Table 1.

Surface topography of natural surfaces exhibiting antibacterial properties

Natural surface	Surface	Species	Nano-texture	Geometry	Contact angle (°)	References
Plant	Taro leaf	C. esculenta	Polygon shape	Bulge: 15–30 μm diameter, Papilla: 10–15 μm diameter	159 ± 2	[31, 56]
	Lotus leaf	N. nucifera	Micro-size bulge shape	Bulge: 1–5 μm height	142 ± 8.6	[34, 57]
Animal	Gecko skin	L. steindachneri	Hair like nano-structure	4 µm length, top radius of 10–20 nm and submicron spacing	150	[42, 43]
	Shark skin	Spiny Dogfish	3D riblet micro-structure	Triangular riblets, 100–300 µm width, 15 µm peak radius, 200–500 nm height and 100–300 µm spacing	–	[37]
		C. brachyurous	3D riblet micro-structure	5 riblets 200–300 µm in height, 20–30 µm diameter and 50–80 µm riblet spacing	–	[38]
Insect	Cicada wing	M. intermedia	Nano-pillar (conical shape)	Height: 241 nm, diameter: 156 nm, spacing: 165 nm	135.5	[46]
		A. spectabile	Nano-pillar (conical shape)	Height: 182 nm, diameter: 207 nm, spacing: 251 nm	113.2	[46]
		C. aguila	Nano-pillar (conical shape)	Height: 182 nm, diameter: 159 nm, spacing: 187 nm	95.7	[46]
		C. maculata	Nano-pillar (conical shape)	Height: 309 nm, diameter: 97 nm, spacing: 92 nm	76.8 ± 13.9	[45]
		P. scitula	Nano-pillar (conical shape)	Height: 282 nm, diameter: 84 nm, spacing 84 nm	91.9 ± 5.9	[45]
		M. hebes	Nano-pillar (conical shape)	Height: 164 nm, diameter: 85 nm, spacing: 95 nm	78.4 ± 5	[45]
		L. bifuscata	Nano-pillar (conical shape)	Height: 200 nm, diameter: 90 nm, spacing: 117 nm	81.3 ± 8.3	[45, 58]
		M. conica	Nano-pillar (conical shape)	Height: 159 nm, diameter: 95 nm, spacing: 115 nm	93.9 ± 8.3	[45]
		M. durga	Nano-pillar (conical shape)	Height: 257 nm, diameter: 89 nm, spacing: 89 nm	134.8 ± 5.7	[45]
		A. bindusara	Nano-pillar (conical shape)	Height: 234 nm, diameter: 84 nm, spacing: 91 nm	135.5 ± 5.2	[45, 58]
		M. mongolica	Nano-pillar (conical shape)	Height: 417 nm, Diameter: 128 nm, Spacing: 47 nm	123.3 ± 12.7	[45]
		P. radha	Nano-pillar (conical shape)	Height: 288 nm, diameter: 137 nm, spacing: 44 nm	136.5 ± 5.2	[45]
		D. vaginata	Nano-pillar (conical shape)	Height: 363 nm, diameter: 132 nm, spacing: 56 nm	141.3 ± 3.3	[45]
		D. rasingna	Nano-pillar (conical shape)	Height: 316 nm, diameter: 128 nm, spacing: 47 nm	141.6 ± 4.5	[45]
		M. opalifer	Nano-pillar (conical shape)	Height: 418 nm, diameter: 148 nm, spacing: 48 nm	143.8 ± 6	[45, 58]
		T. vacua	Nano-pillar (conical shape)	Height: 446 nm, diameter: 141 nm, spacing: 44 nm	144.2 ± 6.8	[45]
		T. jinpingensis	Nano-pillar (conical shape)	Height: 391 nm, diameter: 141 nm, spacing: 46 nm	146 ± 2.6	[45]
		C. atrata	Nano-pillar (conical shape)	Height: 462 nm, diameter: 85 nm, spacing: 90 nm	137.9	[58]
		P. claripennis	Nano-pillar (conical shape)	Height: 200 nm, base diameter: 100 nm, cap diameter: 60 nm, spacing: 170 nm	147 ± 47	[11, 12]
	Dragonfly wing	S. vulgatum	Nano-pillar	Height: 80–90 nm, diameter: 150–20 nm	–	[49]
	Butterfly wing	Blue M. didius	Scales with aligned micro-grooves	Diameter: 1–2 µm, spacing: 1–2 µm	160	[59]