**6.2 Congo red binding assay**

Congo red (CR) is a small molecule probe traditionally used to identify amyloid fibrils, especially in the form of brain tissue or *in vitro* deposits. CR binds to β-rich structures present in amyloid fibrils and exhibits a characteristic green birefringence with cross-polarization. Newer studies have revealed the use of CR to study fibrillar aggregates [5, 55, 71, 72].
