Enhancing Intracellular Optical Performance and Stability of Engineered Nanomaterials via Aqueous Two-Phase Purification

Abstract

Supramolecular hybrids of DNA and single-walled carbon nanotubes (SWCNTs) have been introduced in numerous biosensing applications due to their unique optical properties. Recent aqueous two-phase (ATP) purification methods for SWCNTs have gained popularity by introducing specificity and homogeneity into the sensor design process. Using murine macrophages probed by near-infrared and Raman microscopies, we show that ATP purification increases the retention time of DNA-SWCNTs within cells while simultaneously enhancing the optical performance and stability of the engineered nanomaterial. Over a period of 6 h, we observe 45% brighter fluorescence intensity and no significant change in emission wavelength of ATP-purified DNA-SWCNTs relative to as-dispersed SWCNTs. These findings provide strong evidence of how cells differentially process engineered nanomaterials depending on their state of purification, lending to the future development of more robust and sensitive biosensors with desirable in vivo optical parameters using surfactant-based ATP systems with a subsequent exchange to biocompatible functionalization.

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“…This supports our hypothesis that M2 and NM cells selectively internalize SWCNTs with more defects, thus having a higher defect ratio. 51 These results underline the intricate relationship between nanotube interaction and the internal cellular make-up, providing valuable insights into the nanomaterial cell dynamics. Near-infrared hyperspectral fluorescence microscopy 15 was performed on macrophage cells with internalized DNA-SWCNTs.…”

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“…Jena, Roxbury, and Heller et al reported a monochiral sensor based on (GT) 6 - (8,6) nanotube that enabled detection of lipid content in endolysosomal organelles, enabling precise mapping of lipid accumulation in live cells. 110 This response mechanism 111 Results showed that ATP purification increased the retention time of DNA−SWCNTs within the cells and enhanced the intracellular optical properties. Advancement in the ATPE purification method further led to separation of a specific single-enantiomer SWCNT, presenting a notable advancement in carbon nanotechnology.…”

“…Nadeem and Roxbury et al used DNA–SWCNTs purified from an aqueous two-phase (ATP) extraction method to compare the intracellular fate of purified and unsorted nanotubes . Results showed that ATP purification increased the retention time of DNA–SWCNTs within the cells and enhanced the intracellular optical properties.…”

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“…[25][26][27] Moreover, with stable SWCNT functionalization, these sensors exhibit very promising biocompatibility. [28,29] Neurotransmitter detection has been demonstrated with a high spatial and temporal resolution for chemical mapping of cellular release processes of dopamine [17,[30][31][32] and serotonin. [26] Recent developments also show that this technology can be tailored for common microscopy equipment [33] and that extracellular dopamine can be reported in 3D by combining time-correlated single photon counting and confocal fluorescence microscopy.…”