Advancing fluorescence imaging: enhanced control of cyanine dye-doped silica nanoparticles.

BACKGROUND: Silica nanoparticles (SNPs) have immense potential in biomedical research, particularly in drug delivery and imaging applications, owing to their stability and minimal interactions with biological entities such as tissues or cells. RESULTS: With synthesized and characterized cyanine-dye-doped fluorescent SNPs (CSNPs) using cyanine 3.5, 5.5, and 7 (Cy3.5, Cy5.5, and Cy7). Through systematic analysis, we discerned variations in the surface charge and fluorescence properties of the nanoparticles contingent on the encapsulated dye-(3-aminopropyl)triethoxysilane conjugate, while their size and shape remained constant. The fluorescence emission spectra exhibited a redshift correlated with increasing dye concentration, which was attributed to cascade energy transfer and self-quenching effects. Additionally, the fluorescence signal intensity showed a linear relationship with the particle concentration, particularly at lower dye equivalents, indicating a robust performance suitable for imaging applications. In vitro assessments revealed negligible cytotoxicity and efficient cellular uptake of the nanoparticles, enabling long-term tracking and imaging. Validation through in vivo imaging in mice underscored the versatility and efficacy of CSNPs, showing single-switching imaging capabilities and linear signal enhancement within subcutaneous tissue environment. CONCLUSIONS: This study provides valuable insights for designing fluorescence imaging and optimizing nanoparticle-based applications in biomedical research, with potential implications for targeted drug delivery and in vivo imaging of tissue structures and organs.

Monitoring in vivo behavior of size-dependent fluorescent particles as a model fine dust.

BACKGROUND: There has been growing concern regarding the impact of air pollution, especially fine dust, on human health. However, it is difficult to estimate the toxicity of fine dust on the human body because of its diverse effects depending on the composition and environmental factors. RESULTS: In this study, we focused on the difference in the biodistribution of fine dust according to the size distribution of particulate matter after inhalation into the body to predict its impact on human health. We synthesized Cy7-doped silica particulate matters (CSPMs) having different particle sizes and employed them as model fine dust, and studied their whole-body in vivo biodistribution in BALB/c nude mice. Image-tracking and quantitative and qualitative analyses were performed on the ex vivo organs and tissues. Additionally, flow cytometric analysis of single cells isolated from the lungs was performed. Smaller particles with a diameter of less than 100 nm (CSPM0.1) were observed to be removed relatively rapidly from the lungs upon initial inhalation. However, they were confirmed to accumulate continuously over 4 weeks of observation. In particular, smaller particles were found to spread rapidly to other organs during the early stages of inhalation. CONCLUSIONS: The results show in vivo behavioral differences that arisen from particle size through mouse experimental model. Although these are far from the human inhalation studies, it provides information that can help predict the effect of fine dust on human health. This study might provide with insights on association between CSPM0.1 accumulation in several organs including the lungs and adverse effect to underlying diseases in the organs.