Near-infrared Laser Light Research Articles

Cetuximab-Coated Thermo-Sensitive Liposomes Loaded with Magnetic Nanoparticles and Doxorubicin for Targeted EGFR-Expressing Breast Cancer Combined Therapy.

BackgroundOne major limitation of cancer chemotherapy is a failure to specifically target a tumor, potentially leading to side effects such as systemic cytotoxicity. In this case, we have generated a cancer cell-targeting nanoparticle-liposome drug delivery system that can be activated by near-infrared laser light to enable local photo-thermal therapy and the release of chemotherapeutic agents, which could achieve combined therapeutic efficiency.MethodsTo exploit the magnetic potential of iron oxide, we prepared and characterized citric acid-coated iron oxide magnetic nanoparticles (CMNPs) and encapsulated them into thermo-sensitive liposomes (TSLs). The chemotherapeutic drug, doxorubicin (DOX), was then loaded into the CMNP-TSLs, which were coated with an antibody against the epidermal growth factor receptor (EGFR), cetuximab (CET), to target EGFR-expressing breast cancer cells in vitro and in vivo studies in mouse model.ResultsThe resulting CET-DOX-CMNP–TSLs were stable with an average diameter of approximately 120 nm. First, the uptake of TSLs into breast cancer cells increased by the addition of the CET coating. Next, the viability of breast cancer cells treated with CET-CMNP-TSLs and CET-DOX-CMNP-TSLs was reduced by the addition of photo-thermal therapy using near-infrared (NIR) laser irradiation. What is more, the viability of breast cancer cells treated with CMNP-TSLs plus NIR was reduced by the addition of DOX to the CMNP-TSLs. Finally, photo-thermal therapy studies on tumor-bearing mice subjected to NIR laser irradiation showed that treatment with CMNP-TSLs or CET-CMNP-TSLs led to an increase in tumor surface temperature to 44.7°C and 48.7°C, respectively, compared with saline-treated mice body temperature ie, 35.2°C. Further, the hemolysis study shows that these nanocarriers are safe for systemic delivery.ConclusionOur studies revealed that a combined therapy of photo-thermal therapy and targeted chemotherapy in thermo-sensitive nano-carriers represents a promising therapeutic strategy against breast cancer.

PEO-CYTOP Fluoropolymer Nanosheets as a Novel Open-Skull Window for Imaging of the Living Mouse Brain.

SummaryIn vivo two-photon deep imaging with a broad field of view has revealed functional connectivity among brain regions. Here, we developed a novel observation method that utilizes a polyethylene-oxide-coated CYTOP (PEO-CYTOP) nanosheet with a thickness of ∼130 nm that exhibited a water retention effect and a hydrophilized adhesive surface. PEO-CYTOP nanosheets firmly adhered to brain surfaces, which suppressed bleeding from superficial veins. By taking advantage of the excellent optical properties of PEO-CYTOP nanosheets, we performed in vivo deep imaging in mouse brains at high resolution. Moreover, PEO-CYTOP nanosheets enabled to prepare large cranial windows, achieving in vivo imaging of neural structure and Ca2+ elevation in a large field of view. Furthermore, the PEO-CYTOP nanosheets functioned as a sealing material, even after the removal of the dura. These results indicate that this method would be suitable for the investigation of neural functions that are composed of interactions among multiple regions.

Biocompatible functionalized AuPd bimetallic nanoparticles decorated on reduced graphene oxide sheets for photothermal therapy of targeted cancer cells

Graphene, which is a unique 2D nanomaterials has received widespread attention for photothermal therapy (PTT) application. Here, we have designed the nanocomposite using polydopamine (PDA) functionalized reduced graphene oxide (rGO) nanosheets and bimetallic AuPd nanoparticles (NPs). The bimetallic AuPd nanoparticles decorated PDA functionalized rGO (AuPd-rGO/PDA) nanocomposite is synthesized by simple chemical reduction technique resulting in an average size of AuPd bimetallic nanostructure of 4.18 nm. The photothermal activity of the AuPd-rGO/PDA nanocomposite is explored under the irradiation of near infrared (NIR) laser sources of wavelength 915 nm. The temperature rises nearly 51 ± 3 °C within 3 min of irradiation NIR laser light resulting in the ablation of MDAMB-231 cancer cells up to concentration of 25 μg mL−1 of AuPd-rGO/PDA nanocomposite. This high performance of the ablation of cancer cells by photothermal therapy technique was facilitated using a low concentration of the nanocomposite by the synergistic effects of the bimetallic AuPd as well as rGO and PDA functionalization. The AuPd-rGO/PDA nanocomposite demonstrated the high biocompatibility towards normal healthy cell lines (L929) and exhibits survival efficiency of more than 85%. We also demonstrated the biocompatibility of the AuPd-rGO/PDA nanocomposite materials on the zebrafish embryos (Danio rerio). This work thus illustrates that the AuPd-rGO/PDA nanocomposite could behave as favourable nanoplatform for tumor therapeutics.

Aza-BODIPY Probe-Decorated Mesoporous Black TiO2 Nanoplatform for the Highly Efficient Synergistic Phototherapy

As an important noninvasive tumor treatment method, phototherapy has drawn extensive research interest. However, the requirements of separate excitation wavelengths, high degree of electron-hole recombination, and low reactive oxygen species (ROS) production capability are still the major barriers. This work reports the construction of a novel nanoplatform: design and synthesis of an aza-BODIPY (AB) probe-decorated mesoporous black titanium dioxide (TiO2) (MT) nanoparticles (NPs) for enhanced photodynamic therapy and photothermal therapy under single-wavelength near-infrared (NIR) laser irradiation for the first time. AB probe-decorated MT NPs (abbreviated as MTAB) were synthesized through the Al reduction of mesoporous anatase TiO2 NPs and subsequent adsorption of the AB probe. The mesoporous structure of MT ensured AB loading capacity and avoided the complicated modification and synthesis processes. Heterogeneous MTAB, which possessed staggered energy levels, were assessed for their capability for effective separation of photogenerated electrons and holes for the first time. Upon NIR laser light irradiation, MTAB exhibited sufficient ROS generation, resulting in distinct tumor cell killing and tumor tissue elimination. This unique heterogeneous nanoplatform with staggered energy levels provides a new strategy to enhance ROS generation and improve the therapeutic efficacy.

Stem Cell Membrane-Coated Au-Ag-PDA Nanoparticle-Guided Photothermal Acne Therapy

The polydopamine coating on Au-Ag nanoparticles (Au-Ag-PDA) possess excellent photothermal conversion efficiency after absorbing near-infrared laser light. After the stem cell membrane (STCM) encapsulates Au-Ag-PDA (Au-Ag-PDA@STCM), the nanoparticles (NPs) exhibit less cytotoxicity, and further optimizing their efficiency in photothermal therapy. The photothermal activity of Au-Ag-PDA@STCM has not yet been reported. Therefore, in this study, the sebaceous gland cell line SZ95 and the golden hamsters were used to observe the photothermal effects of the Au-Ag-PDA@STCM. SZ95 cells were treated with various concen-trations of Au-Ag-PDA@STCM NPs. The photothermal effect on cell proliferation was analyzed after irradiating the cells with a 808 nm laser. After laser treatment of golden hamsters, the flank organs were observed at 4 different time points. Histological analysis was performed to observe tissue damage. The results suggest that Au-Ag-PDA@STCM NPs significantly inhibited the proliferation of sebaceous gland cells in vitro, and reduced the size of sebaceous glands and sebum secretion in vivo. Therefore, NPs can be used to treat acne by thermally injuring sebaceous gland cells.

MON-488 Technologies of Diffuse Optics in the Diagnosis of Thyroid Cancer

BACKGROUND:The most common tool to test malignancy in the study of thyroid nodules (NT) is ultrasound and fine needle aspiration biopsy (FNAB). However, the sensitivity and specificity of the method and the effectiveness in thyroid cancer are limited; therefore new methods to study thyroid nodules are required. In this way our goal is to introduce hybrid diffuse optical instruments that are capable to measure and discriminate altered microvascular blood flow, blood volume and tissue scattering coefficients of TN. Near-infrared diffuse optical technologies aim to overcome the shortcomings of present techniques while screening for malignant thyroid nodules for early and fast diagnosis of cancer. This idea was based on the previous experience in breast cancers with diffuse optical techniques.METHODS:We have developed a device based on near-infrared diffuse correlation spectroscopy (DCS), which is a technology aimed at retrieving the microvascular flow of a certain region of tissue by mean of low power near-infrared laser light, and used in combination with a commercial ultrasound system (US). In order to combine these devices, we have developed a probe enabling multimodal data acquisition and subsequently we have analyzed the optical properties and the blood flow index in the thyroid lobes of eleven subjects who presented a thyroid nodule.RESULTS:Four subjects have required FNAB: P4 and P7 were reported as being malignant (Bethesda VI and IV respectively) while P6 and P8 were evaluated as being benign (Bethesda II). Surgical removal confirmed papillary thyroid carcinoma in P4, while denied the result of FNAB for P7 (Multinodular thyroid hyperplasia). We have considered the contralateral lobe as intra-subject reference to validate the feasibility of the DCS system in a very absorbing tissue as thyroid is. The difference between the blood flow index of the nodule and the contralateral lobe is maximum for subject P4, while the difference in benign subjects is lower. T-test showed no significant difference between benign nodules and contralateral lobes. Subject P7 showed a small difference as for other benign subjects despite the FNAB results indicating presence of malignancy.CONCLUSION:Apparently diffuse optics technologies would be able to differentiate malignant thyroid nodules from benign thyroid nodules, but more measurements require confirming our preliminary results as that diffuse optical technology can complement the current techniques such as US and FNAB.A new measurement campaign is being scheduled with a completed, fully integrated device that was developed within the LUCA project (http://www.luca-project.eu).

NIR Laser-Responsive PNIPAM and Gold Nanorod Composites for the Engineering of Thermally Reactive Drug Delivery Nanomedicine.

When ingesting a drug on its own or injecting it directly into tissue, its concentration increases immediately within the body, which often exacerbates the side effects and increases its toxicity. To solve this problem, we synthesized the thermally reactive polymer poly(N-isopropylacrylamide) (PNIPAM) using reversible addition–fragmentation chain transfer (RAFT) polymerization and prepared nanocarriers by binding PNIPAM to gold nanorods (GRs), with the anticancer agent doxorubicin (DOX) used as a model drug. PNIPAM changes from hydrophilic to hydrophobic at temperatures above its lower critical solution temperature, which represents a coil-to-globule volume phase transition. Because GRs absorb near-infrared (NIR) laser light and emit energy, PNIPAM aggregation occurs when the synthesized PNIPAM/GR are subjected to an NIR laser, and the temperature of the GRs rises. Using this principle, DOX was combined with the PNIPAM/GR complex, and the resulting anticancer effects with and without laser treatment were observed in Hela and MDA-MB-231 cells. In our proposed complex, the GR binding rate of PNIPAM reached 20% and the DOX binding rate reached 15%. The release profile of the drug following laser irradiation was determined using a drug release test and confocal microscopy imaging. It was subsequently confirmed that the release of the drug is higher at higher temperatures, especially with laser treatment. The proposed combination of temperature-reactive polymers and gold nanostructures shows promise for future research into controlled drug release.

Comparison of Mill Suss™-guided radial artery catheterization with the long-axis in-plane ultrasound-guided method under general anesthesia: a randomized controlled trial.

Continuous arterial blood pressure measurement is an effective perioperative monitoring method in patients with high-risk comorbidities. Recently, ultrasound guidance has been reported to facilitate radial artery catheterization. A new device, Mill Suss™, has also been developed for visualization of the radial artery and superficial veins using near-infrared laser light. In this study, we hypothesized that the Mill Suss-guided method might reduce the time and the number of attempts required for radial artery catheterization under general anesthesia, as compared to the long-axis in-plane ultrasound-guided method. Seventy-two adult patients aged 20-80years, ASA physical status I or II, were randomly assigned to the Mill Suss-guided group (Group M: n = 36) or ultrasound-guided group (Group U: n = 36). Primary outcomes were the time required for successful radial artery catheterization and the number of cannulation attempts. There were no significant differences in the characteristics of patients between the two groups. The time required for successful radial artery catheterization was significantly shorter in Group M than in Group U. The number of attempts for successful cannulation was not statistically significantly different between the two groups. However, the results might be different among anesthesiologists well experienced in the ultrasound-guided method.

Light-assisted drying for anhydrous preservation of biological samples: optical characterization of the trehalose preservation matrix.

Protein-based drugs have been developed to treat a variety of conditions and assays use immobilized capture proteins for disease detection. Freeze-drying is currently the standard for the preservation of proteins, but this method is expensive and requires lengthy processing times. Anhydrous preservation in a trehalose amorphous solid matrix offers a promising alternative to freeze-drying. Light assisted drying (LAD) is a processing method to create an amorphous trehalose matrix. Proteins suspended in a trehalose solution are dehydrated using near-infrared laser light. The laser radiation accelerates drying and as water is removed the trehalose forms a protective matrix. In this work, LAD samples are characterized to determine the crystallization kinetics of the trehalose after LAD processing and the distribution of amorphous trehalose in the samples. These characteristics influence the long-term stability of the samples. Polarized light imaging revealed that LAD processed samples are stable against crystallization during low-humidity storage at room temperature. Scanning white light interferometry and Raman spectroscopy indicated that trehalose was present across samples in an amorphous form. In addition, differential scanning microcalorimetry was used to measure the thermodynamic characteristics of the protein lysozyme after LAD processing. These results demonstrate that LAD does not change the properties of this protein.

Intraoperative Coronary Artery Imaging for Planning.

A clear understanding of coronary anatomy is critical in congenital heart surgery, especially when a ventriculotomy is planned, as in right ventricular outflow tract reconstructions and biventricular repairs. Typically, major epicardial coronary arteries are easily identified during first-time operations. However, in reoperative surgery, epicardial adhesions can obscure coronary vessels making their identification challenging. This paper describes the application of intraoperative fluorescence imaging in congenital heart surgery to obtain real-time coronary artery visualization for operative planning in order to avoid coronary injury. The fluorescence imaging utilizes indocyanine green (ICG). ICG is diluted to 0.28 mg/mL, and 0.1-1.0 mL of ICG solution is delivered via the cardioplegia cannula into the coronaries. A handheld imaging probe illuminates the field with near-infrared laser light, which excites ICG fluorescence. The fluorescence is captured by a camera, and the signal is transmitted to a monitor for real-time viewing. The imaging probe shows the precise coronary anatomy, enabling identification of the optimal ventriculotomy site. Intraoperative fluorescence imaging is a safe and effective technique for characterizing coronary anatomy. This technique enhances procedural planning and helps minimize the risk of coronary injury during reoperative congenital heart surgery.

Effect of resin composite filler on digital imaging fiber-optic transillumination.

Using a trans-illumination device that applies digital imaging fiber-optic transillumination (DIFOTI) technology, which involves the use of transmitted near-infrared laser light for inspection, the effect of composite resin (CR) restoration of a tooth on caries detection was evaluated. A cavity was formed in a tooth of the lower jaw cut from the specimen, experimental CRs with various filler rates were filled, and the influence of the filler on the obtained image was investigated. On the near-infrared images, the lightness differences between the CR-restored portion and the tooth portion were measured. The translucency parameter (TP) value and the correlation between the lightness differences and TP value of the CRs were investigated. The experimental results showed that the greater rate of macro-filler is, the lighter image and larger TP value. In other words, CR with hybrid filler to increase the TP value is less likely to affect caries detection by DIFOTI.

Transarterial Delivery of a Biodegradable Single-Agent Theranostic Nanoprobe for Liver Tumor Imaging and Combinatorial Phototherapy.

To assess selective accumulation of biodegradable nanoparticles within hepatic tumors after transarterial delivery for invivo localization and combinatorial phototherapy. A VX2 hepatic tumor model was used in New Zealand white rabbits. Transarterial delivery of silicon naphthalocyanine biodegradable nanoparticles was performed using a microcatheter via the proper hepatic artery. Tumors were exposed via laparotomy, and nanoparticles were observed by near-infrared (NIR) fluorescence imaging. For phototherapy, a handheld NIR laser (785 nm) at 0.6 W/cm2 was used to expose tumor or background liver, and tissue temperatures were assessed with a fiberoptic temperature probe. Intratumoral reactive oxygen species formation was assessed using a fluorophore (2',7'-dichlorodihydrofluorescein diacetate). Nanoparticles selectively accumulated within viable tumor by NIR fluorescence. Necrotic portions of tumor did not accumulate nanoparticles, consistent with a vascular distribution. NIR-dependent heat generation was observed with nanoparticle-containing tumors, but not in background liver. No heat was generated in the absence of NIR laser light. Reactive oxygen species were formed in nanoparticle-containing tumors exposed to NIR laser light, but not in background liver treated with NIR laser or in tumors in the absence of NIR light. Biodegradable nanoparticle delivery to liver tumors from a transarterial approach enabled selective invivo tumor imaging and combinatorial phototherapy.

Plasmonic optical trapping of pyrene-pendant polymer chains by controlling thermophoretic force

Plasmonic optical tweezers (POT) has a high potential for manipulation of nanomaterials due to an enhanced optical force. However, unfavorable thermal effects induced by plasmon excitation have frequently hindered the manipulation. For this issue, we have recently developed a novel non-plasmonic optical tweezers using a nanostructured silicon substrate (B-Si). We called it “Nano-Structured Semi-Conductor-Assisted Optical Tweezers (NASSCA-OT)”. In the present study, we trapped pyrene-pendant polymer chains homogeneously dissolved in water for POT or NASSCA-OT. We used plasmonic gold nanopyramidal dimer arrays or B-Si in contact with the aqueous polymer solution. During plasmon excitation with a near-infrared laser light, any sign of optical trapping was never detected in fluorescence micro-spectroscopy. By contrast, trapping of the polymer chains was obviously observed for NASSCA-OT. Upon laser irradiation, pyrene excimer fluorescence was dramatically increased at the focal spot. These results indicate that NASSCA-OT is a powerful tool for manipulation of molecular materials.

XUV-beamline for attosecond transient absorption measurements featuring a broadband common beam-path time-delay unit and in situ reference spectrometer for high stability and sensitivity.

Measuring bound-state quantum dynamics, excited and driven by strong fields, is achievable by time-resolved absorption spectroscopy. Here, a vacuum beamline for spectroscopy in the attosecond temporal and extreme ultraviolet (XUV) spectral range is presented, which is a tool for observing and controlling nonequilibrium electron dynamics. In particular, we introduce a technique to record an XUV absorption signal and the corresponding reference simultaneously, which greatly improves the signal quality. The apparatus is based on a common beam path design for XUV and near-infrared (NIR) laser light in a vacuum. This ensures minimal spatiotemporal fluctuations between the strong NIR laser and the XUV excitation and reference beams, while the grazing incidence optics enable broadband spectral coverage. The apparatus combines high spectral and temporal resolution together with an increase in sensitivity to weak absorption signatures by an order of magnitude. This opens up new possibilities for studying strong-field-driven electron dynamics in bound systems on their natural attosecond time scale.

NIR LEDs and NIR lasers as feasible alternatives to replace oven processes for treatment of thermal-responsive coatings

Near-infrared (NIR) laser sources (800–1000 nm) can potentially reduce the processing time for curing by a fast heating and incorporation of NIR absorbers into the coating. The latter converts NIR laser light absorbed into thermal energy. This curing technique was successfully applied to one-component thermoset coatings based on blocked polyisocyanate/hydroxy-polyester and melamine formaldehyde/hydroxy-acrylate resins with heptamethine cyanines as near-infrared absorbing material. The laser curing was additionally compared with LED sources. In general, the curing time significantly decreases in comparison with traditional heat sources. Furthermore, the photopolymerization of acrylates or epoxides can be induced simultaneously by adding suitable initiators due to photochemical generation of radicals and cations. Curing of the thermoset resin system and the photopolymerization process created interpenetrating networks. Principally, the techniques reported based on photonic NIR sources may help to substitute oven techniques where thermal activation of curing reactions is typically induced by oven or heating with infrared radiators for coating applications.

Effects of Entangled IR Radiation and Tunneling on the Conformational Interconversion of 2-Cyanophenol.

The conformers of 2-cyanophenol (2CP) and their interconversions were studied by infrared (IR) spectroscopy after trapping the monomers of the gaseous compound into low-temperature (15 K) argon (Ar) and nitrogen (N2) matrixes. To assist in the interpretation of the experimental results, B3LYP, MP2, and QCISD electronic structure calculations were carried out for the 2CP molecule. Two planar conformers, cis and trans (orientation of OH with respect to the cyano group), are predicted with gas-phase populations at the sublimation temperature of ∼98 and ∼2%, respectively. The most stable form (cis) was experimentally identified in both cryomatrixes, whereas the less stable one (trans) was not detected in Ar but could be observed in the N2 matrix with an abundance of ∼15%. Selective and bidirectional conversion between the two identified conformers was achieved upon irradiating the compound trapped in N2 matrix with near-infrared (NIR) laser light tuned at the wavenumbers of the 2ν(OH) transitions of the respective conformers. The conformational composition of 2CP was also found to be affected by the broad-band IR radiation emitted by the spectrometer source. This effect could be suppressed, partially or completely, by using different long-pass IR filters, with cutoff values of approximately 2200, 1590, and 1170 cm-1. The observed conformational changes are rationalized in terms of a competition between the over-the-barrier (light-induced) and through-the-barrier (hydrogen atom tunneling) effects. Very interestingly, both effects occur on the same time scale.

Migration of mesenchymal stem cells tethered with carbon nanotubes under a chemotactic gradient.

Carbon nanotubes (CNTs) have been extensively studied for photothermal ablation of malignant cells due to their ability to absorb near-infrared (NIR) laser light and convert it to thermal energy for the lysis of tumor cells. Functionalizing CNTs with tumor-targeting moieties can facilitate the delivery to tumor sites. Instead of using targeting moieties, mesenchymal stem cells (MSCs) have been considered as vehicles to deliver therapeutic agents to cancer cells. In this study, the effects of attaching CNTs to MSCs on cell migration in response to a chemotactic gradient were investigated. Multiwalled carbon nanotubes (MWCNTs) were functionalized with streptavidin–fluorescein isothiocyanate (SA–FITC). The surface of human MSCs was biotinylated by culturing MSCs with biotin–lipid containing medium. CNTs were then attached on the outer cell membrane of biotinylated MSCs through SA–biotin binding. Fluorescence microscopy confirmed CNTs were located on the surface of MSCs. Various amounts of CNTs anchored on the membrane of MSCs were used to examine the effects of CNTs on MSC proliferation and migration. Our transwell migration assay showed that 4.26 ng CNT per cell is the threshold value that would not affect the migration speed of CNT-tagged MSCs toward the established gradient of chemoattractant SDF-1α.

Tailor-made PL-UC-C3 nanoparticles for fluorescence/computed tomography imaging-guided cascade amplified photothermal therapy.

BackgroundDevelopment of the burgeoning number of photothermal therapy (PTT) agents has drawn a huge amount of interest, since PTT treatment is a powerful and effective alternative to traditional treatments. Optimal PTT agents should integrate some essential preconditions including negligible systemic toxicity, deep penetration into tumor tissues, and maximum laser energy absorbance. Unfortunately, only few of the PTT agents reported could meet all of the above mentioned conditions.MethodsHere, we report a brand new PTT agent through the encapsulation of NaGdF4:Yb,Tm@ NaGdF4:Yb (UCNPs) and an organic compound (C3) into poly-e-caprolactone-polyethylene-polyglycol (PCL-PEG) (PL-UC-C3 NPs).ResultsUCNPs as an up-conversion material and C3 as a PTT agent both feature low cytotoxicity, and most importantly, UCNPs with superior conversion efficiency could efficiently absorb the energy of a 980 nm laser, transform the near-infrared laser light into visible light, and translate the palingenetic visible light to C3. The usage of a 980 nm laser ensures a deeper penetration and lower energy, while the highly efficient absorption and transformation process confers a cascade amplified hyperthermia for tumor treatment.ConclusionIn this regard, our research provides a powerful and robust breakthrough for florescence/computed tomography imaging-guided PTT treatment, lighting up the clinical application in cancer treatment.

AgInS2-Coated Upconversion Nanoparticle as a Photocatalyst for Near-Infrared Light-Activated Photodynamic Therapy of Cancer Cells.

The development of high-performance near-infrared (NIR) photocatalysts with long-term stability and the elucidation on the working mechanism along with multifunctional activity toward biomedical applications have not been explored sufficiently. Herein, a novel hybrid material of an upconversion nanoparticle (NaYF4/Yb3+,Er3+) (UCN) coated with a ternary semiconductor (AgInS2, AIS) has been synthesized by a simple and robust two-step solvothermal route for NIR light active photocatalysis. Preparation of oleic acid-capped spherical UC nanoparticles (NPs) (∼25 nm) followed by solvothermal decomposition of two precursor complexes Ag(acda) and In(acda)3 resulted in the formation of well-defined NaYF4/Yb3+,Er3+@AgInS2 core-shell nanoparticles (UCN@AIS NPs) (∼90 nm). It has been found that effective energy transfer occurred from NaYF4/Yb3+,Er3+ to AgInS2 by a nonradiative luminescence resonance energy transfer process. Superior photocatalytic decomposition activity was validated in terms of the degradation of methylene blue dye under the exposure of 980 nm NIR laser light with the presence of a UCN@AIS NP catalyst. The degradation process was mediated primarily owing to the formation of a cytotoxic reactive oxygen species (ROS) by the hybrid material under NIR light irradiation, in which UCN performs as a transducer to sensitize AIS and trigger the ROS generation. In vitro cancer cell imaging potentiality of the UCN@AIS NPs was then studied on cervical cancer cells (HeLa cells). The UCN@AIS NPs induced in vitro cervical cancer cell death (photodynamic therapy) with ∼27% efficiency as measured by the MTT assay and thus proved to be a decent candidate for NIR active photocatalysts for biomedical applications.

Controllable Nucleation of Cavitation from Plasmonic Gold Nanoparticles for Enhancing High Intensity Focused Ultrasound Applications.

In this study, plasmonic gold nanoparticles were simultaneously exposed to pulsed near-infrared laser light and high intensity focused ultrasound (HIFU) for the controllable nucleation of cavitation in tissue-mimicking gel phantoms. This in vitro protocol was developed to demonstrate the feasibility of this approach, for both enhancement of imaging and therapeutic applications for cancer. The same apparatus can be used for both imaging and therapeutic applications by varying the exposure duration of the HIFU system. For short duration exposures (10 µs), broadband acoustic emissions were generated through the controlled nucleation of inertial cavitation around the gold nanoparticles. These emissions provide direct localization of nanoparticles. For future applications, these particles may be functionalized with molecular-targeting antibodies (e.g. anti-HER2 for breast cancer) and can provide precise localization of cancerous regions, complementing routine diagnostic ultrasound imaging. For continuous wave (CW) exposures, the cavitation activity was used to increase the localized heating from the HIFU exposures resulting in larger thermal damage in the gel phantoms. The acoustic emissions generated from inertial cavitation activity during these CW exposures was monitored using a passive cavitation detection (PCD) system to provide feedback of cavitation activity. Increased localized heating was only achieved through the unique combination of nanoparticles, laser light and HIFU. Further validation of this technique in pre-clinical models of cancer is necessary.