Designing photon upconversion nanoparticles capable of intense emission in whole human blood

The use of energy looping between Tm3+ and Er3+ ions to obtain an intense upconversion under the 1208 nm radiation and its use in temperature sensing

“…29–33 Other possibilities are Nd 3+ ions used for 808 nm excitation, 13,28 Ho 3+ ions capable of absorption of 1156 nm, 34,35 and Er 3+ ions, which show emission under 1490–1580 nm excitation, which is on the edge of the 3 rd biological window. 27,35,36…”

“…red blood cells and lowered transparency of water in the 950–1050 nm range. 26,27 The conception of using 1208 nm excitation radiation and emission bands in the red to NIR range is new and promising for applications in biology, where lowering interactions of biological environment with excitation beam is of high importance. 11…”

“…low penetration of the 975 nm wavelength into tissue and high absorption of water in this range causing heating of the biological medium. [25][26][27] The laser wavelength used for excitation of UCNPs doped with Yb 3+ ions falls between the 1 st and 2 nd biological windows, where tissue shows lower transparency for radiation. [26][27][28] Better for medical applications are NPs excitable within biological windows: 1 st (650 to 950 nm), 2 nd (1100 to 1350 nm) or 3 rd (1600 to 1870 nm).…”

“…[25][26][27] The laser wavelength used for excitation of UCNPs doped with Yb 3+ ions falls between the 1 st and 2 nd biological windows, where tissue shows lower transparency for radiation. [26][27][28] Better for medical applications are NPs excitable within biological windows: 1 st (650 to 950 nm), 2 nd (1100 to 1350 nm) or 3 rd (1600 to 1870 nm). Also optimal is the emission of such NPs within these windows, most favourably within the 1 st optical window, as many popular optical detectors work within this range.…”

Advancements and applications of upconversion nanoparticles in wound dressings

“…One such breakthrough technology that holds immense promise in wound dressing applications is upconversion nanoparticles (UCNPs), which are a type of nanoscale material that can convert low-energy photons into high-energy photons through a process called upconversion. 1 These particles, made of various rare-earth ions, possess unique optical properties that have the potential to develop the field of wound care. Unlike conventional materials, which primarily absorb and emit light in the visible range, UCNPs can harness near-infrared (NIR) light and emit visible or ultraviolet (UV) light.…”