SERS of cells: What can we learn from cell lysates?

Surface-enhanced Raman spectroscopy (SERS) is a promising and emerging technique to analyze the cellular environment. We developed an alternative, rapid and label-free SERS-based method to get information about the cellular environment by analyzing cells lysates, thus avoiding the need to incorporate nanoparticles into cells. Upon sonicating and filtrating cells, we obtained lysates which, mixed with Au or Ag nanoparticles, yield stable and repeatable SERS spectra, whose overall profile depends on the metal used as substrate, but not on the buffer used for the lysis process. Bands appearing in these spectra were shown to arise mostly from the cytosol and were assigned to adenine, guanine, adenosine and reduced glutathione (GSH). Spectral differences among various cell types also demonstrated that this approach is suitable for cell type identification.

Surface-enhanced Raman spectroscopy of the anti-cancer drug irinotecan in presence of human serum albumin.

The development of nanotechnological devices and their clinical application in medicine has become increasingly important, especially in the context of targeted and personalized therapy. This is particularly important in cancer therapy, where antitumor drugs are highly cytotoxic and often exert their therapeutic effect at concentrations close to systemic toxicity. In the last years a growing number of studies has started to report the use of plasmonic nanoprobes in the field of theranostics, broadening the application of vibrational spectroscopies like Raman scattering and surface enhanced Raman scattering (SERS) in biomedicine. The present work aims to identify and characterize the vibrational profiles of a widely used anticancer drug, irinotecan (CPT-11). With a rational approach, SERS experiments have been performed on this analyte employing both Au and Ag colloids, starting from simple aqueous solutions up to albumin mixtures. A major step forward for drug detection in albumin solutions has been taken with the adoption of a simple deproteinization strategy, and a two-in-one-step separation and identification by coupling thin layer chromatography, TLC, with SERS (TLC-SERS). The latter has revealed to be a valid system for protein separation and simultaneous analyte detection, showing a potential to become an innovative, sensitive and low cost method for antineoplastic drug profiling in patients' body fluids.

Raman spectroscopy and imaging: promising optical diagnostic tools in pediatrics.

This review focuses on the use of Raman spectroscopy, an analytical technique based on the inelastic scattering of harmless laser light with biological tissues, as an innovative diagnostic tool in pediatrics. After a brief introduction to explain the fundamental concepts behind Raman spectroscopy and imaging, a short summary is given of the most important and common issues arising when handling spectral data with multivariate statistics. Then, the most relevant papers in which Raman spectroscopy or imaging has been applied with diagnostic purposes to pediatric patients are reviewed, and grouped according to the type of pathology: neoplastic, inflammatory, allergic, malformative as well as other kinds. Raman spectroscopy has been used both in vivo, mostly using optical fibers for tissue illumination, as well as on ex vivo tissue sections in a microscopic imaging approach defined as "spectral histopathology". According to the results reported so far, this technique showed a huge potential for mini- or non-invasive real-time, bedside and intra-operatory diagnosis, as well as for an ex vivo imaging tool in support to pathologists. Despite many studies are limited by the small sample size, this technique is extremely promising in terms of sensitivity and specificity.

Is ceramic-on-ceramic squeaking phenomenon reproducible in vitro? A long-term simulator study under severe conditions.

Clinical and in vitro studies on ceramic hip prostheses correlate cup implant position with hip noise, ceramic wear, or ceramic liner damage. A ceramic cup malposition could lead to edge load, ceramic head wear, and squeaking. A noise of a ceramic hip could also be correlate with implant instability and liner damage. Aim of this study was to investigate the long-term wear behavior of 12 commercial alumina-on-alumina bearings under severe conditions: different angles of inclination (23 degrees, 45 degrees, and 63 degrees) and the addition of third body particles (titanium and alumina powder) to address the effective role of cup position and ceramic particles on wear and hip noise. The study was performed using a 12-stations hip joint wear simulator (Shore Western, Monrovia) under bovine calf serum used as lubricant. Wear was evaluated by gravimetric method and the piezo-spectroscopic technique was used to evaluate the residual stress of the ceramic components and correlate this to the weight loss. After eight million cycles, we found that the inclination of the cup (63 degrees in this study) was the most disadvantaged and it was correlated with a hip noise. Gravimetric measurements showed higher wear than the other configurations and these results were in agreement with the Photoluminescence investigation. In particular, the results obtained in this work revealed a residual stress state greater not only with respect to the other angles of inclination but also to two retrieved alumina acetabular cups with a 10 years follow-up.

Design of a novel MEMS platform for the biaxial stimulation of living cells.

Micromechanical systems are increasingly being used as tools in biological applications, since their characteristic dimensions permit to operate at the same length scale of the structures under investigation. Here, we present a methodology for the design, fabrication and operation of a tool for the assessment of mechanical properties of single cells. In particular, we describe a microsystems platform to study bio-mechanical response of single living cells to in-plane biaxial stretching. The proposed device employs a new linkage design in order to obtain the displacement of the quadrants of a sliced circular plate in mutually-orthogonal directions using just one linear actuator. With this linkage geometry, the whole device has only one degree of freedom. This results in a very predictable and reliable mechanical behaviour, thereby allowing use a simple and easily available control electronics. Results of this study have relevance for the design of a powerful yet simple BioMEMS platform for the characterization of living cells as in-plane bi-axial loading simulated the conditions experienced by cells in vivo more realistically than a uniaxial stretching.

Bioactive porous scaffolds for tissue engineering applications: investigation on the degradation process by Raman spectroscopy and scanning electron microscopy.

Bioactive glasses in the Na2 O-K2 O-MgO-CaO-B2 O3 -P2 O5 -SiO2 system characterized by an unusually large working range were used for the production of fiber porous scaffolds. In vitro tests were carried out by immersing the scaffolds in simulated body fluid (SBF) solution; soaking time and glass composition effects on the degradation of the material are the principal subject of this investigation. Raman spectroscopy and scanning electron microscopy (SEM) were used as the main investigative methods. The study demonstrates the importance of the network modifiers and, in particular, of the amount of alkaline and al-kaline earths in the different stages of the material degradation and in the development of the hydroxyl-carbonate-apatite (HCA) layer.

Mechanical and chemical consequences of the residual stresses in plasma sprayed hydroxyapatite coatings.

The residual stresses in thick hydroxyapatite coatings, deposited by plasma spraying, have been determined experimentally using Raman piezo-spectroscopy. The stress dependence of the centre position of the 980 cm 1 Raman band, owing to the symmetric stretching of the phosphate ion, PO3(4), has been established and found to be 2.47 cm 3 GPa 1. Using this calibration, the residual stresses in hydroxyapatite coatings deposited onto Ti-6A1-4V substrates in air have been found to be 100 MPa (tensile), whereas those deposited in a vacuum have been found to be 60 MPa (compressive). Although desirable from a mechanical point of view, it is shown that coating under residual compression are thermodynamically more stable and, hence, the dissolution of the ionic species, necessary in the exchange between bone and hydroxyapatite coating, can be impeded. It is calculated that for the coating under examination the stresses have an effect comparable with almost an order of magnitude change of the [OH] concentration. The analysis explains the dissolution behaviour of hydroxyapatite coatings subject to cyclic stress reported previously.