title: Development, optimization, and characterization of a novel tea tree oil nanogel using response surface methodology.
abstract: OBJECTIVE
  To develop and optimize nanoemulsion (NE)-based emulgel (EG) formulation as a potential vehicle for topical delivery of tea tree oil (TTO).
  
  
  METHODS
  Central composite design was adopted for optimizing the processing conditions for NE preparation by high energy emulsification method viz. surfactant concentration, co-surfactant concentration, and stirring speed. The optimized NE was developed into emulgel (EG) using pH sensitive polymer Carbopol 940 and triethanolamine as alkalizer. The prepared EG was evaluated for its pH, viscosity, and texture parameters, ex vivo permeation at 37 °C and stability. Antimicrobial evaluation of EG in comparison to conventional gel and pure TTO was also carried out against selected microbial strains.
  
  
  CONCLUSIONS
  Optimized NE had particle size and zeta potential of 16.23 ± 0.411 nm and 36.11 ± 1.234 mV, respectively. TEM analysis revealed the spherical shape of droplets. The pH of EG (5.57 ± 0.05 ) was found to be in accordance with the range of human skin pH. EG also illustrated efficient permeation (79.58 μL/cm(2)) and flux value (JSS) of 7.96 μL cm(2)/h through skin in 10 h. Viscosity and texture parameters, firmness (9.3 ± 0.08 g), spreadability (2.26 ± 0.06 mJ), extrudability (61.6 ± 0.05 mJ), and adhesiveness (8.66 ± 0.08 g) depict its suitability for topical application. Antimicrobial evaluation of EG with same amount of TTO as conventional gel revealed broader zones of growth inhibitions against all the selected microbial strains. Moreover, EG was also found to be nonirritant (PII 0.0833). These parameters were consistent over 90 d.
  
  
  CONCLUSIONS
  TTO EG turned out to be a promising vehicle for the topical delivery of TTO with enhanced therapeutic efficacy.
authors.affiliation: a Department of Herbal Medicinal Products , CSIR - Central Institute of Medicinal and Aromatic Plants, PO CIMAP , Lucknow , UP , India ;
authors.forename: Priyam
authors.initials: P
authors.lastname: Sinha
authors.affiliation: a Department of Herbal Medicinal Products , CSIR - Central Institute of Medicinal and Aromatic Plants, PO CIMAP , Lucknow , UP , India ;
authors.forename: Shruti
authors.initials: S
authors.lastname: Srivastava
authors.affiliation: a Department of Herbal Medicinal Products , CSIR - Central Institute of Medicinal and Aromatic Plants, PO CIMAP , Lucknow , UP , India ;
authors.forename: Nidhi
authors.initials: N
authors.lastname: Mishra
authors.affiliation: b Department of Molecular Bioprospection , CSIR - Central Institute of Medicinal and Aromatic Plants, PO CIMAP , Lucknow , UP , India.
authors.forename: Dhananjay Kumar
authors.initials: DK
authors.lastname: Singh
authors.affiliation: b Department of Molecular Bioprospection , CSIR - Central Institute of Medicinal and Aromatic Plants, PO CIMAP , Lucknow , UP , India.
authors.forename: Suaib
authors.initials: S
authors.lastname: Luqman
authors.affiliation: b Department of Molecular Bioprospection , CSIR - Central Institute of Medicinal and Aromatic Plants, PO CIMAP , Lucknow , UP , India.
authors.forename: Debabrata
authors.initials: D
authors.lastname: Chanda
authors.affiliation: a Department of Herbal Medicinal Products , CSIR - Central Institute of Medicinal and Aromatic Plants, PO CIMAP , Lucknow , UP , India ;
authors.forename: Narayan Prasad
authors.initials: NP
authors.lastname: Yadav
mesh_terms: D000180:Acrylic Resins / Q000737:chemistry; D000279:Administration, Cutaneous; D000818:Animals; D002626:Chemistry, Pharmaceutical / Q000379:methods; D004337:Drug Carriers / Q000737:chemistry; D016503:Drug Delivery Systems / Q000379:methods; D004355:Drug Stability; D004655:Emulsions / Q000008:administration & dosage / Q000737:chemistry; D005079:Excipients / Q000737:chemistry; D006801:Humans; D006863:Hydrogen-Ion Concentration; D000080385:Nanogels; D053758:Nanoparticles / Q000008:administration & dosage / Q000737:chemistry; D010316:Particle Size; D010539:Permeability; D011092:Polyethylene Glycols / Q000008:administration & dosage / Q000737:chemistry*; D011094:Polyethyleneimine / Q000008:administration & dosage / Q000737:chemistry*; D011108:Polymers / Q000737:chemistry; D011817:Rabbits; D012867:Skin / Q000378:metabolism; D012869:Skin Absorption; D013501:Surface-Active Agents / Q000737:chemistry; D020947:Tea Tree Oil / Q000008:administration & dosage / Q000737:chemistry*; D014783:Viscosity
chemical_list: D000180:Acrylic Resins; D004337:Drug Carriers; D004655:Emulsions; D005079:Excipients; D000080385:Nanogels; D011108:Polymers; D013501:Surface-Active Agents; C413692:polyethylene glycol polyethyleneimine nanogel; D011092:Polyethylene Glycols; C006903:carbopol 940; D020947:Tea Tree Oil; D011094:Polyethyleneimine
keywords: Emulgel; nanoemulsion; particle size; permeability; tea tree oil; texture analysis