: Anti-stokes lanthanide based upconversion nanoparticles are widely used for various biological applications like labelling, therapy and biological detection because of their infrared/NIR excitation. Brightness of the upconversion nanoparticles is crucial for all these applications. For bright particles, use of extremely high temperatures with high boiling organic solvents is required followed by transfer of resultant hydrophobic particles to aqueous phase using some suitable process making the synthesis tedious and multistep. In this study one pot facile synthesis of hydrophilic low molecular weight PEI coated fluorescent upconversion particles is demonstrated. Photosensitizer Chlorin e6 was deposited on the surface of the NaYF4(Yb,Er) nanoparticles to form NaYF4@PEI@Chlorin e6 nanostructure. Comparison of singlet oxygen generation capacity with direct excitation using visible light and indirect excitation using NIR laser using same nanostructure is studied. NIR and visible light was made to pass through the beef tissue sandwiched between 2 glass slides and singlet oxygen produced was compared to same measurement done with no beef tissue assembly in beam path. Less penetration of visible light caused decrease in the singlet oxygen generation when passed through tissues, where singlet oxygen generation with NIR excitation was less affected by present of tissues because of the excellent penetration. 9-Anthracene carboxylic acid was used to probe singlet oxygen with fluorescence spectroscopy.

Singlet oxygen generation under NIR and light visible light excitation of Chlorin e6 on the surface of fluorescent polymer coated NaYF4 upconversion nanoparticles

249th National Meeting (2015)

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