Nm Near-infrared Light Research Articles

Effects of Nanoscale Structures on Photothermal Heating Behaviors of Surface-Modified Fe3O4 Nanoparticles

In this investigation, the photothermal heating of superparamagnetic Fe3O4 nanoparticles was carried out by irradiating with either 785[Formula: see text]nm or 808[Formula: see text]nm near infrared (NIR) lasers. The effects of nanoparticle configuration, arrangement, and surface coating on the photothermal heating behavior were investigated for different Fe3O4 nanoparticle systems. Depending on the preparation method, Fe3O4 nanoparticles with mean hydrodynamic diameter ranging from 30[Formula: see text]nm to 250[Formula: see text]nm were synthesized. Photothermal transduction efficiency is a measure of light to thermal energy conversion; the highest efficiency obtained was 56% by 785[Formula: see text]nm and 42% by 808[Formula: see text]nm light irradiation for poly(acrylic) acid (PAA) coated Fe3O4 samples. With this conversion efficiency, the PAA-coated Fe3O4 nanoparticles raised the solution temperature [Formula: see text] [Formula: see text]C above physiological temperature, which is sufficient for cancer therapeutics. Photothermal transduction efficiency was found to decrease as the particle hydrodynamic diameter increased. Nanoparticle absorption and scattering properties were found different due to surface modifications. UV-VIS-NIR absorption spectroscopy was carried out and results were analyzed using the Mie scattering theory. Experimental photothermal transduction efficiency was found to scale with the theoretical results for a particular wavelength. These results have significance in the design and development of the Fe3O4 nanoparticle systems for effective cancer therapy with NIR light.

Intense Red-Emitting Upconversion Nanophosphors (800 nm-Driven) with a Core/Double-Shell Structure for Dual-Modal Upconversion Luminescence and Magnetic Resonance in Vivo Imaging Applications.

In this study, intense single-band red-emitting upconversion nanophosphors (UCNPs) excited with 800 nm near-infrared (NIR) light are reported. When a NaYF4:Nd,Yb active-shell is formed on the 12.7 nm sized NaGdF4:Yb,Ho,Ce UCNP core, the core/shell (C/S) UCNPs show tunable emission from green to red, depending on the Ce3+ concentration under excitation with 800 nm NIR light. Ce3+-doped C/S UCNPs (30 mol %) exhibit single-band red emission peaking at 644 nm via a 5F5 → 5I8 transition of Ho3+. A high Nd3+ concentration in the shell results in strong absorption at around 800 nm NIR light, even though the shell thickness is not large, and small-sized C/S UCNPs (16.3 nm) emit bright red light under 800 nm excitation. The formation of a thin NaGdF4 shell on the C/S UCNPs further enhances the upconversion (UC) luminescence and sub-20 nm sized core/double-shell (C/D-S) UCNPs exhibit 2.8 times stronger UC luminescence compared with C/S UCNPs. Owing to the strong UC luminescence intensity and Gd3+ ions on the surface of nanocrystals, they can be applied as a UC luminescence imaging agent and a T1 contrast agent for magnetic resonance (MR) imaging. In vivo UC luminescence and high-contrast MR images are successfully obtained by utilizing the red-emitting C/D-S UCNPs.

Nd3+ sensitized core-shell-shell nanocomposites loaded with IR806 dye for photothermal therapy and up-conversion luminescence imaging by a single wavelength NIR light irradiation.

To perform photothermal therapy (PTT) and luminescence imaging by a single wavelength NIR light irradiation, we have designed and prepared a novel nanocomposite incorporating the IR806 photothermal sensitizers (PTS) into the core-shell-shell NaYF4:Yb,Er@ NaYF4:Yb@NaYF4:Yb,Nd up-conversion nanoparticles (UCNPs). Irradiation with the 793 nm near-infrared (NIR) laser, the Nd3+ ions in the UCNPs were sensitized to up-convert energy via Yb3+ to the Er3+ ions to emit visible light at 540 nm and 654 nm, as well as to down-convert energy to the Yb3+ ions to emit NIR light at 980 nm. For luminescence imaging, the 793 nm NIR radiation is more suitable to use for deeper-tissue penetration and to reduce overheating problem due to water absorption as compared to 980 nm radiation. Additionally, the same 793 nm NIR radiation could also excite the IR806 dye for effective PTT. Surface modifications of the UCNPs with mesoporous silica (mSiO2) and polyallylamine (PAH) allow stable loading of IR806 dye and further derivatization with polyethylene glycol-folic acid (PEG-FA) for tumor targeting. Preliminary in vitro studies demonstrated that the final UCNP@mSiO2/IR806@PAH-PEG-FA nanocomposites (UCNC-FAs) could be uptaken by the MDA-MB-231 cancer cells and were “dark” viable, and when irradiated with the 793 nm laser, the MDA-MB-231 cell viability was effectively reduced. This indicated that the UCNC-FAs nanocomposites could be potentially useful for targeted photothermal therapy and up-conversion luminescence imaging by a single wavelength NIR light irradiation.

Fabrication of Mesoporous-Silica-Coated Upconverting Nanoparticles with Ultrafast Photosensitizer Loading and 808 nm NIR-Light-Triggering Capability for Photodynamic Therapy.

A novel photodynamic therapy nanoplatform based on mesoporous-silica-coated upconverting nanoparticles (UCNP) with electrostatic-driven ultrafast photosensitizer (PS) loading and 808 nm near infrared (NIR)-light-triggering capabilities has been fabricated. By positively charging inner channels of the mesoporous silica shell with amino groups, a quantitative dosage of negatively charged PS, exemplified with Rose Bengal (RB) molecules, can be loaded in 2 min. In addition, the electrostatic-driven technique simultaneously provides the platform with both excellent PS dispersity and leak-proof properties due to the repulsion between the same-charged molecules and the electrostatic attraction between different-charged PS and silica channel walls, respectively. The as-coated silica shell with an ultrathin thickness of 12±2 nm is delicately fabricated to facilitate ultrafast PS loading and efficient energy transfer from UCNP to PS. The outside surface of the silica shell is capped with hydrophilic β-cyclodextrin, which not only enhances the dispersion of resulting nanoparticles in water but also plays a role of "gatekeeper", blocking the pore opening and preventing PS leaking. The in vitro cellular lethality experiment demonstrates that RB molecules can be activated to effectively generate singlet oxygen and kill cancer cells upon 808 nm NIR light irradiation.

Highly Bright and Photostable Li(Gd,Y)F4:Yb,Er/LiGdF4Core/Shell Upconversion Nanophosphors for Bioimaging Applications

Intense green-emitting Li(Gd,Y)F4:Yb,Er/LiGdF4 core/shell (C/S) upconversion nanophosphors (UCNPs) with a tetragonal bipyramidal morphology are synthesized. The morphology and UC luminescence of the Li(Gd,Y)F4:Yb,Er UCNPs are significantly affected by the Li precursors, and bright UC green-emitting Li(Gd,Y)F4:Yb,Er UCNPs with a tetragonal bipyramidal shape, i.e., UC tetragonal bipyramids (UCTBs), are synthesized using LiOH·H2O as a Li precursor. A LiGdF4 shell is grown on the Li(Gd,Y)F4:Yb,Er UCTBs, and the C/S UCNPs exhibit 4.7 times higher luminescence intensity than core UCTBs. The C/S UCNPs show a high absolute UC quantum yield of 4.6% under excitation with 980 nm near infrared (NIR) light, and the UC luminescence from the C/S UCNPs is stable under continuous irradiation with the 980 nm NIR laser for 1 h. The hydrophobic surfaces of the as-synthesized C/S UCNPs are modified to hydrophilic surfaces by using poly(acrylic acid) (PAA) for bioimaging applications. They are applied to human cervical adenocarcinoma (HeLa) cell imaging and SK-MEL-2 melanoma cell imaging and in vivo imaging, including subcutaneous and intramuscular imaging, and UC luminescence images with high signal-to-noise ratio are obtained. Furthermore, sentinel-lymph-node imaging is successfully conducted with the PAA-capped Li(Gd,Y)F4:Yb,Er/LiGdF4 C/S UCNPs under illumination with NIR light.

Bacterial magnetic nanoparticles for photothermal therapy of cancer under the guidance of MRI

The bacterial magnetic nanoparticles (BMPs) are biomineralized by the magnetotactic bacteria and naturally covered with a layer of biomembrane. Herein, BMPs were isolated and firstly used for the photothermal therapy (PTT) of cancer under the guidance of magnetic resonance imaging (MRI) invitro and invivo. The results showed that BMPs could rapidly convert the energy of 808nm near-infrared (NIR) light into heat. After internalization by the HepG2 tumor cells, BMPs with good biocompatibility could induce an efficient killing effect after NIR light irradiation, along with a change of mitochondrial membrane potential (ΔΨm) and level of intracellular reactive oxygen species (ROS). The invivo therapy also confirms that PTT with BMPs could effectively and completely ablate the tumor in mice without inducing observable toxicity. T2-weighted MRI showed a clear tumor boundary and a 25% enhancement of negative contrast enhancement at the tumor site, suggesting that BMPs can act as an effective MRI contrast agent for guiding the PTT. Our results indicate that BMPs could be a potential theranostic agent for simultaneous MRI and PTT of cancer.

Enhanced Antitumor Efficacy by 808 nm Laser‐Induced Synergistic Photothermal and Photodynamic Therapy Based on a Indocyanine‐Green‐Attached W18O49 Nanostructure

A novel nanoplatform based on tungsten oxide (W18O49, WO) and indocyanine green (ICG) for dual‐modal photothermal therapy (PTT) and photodynamic therapy (PDT) has been successfully constructed. In this design, the hierarchical unique nanorod‐bundled W18O49 nanostructures play roles in being not only as an efficient photothermal agent for PTT but also as a potential nanovehicle for ICG molecules via electrostatic adsorption after modified with trimethylammonium groups on their surface. It is found that the ability of ICG to produce cytotoxic reactive oxygen species for PDT is well maintained after being attached on the WO, thus the as‐obtained WO@ICG can achieve a synergistic effect of combined PTT and PDT under single 808 nm near‐infrared (NIR) laser excitation. Notably, compared with PTT or PDT alone, the enhanced HeLa cells lethality of the 808 nm laser triggered dual‐modal therapy is observed. The in vivo animal experiments have shown that WO@ICG has effective solid tumor ablation effect with 808 nm NIR light irradiation, revealing the potential of these nanocomposites as a NIR‐mediated dual‐modal therapeutic platform for cancer treatment.

Fundus autofluorescence and Photobleaching : Definitions

SummaryFundus autofluorescence (AF) imaging is a non‐invasivemethod for detection of fundus fluorophores. The 488 nm blue (short wavelength: SW) or the 787 nm near‐infrared (NIR) wavelenght are usually used to induce AF of fluorophores located in the retinal pigment epithelium (RPE). In case of excitation with SW light, the resulting AF comes predominantly from A2E located in the lipofuscin granules of the RPE. On the other hand, excitation with NIR light seems to highlight the melanin. Regardless of the type of fluorophore in the RPE, the exciting light has to pass first through the retina and especially through the photoreceptor layer. The photopigment absorbs a part of the light, which will not be transmitted to the RPE. Therefore, RPE fluorophores will be less AF. In the same time, photo‐isomerization of the 11‐cis‐retinal to 11‐trans‐retinal by the photon absorbance will be the beginning of the visual signal. Thereby, retinal photopigment loose its absorption property and the light will be easily distributed to the RPE fluorophores. This photoreceptor bleaching phenomenon could be used to better understand the origin of the hyper‐AF pattern: hyper‐AF of the RPE or lack of absorbance of signal due to photopigment loss

An imaging-guided platform for synergistic photodynamic/photothermal/chemo-therapy with pH/temperature-responsive drug release

To integrate biological imaging and multimodal therapies into one platform for enhanced anti-cancer efficacy, we have designed a novel core/shell structured nano-theranostic by conjugating photosensitive Au25(SR)18 – (SR refers to thiolate) clusters, pH/temperature-responsive polymer P(NIPAm-MAA), and anti-cancer drug (doxorubicin, DOX) onto the surface of mesoporous silica coated core–shell up-conversion nanoparticles (UCNPs). It is found that the photodynamic therapy (PDT) derived from the generated reactive oxygen species and the photothermal therapy (PTT) arising from the photothermal effect can be simultaneously triggered by a single 980 nm near infrared (NIR) light. Furthermore, the thermal effect can also stimulate the pH/temperature sensitive polymer in the cancer sites, thus realizing the targeted and controllable DOX release. The combined PDT, PTT and pH/temperature responsive chemo-therapy can markedly improve the therapeutic efficacy, which has been confirmed by both in intro and in vivo assays. Moreover, the doped rare earths endow the platform with dual-modal up-conversion luminescent (UCL) and computer tomography (CT) imaging properties, thus achieving the target of imaging-guided synergistic therapy under by a single NIR light.

Rose-bengal-conjugated gold nanorods for in vivo photodynamic and photothermal oral cancer therapies

Gold nanorods (GNRs) conjugated with rose bengal (RB) molecules exhibit efficient singlet oxygen generation when illuminated by 532 nm green light and high photothermal efficiency under 810 nm near-infrared (NIR) irradiation. In vitro experiments show that reactive oxygen species generated by green light and hyperthermia produced by NIR light constitute two different mechanisms for cancer cell death. The RB-GNRs also exhibit improved photodynamic efficacy by enhancing the uptake of RB by cancer cells. In vivo experiments are conducted on hamster cheek pouches to resemble the human oral cancer conditions more accurately to assess the therapeutic effectiveness. Compared to the single photodynamic therapy (PDT) or photothermal therapy (PTT), the RB-GNRs with combined PDT-PTT capabilities provide better therapeutic effects against oral cancer and have large potential in cancer treatment.

ZnO:Er,Yb,Gd Particles Designed for Magnetic-Fluorescent Imaging and Near-Infrared Light Triggered Photodynamic Therapy

In this paper, fluorescent and magnetic bifunctional ZnO:Er,Yb,Gd particles were synthesized via a simple homogeneous precipitation method. The morphology, size, fluorescent properties, and magnetic properties of the particles can be readily modified by doping with Er3+, Yb3+, and Gd3+. The results revealed that the ZnO:Er,Yb,Gd particles have both down-conversion and up-conversion fluorescence after calcination at high temperatures (>700 °C). The products successfully labled the human hepatocellular carcinoma (HepG2) cells and presented low toxicity even at a high concentration of 2 mg/mL. Being upconverting nanoparticles (UCNPs), the prepared ZnO:Er,Yb,Gd particles exposed to 980 nm near-infrared (NIR) laser light emitted up-conversion fluorescence which could be absorbed by a photodynamic therapy (PDT) drug, methylene blue (MB), and then killed the HepG2 cells via PDT mechanism. In vitro therapeutic investigation evidenced the prominent PDT effects of MB-loaded ZnO:Er,Yb,Gd UCNPs upon NIR light irradia...

Bright dual-mode green emission from selective set of dopant ions in β-Na(Y,Gd)F4:Yb,Er/β-NaGdF4:Ce,Tb core/shell nanocrystals

Bright dual-mode green-emitting core/shell nanoparticles (NPs) were synthesized by doping selective set of lanthanide ions. Up-conversion (UC) green-emitting β-NaY0.2Gd0.6F4:Yb0.18,Er0.02 NPs (8.3 nm) were used as core material. Bright down-conversion (DC) green-emitting β-NaGd0.8F4:Ce0.15,Tb0.05 NPs showed ca. 31 times higher photoluminescence (PL) intensity than β-NaGdF4:Tb NPs and they were served as shell material with their excellent PL properties. The UC/DC core/shell NPs showed bright green light under excitations of 980 nm near infrared (NIR) light and 254 nm ultraviolet (UV) light, respectively. The UC/DC core/shell NPs showed ca. 11 times higher UC PL intensity than core UCNPs. Consequently, the core/shell NPs doped with selective set of lanthanide ions showed bright dual-mode green emission under excitations of NIR light and UV light, indicating that they are promising for application to optical imaging.

Immunolabeling and NIR-Excited Fluorescent Imaging of HeLa Cells by Using NaYF4:Yb,Er Upconversion Nanoparticles

Upconversion fluorescent nanoparticles can convert a longer wavelength radiation (e.g., near-infrared light) into a shorter wavelength fluorescence (e.g., visible light) and thus have emerged as a new class of fluorescent probes for biomedical imaging. Rare-earth doped beta-NaYF(4):Yb,Er upconversion nanoparticles (UCNPs) with strong UC fluorescence were synthesized in this work by using a solvothermal approach. The UCNPs were coated with a thin layer of SiO(2) to form core-shell nanoparticles via a typical Stober method, which were further modified with amino groups. After surface functionalization, the rabbit anti-CEA8 antibodies were covalently linked to the UCNPs to form the antibody-UCNP conjugates. The antibody-UCNP conjugates were used as fluorescent biolabels for the detection of carcinoembryonic antigen (CEA), a cancer biomarker expressed on the surface of HeLa cells. The successful conjugation of antibody to the UCNPs was found to lead to the specific attachment of the UCNPs onto the surface of the HeLa cells, which further resulted in the bright green UC fluorescence from the UCNP-labeled cells under 980 nm near-infrared (NIR) excitation and enabled the fluorescent imaging and detection of the HeLa cells. These results indicate that the amino-functionalized UCNPs can be used as fluorescent probes in cell immunolabeling and imaging. Because the UCNPs can be excited with a NIR light to exhibit strong visible fluorescence and the NIR light is safe to the body and can penetrate tissue as deep as several inches, our work suggests that, with proper cell-targeting or tumor-homing peptides or proteins conjugated, the NaYF(4):Yb,Er UCNPs can find potential applications in the in vivo imaging, detection, and diagnosis of cancers.