Size- and shape-dependent clinical and mycological efficacy of silver nanoparticles on dandruff

Abstract

Dandruff is a prominent scalp problem caused by the growth of fungus Malassezia furfur, potentially cascading into dermal inflammation, itching, and tissue damage. The present work outlines a detailed analysis of the treatment of scalp infection using silver nanomaterials (Ag NMs), and focuses on biocidal activity owing to manipulation of size, shape, and structure. Monodisperse silver spherical nanoparticles (NPs) and nanorods (NRs) were synthesized by chemical routes that were characterized using analytical and spectroscopic techniques. Ag NMs demonstrated enhanced biocidal tendencies compared to market available drugs, itracanozole and ketoconazole, showing greater zones of inhibition. The obtained 20 nm and 50 nm spherical-shaped NPs and 50 nm NRs showed concentration-, size-, and shape-dependent antifungal activity, with 20 nm spherical-shaped NPs exhibiting excellent potency. Minimum inhibitory concentration for 20 nm was lowest at 0.2 mg/mL in comparison to 0.3 mg/mL for NRs. Primary irritation index was 0.33 and 0.16 for 20 nm and 50 nm spherical-shaped NPs, respectively, while 50 nm rod-shaped NMs exhibited negligible redness. An in vivo model for M. furfur infection was generated by passing fungi subcutaneously in rats' skin. Again, 20 nm particles showed best normalization of skin after 10 days on regular dosing, in comparison with bigger and rod-shaped particles. The statistical clinical score was highest for Ag nanorods, followed by 50 nm Ag NPs-treated animals. It was observed that 20 nm spherical particles exhibited the lowest score (0) compared with others as well as with antifungal drugs. Biochemical analysis performed by checking antioxidant enzymatic activities indicated tissue repair and normalization of enzymes and protein concentration by Ag NPs.

Keywords: Malassezia furfur; Wistar rat model; in vivo analysis; nanorods.

Figure 1

TEM micrograph. Notes: (A) 20 nm spherical-shaped Ag NPs; (B) 50 nm with spherical-shaped Ag NPs; (C) TEM image showing 50 nm of rod-shaped Ag NPs. The insets show the diffraction pattern recorded by aligning the electron beam perpendicular to one of the square faces of an individual nanoparticle. (D) XRD pattern of Ag NR. Abbreviations: TEM, transmission electron microscopy; NPs, nanoparticles; XRD, X-ray diffraction; NR, nanorod.

Figure 2

Comparison of different antifungal agents and correlation of their concentration with biocidal efficiency. Notes: (A) Represents the concentration dependent antifungal activity of Ag NPs on M. furfur. (B) Represents the comparative antifungal activity of Ag NPs with standard drugs. Abbreviations: NPs, nanoparticles; M. furfur, Malassezia furfur.

Figure 3

Skin photographs of the dorsal surface of rats. Notes: (A) Control group I showing no redness, no inflammation; (B) M. furfur diseased group, scales on the skin; (C) and (D) Groups III and IV treated with itracanozole and ketoconazole, respectively, showing skin with decreased scales as compared to Group II with pinkish color; (E) Group V (20 nm spherical Ag NPs) showing complete treatment of M. furfur as compared to Group II; (F) and (G) Groups VI and VII (50 nm spherical- and rod-shaped Ag NPs) also showed normalization of the skin but less as compared to group V. Abbreviations: M. furfur, Malassezia furfur; NPs, nanoparticles.

Figure 4

Histopathological microphotographs of different groups of studied rats. Notes: (A) Control I; (B) M. furfur diseased model group II; antifungal agent-treated groups; (C) III (itracanozole); (D) IV (ketoconazole); (E) V (20 nm spherical-shaped Ag NPs); (F) VI (50 nm spherical), and (G) VII (50 nm rod-shaped Ag NPs). Abbreviations: M. furfur, Malassezia furfur; NPs, nanoparticles.