Gelatin-stabilized composites of silver nanoparticles and curcumin: characterization, antibacterial and antioxidant study

Figures & data

Figure 1. General schematics of methodology: (a) the fabrication of GelAg solution and (b) the encapsulation of curcumin using GelAg solution.

Table 1. Formulation compositions (weight basis) for the preparation of GelCurAg.

Code	Gelatin (mg)	Curcumin (mg)	POX 407 (mg)	AgNO3 (ppm)
Gel0.5CurAg	100	20	250	120
Gel0.75CurAg	150	20	250	120
Gel1CurAg	200	20	250	120
Gel1.25CurAg	250	20	250	120

*The numbers after Gel present the gelatin concentration in wt.%.

Figure 2. UV–vis absorbance of (a) GelAg solutions: (a) Gel_0.5Ag, (b) Gel_0.75Ag, (c) Gel₁Ag and (d) Gel_1.25Ag; (b) Gel₁Cur, Gel₁Ag and Gel₁CurAg and (c) Gel_0.5CurAg, Gel_0.75CurAg, Gel₁CurAg and Gel_1.25CurAg.

Table 2. Analysis of particle size and stability of GelCurAg composites.

Code	Particle size (nm)	PdI	Zeta potential (mV)
Gel0.5CurAg	330 ± 90	0.42 ± 0.15	11.6 ± 1.2
Gel0.75CurAg	390 ± 60	0.32 ± 0.03	26.7 ± 1.6
Gel1CurAg	375 ± 45	0.24 ± 0.10	27.5 ± 0.9
Gel1.25CurAg	730 ± 220	0.38 ± 0.09	11.7 ± 1.0

Figure 3. SEM micrographs of (a) Gel_0.5CurAg, (b) Gel_0.75CurAg, (c) Gel₁CurAg and (d) Gel_1.25CurAg. Scale bar: 5 µm.

Figure 4. Quantitative analysis of AgNPs within GelCurAg composites.

Table 3. The loading efficiency of curcumin in the studied GelCurAg formulations.

Code	Entrapment efficiency (%)	Drug loading (%)
Gel0.5CurAg	52 ± 3*	2.76 ± 0.07*
Gel0.75CurAg	55.7 ± 0.4*	2.65 ± 0.02*
Gel1CurAg	69 ± 8*	3.0 ± 0.4*
Gel1.25CurAg	42 ± 2*	1.61 ± 0.09*

*Indicating the significant difference between samples. The same indicates p < 0.05 (n = 3).

Figure 5. X-ray diffraction patterns of curcumin (black) and GelCurAg lyophilized powders.

Figure 6. Drug release rate of GelCurAg samples.

Figure 7. Images of (a) inhibition zone of GelCur and GelCurAg and (b) their measured inhibitory zones against S. aureus and P. aeruginosa.

Figure 8. The bactericidal and inhibitory effects against (a) S. aureus and (b) P. aeruginosa of different concentration of (a) Gel_0.5CurAg, (b) Gel_0.75CurAg, (c) Gel₁CurAg and (d) Gel_1.25CurAg (MIC [inhibitory] – red; MBC [bactericidal] – black).

Table 4. Summary of antibacterial activities of four GelCurAg samples against S. aureus and P. aeruginosa (unit: µl/ml).

	MIC		MBC
	S. aureus	P. aeruginosa	S. aureus	P. aeruginosa
Gel0.5CurAg	250	250	>250	250
Gel0.75CurAg	125	125	250	125
Gel1CurAg	125	125	250	125
Gel1.25CurAg	250	125	>250	250

Table 5. Summary of the results of in vitro performances of GelCurAg composites.

	Antibacterial					Antioxidant		Biocompatibility
		MIC (µl/ml)		MBC (µl/ml)
Formulation	Level of inhibitory zone	S.a	P.a	S.a	P.a	250 µl/ml	125 µl/ml	250 µl/ml	125 µl/ml
Gel0.5CurAg	1st	250	250	>250	250	✓	✓	✓	✓
Gel0.75CurAg	2nd	125	125	250	125	✓	✓	X	✓
Gel1CurAg	3rd	125	125	250	125	✓	✓	✓	✓
Gel1.25CurAg	4th	250	125	>250	250	✓	✓	X	✓

S.a stands for S. aureus and P.a for P. aeruginosa.

Figure 9. Images of (a) antioxidant activities of different concentration of GelCurAg suspensions through decoloring of DPPH solution and (b) their corresponding percentage of oxidation inhibition after 90 min incubation.

Figure 10. MTT results of different concentration of GelCurAg samples.