Vadim V. Elagin

OCT‐guided laser hyperthermia with passively tumor‐targeted gold nanoparticles

The goal of this study is the development of a method of local laser hyperthermia with gold nanoparticles under noninvasive optical monitoring of nanoparticle accumulation in tumor tissue in vivo. Bifunctional plasmon resonant nanoparticles that are optimal for OCT diagnostics and laser heating at the wavelength of 810 nm were used in the study. The OCT examination showed that the accumulation of gold nanoparticles in the tumor invading into skin was maximal 4-5 h after intravenous injection. It was demonstrated that nanoparticle accumulation in tumor allowed more local heating and enhanced thermal sensitivity of tumor tissue. Laser hyperthermia that heated tumor up to 44-45 °C at maximum nanoparticle accumulation induced apoptotic death of tumor cells and inhibited tumor growth by 104% on the 5th day after treatment.

The influence on biotissue laser resection of a strongly absorbing layer at the optical fiber tip

In this paper, we consider a method of laser resection using the silica glass core from which the cladding layer has been removed as the cutting part of a laser scalpel. An absorbing layer coating the silica fiber tip markedly alters its biotissue cutting characteristics. The results of histological studies of skin after exposure to a laser scalpel with and without a strongly absorbing coating (SAC) at a wavelength of 0.97 μm show that resection using a coated scalpel is more sparing. When an uncoated scalpel was used, skin injury was more apparent in both its surface spread and the depth of structural damage, resulting in poorer tissue regeneration.

Selection of stabilizing agents to provide effective penetration of gold nanoparticles into cells

Abstract Objective: Gold nanorods are known to be promising agents for photothermal therapy. But the uptake of rod-shaped nanoparticles is lower than their spherical counterpart. It was therefore the objective of this study to select gold nanoparticles (GNPs)-stabilizing agents in order to provide effective penetration into cancer cells. Materials and methods: The work was carried out on human ovarian adenocarcinoma SKOV-3 cells. The gold nanorods used in this work had a plasmon resonance peak at 800 nm. The nanoparticles were stabilized by Pluronic® F-127 (PF127), chitosan or polyethylene glycol (PEG); the latter with 6000 Da and 40,000 Da molecular weight. Penetration and intracellular distribution of GNPs were investigated by transmission electron microscopy (TEM) and two-photon luminescence microscopy (2PLM) techniques. Results: By means of 2PLM and TEM, it could be shown that PF127 facilitates cellular uptake of GNPs very effectively. PF127-stabilized GNPs rapidly (by 1.5 h) penetrated the cell membrane and into the cytoplasm and cell nucleus. GNPs stabilized by chitosan were slowly internalized by the cells in smaller amount. GNPs stabilized by PEG with different molecular weights had difficulty to penetrate into the cells – GNPs were localized on the outer side of the cell membrane after short incubation, and single agglomerates were found in the cells after an extended incubation time. Conclusion: Nanoparticles stabilized with PF127 were the most effective nanoparticles to penetrate into the cells and were located in the cytoplasm and cell nuclei. Nanoparticles stabilized with chitosan were internalized into cells at a slower rate and in smaller amounts than those stabilized with PF127. Nanoparticles stabilized with PEG6000 Da and PEG40.000 Da were located mainly on cell membranes and could be found in the cytoplasm only after a longer incubation time.

Multimodal optical coherence tomography for in vivo imaging of brain tissue structure and microvascular network at glioblastoma

In the case of infiltrative brain tumors the surgeon faces difficulties in determining their boundaries to achieve total resection. The aim of the investigation was to evaluate the performance of multimodal OCT (MM OCT) for differential diagnostics of normal brain tissue and glioma using an experimental model of glioblastoma. The spectral domain OCT device that was used for the study provides simultaneously two modes: cross-polarization and microangiographic OCT. The comparative analysis of the both OCT modalities images from tumorous and normal brain tissue areas concurrently with histologic correlation shows certain difference between when accordingly to morphological and microvascular tissue features.

Photothermolysis of tumor with gold nanoparticles guided by NIR and acoustic thermometries

In the current paper we present preliminary data demonstrating therapeutic efficiency of local laser hyperthermia of mouse tumors with gold nanoparticles. Measuring the tumor temperatures both superficial and inner by means of standard NIR-thermograph and original acoustic thermometer correspondingly we show that the gold nanoparticles increase thermal sensitivity of tumor tissue. Transmission electron microscopy and histopathology of the tumor tissue indicated that the mechanism of apoptotic death of tumor cells is triggered following the laser treatment. 5 days after the treatment tumor growth inhibition was 104 %.

Metabolic imaging of tumor for diagnosis and response for therapy

Nonlinear optical microscopy combined with fluorescence lifetime imaging is a non-invasive imaging technique, based on the study of fluorescence decay times of naturally occurring fluorescent molecules, enabling a noninvasive investigation of the biological tissue with subcellular resolution. Cancer exhibits altered cellular metabolism, which affects the autofluorescence of metabolic cofactors NAD(P)H and FAD. In this study features of tumor metabolism in different systems of organization (from cell culture to patient lesion) was showed. The observed differences in the relative contributions of free NAD(P)H and FAD testify to an increased a glycolytic metabolism in cancer cells compare to fibroblasts. In 3D spheroids, the cells of the proliferating zone had greater a1 and lower tm values than the cells of the quiescent zone, which likely is a consequence of their higher glycolytic rate. During the growth of colorectal cancer in the experimental mouse model, the contribution of the free component of NAD(P)H was increased. Dysplastic nevus and melanoma is characterized by raised contribution of free NADH compare to healthy skin. Therefore, melanoma cells had very short value of τ1.

Multiphoton tomography and multimodal OCT for in vivo visualization of oral malignancy in the hamster cheek pouch

The main purpose of this work is to evaluate the possibility to distinguish in vivo benign papilloma, severe dysplasia and squamous cell carcinoma by establishing quantitative image characteristics of multiphoton tomography (MPT) and multimodal optical coherence tomography images (MM OCT). Specific features of papillomatous outgrowths at different stages were revealed using 7,12-dimethylbenz[a]anthracen (DMBA)-induced hamster oral carcinoma. Analysis of MPT images included assessment of nuclear-cytoplasmic (NC) ratio, nuclear density and heterogeneity parameter F. Crosspolarization OCT images were quantified via the integral depolarization factor (IDF). Analysis of OCT microvascular maps enabled differential analysis based on the number of smallest-diameter blood vessels present in a particular pathology. Both MPT and MM OCT metrics showed some difference between benign papilloma, dysplastic papilloma, and squamous cell carcinoma tissue states. The results suggested that combined use of MPT and MM OCT have great potential for in vivo differentiation between benign and malignant papillomas.

Laser hyperthermia of tumors using gold nanoparticles monitored by optical coherence tomography and acoustic thermometry

Local laser hyperthermia of grafted RShM-5 tumors in mice with the use of plasmon resonant gold nanoparticles has been carried out. Accumulation of particles in the tumor was monitored in vivo noninvasively by optical coherence tomography. Thereby it was determined that the maximal content of nanoparticles in the tumor was reached within 5 h after intravenous administration, and laser hyperthermia was performed at this time. Monitoring the tumor temperature during the treatment by IR thermography and acoustic thermometry showed that the nanoparticles provided efficient temperature elevation inside the tumor as well as more selective heating. Local laser hyperthermia with gold nanoparticles, but not the laser exposure alone, substantially inhibited tumor growth in several days after a single session.

Plasmon resonance gold nanoparticles for improving optical diagnostics and photothermal therapy of tumor

The study was performed on 16 CBA-line female mice with transplanted cervical cancer. 0.2 ml of gold nanoparticle solution with a concentration of 109 particles/ml were injected into the animals intravenously. The particles were 200-250 nm in size; the plasmon-resonance related extinction maximum was at the wavelength of 850-950 nm. Accumulation of the nanoparticles into tumor node was visualized by the method of optical coherence tomography (OCT). When the accumulation of nanoparticles in the tumor was maximal, hyperthermia was accomplished using the LSP-AZOR laser setup generating cw radiation at 810 nm. The duration of exposition was 20 min. The therapeutical effect was assessed by the rate of tumor growth inhibition (TGI, %). Determining the instant when nanoparticle concentration in tumor tissue reaches its maximum enables more efficient laser impact. The use of nanoparticles decreases laser irradiation power and ensures local action.