Colourimetric redox-polyaniline nanoindicator for in situ vesicular trafficking of intracellular transport

Abstract

Vesicular pH modulates the function of many organelles and plays a pivotal role in cell metabolism processes such as proliferation and apoptosis. Here, we introduce a simple colorimetric redox-polyaniline nanoindicator, which can detect and quantify a broader biogenic pH range with superior sensitivity compared to pre-established trafficking agents employing one-dimensional turn-on of the fluorescence resonance-energy-transfer (FRET) signal. We fabricated polyanilinebased nanoprobes, which exhibited convertible transition states according to the proton levels, as an in situ indicator of vesicular transport pH. Silica-coated Fe 3 O 4 -MnO heterometal nanoparticles were synthesised and utilised as a metal oxidant to polymerise the aniline monomer. Finally, silica-coated polyaniline nanoparticles with adsorbed cyanine dye fluorophores Cy3 and Cy7 (FPSNI Cy3 and FPSNI Cy7 ) were fabricated as proton-sensitive nanoindicators. Owing to the selective quenching induced by the local pH variations of vesicular transport, FPSNI Cy3 and FPSNI Cy7 demonstrated excellent intracellular trafficking and provided sensitive optical indication of minute proton levels.

Polyaniline nanoparticles for near-infrared photothermal destruction of cancer cells

“…This organelle presents an acidic pH (4-5.5), and for this reason, the polyaniline triggers transition state from an emeraldine base (EB) to an emeralidine salt (ES). This phenomenon occurs due to the increment of proton concentration influencing the conductivity of polyaniline (Choi et al 2014). The only electrically conducting form is ES, as the EB/ES transition takes place mainly between pH 3 and 6, which suggests that the lysosomal pH improves its photothermal activity.…”

Recent Advances in Bioimaging for Cancer Research

“…In addition, vascular endothelial growth factor (VEGF121)/ rGel modified MRI imaging agents were developed to obtain sensitive angiogenesis imaging of orthotopic bladder tumors that showed the development of a clear neoangiogenic vascular distribution [53]. The tumor microenvironment plays a critical role in tumor initiation, progression, metastasis, and resistance to therapy [54][55][56][57][58][59][60][61]. The microenvironment differs from that of normal tissues because of the dynamic network within normal tissues, including blood and lymphatic vessels, extracellular matrix proteins, and both enzyme and immune components.…”

“…Vesicular pH plays a pivotal role in cell metabolism processes, such as proliferation and apoptosis. Choi et al [58] developed a colorimetric redox-polyaniline nanoindicator to simply detect and quantify a broader biogenic pH range with superior sensitivity by employing one-dimensional turn-on of the FRET signal (Figure 4). They fabricated polyaniline-based nanoprobes that exhibited convertible transition states according to the proton concentration as an in situ indicator of the vesicular transport pH [58].…”

Controlling and Monitoring Intracellular Delivery of Anticancer Polymer Nanomedicines

“…This caused the quenching of Cy7 emission and increase of Cy3 fluorescence. [214] Ratiometric pH sensitive probes based on silica nanoparticles incorporating Atto647 as pH insensitive reference dye and FITC as pH sensor have been used to monitor intracellular pH upon internalization of various polyplexes. It was found that the FITC:Atto647 fluorescence ratio was highly correlated with the pH over the pH range 4-7.5.…”

“…On the other hand, after 4 h incubation, the decreased pH of the lysosomes resulted in PANI protonation and a shift of its absorption peak to 770 nm. This caused the quenching of Cy7 emission and increase of Cy3 fluorescence . Ratiometric pH sensitive probes based on silica nanoparticles incorporating Atto647 as pH insensitive reference dye and FITC as pH sensor have been used to monitor intracellular pH upon internalization of various polyplexes.…”