Fig. 1.

Scheme of phage surface engineering and using engineered phage to grow bone mineral nanocrystals (hydroxyapatite, HAP). Structurally, wild-type M13 phage is composed of coat proteins surrounding a circular ssDNA, which encodes its coat proteins including major coat protein (pVIII) constituting the sidewall and four other structural proteins (pIII, pVI, pVII, and pIX) at two tips (called minor coats). By taking advantage of phage display technique, engineered phage displaying HAP-nucleating peptides (pE: ESQES and pQ: QESQSEQDS) can be produced and assembled into phage bundles driven by the formation of beta-structure between pE and pQ. The nucleation of HAP nanocrystals is induced by the beta-structures formed between pE and pQ within phage bundles