Luminescence nanoparticles

The most prominent nanomaterials for bioanalysis at present are semiconductor QDs. Rare-earth doped upconverting nanocrystals and precious metal nanoparticles are becoming increasingly popular, yet they are still far from reaching the level of use of QDs. Other luminescent nanoparticles like carbon-based nanoparticles start to appear, but the synthesis and application of these materials are still in their infancy and not significant for practitioners in the field of bioanalysis. 

The photoluminescence of these nanoparticles has very different causes, depending on the type of nanomaterial semiconductor QDs luminescence by recombination of excitons, rare-earth doped nanoparticles photoluminescence by atom orbital (AO) transitions within the rare-earth ions acting as luminescent centers, and metallic nanoparticles emit light by various mechanisms. Consequently, the optical properties of luminescent nanoparticles can be very different, depending on the material they consist of. 

From our research group Santra et al. [11,41,42] reported the development of novel luminescent nanoparticles composed of inorganic luminescent dye RuBpy, doped inside a sihca network. These dye-doped silica nanoparticles were synthesized using a w/o microemulsion of Tx-lOO/cyclohexane/ n-hexanol/water in which controlled hydrolysis of the TEOS leads to the formation of mono dispersed nanoparticles ranging from 5-400 nm. This research illustrates the efficiency of the microemulsion technique for the synthesis of uniform nanoparticles. These nanoparticles are suitable for biomarker application since they are much smaller than the cellular dimension and they are highly photostable in comparison to most commonly used organic dyes. It was shown that maximum liuninescence intensity was achieved when the dye content was around 20%. Moreover, for demonstration... 

While CdS and CeSe quantum dots are particularly luminescent and have been used extensively, there are concerns over their application in medical imaging in particular because of the potential toxicity associated with cadmium. As a result the syntenthesis of alternative luminescent nanoparticles based on less toxic materials such as Zn3P2 stabilised by tri-/j-octylphosphine oxide is an active area of endeavour.41... 

Nichkova, M., Dosev, D., Gee, S.J., Hammock, B.D., and Kennedy, I.M. 2007. Multiplexed immunoassays for proteins using magnetic luminescent nanoparticles for internal calibration. Anal Biochem 369(1) 34 10. 

FloDots Luminescent nanoparticles. Anal Bioanal Chem 385(3) 518-524. 

Wang, L.Y, Yan, R.X., Hao, Z.Y., etal. (2005) Fluorescence resonant energy transfer biosensor based on upconversion-luminescent nanoparticles. Angewandte Chemie International Edition, 44, 6054—6057. 

Warad, H. C., Ghosh, S. C., Hemtanon, B., Thanachayanont, C., and Dutta, J. 2005. Luminescent nanoparticles of Mn doped ZnS passivated with sodium hexametaphosphate. Sci. Technol. Adv. Mater. 6 296-301. 

Maia AS, Stefani R, Kodaira CA, Eelinto MCFC, Teotonio EES, Brito HF (2008) Luminescent nanoparticles of MgAl204 Eu, Dy prepared by citrate sol-gel method. Opt Mater 31 440 44... 

Wang LY, Yan RX, Hao ZY, Wang L, Zeng JH, Bao H, et al. Eluorescence resonant energy transfer biosensor based on upconversion-luminescent nanoparticles. Angew Chem Int Ed 2005 44(37) 6054. 

Weiler V, Haase M, Walter C et al (2007) Luminescent nanoparticles for molecular medicine. Biophotonics 2007 Optics in life. Science 6633 16332... 

Patterns were obtained out of metal chalcogenides which were comparable in size and penetration depth to those obtained for metals. Nanoparticles grew in size with irradiation time. Shallow patterns consisted of small, highly luminescent nanoparticles. Deep patterns, where long irradiation times were required, contained large particles with a comparatively low luminescence quantum yield. 

Keywords Biosensor, Chemical sensor. Luminescence, Nanoparticles, Upconversion... 

Ali R, Saleh SM, Meier RJ, Azab HA, Elgawad I, Wolfbeis OS (2010) Upconverting Nanoparticle Based Optical Sensor for Carbon Dioxide. Sens Actuators B Chem 150 126-131 Mader HS, Wolfbeis OS (2010) Optical ammonia sensor based on upconverting luminescent nanoparticles. Anal Chem 82 5002-5004... 

Rare earth oxides and oxysulfides are excellent host materials of rare earth ions to produce phosphors with high luminescence intensity. Nanophosphors are useM for the miniaturization of electronic devices and improved resolution of displays. Nanophosphors are also useM in biomedical applications such as biomarkers and diagnostic imaging agents, because nanoparticles are smaller titan cellular dimensions and similar in size to common biomolecules. Some of the applications of luminescent nanoparticles are listed in Tables. 

A variety of luminescent nanoparticles have been specifically devised for con-focal and multiphoton microscopy. These include nanomaterials, such as silica-based nanoparticles doped with two-photon-absorbing fluorophores, able to exhibit aggregation-enhanced fluorescence, gold nanoparticles, semiconductor nanocrystals (quantum dots/rods), and nanophosphors, viz., ceramic nanoparticles containing luminescent lanthanide ions. 

Ohulchanskyy TY, Roy I, Yong KT, Pudavar HE, Prasad PN (2014) High-resolution light microscopy using luminescent nanoparticles. Wiley Intindiscip Rev Nanomed Nanobiotechnol 2 162-175... 

The rare earth tetrakis P-diketonate complex functionalized silica spheres are conveniently prepared by a one-pot synthesis method which is based on the modified Stober process [56]. The resulted luminescent nanoparticles are shown schematically in Fig. 8.9 (top). Because the introduction of siloxy-bearing rare earth complex precursor can result in coagulation, a step-by-step approach is adopted to implement the synthesis of uniform silica sphere. The rare earth complex precursors added into the reaction system in the second step can ensure the size uniformity of the nanoparticles furthest. As a result, the rare earth chelate mainly lies in the outer layer of the silica sphere, which has been shown schematically in Fig. 8.9 [55]. As shown in Fig. 8.9 (bottom), the nanoparticles obtained are uniform spheres, approximately 61 5 nm in diameter. And there is no obviously change in the particle size or morphology. All nanoparticles show relatively high luminescent lifetimes. Among the quantum efficiencies, the experiment values of Eu-TTA-SS (34.8 %)... 

FloDots luminescent nanoparticles. Analytical and Bioanalytical Chemistry, 385, 518-24. 

---