Upconverting and NIR emitting rare earth based nanostructures for NIR-bioimaging

Abstract

In recent years, significant progress was achieved in the field of nanomedicine and bioimaging, but the development of new biomarkers for reliable detection of diseases at an early stage, molecular imaging, targeting and therapy remains crucial. The disadvantages of commonly used organic dyes include photobleaching, autofluorescence, phototoxicity and scattering when UV (ultraviolet) or visible light is used for excitation. The limited penetration depth of the excitation light and the visible emission into and from the biological tissue is a further drawback with regard to in vivo bioimaging. Lanthanide containing inorganic nanostructures emitting in the near-infrared (NIR) range under NIR excitation may overcome those problems. Due to the outstanding optical and magnetic properties of lanthanide ions (Ln(3+)), nanoscopic host materials doped with Ln(3+), e.g. Y2O3:Er(3+),Yb(3+), are promising candidates for NIR-NIR bioimaging. Ln(3+)-doped gadolinium-based inorganic nanostructures, such as Gd2O3:Er(3+),Yb(3+), have a high potential as opto-magnetic markers allowing the combination of time-resolved optical imaging and magnetic resonance imaging (MRI) of high spatial resolution. Recent progress in our research on over-1000 nm NIR fluorescent nanoprobes for in vivo NIR-NIR bioimaging will be discussed in this review.

LaF3 core/shell nanoparticles for subcutaneous heating and thermal sensing in the second biological-window

“…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 vivo fluorescence thermal sensing, as it has already been demonstrated in imaging applications. [18][19][20][21][22][23][24][25] As an additional requirement, the multifunctional NPs to be used should operate under infrared radiation single beam excitation at wavelength avoiding any non-selective cellular damage.…”

Over-1000 nm Near-infrared Fluorescence and SPECT/CT Dual-modal <i>in vivo</i> Imaging Based on Rare-earth Doped Ceramic Nanophosphors

“…In 2010 and 2011, our group have first reported and developed the OTN-NIR in vivo fluorescence imaging based on rare-earth ion doped ceramic nanophosphors (RED-CNPs) [5,6]. RED-CNPs are known to show strong OTN-NIR emission under NIR excitation [7,8]. Since then, other groups have reported the in vivo OTN-NIR fluorescence imaging by using RED-CNPs [9][10][11][12][13][14].…”

“…The in vivo OTN-NIR fluorescence imaging was carried out by using the home-made NIR imaging system at 0 -300 sec after intravenous injection of samples. The OTN-NIR fluorescence imaging system consists of 980 nm laser excitation and InGaAs CCD camera [6,7]. SPECT/CT fusion images were obtained using a SPECT/CT combined scanner (NanoSPECT/CT, Bioscan Inc., Washignton, D.C., USA) [15,16].…”

Near-Infrared to Visible Upconversion Emission Induced Photopolymerization: Polystyrene Shell Coated NaYF₄ Nanoparticles for Fluorescence Bioimaging and Nanothermometry

“…On the other hand, it is well known that near-infrared (NIR: < 700 nm) light has high tissue permeability as compared to visible light, and thus it can be used for deep-tissue in vivo fluorescence imaging [3,4]. Especially, over-1000-nm (OTN-) NIR fluorescence imaging has attracted much attention because NIR light in this region can penetrate the body more deeply than the commonly used first biological window (NIR-I: 700-900 nm) region [5][6][7][8][9][10]. The OTN-NIR region is also called the second (NIR-II or NIR-IIa: 1000-1350 nm) and third (NIR-III or NIR-IIb: 1550-1850 nm) biological windows [11].…”