Carolina Garín

Bio: Carolina Garín is an academic researcher from Pontifical Catholic University of Valparaíso. The author has contributed to research in topics: Graphene & Surface modification. The author has an hindex of 4, co-authored 5 publications receiving 298 citations. Previous affiliations of Carolina Garín include Federico Santa María Technical University.

FTIR and Raman Characterization of TiO2 Nanoparticles Coated with Polyethylene Glycol as Carrier for 2-Methoxyestradiol

Abstract: The aim of this study was to prepare a novel targeting drug delivery system for 2-Methoxyestradiol (2ME) in order to improve the clinical application of this antitumor drug. It is based in nanoparticles (NPs) of titanium dioxide (TiO2) coated with polyethylene glycol (PEG) and loaded with 2ME. A complete IR and Raman characterization have been made to confirm the formation of TiO2–PEG–2ME composite. Vibrational modes have been assigned for TiO2, PEG, and 2ME and functionalized TiO2–PEG and TiO2–PEG–2ME. The observed variation in peak position of FTIR and Raman of each for these composites has been elucidated in terms of intermolecular interactions between PEG–2ME and TiO2, obtaining step-by-step the modification processes that were attributed to the conjugation of PEG and 2ME to TiO2 NPs. Modifying TiO2 NPs with PEG loaded with the 2ME drug revealed that the titanium dioxide nanocarrier possesses an effective adsorption capability, and we discuss their potential application as a system of drug delivery.

Suppressing Bacterial Interaction with Copper Surfaces through Graphene and Hexagonal-Boron Nitride Coatings

Abstract: Understanding biological interaction with graphene and hexagonal-boron nitride (h-BN) membranes has become essential for the incorporation of these unique materials in contact with living organisms. Previous reports show contradictions regarding the bacterial interaction with graphene sheets on metals. Here, we present a comprehensive study of the interaction of bacteria with copper substrates coated with single-layer graphene and h-BN. Our results demonstrate that such graphitic coatings substantially suppress interaction between bacteria and underlying Cu substrates, acting as an effective barrier to prevent physical contact. Bacteria do not “feel” the strong antibacterial effect of Cu, and the substrate does not suffer biocorrosion due to bacteria contact. Effectiveness of these systems as barriers can be understood in terms of graphene and h-BN impermeability to transfer Cu2+ ions, even when graphene and h-BN domain boundary defects are present. Our results seem to indicate that as-grown graphene and ...

The Many Faces of Graphene as Protection Barrier. Performance under Microbial Corrosion and Ni Allergy Conditions

Abstract: In this work we present a study on the performance of CVD (chemical vapor deposition) graphene coatings grown and transferred on Ni as protection barriers under two scenarios that lead to unwanted metal ion release, microbial corrosion and allergy test conditions. These phenomena have a strong impact in different fields considering nickel (or its alloys) is one of the most widely used metals in industrial and consumer products. Microbial corrosion costs represent fractions of national gross product in different developed countries, whereas Ni allergy is one of the most prevalent allergic conditions in the western world, affecting around 10% of the population. We found that grown graphene coatings act as a protective membrane in biological environments that decreases microbial corrosion of Ni and reduces release of Ni2+ ions (source of Ni allergic contact hypersensitivity) when in contact with sweat. This performance seems not to be connected to the strong orbital hybridization that Ni and graphene interface present, indicating electron transfer might not be playing a main role in the robust response of this nanostructured system. The observed protection from biological environment can be understood in terms of graphene impermeability to transfer Ni2+ ions, which is enhanced for few layers of graphene grown on Ni. We expect our work will provide a new route for application of graphene as a protection coating for metals in biological environments, where current strategies have shown short-term efficiency and have raised health concerns.

Electronic transfer mechanism in self-assembled monolayers of silicon

Abstract: This work presents a theoretical-experimental study on electronic transfer mechanism on crystal silicon surface modified with redox molecules derived from ferrocene. The surface modification consists in the reaction of hydrogenated silicon with decyl bromide (10-bromo-1-decene) activated with white light, and its subsequent reaction with monolithio-ferrocene. The samples were analyzed by X-ray photoelectron spectroscopy (XPS) and electrochemical measurements. The layers formed are electrochemically active and present a quasi-reversible electrochemical process which is attributed to the ferrocene molecules bound to the silicon surface. In the experimental results, we found an apparent discrepancy, with respect to the results of the cyclic voltammetry, indicating that the redox centers have a diffusive behavior, like to molecules in solution, in spite of these molecules are linked to the silicon surface. While another technique indicates that these redox centers could be attached to the substrate. To understand these results, we have formulated a phenomenological model, based on a cellular automaton, that describes the mechanism of electronic transfer in molecules attached to the substrate. The parameters of the model are obtained from calculations of first principles, based on the density functional theory (DFT). Our results show that the electronic transfer mechanism is influenced by the movement of the redox centers of the molecules attached to the substrate. The latter would explain the apparent discrepancy in the experimental results.

Functional Graphene Nanomaterials Based Architectures: Biointeractions, Fabrications, and Emerging Biological Applications

Abstract: Functional graphene nanomaterials (FGNs) are fast emerging materials with extremely unique physical and chemical properties and physiological ability to interfere and/or interact with bioorganisms; as a result, FGNs present manifold possibilities for diverse biological applications. Beyond their use in drug/gene delivery, phototherapy, and bioimaging, recent studies have revealed that FGNs can significantly promote interfacial biointeractions, in particular, with proteins, mammalian cells/stem cells, and microbials. FGNs can adsorb and concentrate nutrition factors including proteins from physiological media. This accelerates the formation of extracellular matrix, which eventually promotes cell colonization by providing a more beneficial microenvironment for cell adhesion and growth. Furthermore, FGNs can also interact with cocultured cells by physical or chemical stimulation, which significantly mediate their cellular signaling and biological performance. In this review, we elucidate FGNs–bioorganism int...

Two-Dimensional Materials in Biosensing and Healthcare: From In Vitro Diagnostics to Optogenetics and Beyond

Abstract: Since the isolation of graphene in 2004, there has been an exponentially growing number of reports on layered two-dimensional (2D) materials for applications ranging from protective coatings to biochemical sensing. Due to the exceptional, and often tunable, electrical, optical, electrochemical, and physical properties of these materials, they can serve as the active sensing element or a supporting substrate for diverse healthcare applications. In this review, we provide a survey of the recent reports on the applications of 2D materials in biosensing and other emerging healthcare areas, ranging from wearable technologies to optogenetics to neural interfacing. Specifically, this review provides (i) a holistic evaluation of relevant material properties across a wide range of 2D systems, (ii) a comparison of 2D material-based biosensors to the state-of-the-art, (iii) relevant material synthesis approaches specifically reported for healthcare applications, and (iv) the technological considerations to facilitate mass production and commercialization.

Boron nitride nanomaterials: biocompatibility and bio-applications

Abstract: Boron nitride has structural characteristics similar to carbon 2D materials (graphene and its derivatives) and its layered structure has been exploited to form different nanostructures such as nanohorns, nanotubes, nanoparticles and nanosheets Unlike graphene and other carbon based 2D materials, boron nitride has a higher chemical stability Owing to these properties, boron nitride has been used in different applications as a filler, lubricant and as a protective coating Boron nitride has also been applied in the biomedical field to some extent, but far less than other 2D carbon materials This review explores the potential of boron nitride for biomedical applications where the focus is on boron nitride biocompatibility in vivo and in vitro, its applicability as a coating material/composite and its anti-bacterial properties Geometry, material processing and the type of biological analysis appear to be relevant parameters in assessing boron nitride bio-compatibility Engineering of both these variables and the coating would open the door for some applications in the medical field for boron nitride, such as drug delivery, imaging and cell stimulation

Characterization, Bioactivity and Antibacterial Properties of Copper-Based TiO2 Bioceramic Coatings Fabricated on Titanium

Abstract: The bioactive and anti-bacterial Cu-based bioceramic TiO2 coatings have been fabricated on cp-Ti (Grade 2) by two-steps. These two-steps combine micro-arc oxidation (MAO) and physical vapor deposition–thermal evaporation (PVD-TE) techniques for dental implant applications. As a first step, all surfaces of cp-Ti substrate were coated by MAO technique in an alkaline electrolyte, consisting of Na3PO4 and KOH in de-ionized water. Then, as a second step, a copper (Cu) nano-layer with 5 nm thickness was deposited on the MAO by PVD-TE technique. Phase structure, morphology, elemental amounts, thickness, roughness and wettability of the MAO and Cu-based MAO coating surfaces were characterized by XRD (powder- and TF-XRD), SEM, EDS, eddy current device, surface profilometer and contact angle goniometer, respectively. The powder- and TF-XRD spectral analyses showed that Ti, TiO2, anatase-TiO2 and rutile-TiO2 existed on the MAO and Cu-based MAO coatings’ surfaces. All coatings’ surfaces were porous and rough, owing to the presence of micro sparks through MAO. Furthermore, the surface morphology of Cu-based MAO was not changed. Also, the Cu-based MAO coating has more hydrophilic properties than the MAO coating. In vitro bioactivity and in vitro antibacterial properties of the coatings have been investigated by immersion in simulated body fluid (SBF) at 36.5 °C for 28 days and bacterial adhesion for gram-positive (S. aureus) and gram-negative (E. coli) bacteria, respectively. The apatite layer was formed on the MAO and Cu-based MAO surfaces at post-immersion in SBF and therefore, the bioactivity of Cu-based MAO surface was increased to the MAO surface. Also, for S. aureus and E. coli, the antibacterial properties of Cu-based MAO coatings were significantly improved compared to one of the uncoated MAO surfaces. These results suggested that Cu-based MAO coatings on cp-Ti could be a promising candidate for biomedical dental implant applications.