Lawsonia inermis mediated synthesis of silver nanoparticles (Ag-NPs) and its efficacy against Candida albicans, Microsporum canis, Propioniabacterium acne and Trichophyton mentagrophytes is reported. A two-step mechanism has been proposed for bioreduction and formation of an intermediate complex leading to the synthesis of capped nanoparticles was developed. In addition, antimicrobial gel for M. canis and T. mentagrophytes was also formulated. Ag-NPs were synthesized by challenging the leaft extract of L. inermis with 1mM AgNO 3. The Ag-NPs were characterized by Ultraviolet-Visible (UV-Vis) spectrophotometer and Fourier transform infrared spectroscopy (FTIR). Transmission electron microscopy (TEM), nanoparticle tracking and analysis sytem (NTA) and zeta potential was measured to detect the size of Ag-NPs. The antimicrobial activity of Ag-NPs was evaluated by disc diffusion method against the test organisms. Thus these Ag-NPs may prove as a better candidate drug due to their biogenic nature. Moreover, Ag-NPs may be an answer to the drug-resistant microorganisms. © The Institution of Engineering and Technology 2014.83172178Bandyopadhyay, U., Biswas, K., Chattopadhyay, I., Banerjee, R.K., Biological activities and medicinal properties of neem (Azadirachta indica) (2002) Curr. Sci., 82 (11), pp. 1336-1345Cragg, G.M., Newman, D.J., Sander, K.M., Natural products in drug discovery and development (1997) J. Nat. Prod., 60, pp. 52-60Chung, W.H., Chang, Y.C., Yang, L.J., Hung, S.I., Wong, W.R., Lin, J.Y., Clinicopathologic features of skin reactions to temporary tattoos and analysis of possible causes (2002) Arch. Dermatol., 138, pp. 88-92Habbal, O.A., Al-Jabri, A.A., El-Hag, A.G., Antimicrobial properties of Lawsonia inermis (henna): A review (2007) Aust. J. Med. Herbalism, 19, pp. 114-125Abulyazid, I., Elsayed, M.E., Mahdy, B., Ragaa, M., Ahmed, M., Biochemical study for the effect of henna (Lawsonia inermis) on Escherichia coli (2013) Arab. J. Chem., 6 (3), pp. 265-273Ahmadian, S., Fakhree, M.A., Henna (Lawsonia inermis) might be used to prevent mycotic infection (2009) Med. Hypotheses, 73, pp. 629-630Siddiqui, B.S., Kardar, M.N., Ali, S.T., Khan, S., Two new and a known compound from Lawsonia inermis (2003) Helv. Chim. Acta, 86 (6), pp. 2164-2169Thevenot, D.R., Toth, K., Durst, R.A., Wilson, G.S., Electrochemical biosensors: Recommended definitions and classification (2001) Biosens. Bioelectron., 16, pp. 121-131Lavhate, M.S., Mishra, S.H., A review: Nutritional and therapeutic potential of Ailanthus excelsa (2007) Pharmacognosy Rev., 1 (1), pp. 105-113Woodfolk, J.A., Allergy and dermatophytes (2005) Clin. Microbiol. Rev., 18, pp. 30-43Mirmirani, P., Hessol, N.A., Maurer, T.A., Berger, T.G., Nguyen, P., Khalsa, A., Prevalence and predictors of skin disease in the women's interagency HIV study (WIHS) (2001) J. Am. Acad. Dermatol., 44, pp. 785-788Ingle, A., Gade, A., Pierrat, S., Sonnichsen, C., Rai, M., Mycosynthesis of silver nanoparticles using the fungus Fusarium acuminatum and its activity against some human pathogenic bacteria (2008) Curr. Nanosci., 4, pp. 141-144Rai, M., Yadav, A., Gade, A., Silver nanoparticles as a new generation of antimicrobials (2009) Biotechnol. Adv., 27 (1), pp. 76-83Gade, A.K., Bonde, P., Ingle, A.P., Marcato, P.D., Duran, N., Rai, M.K., Exploitation of Aspergillus niger for synthesis of silver nanoparticles (2008) J. Biobased Mater. Bioenergy, 2, pp. 243-247Duran, N., Marcarto, P.D., De Souza, G.I.H., Alves, O.L., Esposito, E., Antibacterial effect of silver nanoparticles produced by fungal process on textile fabrics and their effluent treatment (2007) J. Biomed. Nanotechnol., 3, pp. 203-208Li, Y., Leung, P., Yao, L., Song, Q.W., Newton, E., Antimicrobial effects of surgical masks coated with nanoparticles (2006) J. Hosp. Infection, 62, pp. 58-63Montes-Burgos, D., Hole, W.P., Smith, J., Lynch, I., Dawson, K., Characterisation of nanoparticle size and state prior to nanotoxicological studies (2010) J. Nanoparticle Res., 12, pp. 47-53Bonde, S.R., A biogenic approach for green synthesis of silver nanoparticles using extract of Foeniculum vulgare and its activity against Staphylococcus aureus and Escherichia coli (2011) Nusantara Biosci., 3 (2), pp. 59-63Bonde, S.R., Rathod, D.P., Ingle, A.P., Ade, R.B., Gade, A.K., Rai, M.K., Murraya koenigii mediated synthesis of silver nanoparticles and its activity against three human pathogenic bacteria (2012) Nanoscience Meth., 1, pp. 25-36Sun, L., Simmons, B.A., Singh, S., Understanding tissue specific compositions of bioenergy feedstocks through hyperspectral Raman imaging (2011) Biotechnol. Bioeng., 108 (2), pp. 286-295Chaudhary, G., Golyal, S., Poonia, P., Lawsonia inermis Linnaeus: A phytopharmacological review (2010) Int. J. Pharm. Sci. Drug Res., 2 (2), pp. 91-98Rajendran, R., Hemalatha, S., Akasakalai, K., Madhukrishna, C.H., Sohil, B., Sundaram, M.R., Hepatoprotective activity of Mimosa pudica leaves against carbontetrachloride induced toxicity (2010) J. Nat. Prod., 2, pp. 116-122Iravani, S., Green synthesis of metal nanoparticles using plants (2011) Green Chem., 13, pp. 2638-2650Kasthuri, J., Veerapandian, S., Rajendiran, N., Biological synthesis of silver and gold nanoparticles using apiin as reducing agent (2009) Colloids Surf., B, 68, pp. 55-60Begum, N.A., Mondal, S., Basu, S., Laskar, R.A., Mandal, D., Biogenic synthesis of Au and Ag nanoparticles using aqueous solutions of Black Tea leaf extracts (2009) Colloids Surf., B, 71, pp. 113-118Kora, A.J., Sashidhar, R.B., Arunachalam, J., Gum kondagogu (Cochlospermum gossypium): A template for the green synthesis and stabilization of silver nanoparticles with antibacterial application (2010) Carbohydrate Polym., 82 (3), pp. 670-679Gade, A.K., Gaikwad, S.C., Tiwari, V., Yadav, A., Ingle, A.P., Rai, M.K., Biofabrication of silver nanoparticles by Opuntia ficus-indica: In vitro antibacterial activity and study of the mechanism involved in the syntheses (2010) Curr. Nanosci., 6, pp. 370-375Gade, A., Rai, M., Kulkarni, S., Phoma sorghina, a phytopathogen mediated synthesis of unique silver rod (2011) Int. J. Green Nanotechnol., 3 (3), pp. 153-159