Microspectroscopy of nanomaterials, biological species, and live cells

Spectroscopic investigations of material samples on the microscopic and nano-scales, incorporating different modalities such as Raman, photoluminescence, Transmission- Absorption-Reflection(TAR), and transient spectroscopy, are growing increasingly popular to collect quantitative and functional information of materials. Typical samples can range from invitro and in-vivo tissue samples, living cells, quantum structures (dots, wires), material surfaces, microfluidics and nano-crystals. Enhancing traditional microscopy systems by coupling a spectrometer to them offers the added dimension of higher density multichannel spectral information. This information can unlock deeper chemical, dynamic and conformational information on various materials. Different approaches are taken in configuring such systems from the commercially available fully integrated ‘black box’ tailored for specific types of application and/or spectral modalities, to the in-house purpose-built modular systems where the end-users build and integrate their own system from various individual components. There are advantages and limitations with either approach. This article outlines various aspects and implications for taking the modular approach to constructing one’s microspectroscopy setup. In particular, examples are illustrated where Andor Technology’s dedicated, highly configurable interfaces for microspectroscopy utilize various optical and optomechanical components to facilitate flexible direct and indirect coupling of the spectrometer to the microscope. Software options are discussed for control of the system and data collection/processing to allow for multitrack and hyperspectral imaging, as well as fast chemical mapping. Sensitivity is a key technical challenge in most scenarios when dealing with such small sample volumes; an outline of where the latest CCD, EMCCD, and sCMOS technology offers benefits in sensitivity are also discussed.