Photothermal therapy (PTT) at present, following the temperature definition for conventional thermal therapy, usually keeps the temperature of lesions at 42–45 °C or even higher. Such high temperature kills cancer cells but also increases the damage of normal tissues near lesions through heat conduction and thus brings about more side effects and inhibits therapeutic accuracy. Here we use temperature-feedback upconversion nanoparticle combined with photothermal material for real-time monitoring of microscopic temperature in PTT. We observe that microscopic temperature of photothermal material upon illumination is high enough to kill cancer cells when the temperature of lesions is still low enough to prevent damage to normal tissue. On the basis of the above phenomenon, we further realize high spatial resolution photothermal ablation of labelled tumour with minimal damage to normal tissues in vivo. Our work points to a method for investigating photothermal properties at nanoscale, and for the development of new generation of PTT strategy.

Anti-Stokes shift luminescence is a special optical process, which converts long-wavelength excitation to short-wavelength emission. This unique ability is especially helpful for bio-applications, because the longer-wavelength light source, usually referring to near infrared light, has a larger penetration depth offering a longer working distance for in vivo applications. The anti-Stokes shift luminescence signal can also be distinguished from the auto-fluorescence of biological tissues, thus reducing background interference during bioimaging. Herein, we summarize recent advances in anti-Stokes shift luminescent materials, including lanthanide and triplet-triplet-annihilation-based upconversion nanomaterials, and newly improved hot-band absorption-based luminescent materials. We focus on the synthetic strategies, optical optimization and biological applications as well as present comparative discussions on the luminescence mechanisms and characteristics of these three types of luminescent materials.

No abstract

No abstract

Multimodality imaging overcomes the shortage and incorporates the advantages of different imaging tools. Lanthanide-based nanoprobes are unique and have rich optical, magnetic, radioactive, and X-ray attenuation properties; however, simple doping of different lanthanide cations into one host can result in a material with multifunction but not the optimized properties. In this study, using NaLuF4:Yb,Tm as the core and 4 nm of (153)Sm(3+)-doped NaGdF4 (half-life of (153)Sm = 46.3 h) as the shell, we developed a lanthanide-based core-shell nanocomposite as an optimized multimodal imaging probe with enhanced imaging ability. The lifetime of upconversion luminescence (UCL) at 800 nm and relaxation rate (1/T1) were at 1044 μs and 18.15 s(-1)·mM(-1), respectively; however, no significant decrease in the attenuation coefficient was observed, which preserved the excellent X-ray imaging ability. The nanomaterial NaLuF4:Yb,Tm@NaGdF4((153)Sm) was confirmed to be effective and applicable for UCL imaging, X-ray computed tomography (CT), magnetic resonance imaging, and single-photon emission computed tomography (SPECT) in vivo. Furthermore, the NaLuF4:Yb,Tm@NaGdF4((153)Sm) nanoparticles were applied in tumor angiogenesis analysis by combining multimodality imaging of CT, SPECT, and confocal UCL imaging, which shows its value of multifunctional nanoparticles NaLuF4:Yb,Tm@NaGdF4((153)Sm) in tumor angiogenesis imaging.

No abstract

No abstract

This study was conducted to discover whether the rat cortex contains neurons that signal information concerning the previous occurrence of stimuli, as has been found in the primate. Recordings of the activity of 396 single neurons were made while unanaesthetized rats were shown objects. The effects on neuronal responsiveness of stimulus repetition and of the relative familiarity of the stimuli were sought. The areas sampled were the rhinal (entorhinal and perirhinal) cortex, area TE of the temporal cortex, the lateral occipital cortex and the hippocampal formation. The response to the first presentations of objects was significantly different from that to their second presentations for 63 (34%) of the 185 responsive neurons; for 39 of the neurons the response was smaller when the stimulus was repeated, whereas for 24 it was larger. The incidence of decremental responses was higher in the non-hippocampal cortex than in the hippocampal formation, while the incidence of incremental responses was higher in the hippocampal formation than other cortical areas. The response to unfamiliar objects was significantly different from that to highly familiar objects for 15 (22%) of 67 responsive neurons so tested; for 12 of the neurons the response was smaller when the stimulus was repeated, and for three it was larger; most of these neurons were found in area TE. The responses of ten familiarity neurons varied significantly with the relative familiarity of the stimuli but not with stimulus repetition; the responses of seven recency neurons varied significantly upon stimulus repetition but not with the relative familiarity of the stimuli. Thus information concerning stimulus repetition and familiarity is separably encoded at the single neuron level in the rat cortex. The results demonstrate that in the rat cortex as in the monkey cortex there are neurons that signal information concerning the prior occurrence of stimuli; such information is of importance to recognition memory, working memory and priming memory.