Proper treatment of dental caries demands detection of carious lesions at an early stage and a minimal invasive cavity preparation to preserve the maximum tooth structure. Various devices use fluorescence for caries detection via recording the red fluorescence generated by dentin caries under illumination.The aim of this study was to evaluate the porphyrin and pentosidine involvement in the red fluorescence observed in enamel and dentin caries when illuminated with the Soprolife® camera (Sopro, Acteon Group, La Ciotat, France) and Vistacam® camera (Dürr Dental AG, Bietigheim-Bissingen, Germany). Three techniques were used: single photon fluorescence spectroscopy, micro-Raman spectroscopy, and color analysis with ImajeJ software. Cross-sections of human teeth, scored from 0-6 with the International Caries Detection and Assessment System (ICDAS), were examined by fluorescence microscopy. Teeth spectra of each ICDAS score were compared with those of protoporphyrin IX (PpIX), porphyrin I, and pentosidine solutions. A specific confocal Raman microscopy analysis was realized and a Red-Green-Blue model analysis of Soprolife® images was performed using ImageJ software to compare the color variations on ICDAS score 1 and 2. Fluorescence spectroscopy and micro- Raman spectroscopy revealed the presence of PpIX in carious enamel and dentin. The clinical relevance of this experimentation was that the increased knowledge of the fluorescence aids for caries detection could improve the preventive approach, thus reducing the operative one.

Organic–inorganic interactions are of high importance in several biological pro- cesses and in modern nanobiotechnological applications. Despite its signifi- cance in interface sciences, the basic mechanism of biomolecules’ specific binding to a surface is still not well understood. Current experimental methods have not reached the level either to follow the dynamics of interactions at the picosecond scale or to observe the surface morphology at the nanoscale level. The increasing interest in bio-interfaces particularly for engineering applica- tions demands proteins or peptides to be designed to recognize the inorganic surface with high specificity. Molecular simulation has been well adopted in the past couple of decades to decipher the protein–surface interactions at differ- ent levels of time and length scales. Several molecular simulation methods such as quantum mechanics, atomistic, and coarse grain simulations were employed in this domain of research, but the continuous improvements in interfacial force field (FF) development, availability of experimental data and new sampling methods make the atomistic simulation more attractive due to the offered accu- rate representation of protein adsorption behavior at the atomic level. However, the exactitude of such simulations entirely depends on the applied FF para- meters, conformational sampling, and the solvation effects. In this overview, we briefly summarize the applicability of different simulation methods and of interface FFs. We also present the recent advances in the simulation of protein– surface interactions, and the challenges posed by the current simulation meth- ods to reproduce the exact phenomenon. Future directions in this research field are also discussed.

The morphology and the nanomechanical properties of single casein micelles (CMs) in their native state were investigated using AFM in liquid environment. A novel immobilization method of CMs using low energy interactions was developed and compared with a well-known chemical immobilization method involving direct covalent bonds.For the classic method, CMs were covalently bound via carbodiimide chemistry to a gold-sputtered glass surface precoated with carboxyl groups. For the proposed method an indirect immobilization of CMs was realized via anti-human phospho-Ser/Thr/Tyr mouse monoclonal antibody covalently bound onto a gold-coated slide via carbodiimide chemistry. In both methods, immobilized CMs were then analyzed by AFM in their native environment represented by a simulated milk ultrafiltrate at room temperature.With the classic method of immobilization, some CMs remained mobile in liquid condition during the probe sample interaction. Conversely, with the novel method, CMs were well immobilized allowing the extraction of both surface topography and elastic properties by AFM in liquid. Morphologic characteristics were obtained from 2D and 3D images (Figure1). Data analyses allowed the calculation of diameters, heights and contact angles of native CMs. They are characterized by a mean width of 148 ± 8 nm and a mean height of 42 ± 1 nm. Low forces were applied on immobilized CM to calculate force-vs-indentation curves fitted using Hertz theory in order to determine Young Moduli (E*) which represents elasticity. Their elasticity distribution exhibited a unimodal trend, with an elasticity pic centered at 269 ± 14 kPa.

Selective deposition of peptides from liquid solutions to n- and p-doped silicon has been demonstrated. The selectivity is governed by peptide/silicon adhesion differences. A noninvasive, fast characterization of the obtained peptide layers is required to promote their application for interfacing silicon-based devices with biological material. In this study we show that spectroscopic ellipsometrya method increasingly used for the investigation of biointerfacescan provide essential information about the amount of adsorbed peptide material and the degree of coverage on silicon surfaces.We observed the formation of peptide multilayers for a strongly binding adhesion peptide on p-doped silicon.Application of the patterned layer ellipsometric evaluation method combined with Sellmeier dispersion led to physically consistent results, which describe well the optical properties of peptide layers in the visible spectral range. This evaluation allowed the estimation of surface coverage, which is an important indicator of adsorption quality. The ellipsometric findings were well supported by atomic force microscopy results.