Monitoring and manipulating cellular transmembrane potentials using nanostructures

Abstract

The use of nanostructures to monitor or modulate changes in cellular membrane potentials is disclosed. Nanoparticles having phospholipid coatings were found to display improved responses relative to nanoparticles having other coatings that do not promote localization or attraction to membranes.

1 . A method for assaying changes in transmembrane potential, the method comprising:
 providing at least one target, wherein the target is a cell, cellular fraction, or artificial membrane structure;   contacting the target with at least one nanostructure to form a treated target;   stimulating the treated target;   assaying emission from the nanostructure; and   correlating the emission with the change in transmembrane potential.   
     
     
         2 . The method of  claim 1 , wherein the contacting step comprises introducing the nanostructure into the target. 
     
     
         3 . The method of  claim 1 , wherein the contacting step comprises introducing the nanostructure into a cellular membrane of the target. 
     
     
         4 . The method of  claim 1 , wherein the contacting step comprises introducing the nanostructure onto or near a cellular membrane of the target. 
     
     
         5 . The method of  claim 1 , further comprising assaying emission from the nanostructure after the contacting step but before the stimulating step. 
     
     
         6 . The method of  claim 1 , wherein the stimulating step comprises electrical stimulation, magnetic stimulation, chemical stimulation, biological stimulation, contacting the target with a drug suspected of being able to activate ion channels, contacting the target with a drug suspected of being able to inhibit ion channels, or combinations thereof. 
     
     
         7 . The method of  claim 6 , wherein the electrical stimulation comprises use of a patch clamp, or application of an external electric field. 
     
     
         8 . The method of  claim 6 , wherein the chemical stimulation comprises contacting the target with a potassium salt or a sodium salt. 
     
     
         9 . The method of  claim 6 , wherein the biological stimulation comprises contacting the target with a light-sensitive ion channel. 
     
     
         10 . The method of  claim 1 , wherein the stimulating step comprises maintaining the target at a first membrane potential voltage, depolarizing or hyperpolarizing the target to a second membrane potential voltage, and returning the target to the first membrane potential voltage. 
     
     
         11 . The method of  claim 10 , wherein the second membrane potential voltage is more positive than the first membrane potential voltage. 
     
     
         12 . The method of  claim 10 , wherein the second membrane potential voltage is positive, and the first membrane potential voltage is negative. 
     
     
         13 . The method of  claim 10 , wherein one of the first membrane potential voltage and the second membrane potential voltage is about 0 mV. 
     
     
         14 . The method of  claim 10 , wherein the first membrane potential voltage is about −70 mV and the second membrane potential voltage is about +40 mV. 
     
     
         15 . The method of  claim 1 , wherein the cell is a eucaryotic cell, a procaryotic cell, bacterial cell, a Gram-positive bacterial cell, a Gram-negative bacterial cell, a fungal cell, an insect cell, an avian cell, a reptilian cell, an oocyte, a fly cell, a zebrafish cell, a nematode cell, a fish cell, an amphibian cell, or a mammalian cell. 
     
     
         16 . The method of  claim 1 , wherein the cell is a eucaryotic cell. 
     
     
         17 . The method of  claim 1 , wherein the cellular fraction is a nucleus, a ribosome, a mitochondria, an endoplasmic reticulum, a Golgi apparatus, a vacuole, a synaptic vesicle, or a lysosome. 
     
     
         18 . The method of  claim 1 , wherein the artificial membrane structure is a phospholipid micelle. 
     
     
         19 . The method of  claim 1 , wherein the nanostructure is a nanocrystal, a film, a nanowire, a patterned substrate, or a mesh. 
     
     
         20 . The method of  claim 1 , wherein the nanostructure is a semiconductor nanocrystal. 
     
     
         21 . The method of  claim 1 , wherein the nanostructure is a semiconductor core-shell nanocrystal. 
     
     
         22 . A method for assaying changes in transmembrane potential, the method comprising:
 providing at least one cell;   contacting the cell with at least one semiconductor nanocrystal to form a treated cell;   stimulating the treated cell with light;   assaying emission from the nanocrystal; and   correlating the emission with the change in transmembrane potential.   
     
     
         23 . A method for the optical control of the transmembrane potential of a target, the method comprising:
 providing at least one target, wherein the target is a cell or cellular fraction;   contacting the target with at least one nanostructure under conditions suitable for interaction or insertion of the nanostructure with a cellular or subcellular membrane to prepare a treated target;   delivering energy to the treated target; and   detecting response of the target.   
     
     
         24 . The method of  claim 23 , wherein the conditions suitable for interaction or insertion comprise active uptake via endocytosis, electroporation, liposome-mediated delivery, pluronic block copolymer-mediated delivery, cell-penetrating peptide-mediated uptake, protein-mediated uptake, microinjection, transfection, viral delivery, optoporation, pore-forming substrates, membrane intercalators, or combinations thereof. 
     
     
         25 . The method of  claim 23 , wherein the delivering energy step comprises illuminating at a wavelength or wavelength range suitable for absorption by the nanostructure. 
     
     
         26 . The method of  claim 23 , wherein the delivering energy step comprises laser illumination, mercury lamp illumination, xenon lamp illumination, halogen lamp illumination, or LED illumination. 
     
     
         27 . The method of  claim 23 , wherein the detecting step comprises use of a camera, a digital camera, a video camera, a CCD camera, a digital camera mounted on a fluorescent microscope, a photomultiplier, a fluorometer, a luminometer, a microscope, or the human eye. 
     
     
         28 . The method of  claim 23 , wherein the detecting step comprises use of a secondary detection mechanism. 
     
     
         29 . The method of  claim 23 , wherein the detecting step comprises detection at a single time point, detection at multiple time points, or continuous detection.