Tag Archives: AFM microscopy

Novel Formulation Based on Chitosan-Arabic Gum Nanoparticles Entrapping Propolis Extract: Production, physico-chemical and structural characterization

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By Simona Cavalu et al.

UV-Vis spectra of propolis extract and chitosan/Arabic gum
nanoparticles loaded with propolis. Copyright Simona Cavalu et al.
DLS analyses of colloidal chitosan/Arabic gum/propolis
mixture: a) Particle size distribution; b) Zeta potential. Copyright Simona Cavalu et al.
AFM images of chitosan/Arabic gum nanoparticles
entrapping propolis extract; a) 2D view; b) 3D topography; c)
Surface profile. Copyright Simona Cavalu et al.
AFM images of chitosan/Arabic gum nanoparticles
entrapping propolis extract; a) 2D view; b) 3D topography; c)
Surface profile. Copyright Simona Cavalu et al.
ATR FTIR spectra: a) raw propolis and powder chitosan/Arabic gum/propolis nanoparticles; b) powder chitosan and Arabic gum. Copyright Simona Cavalu et al.

Due to the limitation of chitosan in drug delivery systems, because of its hydrophilicity and solubility, chemical modification was performed in our study by combining with a second natural polymer, Arabic gum, in order to
improve the stability of nanoparticles. Copyright Simona Cavalu et al.

Morphological and structural characterization, using AFM, operating in tapping mode, along with the surface profile. Although the lateral dimensions are influenced by the shape of the probe, the height measurements can provide the height of nanoparticles with a high degree of accuracy and precision. However, larger particles are formed due to the aggregation during storage time. Copyright Simona Cavalu et al.

Structural characterization of polymeric powder
nanoparticles entrapping propolis was performed by ATR
FTIR spectroscopy, and compared with recorded spectrum of raw propolis, chitosan powder and Arabic gum as reference. In the same time, the
marker bands of propolis are well preserved in the polymeric mixture, indicating that the bioactive compounds are stable upon the encapsulation procedure. Copyright Simona Cavalu et al.

In this study we succeeded to prepare and characterize natural polymeric nanoparticles based on chitosan/Arabic gum, entrapping propolis extract. The physico-chemical properties of nanoparticles were assessed by UV-visible and FTIR spectroscopy, along with Dynamic Light Scattering, revealing that particle size obtained from highly dispersed mixture was in the range of 50-400 nm, with large Gaussian distribution, the maximum percentage of size distribution being at around 120 nm. In the same time,
an efficient encapsulation procedure was described using glutaraldehyde as cross-linking agent. The morpholological features of nanoparticles were emphasized by AFM microscopy, demonstrating a good correlation between
the results obtained by DLS technique. The FTIR analysis demonstrated that the marker bands of propolis are well preserved in the polymeric mixture, indicating that the bioactive compounds are stable upon the encapsulation
procedure. In our formulation, we consider that a balanced crosslinking toward electrostatic interaction was established. Propolis release from polymeric matrix was monitored in both simulated gastric acid and simulated intestinal fluids, concluding that our proposed formulation
is suitable for controlled release and pharmaceutical applications. Our results may provide a novel drug design, with improved bioavailability, stability and nutritional value of propolis bioactive compounds during processing and storage, with possible applications in food and nutraceutical industries. Copyright Simona Cavalu et al.

Full text at https://revistadechimie.ro/Articles.asp?ID=6836

PRGF-Modified Collagen Membranes for Guided Bone Regeneration: Spectroscopic, Microscopic and Nano-Mechanical Investigations

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By C. Ratiu, Simona Cavalu et al.

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.

Whole blood separation upon centrifugation at 580 G for 8 minutes at room temperature (a) and subsequent platelets rich in growth factor (PRGF) separation by pipetting (b); membrane immersion in PRGF (c). Copyright C. Ratiu, Simona Cavalu et al.

Hematology parameters of whole blood and PRGF fraction:

ComponentWhole bloodPRGF
Leukocytes (x 103/μL)5.9 ± 1.20.3 ± 0.2
Erythrocytes (x 106/μL)4.5 ± 0.40.01 ± 0.0
Platelets (x 103/μL)210 ± 20655 ± 85
Hematology parameters of whole blood and PRGF fraction. Copyright Simona Cavalu et al.
Growth factor contentValue
Transforming growth factor TGFβ1: enhances the proliferative activity of fibroblasts and stimulates the biosynthesis of collagen and fibronectin43 ng/mL
Vascular endothelial growth factor VEGF: induces angiogenesis via migrating endothelial cells220 pg/mL
Insulin –like growth factor IGF-1:  is a primary mediator of the effects of growth hormone ; can also regulate cellular DNA synthesis105 ng/mL
Platelet-derived growth factor PDGR: enhances collagen synthesis and bone cells proliferation14 ng/mL
Quantitative assessment of the main growth factors, cytokines, and chemokines in PRGF fraction. Copyright Simona Cavalu et al.
Cross-sectional scanning electron microscopy (SEM) images of different commercial collagen membranes before (a,d,g) and after (b,e,h) PRGF treatment; AFM 3D topography of the membrane surface after PRGF treatment (c,f,i) showing the details of collagen fibers. The images correspond to Biocollagen® (a–c), CovaTM Max (d–f), and Jason® (g–i). Copyright Simona Cavalu et al.
Nanoindentation measurements: load–displacement curves recorded for each membrane before (a,c,e) and after (b,d,f) PRGF treatment. The images correspond to Jason® (a,b), Biocollagen® (c,d), and CovaTM Max (e,f). Legend: MC1/MC2 = Jason® membrane before/after PRGF treatment; MCP1/MCP2 = Biocollagen® membrane before/after PRGF treatment; MPP1/MPP2 = CovaTM Max membrane before/after PRGF treatment. Copyright Simona Cavalu et al.
Young modulus calculations with respect to the three collagen membranes before (a) and after PRGF treatment (b). Legend: MPP1/MPP2 = CovaTMMax membrane before/after PRGF treatment; MC1/MC2 = Jason® membrane before/after PRGF treatment; MCP1/MCP2 = Biocollagen® membrane before/after PRGF treatment. Copyright Simona Cavalu et al.
Results of enzymatic degradation test of native (unmodified) and PRGF-modified collagen membranes. 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.