ABSTRACT
Tissue engineering leads to the development of biomaterial scaffolds where its biocompatibility and bioactivity are often improved after performing physical or chemical surface modification treatments. Micropatterning, soft lithography, and biofabrication are also approaches that provide a biomimetic microenvironment but have proven very costly and time consuming. In this concern, an appropriate substrate with suitable sites for cell attachment represents a major factor in cell behavior and biological functions. For this reason, our strategy was to fabricate a standard fibrous biomaterial with reproducible surface topography, incorporating microbeads and nanofeatures, and show the positive outcomes of the new substrate reflected on cell functions of bone cells. The electrospun polycaprolactone (PCL) beads-on-string membranes were obtained by adjusting the spinning solution at different concentrations until continuous beads were formed. Cell adhesion and proliferation, on the PCL scaffold, were analyzed the subsequent 2 days after initial culture. Complementary studies of cytoskeleton spreading and differentiation were analyzed after 7 and 14 days of the initial incubation. The scanning electron microscopy (SEM) images showed evidence of the formation of beads-on-string nanofibers and suggested that as-formed microstructures worked as attachment sites for osteoblasts. We investigated cell proliferation using anti-BrdU fluorescence assay, and results show a similar proliferation rate of cells cultured between PCL scaffolds and control. Finally, Phalloidin TRITC and antisialoprotein antibody were used to analyze cell spreading and differentiation after 7 and 14 days, respectively. This work shows a low-cost fabrication method to produce a biodegradable scaffold with micro/nanostructured characteristics that favor cell adhesion, proliferation, maturation, and subsequent differentiation of osteoblasts. According to the results, the biocompatibility of PCL beads-on-string could be comparable to other complex biomaterials, and we conclude that our scaffold is optimal for applications in bone tissue regeneration.
ABSTRACT
BACKGROUND: Cashew (Anacardium occidentale L.) has become a very important non-traditional tree crop in Ghana. The crop is, however, attacked by sap-sucking insects, particularly the mosquito bug, Helopeltis schoutedeni Reuter, the leaf-footed bug, Pseudotheraptus devastans (Dist.), and the coreid bug, Anoplocnemis curvipes (F.), which feed on shoots, panicles and fruits. Their damage is characterised by withering of the latter. In Ghana, Oecophylla longinoda Latr. occurs in large numbers on cashew and other native plants, but little is known about its relationship with insect pests. The relationship between O. longinoda and shoot and panicle damage by sap-sucking bugs and the effectiveness of O. longinoda as a biocontrol agent in the protection of cashew as compared with two chemical insecticides, lambda-cyhalothrin (Karate) and cypermethrin + dimethoate (Cyperdim), were therefore investigated at Bole in the northern region of Ghana. RESULTS: There was a negative correlation between numbers of O. longinoda nests and pest damage. Trees treated with cypermethrin + dimethoate (969 mg AI mL(-1) tree(-1)) and lambda-cyhalothrin (100 mg AI mL(-1) tree(-1)) recorded the smallest bug numbers, followed by O. longinoda. Trees infested by Oecophylla longinoda and trees treated with cypermethrin + dimethoate and with lambda-cyhalothrin had less than 6% pest damage to shoots, panicles and fruits, while water-sprayed trees recorded damage as high as 36.8% (shoots) in February, 32.9% (panicles) in February and 37.8% (fruits) in March. Cypermethrin + dimethoate again recorded the highest (485.0 kg ha(-1)) nut yield, followed by O. longinoda (431.0 kg ha(-1)), with water recording the lowest (93.0 kg ha(-1)) nut yield. CONCLUSION: The results indicate that O. longinoda can be used to control some sucking bugs as effectively as some insecticides.
