The tremendous development of nanotechnology is bringing us closer to the dream of clinical application of nanoparticles in photothermal therapies of tumors. This requires the use of specifi c nanoparticles that must be highly biocompatible, effi cient light-to-heat converters and fl uorescent markers. Temperature reading by the heating nanoparticles during therapy appears of paramount importance to keep at a minimum the collateral damage that could arise from undesirable excessive heating. In this work, this thermally controlled therapy is possible by using Nd 3+ ion-doped LaF 3 nanocrystals. Because of the particular optical features of Nd 3+ ions at high doping concentrations, these nanoparticles are capable of in vivo photothermal heating, fl uorescent tumor localization and intratumoral thermal sensing. The successful photothermal therapy experiments here presented highlight the importance of controlling therapy parameters based on intratumoral temperature measurements instead of on the traditionally used skin temperature measurements. In fact, signifi cant differences between intratumoral and skin temperatures do exist and could lead to the appearance of excessive collateral damage. These results open a new avenue for the real application of nanoparticle-based photothermal therapy at clinical level.

The future perspective of fluorescence imaging for real in vivo application are based on novel efficient nanoparticles which is able to emit in the second biological window (1000-1400 nm). In this work, the potential application of Nd(3+) -doped LaF(3) (Nd(3+) :LaF(3) ) nanoparticles is reported for fluorescence bioimaging in both the first and second biological windows based on their three main emission channels of Nd(3+) ions: (4) F(3/2) →(4) I(9/2) , (4) F(3/2) →(4) I(11/2) and (4) F(3/2) →(4) I(13/2) that lead to emissions at around 910, 1050, and 1330 nm, respectively. By systematically comparing the relative emission intensities, penetration depths and subtissue optical dispersion of each transition we propose that optimum subtissue images based on Nd(3+) :LaF(3) nanoparticles are obtained by using the (4) F3/2 →(4) I11/2 (1050 nm) emission band (lying in the second biological window) instead of the traditionally used (4) F(3/2) →(4) I(9/2) (910 nm, in the first biological window). After determining the optimum emission channel, it is used to obtain both in vitro and in vivo images by the controlled incorporation of Nd(3+) :LaF(3) nanoparticles in cancer cells and mice. Nd(3+) :LaF(3)nanoparticles thus emerge as very promising fluorescent nanoprobes for bioimaging in the second biological window.

The continuous development of nanotechnology has resulted in the actual possibility of the design and synthesis of nanostructured materials with pre-tailored functionabilities. Nanostructures capable of simultaneous heating and local thermal sensing are in strong demand as they would constitute a revolutionary solution to several challenging problems in bio-medicine, including the achievement of real time control during photothermal therapies. Several approaches have been demonstrated to achieve simultaneous heating and thermal sensing at the nanoscale. Some of them lack of sufficient thermal sensitivity and others require complicated synthesis procedures for heterostructure fabrication. In this study, we demonstrate how single core/shell dielectric nanoparticles with a highly Nd(3+) ion doped shell and an Yb(3+),Er(3+) codoped core are capable of simultaneous thermal sensing and heating under an 808 nm single beam excitation. The spatial separation between the heating shell and sensing core provides remarkable values of the heating efficiency and thermal sensitivity, enabling their application in single beam-controlled heating experiments in both aqueous and tissue environments.

We report on Ytterbium and Neodymium codoped LaF 3 core/shell nanoparticles capable of simultaneous heating and thermal sensing under single beam infrared laser excitation. Efficient light-to-heat conversion is produced at the Neodymium highly doped shell due to non-radiative deexcitations. Thermal sensing is provided by the temperature dependent Nd 3þ ! Yb 3þ energy transfer processes taking place at the core/shell interface. The potential application of these core/shell multifunctional nanoparticles for controlled photothermal subcutaneous treatments is also demonstrated. Published by AIP Publishing. [http://dx.doi.org/10.1063/1.4954170] Photothermal therapy (PTT) is a therapeutic strategy in which photon energy is converted into heat to cause irreversible damage at the cellular level and that could efficiently treat a great variety of diseases including cancer tumors. [1][2][3] In particular, nanoparticle (NP) based PTTs are attracting great attention nowadays. They are based on the use of nanoheaters (NHs), which are NPs with large light-to-heat conversion efficiencies. [4][5][6] The selective incorporation of NHs into cancer cells or tumors provides the means by which a subsequent optical excitation produces a temperature increment that will only affect the tissues aimed to be treated. The net effects caused on cancer tumors during PTTs strongly depend on both the magnitude of the heating as well as the treatment duration. [7][8][9][10] In this regard, in order to achieve an efficient treatment and keep the collateral damage at minimum it is extremely necessary to have a temperature reading during NP based PTTs. As a consequence, there has been an increasing interest in the design of multifunctional luminescent NPs capable of simultaneous heating and thermal sensing under single power excitation as they would constitute significant building blocks toward the achievement of real controlled PTTs as well as subcutaneous studies. 11 Despite the continuously growing list of systems that could operate as simultaneous NHs and nanothermometers (NThs), including polymeric NPs, quantum dots, nanodiamonds, metallic NPs, and rare earth-doped NPs, only a few of them show real potential of working subcutaneously. 12-14 This is so because most of them operate in the visible spectrum domain, where optical penetration into tissues is minimal. To avoid this limitation, it is necessary to shift their operation spectral range from the visible to the spectral infrared ranges where tissues become partially transparent (due to simultaneous attenuation in both tissue absorption and scattering), lying in the so-called biological windows (BWs). 15,16 Traditionally, three biological windows are defined: the first extending from 650 up to 950 nm, the second covering the infrared region about 1000-1350 nm and the third extending from 1500 up to 1750 nm. 17 In particular, the applicability in the second biological window (II-BW) opens up the possibility of not only deep tissue imaging but also of high contrast, autofluorescence free in ...

No abstract

No abstract

No abstract

No abstract