Investigation of thermal distribution for pulsed laser radiation in cancer treatment with nanoparticle-mediated hyperthermia

In this paper, we have simulated the efficacy of gold/gold sulfide (GGS) nanoshells in NIR laser hyperthermia to achieve effective targeting for tumor photothermal therapy. The problem statement takes into account the heat transfer with the blood perfusion through capillaries, and pulsed laser irradiation during the hyperthermia. Although previous researchers have used short laser pulses (nanosecond and less), in order to prevent heat leakage to the neighbor tissues, we have examined the effect of millisecond pulses, as the extent of the target volume to which hyperthermia is induced is usually larger and also the lasers with this specification are more available. A tumor with surrounding tissue was simulated in COMSOL software (a finite element analysis, solver and simulation software) and also in a phantom made of agarose and intralipid. The tumor was irradiated by 10, 20 and 30 laser pulses with durations of 15, 50 and 200 ms and fluences of 20, 40 and 60 J/cm². Experimental tests performed on a phantom prove the ability of the applied numerical model to capture the temperature distribution in the target tissue. We have shown that our simulation permits prediction of treatment outcome from computation of thermal distribution within the tumor during laser hyperthermia using GGS nanoshells and millisecond pulsed laser irradiation. The advantage of this simulation is its simplicity as well as its accuracy. Although, to develop the model completely for a given organ and application, all the parameters should be estimated based on a real vasculature of the organ, physiological conditions, and expected variation in those physiological conditions for that application in the organ.     

Laser-induced hyperthermia of nanoshell mediated vascularized tissue – A numerical study

Laser-induced hyperthermia treatment of tumor in a 2-D axisymmetric tissue embedded with moderate size (100–150 µm) blood vessels is studied. Laser absorption is enhanced by embedding gold–silica nanoshells in the tumor. Heat transfer in the tissue is modeled using Weinbaum–Jiji bioheat transfer equation. With laser irradiation, the volumetric radiation is accounted in the governing bioheat equation. Radiative information needed in the bioheat equation is calculated using the discrete ordinate method, and the coupled bioheat-radiation equation is solved using the finite volume method. Effects of power density, laser exposure time, beam radius, diameter of blood vessel and volume fractions of nanoshells on temperature spread in the tissue are analyzed.     

Preparation of Gold Nanoparticles and their Applications in Anisotropic Nanoparticle Synthesis and Bioimaging

In this review, we highlight our recent achievements in using colloidal gold nanoparticles as building blocks for fabrication of anisotropic and multicomponent nanoparticles (e.g., nanoshells, semiconductor nanocrystals, and gold nanorods). The tunable optical properties of these nanoparticles are well suited for various biomedical and biophotonic applications.     

Plasmonic Heating-Assisted Transformation of SiO2/Au Core/Shell Nanospheres (Au Nanoshells): Caveats and Opportunities for SERS and Direct Laser Writing

The selective modification of silica/gold nanospheres (gold nanoshells) driven by plasmonic heating is demonstrated. Direct laser writing and reshaping of nanoshell assemblies can be easily controlled and exploited for nanofabrication purposes. The modified nanoshells exhibit improved surface enhanced Raman scattering, allowing to settle most of the issues related to nanoshell stability under working conditions.

Immunonanoshells for targeted photothermal ablation of tumor cells

Consisting of a silica core surrounded by a thin gold shell, nanoshells possess an optical tunability that spans the visible to the near infrared (NIR) region, a region where light penetrates tissues deeply. Conjugated with tumor-specific antibodies, NIR-absorbing immunonanoshells can preferentially bind to tumor cells. NIR light then heats the bound nanoshells, thus destroying the targeted cells. Antibodies can be consistently bound to the nanoshells via a bifunctional polyethylene glycol (PEG) linker at a density of approximately 150 antibodies per nanoshell. In vitro studies have confirmed the ability to selectively induce cell death with the photothermal interaction of immunonanoshells and NIR light. Prior to incubation with anti-human epidermal growth factor receptor (HER2) immunonanoshells, HER2-expressing SK-BR-3 breast carcinoma cells were seeded alone or adjacent to human dermal fibroblasts (HDFs). Anti-HER2 immunonanoshells bound to HER2-expressing cells resulted in the death of SK-BR-3 cells after NIR exposure only within the irradiated area, while HDFs remained viable after similar treatment since the immunonanoshells did not bind to these cells at high levels. Control nanoshells, conjugated with nonspecific anti-IgG or PEG, did not bind to either cell type, and cells continued to be viable after treatment with these control nanoshells and NIR irradiation.     

Numerical investigation of thermal response of laser-irradiated biological tissue phantoms embedded with gold nanoshells

The work presented in this paper focuses on numerically investigating the thermal response of gold nanoshells-embedded biological tissue phantoms with potential applications into photo-thermal therapy wherein the interest is in destroying the cancerous cells with minimum damage to the surrounding healthy cells. The tissue phantom has been irradiated with a pico-second laser. Radiative transfer equation (RTE) has been employed to model the light-tissue interaction using discrete ordinate method (DOM). For determining the temperature distribution inside the tissue phantom, the RTE has been solved in combination with a generalized non-Fourier heat conduction model namely the dual phase lag bio-heat transfer model. The numerical code comprising the coupled RTE-bio-heat transfer equation, developed as a part of the current work, has been benchmarked against the experimental as well as the numerical results available in the literature. It has been demonstrated that the temperature of the optical inhomogeneity inside the biological tissue phantom embedded with gold nanoshells is relatively higher than that of the baseline case (no nanoshells) for the same laser power and operation time. The study clearly underlines the impact of nanoshell concentration and its size on the thermal response of the biological tissue sample. The comparative study concerned with the size and concentration of nanoshells showed that 60 nm nanoshells with concentration of 5×10¹⁵ mm⁻³ result into the temperature levels that are optimum for the irreversible destruction of cancer infected cells in the context of photo-thermal therapy. To the best of the knowledge of the authors, the present study is one of the first attempts to quantify the influence of gold nanoshells on the temperature distributions inside the biological tissue phantoms upon laser irradiation using the dual phase lag heat conduction model.     

Evaluation of Immunotargeted Gold Nanoshells as Rapid Diagnostic Imaging Agents for HER2-Overexpressing Breast Cancer Cells: A Time-based Analysis

Biomedical nanotechnology offers superior potential for diagnostic imaging of malignancy at the microscopic level. In addition to current research focused on dual-imaging and therapeutic applications in vivo, these novel particles may also prove useful for obtaining immediate diagnostic results in vitro at the patient bedside. However, translating the use of nanoparticles for cancer detection to point-of-care applications requires that conditions be optimized such that minimal time is needed for diagnostic results to become available. Thus far, no reports have been published on minimizing the time needed to achieve acceptable optical contrast of cancer cells incubated with nanoparticles. In this study, we demonstrate the use of gold nanoshells targeted to anti-HER2 antibodies that produce sufficient optical contrast with HER2-overexpressing SK-BR-3 breast cancer cells in only 5 min. This work validates the proof of concept that nanoshells targeted to extracellular biomarkers can be used to enhance cancer diagnostic imaging for use in point-of-care applications.     

Tunable Assembly of Peptide-coated Gold Nanoparticles

The interaction between peptides and gold surfaces has increasingly been of interest for bionanotechnology applications. To more fully understand how to control such interactions, we have studied the optical properties of peptide-modified gold nanoparticles as a function of peptide composition, pH of the surrounding medium, and peptide concentration. We show using localized surface plasmon resonance, transmission electron microscopy, and surface-enhanced Raman scattering (SERS) that selected “gold-binding peptides” (GBPs), similar to those isolated for binding to gold films using yeast display, can bind to gold nanoparticles at a variety of pHs. Peptide modifications of nanoparticles can lead to irreversible particle aggregation when the pH of the solution is kept below the isoelectric point (pI) of the peptide. However, at pHs above the peptide’s pI, particles remain stable in solution, and peptides remain bound to the particles possibly through amine coordination of gold. Additionally, we demonstrate the potential in using SERS for the direct detection of GBPs on gold-silica nanoshells, eliminating the need for indirect labeling methods.     

EphrinA I-targeted nanoshells for photothermal ablation of prostate cancer cells

Gold-coated silica nanoshells are a class of nanoparticles that can be designed to possess strong absorption of light in the near infrared (NIR) wavelength region. When injected intravenously, these nanoshells have been shown to accumulate in tumors and subsequently mediate photothermal treatment, leading to tumor regression. In this work, we sought to improve their specificity by targeting them to prostate tumor cells. We report selective targeting of PC-3 cells with nanoshells conjugated to ephrinA I, a ligand for EphA2 receptor that is overexpressed on PC-3 cells. We demonstrate selective photo-thermal destruction of these cells upon application of the NIR laser.     

Thermal Chemosensitization of Breast Cancer Cells to Cyclophosphamide Treatment Using Folate Receptor Targeted Gold Nanoparticles

This article explores the application of hyperthermia mediated by alpha human folate receptor (αHFR) targeted gold nanoparticles (GNPs) for potentiating the cytotoxicity of cyclophosphamide (CPA) in αHFR positive breast cancer cells. Folate functionalized GNPs were delivered to highly αHFR positive breast cancer cells MDA-MB-231 and to MCF-7 breast cancer cells that does not express detectable levels of αHFR followed by hyperthermia. We have shown that hyperthermia induced by folate functionalized GNPs sensitized MDA-MB-231 cells by ten-fold to CPA treatment, whereas MCF-7 cells exhibited only onefold chemosensitization. Collectively, the study suggests the feasibility of using αHFR targeted GNPs for facilitating increased cellula r uptake of CPA in cancer cells expressing elevated αHFR, allowing reduction in drug dosage.     

Effect of hyperthermia on the antitumor actions of interferons.

Hyperthermia treatment has been shown to enhance the in vitro antiproliferative effects of IFN-alpha, IFN-beta, and IFN-gamma, with IFN-gamma being more strongly enhanced than IFN-alpha. The comparative effects of hyperthermia on the in vivo antitumor activities of IFN-alpha and IFN-gamma were evaluated in the murine system using both subcutaneous and intraperitoneal B16 melanoma tumor model systems. Heat-induced whole body hyperthermia, resulting in a 2 degree C rise in body temperature, was administered by incubating the mice for 8 hours in a dry incubator at 37.1 degrees C. Whole body hyperthermia was found to enhance the antitumor activity of IFN-alpha by approximately 1.0 fold and 1.2 fold for the subcutaneous and intraperitoneal tumor models, respectively. This represented an additive effect of hyperthermia and IFN-alpha. Hyperthermia was found to enhance the antitumor activity of IFN-gamma by approximately 2.9 fold and 2.2 fold for the subcutaneous and intraperitoneal tumor models, respectively. This represented a synergistic effect of hyperthermia and IFN-gamma. The results of this in vivo study confirm and extend the in vitro observation that hyperthermia more strongly enhances the antitumor action of IFN-gamma than IFN-alpha. These results may have clinical importance because they suggest that hyperthermia may be used in combination with IFN-gamma to provide a synergistically enhanced antitumor action.     

Solid and Hollow Gold Nanostructures for Nanomedicine: Comparison of Photothermal Properties

The photothermal properties of solid and hollow gold nanostructures represented by colloidal solutions of spherical nanoparticles, nanoshells, and nanocages upon irradiation with a 100 mW 808 nm continuous-wave laser for the first time were experimentally compared under identical optical density and nanoparticle concentration conditions. Accompanying computer modeling of light absorption by the studied gold nanostructures revealed the general parameters influencing the photothermal efficiency, which is of significance for nanomedical applications. The spectral position of localized plasmonic excitations of the studied nanostructures ranged from 518 nm for solid gold nanoparticles to 718 nm for gold nanocages, which provided a possibility to observe a direct influence of the wavelength proximity between the localized surface plasmon resonance and laser line on the heat generation capability of the nanostructures. As a result, the best photothermal efficiency was registered for gold nanocages, which proves them as an efficient photothermal treatment agent and a possible candidate to build a nanocarrier platform for drug delivery with a controlled release. Light absorption modeling demonstrated an existence of optimal wall thickness for gold nanoshells that should lead to the maximum photothermal efficiency when irradiated with 808 nm light, which varied from about 0.1 to 0.4 in units of external nanoshell radius with an increase of the wall porosity. Additionally, computer modeling results show that increased wall porosity should lead to enhanced photothermal efficiency of polydisperse colloidal solutions of hollow gold nanostructures.     

Near- and Far-Field Plasmonic Properties of Different Types of Eccentric Core-Shell Nanodimers

Finite element method (FEM) simulations have been carried out on free-standing and finite dielectric substrate-supported eccentric (i) silica core-gold nanoshell dimers and (ii) gold core-silica nanoshell dimers for understanding their near- and far-field plasmonic properties. In the case of eccentric silica core-gold nanoshell dimers, multiple peaks are observed in the near- and far-field spectra due to the plasmon hybridization. The number of peaks is found to be sensitive to the core offset parameters of the nanoshells forming nanodimer. The wavelength locations of the peaks due to the constructive coupling of the lower order modes found relatively more sensitive to the dielectric substrate. The number of peaks in the near- and far-field spectra found the same presence and absence of the dielectric substrate. The values of full width at half maximum (FWHM) of the peaks observed in the near-field spectra are found larger as compared to those observed in the far-field spectra. In contrast, in the case of eccentric gold core-silica nanoshell dimers, multiple peaks have not been observed. The FWHM of the observed peak is found sensitive to the core offset parameters of the nanoshells, and the number of peaks in the near field- and far-field spectra found not same in the presence and absence of the dielectric substrate. Moreover, the differences in near- and far-field spectra of plasmonically coupled (i) concentric nanoshells, (ii) eccentric nanoshells, and (iii) concentric and eccentric nanoshells also investigated numerically.

     

Targeted dual inhibition of c-Met/VEGFR2 signalling by foretinib improves antitumour effects of nanoparticle paclitaxel in gastric cancer models

Elevated expression of multiple growth factors and receptors including c-Met and VEGFR has been reported in gastric adenocarcinoma (GAC) and thus provides a potentially useful therapeutic target. The therapeutic efficacy of foretinib, a c-Met/VEGFR2 inhibitor, was determined in combination with nanoparticle paclitaxel (NPT) in GAC. Animal studies were conducted in NOD/SCID mice in subcutaneous and peritoneal dissemination xenografts. The mechanism of action was assessed by Immunohistochemical and Immunoblot analyses. In c-Met overexpressing MKN-45 cell-derived xenografts, NPT and foretinib demonstrated inhibition in tumour growth, while NPT plus foretinib showed additive effects. In c-Met low-expressing SNU-1 or patient-derived xenografts, the foretinib effect was smaller, while NPT had a similar effect compared with MKN-45, as NPT plus foretinib still exhibited an additive response. Median mice survival was markedly improved by NPT (83%), foretinib (100%) and NPT plus foretinib (230%) in peritoneal dissemination xenografts. Subcutaneous tumour analyses exhibited that foretinib increased cancer cell death and decreased cancer cell proliferation and tumour vasculature. NPT and foretinib suppressed the proliferation of GAC cells in vitro and had additive effects in combination. Further, foretinib caused a dramatic decrease in phosphorylated forms of c-Met, ERK, AKT and p38. Foretinib led to a decrease in Bcl-2, and an increase in p27, Bax, Bim, cleaved PARP-1 and cleaved caspase-3. Thus, these findings highlight the antitumour impact of simultaneous suppression of c-Met and VEGFR2 signalling in GAC and its potential to enhance nanoparticle paclitaxel response. This therapeutic approach might lead to a clinically beneficial combination to increase GAC patients’ survival.     

The Effect of Negative Curvature on the Plasmonic Coupling of Concentric Core–Shell Metallic Nanostructures

Negative curvature-dependent localized surface plasmon resonance (LSPR) properties of concentric core–shell metallic nanostructure have been studied using quasistatic approach and plasmon hybridization theory. Whether in single-layered gold nanoshell or double gold nanoshells, the oscillating surface charges always concentrate close to the poles of the metal surface with negative curvature, which results in the anisotropic local electric field distribution and affects both the inter-surface plasmonic coupling and inter-shell plasmonic coupling. Therefore, the change of the radius of the gold surface with negative curvature could modulate the plasmon hybridization and lead to the LSPR shifting. The physical mechanism of the negative curvature-dependent LSPR presents a potential for design and fabrication of nanoscale optical device based on core–shell type metallic nanostructures.     

Expression of a human NPT1/SLC17A1 missense variant which increases urate export

ABSTRACT

Human sodium-dependent phosphate cotransporter type 1 (NPT1/SLC17A1) is one of the urate transporters in the kidney. Our recent study revealed that a common missense variant, I269T (rs1165196), of NPT1 decreases the risk of renal underexcretion gout. Moreover, we demonstrated that human NPT1 is localized to the apical membrane of the renal proximal tubule, and that I269T is the gain-of-function variant which increases the NPT1-mediated urate export. However, the mechanism by which I269T variant increases the urate export remains to be clarified. Thus, we performed immunostaining and functional analysis of human NPT1 using the Xenopus oocyte expression system. For comparison of human NPT1 expression levels of oocyte membrane between 269I (wild type) and 269T (variant), immunostaining was performed with anti-human NPT1 antibodies. As a result, we showed that NPT1 I269T variant did not change the human NPT1 membrane expression levels, although NPT1 I269T variant increased the urate transport compared with NPT1 wild type. Combined with the previous report that I269T variant did not induce Km changes but increased the Vmax of urate transport in a proteoliposome system, our findings suggest that I269T variant increases NPT1-mediated urate export without increase of NPT1 expression levels on the membrane. Thus, I269T, a common missense variant of NPT1, might have faster conformation changes than NPT1 wild type in terms of the alternating-access model of transporters, and increases renal urate export in humans.     

The potential role of neopterin in Covid-19: a new perspective

Neopterin (NPT) is a member of pteridines group, synthesized by macrophages when stimulated by interferon gamma (INF-γ). NPT is regarded as a macrophage stimulation indicator, marker of cellular immune activation and T helper 1 (Th1) type 1 immune response. Here, we aimed to provide a view point on the NPT features and role in Covid-19. Serum NPT level is regarded as an independent prognostic factor for Covid-19 severity, with levels starting to increase from the 3rd day of SARS-CoV-2 infection, being associated with severe dyspnea, longer hospitalization period and complications. Also, early raise of NPT reflects monocytes/macrophages activation before antibody immune response, despite the NPT level may also remain high in Covid-19 patients or at the end of incubation period before the onset of clinical symptoms. On the other hand, NPT attenuates the activity of macrophage foam cells and is linked to endothelial inflammation through inhibition of adhesion molecules and monocytes migration. However, NPT also exerts anti-inflammatory and antioxidant effects by suppressing NF-κB signaling and NLRP3 inflammasomes. NPT can be viewed as a protective compensatory mechanism to counterpoise hyper-inflammation, oxidative stress, and associated organ damage.

     

Functional interaction between CFTR and the sodium-phosphate co-transport type 2a in Xenopus laevis oocytes

BACKGROUND: A growing number of proteins, including ion transporters, have been shown to interact with Cystic Fibrosis Transmembrane conductance Regulator (CFTR). CFTR is an epithelial chloride channel that is involved in Cystic Fibrosis (CF) when mutated; thus a better knowledge of its functional interactome may help to understand the pathophysiology of this complex disease. In the present study, we investigated if CFTR and the sodium-phosphate co-transporter type 2a (NPT2a) functionally interact after heterologous expression of both proteins in Xenopus laevis oocytes. METHODOLOGY/FINDINGS: NPT2a was expressed alone or in combination with CFTR in X. laevis oocytes. Using the two-electrode voltage-clamp technique, the inorganic phosphate-induced current (IPi) was measured and taken as an index of NPT2a activity. The maximal IPi for NPT2a substrates was reduced when CFTR was co-expressed with NPT2a, suggesting a decrease in its expression at the oolemna. This was consistent with Western blot analysis showing reduced NPT2a plasma membrane expression in oocytes co-expressing both proteins, whereas NPT2a protein level in total cell lysate was the same in NPT2a- and NPT2a+CFTR-oocytes. In NPT2a+CFTR- but not in NPT2a-oocytes, IPi and NPT2a surface expression were increased upon PKA stimulation, whereas stimulation of Exchange Protein directly Activated by cAMP (EPAC) had no effect. When NPT2a-oocytes were injected with NEG2, a short amino-acid sequence from the CFTR regulatory domain that regulates PKA-dependent CFTR trafficking to the plasma membrane, IPi values and NPT2a membrane expression were diminished, and could be enhanced by PKA stimulation, thereby mimicking the effects of CFTR co-expression. CONCLUSION/PERSPECTIVES: We conclude that when both CFTR and NPT2a are expressed in X. laevis oocytes, CFTR confers to NPT2a a cAMPi-dependent trafficking to the membrane. This functional interaction raises the hypothesis that CFTR may play a role in phosphate homeostasis.     

Adjuvant properties of thermal component of hyperthermia enhanced transdermal immunization: effect on dendritic cells

Hyperthermia enhanced transdermal (HET) immunization is a novel needle free immunization strategy employing application of antigen along with mild local hyperthermia (42°C) to intact skin resulting in detectable antigen specific Ig in serum. In the present study, we investigated the adjuvant effect of thermal component of HET immunization in terms of maturation of dendritic cells and its implication on the quality of the immune outcome in terms of antibody production upon HET immunization with tetanus toxoid (TT). We have shown that in vitro hyperthermia exposure at 42°C for 30 minutes up regulates the surface expression of maturation markers on bone marrow derived DCs. This observation correlated in vivo with an increased and accelerated expression of maturation markers on DCs in the draining lymph node upon HET immunization in mice. This effect was found to be independent of the antigen delivered and depends only on the thermal component of HET immunization. In vitro hyperthermia also led to enhanced capacity to stimulate CD4+ T cells in allo MLR and promotes the secretion of IL-10 by BMDCs, suggesting a potential for Th2 skewing of T cell response. HET immunization also induced a systemic T cell response to TT, as suggested by proliferation of splenocytes from immunized animal upon in vitro stimulation by TT. Exposure to heat during primary immunization led to generation of mainly IgG class of antibodies upon boosting, similar to the use of conventional alum adjuvant, thus highlighting the adjuvant potential of heat during HET immunization. Lastly, we have shown that mice immunized by tetanus toxoid using HET route exhibited protection against challenge with a lethal dose of tetanus toxin. Thus, in addition to being a painless, needle free delivery system it also has an immune modulatory potential.     

Circulation and distribution of gold nanoparticles and induced alterations of tissue morphology at intravenous particle delivery

Kinetics, biodistribution, and histological studies were performed to evaluate the particle‐size effects on the distribution of 15 nm and 50 nm PEG‐coated colloidal gold (CG) particles and 160 nm silica/gold nanoshells (NSs) in rats and rabbits. The above nanoparticles (NPs) were used as a model because of their importance for current biomedical applications such as photothermal therapy, optical coherence tomography, and resonance‐scattering imaging. The dynamics of NPs circulation in vivo was evaluated after intravenous administration of 15 nm CG NPs to rabbit, and the maximal concentrations of gold were observed 15–30 min after injection. Rats were injected in the tail vein with PEG‐coated NPs (about 0.3 mg Au/kg rats). 24 h after injection, the accumulation of gold in different organs and blood was determined by atomic absorption spectroscopy. In accordance with the published reports, we observed 15 nm particles in all organs with rather smooth distribution over liver, spleen and blood. By contrast, the larger NSs were accumulated mainly in the liver and spleen. For rabbits, the biodistribution was similar (72 h after intravenous injection). We report also preliminary data on the light microscopy and TEM histological examination that allows evaluation of the changes in biotissues after gold NPs treatment. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)