There has been a new approach in the development of antibacterials in order to enhance the antibacterial potential. The nanoparticles are tagged on to the surface of other metals or metal oxides and polymers to achieve nanocomposites. These have shown significant antibacterial properties when compared to nanoparticles. In this article we explore the antibacterial potentials of metal-based and metal–polymer-based nanocomposites, various techniques which are involved in the synthesis of the metal–polymer, nanocomposites, mechanisms of action, and their advantages, disadvantages, and applications.

The rise in the resistance to antibiotics is due to their inappropriate use and the use of a broad spectrum of antibiotics. This has also contributed to the development of multidrug-resistant microorganisms, and due to the unavailability of suitable new drugs for treatments, it is difficult to control. Hence, there is a need for the development of new novel, target-specific antimicrobials. Nanotechnology, involving the synthesis of nanoparticles, may be one of the best options, as it can be manipulated by using physicochemical properties to develop intelligent NPs with desired properties. NPs, because of their unique properties, can deliver drugs to specific targets and release them in a sustained fashion. The chance of developing resistance is very low. Polymeric nanoparticles are solid colloids synthesized using either natural or synthetic polymers. These polymers are used as carriers of drugs to deliver them to the targets. NPs, synthesized using poly-lactic acid (PLA) or the copolymer of lactic and glycolic acid (PLGA), are used in the delivery of controlled drug release, as they are biodegradable, biocompatible and have been approved by the USFDA. In this article, we will be reviewing the synthesis of PLGA-based nanoparticles encapsulated or loaded with antibiotics, natural products, or metal ions and their antibacterial potential in various medical applications.

The total oil yield and the fatty acid composition were determined in theAnnona muricataL. fixed oil using organic solvent extraction and GC-FID. The seeds were found to contain about ~21.5% of crude fixed oil on a dry weight basis. The crude oil containing fatty acid was converted into methyl esters and analysed by GC-FID. Fourteen fatty acids were identified using GC-FID. The major monounsaturated and saturated fatty acids were oleic acid (39.2%) and palmitic acid (19.1–19.2%), respectively, whereas theα-linolenic acid (1.2%) and linoleic acid (34.9%) were polyunsaturated fatty acid. The other saturated acids were stearic acid (3.3%), arachidic acid (0.4%), myristic acid (0.1%), heptadecanoic acid (0.1%), behenic acid (0.1%), and lignoceric acid (0.1%). Some of the fatty acids have not been reported earlier from the oil ofAnnona muricataL. Fixed oil exhibited significant free radical scavenging activity which was measured using DPPH and is also known to inhibit the gastrointestinal motility significantly.