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. The capability of the probe to deliver complementary chemical information from the same measurement point has been illustrated using model samples of biological tissue. Qualitative analysis of the biological tissue is one of the most important applications of the developed multispectral probe.

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. Effective light guidance in central HC (diameter ∼240 µm) was observed from 0.4 to 6.5 µm despite high waveguide losses (0.4 and 1 dB/cm in near- and mid-IR, respectively). Additional optimization of the waveguide structure can potentially extend its operating range and decrease transmission losses, offering an attractive alternative to tellurite and chalcogenide-based fibers. Featuring the transparency in mid-IR, HC MOWs are promising candidates for the creation of MOW-based sensors for chemical and biomedical applications.

Multimodal fiber probe for simultaneous mid-infrared and Raman spectroscopy.

A fiber probe has been developed that enables simultaneous acquisition of mid-infrared (MIR) and Raman spectra in the region of 3100-2600 cm-1. Multimodal measurement is based on a proposed ZrO2 crystal design at the tip of an attenuated total reflection (ATR) probe. Mid-infrared ATR spectra are obtained through a pair of chalcogenide infrared (CIR) fibers mounted at the base of the crystal. The probe enables both excitation and acquisition of a weak Raman signal from a portion of the sample in front of the crystal using an additional pair of silica fibers located in a plane perpendicular to the CIR fibers. The advantages of combining MIR and Raman spectra in a single probe have been discussed.

Optoacoustic monitoring of bilirubin photodegradation.

Hematomas resulted from trauma are very common, and the efficacy of existing treatment techniques is limited. Phototherapy can be used to expedite healing and improve the appearance of the damaged tissue. Efficient phototherapy requires determination of chromophore composition in hematoma, which can be provided by the optoacoustic (OA) technique, as it combines high spatial resolution and optical contrast. Here, we conducted experiments on photodegradation of bilirubin in gelatin slin phantoms. We have demonstrated that the OA technique allows monitoring of bilirubin concentration during photodegradation, and also distinguishing bilirubin concentration in depth. The obtained results suggest that OA monitoring may be used for efficient hematoma phototherapy.

Multifunctional nanostructured drug delivery carriers for cancer therapy: Multimodal imaging and ultrasound-induced drug release.

Development of multimodal systems for therapy and diagnosis of neoplastic diseases is an unmet need in oncology. The possibility of simultaneous diagnostics, monitoring, and therapy of various diseases allows expanding the applicability of modern systems for drug delivery. We have developed hybrid particles based on biocompatible polymers containing magnetic nanoparticles (MNPs), photoacoustic (MNPs), fluorescent (Cy5 or Cy7 dyes), and therapeutic components (doxorubicin). To achieve high loading efficiency of MNP and Dox to nanostructured carriers, we utilized a novel freezing-induced loading technique. To reduce the systemic toxicity of antitumor drugs and increase their therapeutic efficacy, we can use targeted delivery followed by the remote control of drug release using high intensity-focused ultrasound (HIFU). Loading of MNPs allowed performing magnetic targeting of the carriers and enhanced optoacoustic signal after controlled destruction of the shell and release of therapeutics as well as MRI imaging. The raster scanning optoacoustic mesoscopy (PA, RSOM), MRI, and fluorescent tomography (FT) confirmed the ultrasound-induced release of doxorubicin from capsules: in vitro (in tubes and pieces of meat) and in vivo (after delivery to the liver). Disruption of capsules results in a significant increase of doxorubicin and Cy7 fluorescence initially quenched by magnetite nanoparticles that can be used for real-time monitoring of drug release in vivo. In addition, we explicitly studied cytotoxicity, intracellular localization, and biodistribution of these particles. Elaborated drug delivery carriers have a good perspective for simultaneous imaging and focal therapy of different cancer types, including liver cancer.