Measuring Cellular Uptake of Polymer Dots for Quantitative Imaging and Photodynamic Therapy

Abstract

There is a great deal of interest in the development of nanoparticles for biomedicine. The question of how many nanoparticles are taken up by cells is important for biomedical applications. Here, we describe a fluorescence method for the quantitative measurement of the cellular uptake of polymer dots (Pdots) and a further estimation of intracellular Pdots photosensitizer for fluorescence imaging and photodynamic therapy. The approach relies on the high brightness, excellent stability, minimal aggregation quenching, and metalloporphyrin doping properties of the Pdots. We correlated the single-cell fluorescence brightness obtained from fluorescence spectrometry, confocal microscopy, and flow cytometry with the number of endocytosed Pdots, which was validated by inductively coupled plasma mass spectrometry. Our results indicated that, on average, ∼1.3 million Pdots were taken up by single cells that were incubated for 4 h with arginine 8-Pdots (40 μg/mL, ∼20 nm diameter). The absolute number of endocytosed Pdots of individual cells could be estimated from confocal microscopy by comparing the single-cell brightness with the average intensity. Furthermore, we investigated the cell viability as a result of an intracellular Pdots photosensitizer, from which the half maximal inhibitory concentration was determined to be ∼7.2 × 105 Pdots per cell under the light dose of 60 J/cm2. This study provides an effective method for quantifying endocytosed Pdots, which can be extended to investigate the cellular uptake of various conjugated polymer carriers in biomedicine.

Exciton Diffusion, Antenna Effect, and Quenching Defects in Superficially Dye-Doped Conjugated Polymer Nanoparticles

“…These observations are attributed to the presence of non-emissive exciton quenching sites or recombination centers (Q). , The number, nature, and location of Q centers appear to be highly dependent on several parameters associated with CPN preparation conditions. For example, the fluorescence lifetime (τ 0 CPN ) and quantum yield (Φ F0 CPN ) of our F8BT CPNs in the absence of dyes are different from those reported by some authors − but matches those reported by other authors. , The nature of Q sites has been associated with a number of entities such as polymer synthesis defects and charged species such as hole/electron–polarons. In particular, there are a significant number of publications describing efficient exciton quenching by charged species (polarons).…”

“…For example, the fluorescence lifetime (τ 0 CPN ) and quantum yield (Φ F0 CPN ) of our F8BT CPNs in the absence of dyes are different from those reported by some authors 33−35 but matches those reported by other authors. 36,37 The nature of Q sites has been associated with a number of entities such as polymer synthesis defects and charged species such as hole/electron−polarons. In particular, there are a significant number of publications describing efficient exciton quenching by charged species (polarons).…”

Coreactant-free polyfluorene nanoparticles for the electrochemiluminescence quantitative analysis of dopamine and norepinephrine

“…Polyfluorene and its derivatives have attracted considerable attention in fluorescent imaging, 22 cellular labeling 23,24 as well as ECL sensing 25,26 because of the high fluorescence quantum yield, excellent photostability and non-toxic. 27,28 Two kinds of polymer dots were prepared using different polyfluorene derivatives to construct ECL biosensors for detecting Pb 2+ and proteins in the case of amine as coreactant, respectively.…”

Selective Photo-Assisted Eradication of Triple-Negative Breast Cancer Cells through Aptamer Decoration of Doped Conjugated Polymer Nanoparticles

“…Additionally, CPN biocompatibility in vitro and in vivo has been reported, which encouraged us to continue evaluating this type of nanomaterial for clinical use [ 19 , 21 , 22 ]. In accordance with the development of CPNs that specifically target cancer cells, thus reducing adverse side effects while improving therapeutic efficacy, different approaches have been considered to conjugate these types of nanoparticles to highly selective recognition molecules, such as antibodies or peptides, against cell-membrane receptors overexpressed on cancer cells [ 23 , 24 , 25 ]. The exquisite selectivity of oligonucleotide aptamers for cancer cell targeting and their ability to actively internalize into target cells via receptor-mediated endocytosis [ 26 ] make these biomolecules excellent candidates to improve the cancer cell labelling capacity and PDT efficacy.…”