TE) strategies are aimed at the design of biomimetic scaffolds whose structural and mechanical properties are provided by biocompatible and bioresorbable synthetic polymers while the cell response is mediated by the presence of biomimetic natural polymers (proteins and polysaccharides) or short peptide sequences derived from intact extracellular matrix (ECM) proteins. The chapter reviews current approaches for the preparation of bioartificial materials with biomimetic properties for TE applications. Bulk functionalization techniques are based on blending between natural and synthetic polymers or on the synthesis of bioartificial copolymers for the preparation of biomimetic hydrogels. Surface functionalization techniques preserve the biomaterial bulk characteristics and only modify the surface properties at the micro- or nanoscale. Several surface modification techniques are available involving physical adsorption, affinity bonding, and covalent grafting. Besides the traditional approaches using natural polymers or peptides, a new trend is evolving based on scaffold functionalization with decellularized ECM.

Synthetic biomaterial for regenerative medicine applications

Tissue engineering (TE) strategies are aimed at the restoration of tissue architecture and functions by the use of cells in combination with supportive scaffolds. The scaffold should act as a temporary matrix for cell proliferation and extracellular matrix deposition, with subsequent tissue ingrowth. Biomaterials play a critical role in the design of scaffolds and, hence, in the realization of a new functional tissue. A variety of synthetic biomaterials have proved to be useful in the reconstruction of tissues, such as bone, cartilage, and nerve, and some of these are currently used in clinical practice. In this chapter, an overview of the different types of synthetic polymers and their properties and TE applications is reported. They can be nonbiodegradable and biodegradable, and able to produce hydrogel matrices. Special attention has been given to addressing polyurethanes that are available as bioresorbable or biostable biomaterials as well as hydrogels.