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22 results on '"Sabino, Roberta M."'

14. Surface Modification of the Ti25Ta25Nb3Sn Alloy and its Influence on The Cell and Bacteria Adhesion - In Vitro Studies

Author

Souza, Marisa A., Lima, Marcia C. M., Escada, Ana L. A., Pimentel, Bruna N. A. S., Vergani, Carlos E., Sabino, Roberta M., Popat, Ketul C., and Alves, Ana P. Rosifini

Subjects
titanium alloys, cell adhesion, surface treatment, alkaline treatment, nanoporous layer
Abstract

In this study, alkaline treatment was used to change the surface of the new beta titanium alloy Ti25Ta25Nb3Sn and enhance its bioactivity. Ti25Ta25Nb3Sn, a new experimental alloy was processed in the laboratory and the surfaces were modified using alkaline treatment. Samples were soaked at 60 0C for 24 hours in different NaOH solutions to obtain surfaces with different morphologies. The surfaces were characterized by different techniques such as X-ray diffraction (XRD), scanning electron microscopy (SEM), and Atomic Force Microscopy (AFM). The wettability of the surfaces was measured using the sessile drop method. In vitro studies were carried out to evaluate cell adhesion, proliferation, and bacteria adhesion. As a result of the alkaline treatment, a nanoporous and amorphous layer was formed on the Ti25Ta25Nb3Sn alloy surface with super hydrophilic behavior for all conditions evaluated. However, different nano topography was observed which affected biological response. The morphology obtained after immersion in 1.5 NaOH solution led to bacteria adhesion decreased and osteoblasts cells differentiation. Results of this study show that is possible to obtain a new titanium experimental alloy with excellent bulk and surface properties that may decrease the risk of infections and increase osseointegration.

Published
2023

15. Collaborative Impact of Cryo-Treated Cutting Tool and Hybrid Milling Environment Towards Improved Sustainable Milling of ASTM F2063 Ni55.6Ti44.4 Alloy

Author

Massachusetts Institute of Technology. Institute for Medical Engineering & Science, Davis, Rahul, Singh, Abhishek, Pereira, Robson B. D., Sabino, Roberta M., Popat, Ketul, Soares, Paulo, Brandão, Lincoln C., Massachusetts Institute of Technology. Institute for Medical Engineering & Science, Davis, Rahul, Singh, Abhishek, Pereira, Robson B. D., Sabino, Roberta M., Popat, Ketul, Soares, Paulo, and Brandão, Lincoln C.

Abstract

Shape memory alloys are mainly used in medical devices and surgical implants due to their biocompatibility. Machining these alloys into intricate patterns can be challenging due to their poor thermal conductivity which could lead to a poor surface finish. The poor surface finish causes a release of toxic elements such as Nickel, leading to contact allergies and thus deteriorating its biocompatibility. Using the right cooling technology can help improve their machinability and overcome issues related to surface integrity. The current study investigates the effect of milling parameters (cutting-speed, feed rate, and depth of cut) and different cooling strategies (flood coolant, cryogenic liquid nitrogen, and a hybrid approach) on the surface integrity of F2063 Ni55.6Ti44.4 shape memory alloy. In addition, the effect of cryogenically treating the cutting tool for further enhancement of surface finish was investigated. A considerable modification on the milled surfaces was observed when using the hybrid cooling/milling approach and cryo-treated tools in terms of morphological, chemical compositional, crystallographic, and microhardness. In addition, this modified surface had a noticeably improved bioactivity due to enhanced hydrophobicity (with contact angle 92°) and surface topography (Ra: 341.69 nm), which favoured cell adhesion and proliferation. The results indicate that the modified Ni55.6Ti44.4 alloy surface might be adequate for use in medical applications.

Published
2023

18. Improved in vitro endothelialization on nanostructured titania with tannin/glycosaminoglycan-based polyelectrolyte multilayers

Author

Massachusetts Institute of Technology. Institute for Medical Engineering & Science, Sabino, Roberta M., Kipper, Matt J., Martins, Alessandro F., Popat, Ketul C., Massachusetts Institute of Technology. Institute for Medical Engineering & Science, Sabino, Roberta M., Kipper, Matt J., Martins, Alessandro F., and Popat, Ketul C.

Abstract

Purpose Blood compatibility of cardiovascular implants is still a major concern. Rapid endothelialization of these implant surfaces has emerged as a promising strategy to enhance hemocompatibility and prevent complications such as thrombus formation and restenosis. The successful endothelialization of implant surfaces mostly depends on the migration of endothelial cells (ECs), the differentiation of stem cells, and the inhibition of smooth muscle cell (SMC) proliferation. Our previous study demonstrated that nanostructured titania surfaces modified with polyelectrolyte multilayers based on tanfloc (a cationic tannin derivative) and glycosaminoglycans (heparin and hyaluronic acid) have improved antithrombogenic properties. Methods In this work, we used in vitro cell culture of ECs and SMCs to investigate the outcomes of these surface modifications on endothelialization. The cells were seeded on the surfaces, and their viability, adhesion, and proliferation were evaluated after 1, 3, and 5 days. Indirect immunofluorescent staining was used to determine the cellular expression of ECs through the presence of specific marker proteins after 7 and 10 days, and EC migration on the NT surfaces was also investigated. Results The surfaces modified with tanfloc and heparin showed enhanced EC adhesion, proliferation, and migration. However, SMC proliferation is not promoted by the surfaces. Therefore, these surfaces may promote endothelialization without stimulating SMC proliferation, which could improve the hemocompatibility without enhancing the risk of SMC proliferation leading to restenosis. Conclusions The surface modification here proposed is a promising candidate to be used in cardiovascular applications due to enhanced antithrombogenic and endothelialization properties.

Published
2022

21. Zein supports scaffolding capacity toward mammalian cells and bactericidal and anti-adhesive properties on poly(ε-caprolactone)/zein electrospun fibers

Author

Plath, André M.S., Facchi, Suelen P., Souza, Paulo R., Sabino, Roberta M., Corradini, Elisângela, Muniz, Edvani C., Popat, Ketul C., Filho, Lucio C., Kipper, Matt J., and Martins, Alessandro F.

Abstract

Studies investigate the electrospinnability of poly(ε-caprolactone)/protein blends to produce fibers for tissue engineering applications. However, no reports show that zein can improve the scaffolding capacity toward stem cells and promote anti-adhesive and bactericidal properties to the poly(ε-caprolactone)/zein fibers. We create fibers with average diameters ranging from 200 to 400 nm from the electrospinning of poly(ε-caprolactone)/protein mixtures. Poly(ε-caprolactone)/zein blends are electrospinnable at zein concentration between 20 and 40 wt% in a 70/30 formic acid/acetic acid mixture. Water contact angle measurements indicate that zein increases fiber hydrophilicity. The water contact angle decreases from 118° (pure poly(ε-caprolactone) fiber) to 73° for the scaffold containing 40 wt% zein. The zein (40 wt%) significantly increases Young’s modulus from 260 MPa (pure poly(ε-caprolactone) fibers) to 980 MPa (poly(ε-caprolactone)/zein fibers) with no substantial influence on elongation at break (ε≥125%) and tensile strength (≥0.040 MPa). The electrospun scaffolds containing zein also promote cell adhesion, proliferation, and spreading of adipose-derived human mesenchymal stem cells for at least 7 days of culture. The zein on poly(ε-caprolactone)/zein fibers can prevent the attachment and proliferation of Escherichia coliand Staphylococcus aureus. We propose these materials for wound healing and skin repair.

Published
2021
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22. Evaluating Whole Blood Clotting in vitro on Biomaterial Surfaces.

Author

Sabino RM and Popat KC

Abstract

Biomaterial-associated thrombosis is still a major concern for blood-contacting implants. After the medical device is implanted and comes in contact with blood, several complex reactions occur, which may lead to thrombus formation and failure of the device. Therefore, it is essential to evaluate the biomaterial interaction with the whole blood. Several studies have been reported in the literature that evaluate different steps in the coagulation cascade, such as protein adsorption, plasma activation, and platelet adhesion in vitro , however, evaluation of whole blood clotting on biomaterial surfaces is not widely reported. Here, a protocol to evaluate whole blood clotting in vitro on 2D biomaterials surfaces via a simple and fast hemolysis assay is presented. Whole human blood is placed onto the biomaterial surfaces and is allowed to clot for different time periods. After the specific time intervals, the surfaces are transferred into deionized (DI) water to release the free hemoglobin and the absorbance of this solution is measured. The absorbance value is proportional to the free hemoglobin concentration in the DI water due to lysis of red blood cells and gives an indirect correlation to the extent of blood clotting on the biomaterial surfaces. This protocol provides a fast, facile and effective method to measure the anti-thrombogenic properties of biomaterials., Competing Interests: Competing interestsThe authors declare no conflict of interest., (Copyright © 2020 The Authors; exclusive licensee Bio-protocol LLC.)

Published
2020
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