Bromelain-loaded silver nanoparticles: Formulation, characterization and biological activity

Bromelain (BL), a type of proteolytic enzymes from Ananas comosus (pineapple), has a variety of therapeutic potentials; nevertheless, its low bioavailability has restricted the clinical applications. The main aim of the current research was to develop a green synthesized Ag-BL nanoparticles via a cost-effective route to improve the physicochemical and antimicrobial characteristics as a novel agent for medical applications. In the present study, Bromelain was loaded on the silver nanoparticle surface via covalent bonds through green synthesis method. The physicochemical properties of Ag-BL nanoparticles characterized by following a detailed analysis over scanning electron microscopy, zeta potential, ultraviolet-visible absorption spectroscopy, transmission electron microscopy, fourier transform infrared spectroscopy, and X-ray diffraction studies. The antifungal and antibacterial activity were investigated by the Clinical and Laboratory Standards Institute methods and the results were compared with Ag NPs and plain bromelain. The cytotoxicity of Ag-BL nanoparticles was investigated by MTT assay. The TEM and XRD techniques revealed the successful biosynthesis of Ag-BL nanoparticles in spherical shape with the mean size of 7 to 24 nm and FTIR analysis pattern proved the attachments of bromelain and Ag nanoparticles in the fabricated nanostructure. The negative zeta value of the Ag-BL nanoparticles (- 50 to -32 mV) indicates their high stability in the suspension. The Ag-BL nanoparticles demonstrated significant antimicrobial activity against various types of fungi and bacteria strains with a MIC range of 4-32 and 4-64 mu g/mL, respectively. The MTT assay analysis determined the acceptable cell safety of Ag-BL nanoparticles. Generally, the results confirmed that Ag-BL nanoparticles could develop a new insight to produce antimicrobial products for biomedical applications.