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| Main Authors: | , , , , , , , , , |
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| Format: | Preprint |
| Published: |
2025
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| Subjects: | |
| Online Access: | https://arxiv.org/abs/2503.05325 |
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| _version_ | 1866917947708014592 |
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| author | Bagheri, Niusha Wang, Chenyi Guo, Du Lakshmanan, Anbharasi Zhu, Qi Ghazyani, Nahid Zhan, Qiuqiang Sotiriou, Georgios A. Liu, Haichun Widengren, Jerker |
| author_facet | Bagheri, Niusha Wang, Chenyi Guo, Du Lakshmanan, Anbharasi Zhu, Qi Ghazyani, Nahid Zhan, Qiuqiang Sotiriou, Georgios A. Liu, Haichun Widengren, Jerker |
| contents | Lanthanide-based upconversion nanoparticles (UCNPs) have attracted considerable attention in biomedical applications, largely due to their anti-Stokes shifted emission enabling autofluorescence-free signal detection. However, residual excitation light can still interfere with their relatively low brightness. While commonly used lock-in detection can distinguish weak signals from substantial random background, concurrently modulated residual excitation light is not eliminated. This remains a challenge, particularly under demanding experimental conditions.
Here, we explore the inherent nonlinear response of UCNPs and discover that UCNPs can act as frequency mixers in response to intensity-modulated excitation. Particularly, modulated excitation with more than one base modulation frequency can generate additional low-frequency beating-signals. We show how these signals are resolvable by low-speed detectors such as cameras, are devoid of ambient and residual excitation light, and how they can be enhanced through nanoparticle engineering. Detection of beating-signals thus provides a strategy to significantly enhance signal-to-background conditions in UCNP-based bioimaging and biosensing. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2503_05325 |
| institution | arXiv |
| publishDate | 2025 |
| record_format | arxiv |
| spellingShingle | Lanthanide upconversion nonlinearity: a key probe feature for background-free deep-tissue imaging Bagheri, Niusha Wang, Chenyi Guo, Du Lakshmanan, Anbharasi Zhu, Qi Ghazyani, Nahid Zhan, Qiuqiang Sotiriou, Georgios A. Liu, Haichun Widengren, Jerker Optics Applied Physics Lanthanide-based upconversion nanoparticles (UCNPs) have attracted considerable attention in biomedical applications, largely due to their anti-Stokes shifted emission enabling autofluorescence-free signal detection. However, residual excitation light can still interfere with their relatively low brightness. While commonly used lock-in detection can distinguish weak signals from substantial random background, concurrently modulated residual excitation light is not eliminated. This remains a challenge, particularly under demanding experimental conditions. Here, we explore the inherent nonlinear response of UCNPs and discover that UCNPs can act as frequency mixers in response to intensity-modulated excitation. Particularly, modulated excitation with more than one base modulation frequency can generate additional low-frequency beating-signals. We show how these signals are resolvable by low-speed detectors such as cameras, are devoid of ambient and residual excitation light, and how they can be enhanced through nanoparticle engineering. Detection of beating-signals thus provides a strategy to significantly enhance signal-to-background conditions in UCNP-based bioimaging and biosensing. |
| title | Lanthanide upconversion nonlinearity: a key probe feature for background-free deep-tissue imaging |
| topic | Optics Applied Physics |
| url | https://arxiv.org/abs/2503.05325 |