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A core-shell-shell nanoplatform upconverting near-infrared light at 808 nm for luminescence imaging and photodynamic therapy of cancer.

ABSTRACT: Upconversion nanoparticles (UCNPs) have been extensively explored for photodynamic therapy (PDT) and imaging due to their representative large anti-Stokes shifts, deep penetration into biological tissues, narrow emission bands, and high spatial-temporal resolution. Conventional UCNP-based PDT system, however, utilizes exitation at 980 nm, at which water has significant absorption, leading to a huge concern that the cell killing effect is from the irradiation due to overheating effect. Here we report an efficient nanoplatform using 808-nm excited NaYbF4:Nd@NaGdF4:Yb/Er@NaGdF4 core-shell-shell nanoparticles loaded with Chlorin e6 and folic acid for simultaneous imaging and PDT. At this wavelength, the absorption of water is minimized. High energy transfer efficiency is achieved to generate cytotoxic singlet oxygen. Our nanoplatform effectively kills cancer cells in concentration-, time-, and receptor-dependent manners. More importantly, our nanoplatform is still able to efficiently generate singlet oxygen beneath 15-mm thickness of muscle tissue but 980 nm excitation cannot, showing that a higher penetration depth is achieved by our system. These results imply that our nanoplatform has the ability to effectively kill intrinsic tumor or the center of large tumors through PDT, which significantly improves the anticancer efficacy using UCNP-based PDT system and broadens the types of tumors that could be cured.

SUBMITTER: Ai F

PROVIDER: S-EPMC4451683 | biostudies-literature | 2015

REPOSITORIES: biostudies-literature

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A core-shell-shell nanoplatform upconverting near-infrared light at 808 nm for luminescence imaging and photodynamic therapy of cancer.

Ai Fujin F Ju Qiang Q Zhang Xiaoman X Chen Xian X Wang Feng F Zhu Guangyu G

Scientific reports 20150602

Upconversion nanoparticles (UCNPs) have been extensively explored for photodynamic therapy (PDT) and imaging due to their representative large anti-Stokes shifts, deep penetration into biological tissues, narrow emission bands, and high spatial-temporal resolution. Conventional UCNP-based PDT system, however, utilizes exitation at 980 nm, at which water has significant absorption, leading to a huge concern that the cell killing effect is from the irradiation due to overheating effect. Here we re ...[more]

PMID: 26035527

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Project description:BACKGROUND:The unique upconversion properties of rare-earth-doped nanoparticles offers exciting opportunities for biomedical applications, in which near-IR remote activation of biological processes is desired, including in vivo bioimaging, optogenetics, and light-based therapies. Tuning of upconversion in purposely designed core-shell nanoparticles gives access to biological windows in biological tissue. In recent years there have been several reports on NIR-excitable upconverting nanoparticles capable of working in biological mixtures and cellular settings. Unfortunately, most of these nanosystems are based on ytterbium's upconversion at 980 nm, concurrent with water's absorption within the first biological window. Thus, methods to produce robust upconverting nanoplatforms that can be efficiently excited with other than 980 nm NIR sources, such as 808 nm and 1064 nm, are required for biomedical applications. RESULTS:Herein, we report a synthetic method to produce aqueous stable upconverting nanoparticles that can be activated with 808 nm excitation sources, thus avoiding unwanted heating processes due to water absorbance at 980 nm. Importantly, these nanoparticles, once transferred to an aqueous environment using an amphiphilic polymer, remain colloidally stable for long periods of time in relevant biological media, while keeping their photoluminescence properties. The selected polymer was covalently modified by click chemistry with two FDA-approved photosensitizers (Rose Bengal and Chlorin e6), which can be efficiently and simultaneously excited by the light emission of our upconverting nanoparticles. Thus, our polymer-functionalization strategy allows producing an 808 nm-activable photodynamic nanoplatform. These upconverting nanocomposites are preferentially stored in acidic lysosomal compartments, which does not negatively affect their performance as photodynamic agents. Upon 808 nm excitation, the production of reactive oxidative species (ROS) and their effect in mitochondrial integrity were demonstrated. CONCLUSIONS:In summary, we have demonstrated the feasibility of using photosensitizer-polymer-modified upconverting nanoplatforms that can be activated by 808 nm light excitation sources for application in photodynamic therapy. Our nanoplatforms remain photoactive after internalization by living cells, allowing for 808 nm-activated ROS generation. The versatility of our polymer-stabilization strategy promises a straightforward access to other derivatizations (for instance, by integrating other photosensitizers or homing ligands), which could synergistically operate as multifunctional photodynamic platforms nanoreactors for in vivo applications.

Project description:Recently, the functionalization of nanoparticles, either within themselves or on the outer surface and its application in medicine, turned out to be the ultimate goal of nanotechnology. By providing these nanoparticles with chemical functional groups, one can force the nanoparticles to target the markers of the particular diseases or to measure the quantity and distribution of various intracellular species. In this paper, we report our development of a pH-responsive nanocomposite based on lanthanide-doped upconverting nanoparticles (UCNPs). Through multiphoton absorption and energy migration between spatially separated Nd3+, Yb3+, and Tm3+ in a three-layered NaYF4 host coated with FITC (fluorescein-5-isothiocyanate), this nanocomposite can measure the pH with high sensitivity. The fundamental acidity measurement is based on the pH-dependent equilibrium of the bright and dark states of FITC. The tremendous advantages of this system, regarding the pH measurement, come from the fact that the versatility of UCNP-imaging can fully be exploited. This includes the fact that (a) the optical wavelengths for the sensitization (980 nm and/or 808 nm) and the emission bands (UV, visible) are well separated, (b) the spectral overlap between FITC (absorption) and Tm3+ (emission) is substantially high, (c) there is no background signal due to the near-infrared laser, and (d) the signals are consistent regardless of the fluctuations by monitoring the ratio of blue band with respect to the unaffected self-reference (red and near-infrared bands). Moreover, the double shell structure is obviously superior to the core-shell structure in that it enhances the spectral separation between the sensitizer and the emitter in the upconversion process, inhibiting any unnecessary contamination in the spectra. Finally, it is noteworthy that Yb3+ plays crucial roles as a sensitizer at 980 nm excitation and a bridge above which 808 nm excitation migrates from Nd3+ to Tm3+ via the Yb3+ excited state.

Project description:We report the synthesis and properties of the first representative of a new class of PtL2 complexes with ambidentate mixed-donor cyanoxime ligands [L = 2-cyano-2-oximino-N,N'-diethylaminoacetamide, DECO (1)]. Three differently colored polymorphs of "Pt(DECO)2" (3-5) were isolated, with the first two being crystallographically characterized. The dark-green complex [Pt(DECO)2]n (5) spontaneously forms in aqueous solution via aggregation of yellow monomeric complex 3 into the red dimer [Pt(DECO)2]2 (4), followed by further oligomerization into coordination polymer 5. A spectroscopic and light-scattering study revealed a "poker-chips"-type 1D polymeric structure of 5 in which units are held by noncovalent metallophilic interactions, forming a Pt---Pt wire. The polymer 5 shows a broad absorption at 400-900 nm and emission at unusually long wavelengths in the range of 1000-1100 nm in the solid state. The near-infrared (NIR) emission of polymer 5 is due to the formation of a small amount of nonstoichiometric mixed-valence Pt(II)/Pt(IV) species during synthesis. A featureless electron paramagnetic resonance spectrum of solid sample 5 recorded at +23 and -193 °C evidences the absence of Pt(III) states, and the compound represents a "solid solution" containing mixed-valence Pt(II)/Pt(IV) centers. Exposure of KBr pellets with 5% 5 to Br2 vapors leads to an immediate ∼30% increase in the intensity of photoluminescence at 1024 nm, which confirms the role and importance of mixed-valence species for the NIR emission. Thus, the emission is further enhanced upon additional oxidation of Pt(II) centers, which improves delocalization of electrons along the Pt---Pt vector. Other polymorph of the "Pt(DECO)2" complex--monomer--did not demonstrate luminescent properties in solutions and the solid state. An excitation scan of 5 embedded in KBr tablets revealed an emission only weakly dependent on the wavelength of excitation. The NIR emission of quasi-1D complex 5 was studied in the range of -193 to +67 °C. Data showed a blue shift of λmax and a simultaneous increase in the emission line intensity with a temperature rise, which is explained by analogy with similar behavior of known quasi-1D K2[Pt(CN)4]-based solids, quantum dots, and quantum wells with delocalized carriers. The presented finding opens a route to a new class of platinum cyanoxime based NIR emissive complexes that could be used in the design of novel NIR emitters and imaging agents.

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A core-shell-shell nanoplatform upconverting near-infrared light at 808 nm for luminescence imaging and photodynamic therapy of cancer.

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A core-shell-shell nanoplatform upconverting near-infrared light at 808 nm for luminescence imaging and photodynamic therapy of cancer.

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