Papers by Maria Helena Santana
The Scientific World Journal, 2015
This study aimed to evaluate thein vitroperformance of activated platelet-rich plasma associated ... more This study aimed to evaluate thein vitroperformance of activated platelet-rich plasma associated with porous sponges of chitosan as a composite scaffold for proliferation and osteogenic differentiation of human adipose tissue-derived mesenchymal stem cells. The sponges were prepared by controlled freezing (−20, −80, or −196°C) and lyophilization of chitosan solutions (1, 2, or 3% w/v). The platelet-rich plasma was obtained from controlled centrifugation of whole blood and activated with calcium and autologous serum. The composite scaffolds were prepared by embedding the sponges with the activated platelet-rich plasma. The results showed the performance of the scaffolds was superior to that of activated platelet-rich plasma alone, in terms of delaying the release of growth factors and increased proliferation of the stem cells. The best preparation conditions of chitosan composite scaffolds that coordinated the physicochemical and mechanical properties and cell proliferation were 3% (...
African Journal of Biotechnology, Aug 18, 2009
With the aim of transferring micropropagation techniques to cassava seed producers, a simple and ... more With the aim of transferring micropropagation techniques to cassava seed producers, a simple and lowcost medium for in vitro micropropagation was developed. CM6740-7 cassava cultivar from CIAT was used as planting material. Commercially available nutrients were used in order to substitute the propagation media components. A Hydro Agri´s fertilizer (12-11-18/3 (MgO-EDTA)) was used as a substitute for Murashige and Skoog macro and micronutrients. Additionally, table sugar and molasses were used as a source of carbohydrates and vitamins. Radixone 3AS from Praquim C.A. was used as a source of auxins and activol as a source of gibberellic acid. Numbers of roots and leaves, height and dry weight of plantlets was determined for each treatment and compared with a conventional micropropagation media. For all the parameter measured, the plantlets obtained on the fully substituted media showed a good growth performance. Canonical biplot analysis showed that this media was especially good for the number of nodes (multiplication rate) in 60-day-old cultured plants. The designed medium is simple, easy to prepare and allows a low-cost strategy to obtain a high quality in vitro micropropagated cassava plants and its ready availability may have an impact on the production of planting material of cassava.
Colloids and surfaces. B, Biointerfaces, 2018
The present study focuses on the characterization of the cytotoxic profile on NIH3T3 mouse embryo... more The present study focuses on the characterization of the cytotoxic profile on NIH3T3 mouse embryonic fibroblasts of solid lipid nanoparticles (SLN) optimized by a 2 full factorial design for skin administration. To build up the surface response charts, a design of experiments (DoE) based on 2 independent variables was used to obtain an optimized formulation. The effect of the composition of lipid and water phases on the mean particle size (z-AVE), polydispersity index (PdI) and zeta potential (ZP) was studied. The developed formulations were composed of 5.0% of lipid phase (stearic acid (SA), behenic alcohol (BA) or a blend of SA:BA (1:1)) and 4.7% of surfactants (soybean phosphatidylcholine and poloxamer 407). In vitro cytotoxicity using NIH3T3 fibroblasts was performed by MTT reduction assay. This factorial design study has proven to be a useful tool in optimizing SLN (z-AVE ∼ 200 nm), which were shown to be non-cytotoxic. The present results highlight the benefit of applying stat...
Molecules, 2016
The aim of this study was to evaluate the skin delivery and in vitro biological activity of trans... more The aim of this study was to evaluate the skin delivery and in vitro biological activity of trans-resveratrol (RES)-loaded solid lipid nanoparticles (SLNs). The SLNs were composed of stearic acid, poloxamer 407, soy phosphatidylcholine (SPC), an aqueous phase and 0.1% RES. The particle size, polydispersity index (PdI) and zeta potential were analyzed by dynamic light scattering (DLS). The SLNs were analyzed by scanning electron microscopy (SEM-FEG) and differential scanning calorimetry (DSC). In vitro RES-SLN skin permeation/retention assays were conducted, and their tyrosinase inhibitory activity was evaluated. An MTT reduction assay was performed on HaCat keratinocytes to determine in vitro cytotoxicity. The formulations had average diameter lower than 200 nm, the addition of SPC promoted increases in PdI in the RES-SLNs, but decreases PdI in the RES-free SLNs and the formulations exhibited zeta potentials smaller than´3 mV. The DSC analysis of the SLNs showed no endothermic peak attributable to RES. Microscopic analysis suggests that the materials formed had nanometric size distribution. Up to 45% of the RES permeated through the skin after 24 h. The RES-loaded SLNs were more effective than kojic acid at inhibiting tyrosinase and proved to be non-toxic in HaCat keratinocytes. The results suggest that the investigated RES-loaded SLNs have potential use in skin disorder therapies.
Journal of Pharmaceutical Analysis, 2012
Didanosine is an effective antiviral drug in untreated and antiretroviral therapy-experienced pat... more Didanosine is an effective antiviral drug in untreated and antiretroviral therapy-experienced patients with Human Immunodeficiency Virus (HIV). An automated system using on-line solid extraction and High Performance Liquid Chromatography (HPLC) with ultraviolet (UV) detection was developed and validated for pharmacokinetic analysis of didanosine in dog plasma. Modifications were introduced on a previous methodology for simultaneous analysis of antiretroviral drugs in human plasma. Extraction was carried out on C18 cartridges, with high extraction yield as stationary phase, whereas mobile phase consisted of a mixture of 0.02 M potassium phosphate buffer, acetonitrile (KH 2 PO 4 : acetonitrile: 96:4, v/v) and 0.5% (w/v) of heptane sulphonic acid. The pH was adjusted to 6.5 with triethylamine. All samples and standard solutions were chromatographed at 28 1C. For an isocratic run, the flux was 1.0 mL/min, detection was at 250 nm and injected volume was 20 mL. The method was selective and linear for concentrations between 50 and 5000 ng/mL. Drug stability data ranged from 96% to 98%, and limit of quantification was 25 ng/mL. Extraction yield was up to 95%. Drug stability in dog plasma was kept frozen at À20 1C for one month after three freeze-thaw cycles, and for 24 h after processing in the auto sampler. Assay was successfully applied to measure didanosine concentrations in plasma dogs.
Journal of Pharmaceutical Analysis, 2012
The purpose of this work was to introduce a new concept of coated pellets containing chitosan mic... more The purpose of this work was to introduce a new concept of coated pellets containing chitosan microspheres loaded with didadosine for oral administration, aiming at reducing the frequency of administration and improving the bioavailability by a suitable release profile. Chitosan microspheres were produced under fluidized bed, followed by extrusion and spheronization to obtain pellets with a mean diameter of about 1 mm. The pellets were then coated with Kollidon s VA64 and Kollicoat s MAE100P in water dispersion to depict a sustained release profile. Conventional hard gelatine capsules were loaded with these pellets and tested in vitro for their release profile of didadosine. Dissolution testing confirmed that chitosan microsphere pellets provides appropriate sustained release up to 2 h behavior for didanosine.
Plant Physiology, 2002
This paper reports the expression and localization of linamarase in roots of two cassava (Manihot... more This paper reports the expression and localization of linamarase in roots of two cassava (Manihot esculentaCrantz) cultivars of low and high cyanide. Two different patterns of linamarase activity were observed. In the low-cyanide type, young leaves displayed very high enzyme activity during the early plant growing stage (3 months), whereas in root peel, the activity increased progressively to reach a peak in 11-month-old plants. Conversely, in the high-cyanide cultivar (HCV), root peel linamarase activity decreased during the growth cycle, whereas in expanded leaves linamarase activity peaked in 11-month-old plants. The accumulation of linamarin showed a similar pattern in both cultivars, although a higher concentration was always found in the HCV. Linamarase was found mainly in laticifer cells of petioles and roots of both cultivars with no significant differences between them. At the subcellular level, there were sharp differences because linamarase was found mainly in the cell wa...
African journal of pharmacy and pharmacology
This study compared the physicochemical characteristics of conventional and elastic liposomes in ... more This study compared the physicochemical characteristics of conventional and elastic liposomes in terms of surfactant incorporation, flow rate, elasticity, mean diameter, phospholipid content and permeation capability. Surfactants were incorporated into conventional liposomes in order to enhance the transdermal transport of drugs through the stratum corneum. The unilamellar liposomes produced composed of egg phosphatidylcholine (PCegg) as the structural component and polyethylene glycol-8lauryl ester (PEG8L) as the elastic component. Results showed fluidity increased of the lipid bilayer with surfactant incorporation, and particle integrity was preserved. These factors determined the ability of elastic liposomes to permeate nanoporous membranes. The elastic liposomes presented a size of ~100 nm and a polydispersity index of 0.38. The flow rate of the liposomes through membranes obeyed Darcy's law, with characteristics similar to those of water. The findings demonstrate the potential of elastic liposomes for transdermal drug administration.
Journal of Stem Cells and Regenerative Medicine, 2016
This study aims at evaluating the clinical effects of Platelet Rich Plasma (PRP) and Hyaluronic A... more This study aims at evaluating the clinical effects of Platelet Rich Plasma (PRP) and Hyaluronic Acid (HA) as individual treatments for mild to moderate Osteoarthritis (OA) and it also examines the potential synergistic effects of PRP in combination with HA. Research continues to emerge examining the potential therapeutic efficacy of HA and PRP as autologous injectable treatments for joint arthritis. However, there is a paucity of research investigating the effects of combining HA and PRP on pain and functional status in patients with OA. Design: In this multi-center, randomized, controlled, double blind, prospective trial, 105 patients with mild to moderate knee osteoarthritis, who met the study criteria, were randomly allocated to one of three interventions: HA (n=36), PRP (n=36), or HA+PRP (n=33). Each patient received 3 intra-articular knee injections of their assigned substance, with 2 week intervals between each injection. Clinical outcomes were evaluated using the Western Ontario and McMaster Universities Arthritis Index (WOMAC) and Visual Analogue Scale (VAS) questionnaire at baseline and after 1,3,6 and 12 months. Results: The study showed that the PRP group have significant reduction in VAS scores at 1 (p= 0.003), 3 (p= 0.0001), 6 (p= 0.0001) and 12 (p= 0.000) months when compared to HA. In addition, the PRP group illustrated greater improvement in WOMAC physical activity scale at 12 months (p= 0.008) when compared to the HA group. Combining HA and PRP resulted in a significant decreases in pain (p=0.0001) and functional limitation (p=0.0001) when compared to HA alone at 1 year post treatment; and significantly increased physical function at 1 (p=0.0004) and 3 (p=.011) months when compared to PRP alone. Conclusion: The findings of the study support the use of autologous PRP as an effective treatment of mild to moderate knee osteoarthritis. It also shows that the combination of HA and PRP resulted to better outcomes than HA alone up to 1 year and PRP alone up to 3 months. Furthermore, the results suggest that combination of PRP and HA could potentially provide better functional outcomes in the first 30 days after treatment with both PRP and HA alone. the extracellular matrix [4] , providing increased joint lubrication. Studies have demonstrated that HA has positive therapeutic efficacy for knee osteoarthritis with initial efficacy at 4 weeks, and peak effectiveness at 8 weeks which lasts for up to 6 months [5]. When compared to continuous oral NSAIDS or other anti-inflammatory medications, HA has illustrated comparable, if not greater, therapeutic effects on knee OA with a better safety profile [5,6]. Autologous platelet rich plasma (PRP) has also emerged as an alternative in the context of injectable treatment for OA. PRP is comprised of a potent cellular milieu containing platelet concentrations above baseline, as well as an undifferentiated mixture of anti-inflammatory, pro-inflammatory, anabolic and catabolic mediators in an attempt to stimulate a supra-physiologic response and elicit the body's natural healing potential. Currently, most studies on PRP are anecdotal or case reports with small sample sizes. However, larger randomized controlled trials have demonstrated superior efficacy in areas such as tendinopathies [7] and knee osteoarthritis [8] .
Colloids and Surfaces B: Biointerfaces, 2015
Polymyxins are a group of antibiotics with a common structure of a cyclic peptide with a long hyd... more Polymyxins are a group of antibiotics with a common structure of a cyclic peptide with a long hydrophobic tail. Polymyxin B sulphate (PLX) has cationic charge, which is an obstacle for the efficient loading into Solid Lipid Nanoparticles (SLN). In the present paper, we describe an innovative method to load PLX into SLN to achieve the sustained release of the drug. PLX was firstly cross-linked with sodium alginate (SA) at different ratios (1:1, 1:2 and 1:3 SA/PLX), and loaded into SLN produced by high pressure homogenization (HPH). Optimized SLN were produced applying 500 bar pressure and 5 homogenization cycles. The best results were obtained with SA/PLX (1:1), recording 99.08 ± 1.2% for the association efficiency of the drug with SA, 0.99 ± 10 g for the loading capacity and 212.07 ± 5.84% degree of swelling. The rheological profile of aqueous SA solution followed the typical behaviour of concentrated polymeric solutions, whereas aqueous SA/PLX solution exhibited a gel-like dynamic behaviour. Micrographs show that SA/PLX depicted a porous and discontinuous amorphous phase in different ratios. The encapsulation efficiency of SA/PLX (1:1) in SLN, the mean particle diameter, polydispersity index and zeta potential were, respectively, 82.7 ± 5.5%; 439.5 ± 20.42 nm, 0.241 ± 0.050 and −34.8 ± 0.55 mV. The effect of SLN on cell viability was checked in HaCat and NIH/3T3 cell lines, and the minimal inhibitory concentrations (MIC) were determined in Pseudomonas aeruginosa strains. SA/PLX-loaded SLN were shown to be less toxic than free PLX. Minimal inhibitory concentrations (MIC) showed the presence of the cross-linker polymer-drug complex, and SLN were shown to enhance MIC in the evaluated strains.
Colloids and Surfaces A: Physicochemical and Engineering Aspects, 2004
Surface-modified liposomes with gangliosides prolong their half life in blood stream that associa... more Surface-modified liposomes with gangliosides prolong their half life in blood stream that associated to the poor immunogenic properties of gangliosides are potentially useful for applications as immunotherapic vehicles. The physical characteristics of these biocolloids play an important role on their stability and exposition of the ganglioside antigens to the immunological system. The present work describes the physical characterization of liposomes incorporating a monosialoganglioside or a mixture of mono-, di-and trisialogangliosides. The liposomal matrix was composed of either dipalmitoylphosphatidylcholine and cholesterol, or in some preparations dihexadecylphosphate, which was added in order to provide a higher negative charge density on the liposome surface. Both types of liposomes were prepared by the dry phospholipids film hydration method and characterized by their phospholipid and ganglioside content, mean diameter, size distribution, morphology, membrane packing, lamellar structure and phase transition behavior.
Clinical Immunology, 2008
Drug administration through the transdermal route has optimized for the comfort of patients and e... more Drug administration through the transdermal route has optimized for the comfort of patients and easy application. However, the main limitation of transdermal drug delivery is the impermeability of the human skin. Recent advances on improvement of drug transport through the skin include elastic liposomes as a penetration enhancer. Entrapment of ferrofluids in the core of liposomes produces magnetoliposomes, which can be driven by a highgradient magnetic field. The association of both strategies could enhance the penetration of elastic liposomes. This work relies on the preparation and characterization of elastic-magnetic liposomes designed to permeate through the skin. The incorporation of colloidal magnetite and the elastic component, octaethylene glycol laurate (PEG-8-L), in the structure of liposomes were evaluated. The capability of the elastic magnetoliposomes for permeation through nanopores of two stacked polycarbonate membranes was compared to conventional and elastic liposomes. Magnetite incorporation was dependent on vesicle diameter and size distribution as well as PEG-8-L incorporation into liposomes, demonstrating the capability of the fluid bilayer to accommodate the surfactant without disruption. On the contrary, PEG-8-L incorporation into magnetoliposomes promoted a decrease of average diameter and a lower PEG-8-L incorporation percentage as a result of reduction on the fluidity of the bilayer imparted by iron incorporation into the lipid structure. Elastic liposomes demonstrated an enhancement of the deformation capability, as compared with conventional liposomes. Conventional and elastic magnetoliposomes presented a reduced capability for deformation and permeation.
This study compared the physicochemical characteristics of conventional and elastic liposomes in ... more This study compared the physicochemical characteristics of conventional and elastic liposomes in terms of surfactant incorporation, flow rate, elasticity, mean diameter, phospholipid content and permeation capability. Surfactants were incorporated into conventional liposomes in order to enhance the transdermal transport of drugs through the stratum corneum. The unilamellar liposomes produced composed of egg phosphatidylcholine (PCegg) as the structural component and polyethylene glycol-8lauryl ester (PEG8L) as the elastic component. Results showed fluidity increased of the lipid bilayer with surfactant incorporation, and particle integrity was preserved. These factors determined the ability of elastic liposomes to permeate nanoporous membranes. The elastic liposomes presented a size of ~100 nm and a polydispersity index of 0.38. The flow rate of the liposomes through membranes obeyed Darcy's law, with characteristics similar to those of water. The findings demonstrate the potential of elastic liposomes for transdermal drug administration.
Applied Biochemistry and Biotechnology
Applied Biochemistry and Biotechnology, 2018
The effects of ethanol/broth proportions and the number of steps at varying pH in the presence or... more The effects of ethanol/broth proportions and the number of steps at varying pH in the presence or absence of sodium chloride (NaCl) were studied as precipitation strategies for the recovery and purification of high molar mass bio-hyaluronic acid (Bio-HA). Bio-HA was synthesized by Streptococcus zooepidemicus in a culture medium containing glucose and soy peptones. A single-step precipitation was more attractive than multistep precipitation in terms of recovery and purity as well as decreased use of ethanol. The best conditions in the absence and presence of salt were 2:1 ethanol/broth (v/v) at pH 4 (55.0 ± 0.2% purity and 85.0 ± 0.7% recovery) and 2:1 ethanol/broth (v/v) at pH 7 + 2 mol L −1 NaCl (59.0 ± 0.9% purity and 82.0 ± 4.3% recovery). Dynamic light scattering (DLS) spectra showed different particle sizes as a consequence of the changes in the molecular structure of HA, mainly with changes in pH. Although slight changes in distribution were observed, the average HA molar mass was not affected by the precipitation strategy, remaining on the order of 10 5 Da. Therefore, pH and NaCl modulated the precipitation performance of HA. These findings are relevant to further optimizing the precipitation step, thus minimizing costs in the later stages of HA purification.
BioResearch Open Access, 2013
The aim of this study was to describe the behavior of the separation of red blood cells (RBCs) by... more The aim of this study was to describe the behavior of the separation of red blood cells (RBCs) by discontinuous centrifugation (DC) of whole blood to modulate and control the platelet recovery in the preparation of pure platelet-rich plasma (P-PRP). P-PRP is a platelet-rich plasma (PRP) in which the white blood cell layer is not included. To achieve this goal, an analytical model was derived that takes into account the packing of RBCs and predicts the behavior of platelet and plasma recovery efficiencies (PtPlRE) based on the volume of whole blood, the hematocrit, and the volume of supernatant, as a function of the operating variables, centrifugal acceleration, and time. The model was derived from the basic equation of DC, which originates from the equilibrium balance of forces on a particle, and included the addition of one factor that corrected the terminal velocity of RBCs and was also correlated to the PtPlRE in the supernatant. This factor was the ratio between the fractional volume concentrations of plasma and RBCs in the centrifugation pellet after centrifugation. The model was validated and the variability of the data was determined using experimental data from 10 healthy donors in the age range of 25-35 years. The predicted behavior for the packing of RBCs and the PtPlRE was consistent with the behavior seen in the experimental data. Thus, the PtPlRE could be modulated and controlled through centrifugal acceleration, time, and hematocrit. Use of this model based on a physical description of events is the first step of a reliable standardization of PRP preparations.
Nanocosmetics and Nanomedicines, 2011
Nanocosmetics and Nanomedicines, 2011
... The first reports on the topical treatment of CL began almost 30 years ago with the studies o... more ... The first reports on the topical treatment of CL began almost 30 years ago with the studies of El-On et al on the paromo-mycin antibiotic showing that a 15% paromomycin sulfate plus 12% methyl ben-zethonium chloride (MBCl) ointment effected cure of L. major lesions in BALB ...
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Papers by Maria Helena Santana