• Physique/Physique/Biophysique
  
• Sciences du Vivant/Ingénierie biomédicale/Biomatériaux
  
• Physique/Matière Condensée/Science des matériaux
  
• Sciences de l'ingénieur/Microélectronique
  
• Sciences du Vivant/Biochimie, Biologie Moléculaire/Biologie moléculaire
  
• Sciences du Vivant/Médecine humaine et pathologie/Rhumatologie et système ostéo-articulaire
  
• Physique/Matière Condensée/Autre
  

Luminescent nanodiamonds (ND) are attractive tools for nanoscale biologic cellular imaging allowing both photoluminescence (PL) and magnetic resonance imaging [1]. Recent technological developments enable to fabricate bright NDs with high content of nitrogen-vacancy centres [2] that are anticipated to serve as a cell probes. In this work we present novel method of NDs detection in cellular environment. We demonstrate simultaneous visualization of NDs and of the non- labeled nucleus of living cells based on Raman and PL detection as a new tool for the localization of internalized nanoparticles.To this end, NDs of size ranging from ultra-small particles ~ 5 nm to 60 nm were used, prepared from Ib synthetic diamond. Cells used for this experiment were from mammalian breast cancer (MCF7). We report on accomplishing to successfully internalize ND particles in MCF7 cells. We show that ND internalization can be monitored by Raman imaging method using K-mean cluster analysis. Whilst standard Raman imaging methods of NDs make use of the sp3 diamond Raman signal, which limits their use to 100 nm size particles or bigger [3], here we employ Raman imaging in a novel way to detect small near-IR cellular probe. Changes of cells stiffness were detected by force measurement in atomic force microscopy after incubating cells with NDs, suggesting cell membrane hardening upon ND uptake.[1] L. Moore, M. Nesladek et al., Nanoscale (2014)[2] J. Havlik, M. Gulka, M. Nesladek et al., Nanoscale (2013) [3] C.-Y. Cheng et al., Applied Physics Letter (2007)

We are interested in the early stage diagnosis of H2B, a clinically important autoantigen in various severe illnesses (can-cers, systemic lupus, rheumatoid arthritis). Accordingly, we have developed a porous-silicon (PSi) based enzyme-linked immunosorbent assay (ELISA) for sensitive detection of H2B antibodies, where H2B antigen were bound to a Si binding 12mer peptide [1] that act as an efficient linker to the surface. The proposed method is a simple, inexpensive sensing meth-od employing a PSi photonic substrate, a material affinity peptide, and a smart phone CCD detector to achieve a 100-fold (~ 10 fg/ml) increase in sensitivity compared to the standard ELISA (0.01 -0.1 ng/ml).

Mineralization of calcium phosphate crystals was examined on porous silicon (PSi) scaffolds with respect to the dependence of crystal formation on the average pore size of PSi. PSi multilayer wafers fabricated by electrochemical etching were moni- tored via their reflectivity spectra over time in a biologically relevant osteogenic solution. The evolution of the mean refractive index of the PSi scaffold is the signature of the in situ crystals nucleation within the pores. Crystals were then characterized using atomic force microscopy (AFM), scanning electron microscopy (SEM) and Raman micro-spectroscopy. The results in- dicate that the average pore size of PSi highly influences nucleation and crystal formation.

In this work, a combination of optical and electrochemical studies are performed in order to elaborate a suitable porous silicon (PSi) substrate for biosensing and biomaterial applications. We report on the electrochemical behavior of PSi multilayer stabilized by thermal oxidation, applying electrochemical impedance spectroscopy and cyclic voltammetry measurements. The strength of the method is evidenced when adsorption of small (12-mer) peptides is monitored. Our aim is to combine the advantages offered by the large sensing area of the PSi multilayers and the high sensitivity of the electrochemical technique for improved biosensing.

Casein micelles (CMs) are colloidal phospho-protein-mineral complexes naturally present in milk. This study used atomic force microscopy (AFM) in a liquid environment to evaluate the topography and nanomechanics of single native CMs immobilized by a novel capture method. The proposed immobilization method involves weak interactions with theantiphospho-Ser/Thr/Tyr monoclonal antibody covalently bound to a carboxylic acid self-assembled monolayer (SAM)on a gold surface. This capture strategy was compared to the commonly used covalent immobilization method of CMs viacarbodiimide chemistry. With this conventional method, CMs remained mainly mobile during AFM measurements in liquid,disturbing the evaluation of their average size and elastic properties. Conversely, when captured by the specific antibody, they were successfully immobilized and their integrity was preserved during the AFM measurement. The characterization of both CM topography and elastic properties was carried out in a liquid ionic environment at native pH 6.6. The CMs’ capture efficiency via antibody was concurrently proved by surface plasmon resonance. The calculation of casein micelles’ width, height, and contact angle was carried out from the recorded 2D AFM images. CMs were characterized by a mean width of 148 ± 8 nm and a mean height of 42 ± 1 nm. Weak forces were applied to single captured CMs. The obtained force versus indentation curves were fitted using the Hertz model in order to evaluate their elastic properties. The elasticity distribution of native CMs exhibited a unimodal trend with a peak centered at 269 ± 14 kPa.