TABLE 1.
Common secondary ion mass spectrometry (SIMS) and electrochemical methods for neuronal and synaptic measurements.
| Methods | Applications | Advantages/disadvantages |
| Time of flight secondary ion mass spectrometry (ToF-SIMS) | Imaging spatial distribution of ions up to ∼ 2,000 Da (metabolites, molecular lipids, small peptides) 2D and 3D imaging possible |
+ Parallel detection within a large mass range (0-2,000 Da) +Suitable for non-targeted imaging (non-labeling) + Many primary ion sources available - Topographical sample effect - Spatial resolution possibly ∼ 250 nm |
| Nanoscale secondary ion mass spectrometry (NanoSIMS) | Imaging spatial distribution of monoatomic or diatomic ions at subcellular resolution 2D and 3D imaging possible |
+ Spatial resolution ∼ 50 nm - Molecular information lost - Parallel detection up to 7 ions - Isotopic labeling often employed |
| Single cell amperometry (SCA) | Quantification of the number of neurotransmitters released from individual vesicles | + High temporal resolution (sub-milliseconds to a few millisecond) - Cannot distinguish between catecholamine and other electroactive molecules at the same time |
| Vesicle impact electrochemical cytometry (VIEC) | Quantification of the total number of neurotransmitters stored inside individual vesicles Investigation of the effects of drug treatments on vesicle properties |
+ easily manipulate the surrounding environment of vesicles - Risk of leakage of vesicular transmitters and changes of vesicle properties during the vesicle isolation process - Cannot distinguish between catecholamine and other electroactive molecules at the same time |
| Intracellular vesicle impact electrochemical cytometry (IVIEC) | In situ approach quantifying total vesicle content within their cellular environment (in the cytoplasm) | + Possible to change external factors such as osmolarity, pH and pharmaceutical treatments with minimal impact on the cells - Cannot distinguish between catecholamine and other electroactive molecules at the same time |
| Fast scan cyclic voltammetry (FSCV) | Study of the behavior, addiction, and disease of live animals by measuring in vivo the rapid changes of neurotransmitters | + Possible to simultaneously quantify and identify various analytes by selecting voltage limits of the interested analyte - Cannot measure basal levels of neurotransmitters, governed by phasic and tonic neuronal activity, only fast change of electroactive species because the background current can be only stable for a brief time |