Alejandro Barrantes

University of Oslo · Oral Research Laboratory

The formation of salivary films onto oral prostheses materials is of central importance for understanding their performance and interaction with oral tissue and flora. The aim of this work was to study and compare the salivary films formed from unstimulated and stimulated whole saliva on two common polymeric materials, polycarbonate and poly(methyl...

The adsorption of blood proteins, serum albumin (BSA), immunoglobulin G (IgG) and fibrinogen (FGN), onto model SiO2 planar surfaces coated with poly-L-lysine/heparin multilayers (PLL/HEP) has been investigated by means of ellipsometry and quartz crystal microbalance with dissipation. Aiming at the development of low fouling coatings, this study has...

Polyphenols can form functional coatings on a variety of different materials through auto-oxidative surface polymerization in a manner similar to polydopamine coatings. However, the mechanisms behind the coating deposition are poorly understood. We report the coating deposition kinetics of the polyphenol tannic acid (TA) and the simple phenolic com...

We show in this work how systems formed by phosphoproteins on calcium phosphate surfaces can be directly characterized, in real time, in liquid medium, without the need for elution or labeling. Specifically, we show how this is possible by applying three different techniques: ellipsometry, quartz crystal microbalance with dissipation, and atomic fo...

Nanocoatings based on plant polyphenols have been recently suggested as a potent strategy for modification of implant surfaces for enhancing host cell attachment and reducing bacterial colonisation. In this study...

Oral biofilms can be a major health problem causing infections and chronic inflammation of mucosal tissue. While much effort is put in the investigation of bacteria in biofilms, the role of fungi is often neglected, despite Candida albicans playing a key role in the formation of multispecies oral biofilms. With the rise of antibiotic resistance, ne...

Metallic implants are widely used in diverse clinical applications to aid in recovery from lesions or to replace native hard tissues. However, the lack of integration of metallic surfaces with soft tissue interfaces causes the occurrence of biomaterial‐associated infections, which can trigger a complicated inflammatory response and, ultimately, imp...

Surface modification with polyphenolic molecules has been pursued in biomedical materials owing to their antioxidant, anti‐inflammatory, and antimicrobial characteristics. Recently, the use of silicic acid (Siaq) as a mediator for efficient surface deposition of tannic acid (TA) was reported, but the postulated Si‐TA polymeric networks were not cha...

In the quest for finding new strategies to enhance tissue integration and to reduce the risk of bacterial colonisation around endosseous implants, we report the application of auto-oxidative phenolic coatings made of tannic acid and pyrogallol to titanium surfaces. The functionalised surfaces were screened for their biological performance using cul...

Tannic acid (TA) adheres to a broad variety of different materials and forms versatile surface coatings for technical and biological applications. In mild alkaline conditions, auto-oxidation processes occur and a firm monolayer is formed. Up to now, thicker coatings are only obtained in cross-linked multilayer fashion. This study presents an altern...

To characterise bioelectrocatalytic oxygen reduction at gold nanoparticles (AuNPs) modified with Trametes hirsuta laccase (ThLc) combined electrochemical and quartz crystal microbalance measurements have been used. The electrodes with different degrees of AuNP-monolayer coverage, θ, have been studied. In every case of θ close to theoretically possi...

In nearly all papers concerning enzyme–nanoparticle based bioelectronic devices, it is stated that the presence of nanoparticles on electrode surfaces per se enhances bioelectrocatalysis, although the reasons for that enhancement are often unclear. Here, we report detailed experimental evidence that neither an overpotential of bioelectrocatalysis,...

Two blue multicopper oxidases (MCOs), viz. Trametes hirsuta laccase (ThLc) and Myrothecium verrucaria bilirubin oxidase (MvBOx), were immobilised on bare polycrystalline gold (Au) surfaces by direct adsorption from both dilute and concentrated enzyme solutions. The adsorption was studied in situ by means of null ellipsometry. Moreover, both enzyme...

Tau protein has been proposed as a trigger of Alzheimer's disease once it is hyperphosphorylated. However, the role that native tau forms play inside the neuronal nucleus remains unclear. In this work we present results concerning the interaction of tau protein with double-stranded DNA, single-stranded DNA, and also with a histone-DNA complex. The...

The formation of salivary films onto different surfaces relevant in dental research like titania, hydroxyapatite, gold, zirconia, silica, and hydrophobized silica has been studied by means of QCM-D. Human whole saliva (HWS), and sterile filtered HWS (sHWS) both diluted in water to a final concentration of 25% (v/v) were used. Main differences betwe...

This chapter discusses some solid surface analytical techniques that are frequently used to investigate protein adsorption and the interactions of adsorbed proteins with other molecules. The techniques included are ellipsometry, dual polarization interferometry (DPI), surface plasmon resonance (SPR), quartz crystal microbalance (QCM), and atomic fo...

Anomalous protein aggregation is closely associated to age-related mental illness. Extraneuronal plaques, mainly composed of aggregated amyloid peptides, are considered as hallmarks of Alzheimer's Disease. According to the amyloid cascade hypothesis, this disease starts as a consequence of an abnormal processing of the amyloid precursor protein res...

We present a novel methodology for the study of proteinaceous films based on the friction force spectroscopy operation mode of the atomic force microscope. It provides information both on the strength at the nanoscale level and on the lateral diffusion properties of these systems. The usefulness of the data generated by this methodology are shown t...

The effect of pH on the build-up of polyelectrolyte multilayers, PEMs, composed by poly-L-lysine and heparin onto two different substrates, silica and gold, has been studied by means of ellipsometry and quartz crystal microbalance with dissipation, QCM-D. Ellipsometry results indicate that the dry mass grows exponentially with the number of layers,...

According to the amyloid hypothesis, abnormal processing of the β-amyloid precursor protein in Alzheimer's disease patients increases the production of β-amyloid toxic peptides, which, after forming highly aggregated fibrillar structures, lead to extracellular plaques formation, neuronal loss and dementia. However, a great deal of evidence has poin...

We present a method to study the strength of layers of biological molecules in liquid medium. The method is based on the Friction Force Spectroscopy operation mode of the Atomic Force Microscope. It works by scratching the sample surface at different applied loads while registering the evolution of the sample topography and of the friction between...

Intracellular neurofibrillary tangles, composed mainly of tau protein, and extracellular plaques, containing mostly amyloid-beta, are the two types of protein aggregates found upon autopsy within the brain of Alzheimer's disease patients. Polymers of tau protein can also be found in other neurodegenerative disorders known as tauopathies. Tau is a h...

Alzheimer's disease is a form of senile mental disorder characterized by the presence of extracellular plaques, containing amyloid-beta (Abeta) as the main component. According to the amyloid hypothesis, an increase of extracellular Abeta production is in the origin of the aberrant plaques causing neuronal loss and dementia. However, a wealth of ev...