Fundamentals and Applications of Raman-Based Techniques for the Design and Development of Active Biomedical Materials.

Raman spectroscopy is an analytical method based on light-matter interactions that can interrogate the vibrational modes of matter and provide representative molecular fingerprints. Mediated by its label-free, non-invasive nature, and high molecular specificity, Raman-based techniques have become ubiquitous tools for in situ characterization of materials. This review comprehensively describes the theoretical and practical background of Raman spectroscopy and its advanced variants.

Fiber Probe for Simultaneous Mid-Infrared and Fluorescence Spectroscopic Analysis.

A multispectral fiber optic probe has been developed that enables simultaneous analysis of various liquid and solid samples using attenuated total reflection mid-infrared spectroscopy and fluorimetry. The probe design was optimized using ray-tracing simulation of the light propagation. Technical evaluation of the probe has confirmed its output signal quality that was comparable to that of respective probes for single methods.

Optical Diagnostics of the Maxillary Sinuses by Digital Diaphanoscopy Technology.

The work is devoted to the development of a scientific and technical basis for instrument implementation of a digital diaphanoscopy technology for the diagnosis of maxillary sinus inflammatory diseases taking into account the anatomical features of patients (differences in skin structure, skull bone thickness, and sinus size), the optical properties of exercised tissues, and the age and gender characteristics of patients. The technology is based on visualization and analysis of scattering patterns of low-intensity radiation as it passes through the maxillary sinuses. The article presents the experimental data obtained using the digital diaphanoscopy method and the results of numerical simulation of the optical radiation passage through the study area.

Synergy Effect of Combined Near and Mid-Infrared Fibre Spectroscopy for Diagnostics of Abdominal Cancer.

Cancers of the abdominal cavity comprise one of the most prevalent forms of cancers, with the highest contribution from colon and rectal cancers (12% of the human population), followed by stomach cancers (4%). Surgery, as the preferred choice of treatment, includes the selection of adequate resection margins to avoid local recurrences due to minimal residual disease. The presence of functionally vital structures can complicate the choice of resection margins.

Light guidance up to 6.5 µm in borosilicate soft glass hollow-core microstructured optical waveguides.

Limited operating bandwidth originated from strong absorption of glass materials in the infrared (IR) spectral region has hindered the potential applications of microstructured optical waveguide (MOW)-based sensors. Here, we demonstrate multimode waveguide regime up to 6.5 µm for the hollow-core (HC) MOWs drawn from borosilicate soft glass.

Fiber-cap biosensors for SERS analysis of liquid samples.

Optical detection techniques based on surface enhanced Raman spectroscopy (SERS) are a powerful tool for biosensing applications. Meanwhile, due to technological advances, different approaches have been investigated to integrate SERS substrates on the tip of optical fibres for molecular probing in liquids. To further demonstrate the perspectives offered by SERS-on-fiber technology for diagnostic purposes, in this study, novel cap-shaped SERS sensors for reversible coupling with customized multimodal probes were prototyped via low-cost polymer casting of polydimethylsiloxane (PDMS) and further assembly of gold nanoparticles (Au NPs) of varied sizes and shapes.

iBEAM: substrate-integrated hollow waveguides for efficient laser beam combining.

Laser light sources are routinely applied building blocks in optical sensor technologies. While lasers are emitting at a precisely defined wavelength within narrow emission bands, chem/bio-sensing applications frequently demand multi-wavelength illumination for addressing a series of species. Instead of using broadband radiation sources, it is a viable strategy to efficiently combine the beams emitted from different lasers to maintain the spectral brightness and yet cover extended wavelength regimes.

Synergy of Fluorescence and Near-Infrared Spectroscopy in Detection of Colorectal Cancer.

Background: Colorectal cancer is one of the most common malignancies worldwide. There is an urgent need for simple and fast methods to improve tumor detection in the diagnostic and intraoperative setting to avoid complications and provide objective information in distinguishing malignant and benign colorectal tissue. Optical spectroscopy methods have recently shown a great potential for this discrimination in different organs.

In vivo and in vitro application of near-infrared fiber optic probe for Ehrlich carcinoma distinction: Towards the development of real-time tumor margins assessment tool.

This report describes a full-scale experiment on intradermal Ehrlich carcinoma (EC) differentiation in mouse model using NIR spectroscopy in diffuse reflectance mode and chemometric data processing. EC is widely used as an experimental tumor model due to its resemblance with human undifferentiated epithelial tumors and can be applied as a preclinical testing in order to verify the capability of NIR spectroscopy to distinguish cancer from healthy tissues before a clinical research with an aim of creating a new analytical tool for on-line intraoperative tumor margins assessment. The study consists of five steps of NIR spectra measurements: in vivo on the early stage of carcinoma growth; in vivo on the advanced stage of carcinoma growth; in vivo during the surgery; in vitro study of the post-operative materials stored in formalin; in vitro study of the post-operative materials stored in paraffin.

Synergy Effect of Combining Fluorescence and Mid Infrared Fiber Spectroscopy for Kidney Tumor Diagnostics.

Matching pairs of tumor and non-tumor kidney tissue samples of four patients were investigated ex vivo using a combination of two methods, attenuated total reflection mid infrared spectroscopy and fluorescence spectroscopy, through respectively prepared and adjusted fiber probes. In order to increase the data information content, the measurements on tissue samples in both methods were performed in the same 31 preselected positions. Multivariate data analysis revealed a synergic effect of combining the two methods for the diagnostics of kidney tumor compared to individual techniques.

Surface enhanced infrared absorption spectroscopy based on gold nanostars and spherical nanoparticles.

Plasmonic anisotropic nanoparticles possess a number of hot spots on their surface due to the presence of sharp edges, tips or vertices, leading to a high electric field strength surrounding the nanostructures. In this paper, we explore different plasmonic nanostructures, including anisotropic gold nanostars (AuNSts) and spherical gold nanoparticles, in surface-enhanced infrared absorption spectroscopy (SEIRAS) in an attenuated total reflection (ATR) configuration. In our experiments, we observed up to 10-times enhancement of the infrared (IR) absorption of thioglycolic acid (TGA) and up to 2-times enhancement of signals for bovine serum albumin (BSA) protein on plasmonic nanostructure-based films deposited on a silicon (Si) internal reflection element (IRE) compared to bare Si IRE.

Towards Effective Photothermal/Photodynamic Treatment Using Plasmonic Gold Nanoparticles.

Gold nanoparticles (AuNPs) of different size and shape are widely used as photosensitizers for cancer diagnostics and plasmonic photothermal (PPT)/photodynamic (PDT) therapy, as nanocarriers for drug delivery and laser-mediated pathogen killing, even the underlying mechanisms of treatment effects remain poorly understood. There is a need in analyzing and improving the ways to increase accumulation of AuNP in tumors and other crucial steps in interaction of AuNPs with laser light and tissues. In this review, we summarize our recent theoretical, experimental, and pre-clinical results on light activated interaction of AuNPs with tissues and cells.

Optical properties of plasmon-resonant bare and silica-coated nanostars used for cell imaging.

We synthesized and characterized gold nanostars and their silica-coated derivatives with 7- to 50-nm shell thicknesses as contrast agents for optical imaging. The scattering and absorption coefficients of the nanoparticles (NPs) were estimated by means of collimated transmittance and diffuse reflectance/transmittance analyses. The contrasting properties of the nanostructures were studied in optical coherence tomography glass capillary imaging.

Titania nanofibers in gypsum composites: an antibacterial and cytotoxicology study.

Further developments of antibacterial coatings based on photocatalytic nanomaterials could be a promising route towards potential environmentally friendly applications in households, public buildings and health care facilities. Hereby we describe a simple chemical approach to synthesize photocatalytic nanomaterial-embedded coatings using gypsum as a binder. Various types of TiO nanofiber-based photocatalytic materials (nitrogen-doped and/or palladium nanoparticle decorated) and their composites with gypsum were characterized by means of scanning (SEM) and transmission (TEM) electron microscopy as well as electron and X-ray diffraction (XRD) and energy-dispersive X-ray spectroscopy (EDX) techniques.

Nanocomposites containing silica-coated gold-silver nanocages and Yb-2,4-dimethoxyhematoporphyrin: multifunctional capability of IR-luminescence detection, photosensitization, and photothermolysis.

We describe novel composite nanoparticles consisting of a gold-silver nanocage core and a mesoporous silica shell functionalized with the photodynamic sensitizer Yb-2,4-dimethoxyhematoporphyrin (Yb-HP). In addition to the long-wavelength plasmon resonance near 750-800 nm, the composite particles exhibited a 400-nm absorbance peak and two fluorescence peaks, near 580 and 630 nm, corresponding to bound Yb-HP. The fabricated nanocomposites generated singlet oxygen under 630-nm excitation and produced heat under laser irradiation at the plasmon resonance wavelength (750-800 nm).