A strategy involving the conjugation of fluorescent quantum dot (QD) with wheat germ agglutinin (WGA) acting as fluorescent and topographic probes prior to cell Surface staining is developed for fluorescence microscopy and atomic force microscopy (AFM). This strategy provided at least two advantages: (a) an amplified fluorescence of WGA-QD aggregates, strongly resistant to photobleaching, ensures repeated/real-time observations of the probe-labeled cells by fluorescence microscopy; (b) the enlarged size of WGA-QD probe makes it possible for labeled WGA to be distinguished from other membrane proteins by AFM. Here, the random distribution Of WGA-binding sites oil non-crosslinked cells and the uneven or polarized reorganization due to WGA-induced crosslinking oil cell Surfaces were studied using AFM-detectable WGA-QD probe. Moreover, we developed a method to rapidly detect the WGA-induced rigidity alternation of the whole cells, which is efficient and has the potentiality of being developed to a useful tool in clinical diagnosis. (c) 2008 Elsevier Inc. All rights reserved.