Reversible Photothermal Modulation of Electrical Activity of Excitable Cells using Polydopamine Nanoparticles

Abstract

Advances in the design and synthesis of nanomaterials with desired biophysicochemical properties can be harnessed to develop non‐invasive neuromodulation technologies. Here, the reversible modulation of the electrical activity of neurons and cardiomyocytes is demonstrated using polydopamine (PDA) nanoparticles as photothermal nanotransducers. In addition to their broad light absorption and excellent photothermal activity, PDA nanoparticles are highly biocompatible and biodegradable, making them excellent candidates for both in vitro and in vivo applications. The modulation of the activity (i.e., spike rate of the neurons and beating rate of cardiomyocytes) of excitable cells can be finely controlled by varying the excitation power density and irradiation duration. Under optimal conditions, reversible suppression (≈100%) of neural activity and reversible enhancement (two‐fold) in the beating rate of cardiomyocytes is demonstrated. To improve the ease of interfacing of photothermal transducers with these excitable cells and enable spatial localization of the photothermal stimulus, a collagen/PDA nanoparticle foam is realized, which can be used as an “add‐on patch” for photothermal stimulation. The non‐genetic optical neuromodulation approach using biocompatible and biodegradable nanoparticles represents a minimally invasive method for controlling the activity of excitable cells with potential applications in nano‐neuroscience and engineering.

Architecting polyelectrolyte hydrogels with Cu-assisted polydopamine nanoparticles for photothermal antibacterial therapy

“…Among these popular PTAs, PDA, a melanin-based biopolymer widely distributed in almost all kinds of living organisms, is the most potential one due to its superior biocompatibility, prominent biodegradability, favorable photostability, and ease of synthesis [ [15] , [16] , [17] , [18] ]. Recently, PDA nano-PTAs possessing various sizes (mainly from 20 to 500 ​nm) and different morphologies (nanosheets and nanospheres) have emerged for utilization in PTT [ [19] , [20] , [21] ]. Nevertheless, two inherent defects of PDA nano-PTAs severely hamper their clinical application.…”

Neuronal Maturation-dependent Nano-Neuro Interaction and Modulation

“…The hippocampal tissues were manually isolated from day E18 embryos of pregnant Sprague Dawley rat brains (Charles River, USA) in Hibernate EB medium (HEB, BrainBits, USA) as previously described. 23 The isolated tissues were incubated in cell dissociation solution comprising of 6 mg papain (P4762, Sigma, USA) in 3 ml of Hibernate E-Ca (HE-Ca, BrainBits, USA) for 10 minutes at 30 o C. Subsequently, the tissues were mechanically dissociated via trituration with fire-polished Pasteur pipette after replacing cell dissociation solution with HEB medium to obtain single cell suspension. The resultant cell suspension was centrifuged at 200xg for 1 minute and the supernatant was decanted, and the pellets were resuspended in NbActiv4 medium (BrainBits, USA).…”

“…have shown great promise and versatility. [15][16][17][18][19][20][21][22][23] Majority of the photothermal neuromodulation studies involve primary neuron culture close to its complete maturation stage as the model system. Although, in most brain regions, neurogenesis (process of generating new functional neurons from precursors) has been confined to a discrete developmental period, life-long neurogenesis has been observed in both the hippocampus and subventricular zone of almost all mammals, including humans.…”

Transmembrane MUC18 Targeted Polydopamine Nanoparticles and a Mild Photothermal Effect Synergistically Disrupt Actin Cytoskeleton and Migration of Cancer Cells

“…Polydopamine nanoparticles (PDA NPs) are believed to be an attractive alternative to gold nanoparticles in the field of nanomedicine. − Not only do they have good biocompatibility and biodegradability, but PDA NPs also possess an outstanding photothermal conversion efficiency, making them an ideal photoabsorbing agent for photothermal therapy. − A typical photothermal therapy involves loading photothermal agents within tumor regions and generating local heat (>50 °C) to ablate cancer cells under near-infrared light irradiation. − However, these conventional photothermal therapy strategies still suffer from some inherent limitations, hindering their clinical implementation: (1) because of the inhomogeneous distribution of photothermal agents and the weak penetration of laser irradiation, certain tumor regions (such as tumor margins) may not yield adequate heat to ablate the cancer cells, leaving some viable cancer cells behind; and (2) the laser power density significantly exceeds the safety limit (i.e., maximal permissible exposure: 0.4 W/cm 2 for 808 nm lasers, according to the American National Standards Institute), which can be harmful to the nearby healthy tissues. , Indeed, these two limitations pose a dilemma for conventional photothermal therapy, because the required elevated temperature for ablation of cancer cells always necessitates higher laser power density and nanoparticle dosage, both factors raising safety concerns. With these considerations, we envision a new strategy that is distinct from the conventional photothermal therapy while potentially addressing its current problems: an intelligent design of PDA NPs to target cancer cells, followed by a mild photothermal effect using a safe laser irradiation, stopping the migration of cancer cells in cases where ablating them is not possible.…”