Monitoring Nanoparticle Dissolution via a Fluorescence-Color Shift

When and Where

Nov 29, 2022
11:30am - 11:45am

Hynes, Level 1, Room 104

Presenter

Christian Ritschel

Joanna Napp

Frauke Alves

Claus Feldmann

Co-Author(s)

Christian Ritschel¹,Joanna Napp^2,3,Frauke Alves^2,3,Claus Feldmann¹

Karlsruhe Institute of Technology (KIT)¹,University Medical Center Goettingen (UMG)²,Max Planck Institute for Multidisciplinary Sciences³

Abstract

Christian Ritschel¹,Joanna Napp^2,3,Frauke Alves^2,3,Claus Feldmann¹

Karlsruhe Institute of Technology (KIT)¹,University Medical Center Goettingen (UMG)²,Max Planck Institute for Multidisciplinary Sciences³

Optical imaging (OI) has emerged as a cost-effective, versatile method for biomedical monitoring and is used to visualize and distinguish cellular compartments and tissues as well as to study active cellular processes.1 Specific markers with suitable fluorescence characteristics, sufficient physiolgical and photochemical stability, as well as high biocompatibility are essential for the success of OI. For this purpose, a variety of molecular fluorescent dyes has been suggested and was attached in different ways to carrier molecules or carrier structures.2 Alternatively, fluorescent nanoparticles, such as quantum dots, plasmonic metal nanoparticles, or up-converting nanoparticles have been widely used and are typically characterized by higher chemical and photochemical stability as compared to molecular fluorescent dyes.3 Aiming at theranostic nanoparticles, we have developed the concept of inorganic-organic hybrid nanoparticles (IOH-NPs).4 These IOH-NPs are characterized by a saline composition with an inorganic cation and a functional organic anion. The functional organic anion can be a fluorescent dye and/or a pharmaceutical drug, which contains a phosphate, sulfonate, or carboxylate group. Together with a suitable inorganic cation, the functional organic anion forms insoluble saline nanoparticles in water. The optical detection of nanoparticles is usually related to a change in intensity, not a change of the wavelength. In some cases, the change of the fluorescence intensity was used to the point of an on-off or off-on behavior. Such fluorescent nanoparticles were exploited, for example, to study cellular uptake, drug delivery, drug release, and all kinds of sensing effects, which can be partly performed in real-time. However, a change of the emission intensity has the disadvantage of being concentration-dependent, which either requires a distinct on-off/off-on emission characteristics or a normalization of the emission intensity on a suitable reference. In this regard, a wavelength change of the emission as a response of a certain effect would be more effective. However, a wavelength shift is more complex in regard of the selection of the fluorescence markers and has only been reported in a few cases until now.5 Aiming at a fluorescence-based monitoring of the dissolution of nanoparticles and specifically the differentiation of the intact solid nanoparticles and the homogeneous solution after the nanoparticle dissolution, we have examined different strategies involving two different fluorescent dyes. We were successful with a mixture of [La(OH)]2+[ICG]–2 and [La(OH)]2+2[PTC]4– inorganic-organic hybrid nanoparticles (IOH-NPs) (ICG: indocyanine green, PTC: perylene-3,4,9,10-tetracarboxylate), which show an emission shift from red (intact nanoparticles in aqueous suspension) to green (aqueous solution after dissolution). Special advantages of the IOH-NPs comprise an aqueous synthesis, a simple material composition, an unprecedented high dye load (70-85 wt-% of total nanoparticle weight).6 This novel system of fluorescence markers – including synthesis, nanoparticle characterization, and first in vitro studies – will be presented with this contribution. 1. S. Kunjachan, J. Ehling, G. Storm, F. Kiessling and T. Lammers, Chem. Rev., 2015, 115, 10907-937. 2. O. S. Wolfbeis, Chem. Soc. Rev., 2015, 44, 4743-4768. 3. K. D. Wegner and N. Hildebrandt, Chem. Soc. Rev., 2015, 44, 4792-4834. 4. a) M. Poß, E. Zittel, C. Seidl, A. Meschkov, L. Muñoz, U. Schepers and C. Feldmann, Adv. Funct. Mater., 2018, 28, 1801074(1-8). b) M. Poß, R. J. Tower, J. Napp, L. C. Appold, T. Lammers, F. Alves, C.-C. Glüer, S. Boretius and C. Feldmann, Chem. Mater., 2017, 29, 3547-3554. 5. a) W. Zhao, Y. Zhao, Q. Wang, T. Liu, J. Sun and R. Zhang, Small, 2019, 15, 1903060. b) G. Shim, S. Ko, D. Kim, Q.-V. Le, G. T. Park, J. Lee, T. Kwon, H.-G. Choi, Y. B. Kim and Y.-K. Oh, J. Contr. Rel., 2017, 267, 67-79. 6. C. Ritschel, J. Napp, F. Alves, C. Feldmann, 2022, submitted.