Table 4:

Summary of the literature pertaining to NPs synthesis mediated by several gum hydrocolloids

Tree gums	Category and composition of NPs	Method of preparation	Characterizations of NPs	References
GA	Ag NPs; GA (0.5 wt%); AgNO₃ (0.5 wt%)	Room temperature synthesis	~ 5 nm in size; face centered cubic structures with crystalline,	(Mohan et al., 2007)
GA	Ag; GA (0.01 wt%; 2.0 mL); AgNO₃ (0.1 wt%; 0.2 mL)	γ- ray irradiation route	3 nm; spherical shape; face centered cubic crystallinity	(Rao et al., 2010)
GA	Ag NPs; 5% GA (5%); PVA (3%) and AgNO₃ (1.0 mM)	γ radiation-induced crosslinking	10–40 nm	(Juby et al., 2012)
GA	Au NPs; GA (12 mg, 6 mL); NaAuCl₄ (0.1 M, 0.1 mL); phosphor amino acid (0.1 M. 20 μL)	Stirring	15–20 nm, spherical shape	(Kattumuri et al., 2007)
GA	Se NPs; GA (1 mg/ml); 0.6 M selenious acid; stirring for 6 h; addition of 4.5 ml of 0.1 M ascorbic acid.	Stirred for 0.5 h	∼34.9 nm, spherical shape	(Kong et al., 2014)
GA	Ag NPs; GA (0.3 g/L, 270 mL); AgNO₃ (2 mM); NaBH₄ (0.08M, 15 mL)	Vigorous stirring	6 nm; spherical in shape and monodispersed.	(Cheng et al., 2011)
GA	¹⁹⁸AuNPs; GA and P(CH₂NHCH(CH₃)COOH)₃ (THPAL)	Spontaneous reaction	Radio labelled Au NPs	(Kannan et al., 2006)
GA	GA (0.01g; 5 mL); ascorbic acid (0.1M, 5mL); KAuBr₄ (5mM, 5 mL)	Sonicated for 5 s at R.T	520mn; flower shape	(L. Wang et al., 2012b)
GA	ZnO NPs; GA (1g); Na acrylate (10.63 mM); N.Ni – methylene bis-acrylamide (486.47 mM); K persulfate (370.3 μM) and Zn(II), 1g)	Sonothermal	40– 60 nm; polar structures	(Webb et al., 1998)
GK	Ag NPs;	Oxidation-reduction reaction	7–10 nm, spherical	(Padil and Černík, 2015)
GK	Au NPs; GK (1 wt%); HAuCl₄ (5×10⁻³ M, 100 μL); shaking at 75°C for 1 h.	Stirring	7.8± 1.8 nm, spherical, stable for 6 months	(Padil and Černík, 2015)
GK	Au NPs; GK (15 mg, 1.0 mL); HAuCl4 (10 mM, 100 μL);	Stirred for 1h at 90 ^oC	20–25 nm, spherical	(Pooja et al., 2015)
GK	Pt NPs; GK (1 wt%); Pt (5×10⁻³ M, 100 μL)	Autoclaving at 103 kPa for 15 min	5.0± 1.2 nm, spherical	(Padil and Černík, 2015)
GK	CuO NPs; GK (1.0 mg, 1.0 mL); CuCl₂.2H₂O (1mM)	Thermal	10.5± 2.4 nm, spherical	(Padil and Černík, 2015; Thekkae Padil and Černík, 2013)
GK	Fe₃O₄ NPs; Fe²⁺ and Fe³⁺ ions and NH₄OH solution.	Co-precipitation	18.5± 3.5nm, spherical	(Padil and Černík, 2015)
KG	Ag NPs; KG (100 mg, 10 mL); AgNO₃ (100 μL, 10mM)	Shaking at 45°C for 1 h.	5.5±2.5nm,spherical, face centered cubic, stable >6 months	(Vinod et al., 2011a)
KG	Ag NPs; KG (0.5%); AgNO₃ (1 mM)	Autoclaving at 121°C at 15 psi for 1 h.	3 nm, spherical, highly stable	(Rastogi et al., 2014)
KG	Ag NPs; Ag NPs; KG (0.5%); AgNO₃ (1 mM)	Autoclaving at 121°C at 15 psi for 1 h.	3 nm, spherical, highly stable	(Kora et al., 2010)
KG	Au NPs; KG (100 mg, 10 mL); HAuCl₄ (100 μL, 10mM)	Shaking at 75 °C for 1 h.	7.8±2.3 nm, spherical, stable >6 months	(Vinod et al., 2011a)
KG	Au NPs; KG (0.5%, 3 mL); HAuCl₄ (1.0 mM, 1.0mL)	Autoclaving at 15 psi, 120 ^oC for 10 min	12 ± 2 nm, nano- crystalline	(Reddy et al., 2015)
KG	Pd NPs; KG (0.5%); PdCl₂ (1.0 mM)	Autoclaving at 121 ^oC and 15 psi for 30 min.	6.5 ± 2.3 nm, crystallized in face centered cubic symmetry.	(Rastogi et al., 2017)
KG	Pt NPs; GK (100mg, 10 mL); H₂PtCl₆ (100 μL, 10mM)	Autoclaving at 15 psi for 15 min.	2.4±0.7 nm, crystalline, stable for more than 6 months	(Vinod et al., 2011a)
KG	Fe₃ O₄ NPs; KG (25 mg, 50 mL); Fe Cl₂ and FeCl₃ (Fe ²⁺/Fe ³⁺ ratio 2:1)	Co-precipitation under hydrothermal conditions.	8– 15 nm; spherical size	(Saravanan et al., 2012)
GT	ZnO NPs	Low-temperature plus ultrasonic	55–80 nm, highly crystalline nature and single phase	(Ghayempour et al., 2016)
GG	Ag NPs; AgNO₃ (1.0 mM); GG (0.5%)	Autoclaving at 121 ^oC and 15 psi for 60 min.	5.7 ± 0.2 nm, spherical NPs	(Kora et al., 2012; Kora and Sashidhar, 2015)
GG	Pd NPs; GG (0.5%); PdCl₂ (1.0 mM)	Autoclaving at 121 ^oC and 103 kPa for 30 min.	4.8± 1.6 nm, spherical shape	(Kora and Rastogi, 2015)
GG	Au NPs; GG (1% w/v; 4 mL); HAuCl₄ (100 mM, 30.7 μLmL)	Stirring and heated at 60 ^oC	112.5 nm; spherical shape	(Alam et al., 2017)