ABSTRACT
This review summarizes essential information about the chemical stability of NaYF4-based upconverting nanoparticles (UCNPs) in aqueous solutions, a crucial aspect for achieving high quality standards for biomedical materials. We present an in-depth analysis of the major experimental evidence and proposed mechanisms that provide a theoretical framework for understanding UCNPs degradation, destabilization, and dissolution under different conditions such as media composition, temperature, particle size, and the synthetic methods employed. The ion release and disintegration of the UCNP crystal structure may trigger cytotoxic events within living organisms and impact on their optical properties, precluding their safe use in biological environments. Also, we present a summary of the characterization techniques' toolbox employed for monitoring and detecting these degradation processes. Closing the existing "information gap" that links UCNP physicochemical properties, such as solubility and chemical stability, with the biological response of living organisms or tissues, is vital for using these nanoparticles as biological tracer probes, theranostic vehicles, or for clinical purposes. The understanding of chemical phenomena at the nanoparticle solid-liquid interface is mandatory to complete the molecular picture of nanosized objects, orienting in a rational manner the efforts of research and development in the early stages of these functional materials.
Subject(s)
Fluorides/metabolism , Metal Nanoparticles/chemistry , Yttrium/metabolism , Animals , Cell Line, Tumor , Drug Stability , Fluorides/chemistry , Fluorides/radiation effects , Fluorides/toxicity , Humans , Light , Metal Nanoparticles/radiation effects , Metal Nanoparticles/toxicity , Optical Phenomena , Yttrium/chemistry , Yttrium/radiation effects , Yttrium/toxicityABSTRACT
The investigation of scintillation properties of europium doped yttrium orthovanadate shows the suitability of this material for fiber-based dose rate measurements. All measurements were carried out with a 6 MV Varian linear accelerator. The temperature dependence of the signal is lower than that of the plastic scintillators reported so far. By measuring the afterglow of probes between Linac-pulses, the signal due to the stem effect can be successfully eliminated. Comparison of depth dose profiles in a water phantom for radiation field dimensions between 1 x 1 cm(2) and 10 x 10 cm(2) shows that the probes are suitable for small fields having dimensions up to 1 x 1 cm(2). The high light yield of probes having dimensions of 1 mm opens up the possibility for their use in spatially confined radiation fields, such as in intensity-modulated radiotherapy (IMRT) and volume-modulated radiation therapy (VMAT).