LAUSR

Numerous dyes and fluorescent compounds, as reported in the literature, exhibit specificity in the staining of materials associated with lignocellulosic fibers and their chemical components, including cellulose, hemicellulose, and lignin. Such effects long have provided analysts with convenient ways to identify cellulosic fiber types, products of different pulping methods, degrees of mechanical refining, estimates of accessibility to enzymes, and localization of chemical components within microscopic sections of cellulosic material. Analytical staining procedures allow for the facile estimation or quantification using simple methods such as light microscopy or UV-vis spectroscopy. More recent developments related to confocal laser micrometry, using fluorescent probes, has opened new dimensions in staining technology. The present review seeks to answer whether the affinity of certain colored compounds to certain cellulose-related domains can improve our understanding of those stained materials – either in terms of their fine-scale porous structure or their ability to accommodate certain colored compounds having suitable solubility characteristics. It is proposed here that successful staining ought to be viewed as being a three-dimensional phenomenon that depends on both the physical dimensions of the colored compounds and also on functional groups that influence their interactions with different components of lignocellulosic materials. Published information about the mechanisms of staining action as well as characteristics of different stain types is reviewed.