The aim of our study was to evaluate the properties of different commercially available resorbable collagen membranes for guided bone regeneration, upon addition of plasma rich in growth factors (PRGF). The structural and morphological details, mechanical properties, and enzymatic degradation were investigated in a new approach, providing clinicians with new data in order to help them in a successful comparison and better selection of membranes with respect to their placement and working condition. Copyright Simona Cavalu et al.
Hematology parameters of whole blood and PRGF fraction:
Leukocytes (x 103/μL)
5.9 ± 1.2
0.3 ± 0.2
Erythrocytes (x 106/μL)
4.5 ± 0.4
0.01 ± 0.0
Platelets (x 103/μL)
210 ± 20
655 ± 85
Hematology parameters of whole blood and PRGF fraction. Copyright Simona Cavalu et al.
Growth factor content
Transforming growth factor TGFβ1: enhances the proliferative activity of fibroblasts and stimulates the biosynthesis of collagen and fibronectin
Insulin –like growth factor IGF-1: is a primary mediator of the effects of growth hormone ; can also regulate cellular DNA synthesis
Platelet-derived growth factor PDGR: enhances collagen synthesis and bone cells proliferation
Quantitative assessment of the main growth factors, cytokines, and chemokines in PRGF fraction. Copyright Simona Cavalu et al.
PRGF-modified collagen membranes investigated in our study present new evidence of several advantages, with respect to a rapid and predictable soft tissue healing. The structural and morphological features of three different commercial collagen membranes for GBG/GTR were investigated upon PRGF treatment, revealing that particular characteristics such as porosity, fiber density, and surface topography may influence the mechanical behavior and performance of the membranes. By FTIR spectroscopy, it was demonstrated that the collagen matrix may act as a natural reservoir for growth factor delivery. Nanoindentation measurements revealed that, upon PRGF treatment, the changes of Young modulus values are correlated with the ultrastructural properties of each membrane type, especially the porosity. The mechanical properties of the membranes were analyzed in a comparative manner, before and after PRGF modification. The enzymatic (trypsin) degradation test also emphasized a different behavior—PRGF-modified membranes exhibited a slower degradation compared with the native ones. Within the limitations of the present study, the results are important with respect to the regulation and kinetic release of multiple growth factors that can be adapted to specific therapeutic conditions. Copyright Simona Cavalu et al.
Knowing the biological and pharmacological properties of propolis, the first goal of our study was to prepare and characterize a propolis nano-formulation (NPs) in order to be used for wound healing applications. The ability of propolis NPs to stimulate the migration of dermal fibroblasts in vitro was assessed by scratch test assay. The concentration of 200 μg/mL propolis NPs was found to have similar effect as the positive control. The second goal was to prepare a propolis-collagen membrane and to investigate the morphological and nanoindentation properties by AFM. The ultrastructure network of collagen fibrils was not affected by incorporation of propolis NPs, showing a nano-porous structure, favorable for soft tissue regeneration applications. Enzymatic degradation assay indicated a reduced degradation rate upon incorporation of propolis NPs in collagen matrix.
Ionotropic gelation method was applied for the preparation of propolis NPS. The nanoparticles were formed spontaneously due to ionic interaction between the protonated amine groups in chitosan and the negatively charged counter-ion TPP, being stabilized by Tween 80.
The tridimensional network of collagen fibrils is visible in both specimens (with or without propolis NPs incorporated) emphasizing the details of repetitive structure of the D-bands pattern of a single collagen fibril, with periodic gaps and grooves, in concordance with some previous published work [32, 33]. The periodicity of D-bands is less visible after propolis NPs incorporation. Moreover, after propolis NPs incorporation and freeze drying procedure, an obvious porous ultrastructure formation was noticed, as a result of fibers self-assembly.
A collagen-based membrane was prepared and investigated by AFM in terms of morphological features and nanoindentation. The network of collagen fibrils was not affected by propolis NPs, showing a nano-porous structure, favorable for soft tissue regeneration applications. Enzymatic degradation assay indicated a reduced degradation rate upon incorporation of propolis NPs in collagen matrix. Corroborating the above mentioned results, we consider that modified-collagen membrane by adding propolis NPs in a controlled concentration, might represent a promising natural alternative to synthetic bandages for wound healing applications. Of course, further in vitro and in vivo tests are necessary to evaluate the biological performances of collagen-modified membranes, in terms of tissue adaptation and integration. (Simona Cavalu, PM Pasca, Digest Journal of Nanomaterials and Biostructures, Volume 16, Issue 3, Pages 929 – 938July-September 2021).