Kalana W. Jayawardana

One-step synthesis of amine-functionalized hollow mesoporous silica nanoparticles as efficient antibacterial and anticancer materials.

In this study, amine-functionalized hollow mesoporous silica nanoparticles with an average diameter of ∼100 nm and shell thickness of ∼20 nm were prepared by an one-step process. This new nanoparticulate system exhibited excellent killing efficiency against mycobacterial (M. smegmatis strain mc(2) 651) and cancer cells (A549).

Maltoheptaose Promotes Nanoparticle Internalization by Escherichia coli

Nanoparticles conjugated with d-maltoheptaose (G7) showed a striking increase in the internalization by Escherichia coli. This applies to strains with and without the maltodextrin transport channel and particles ranging from a few to a hundred nanometers.

Poly(HEMA-co-HEMA-PFPA): Synthesis and preparation of stable micelles encapsulating imaging nanoparticles

We report the preparation of stable micelles from random copolymers of 2-hydroxyethyl methacrylate (HEMA) and perfluorophenyl azide (PFPA)-derivatized HEMA (HEMA-PFPA). The copolymers were synthesized by RAFT polymerization at room temperature under mild conditions without affecting the azide functionality. Upon addition of water to the copolymer solution in DMSO, the random copolymers self-assembled into micelles even at the percentage of HEMA-PFPA as low as 4.5%. The size of the micelles can be controlled by the molecular weight and the concentration of the copolymer, and the percentage of HEMA-PFPA in the copolymer. In addition, iron oxide nanoparticles and quantum dots were successfully encapsulated into the micelles with high encapsulation efficiency (∼80%). These nanoparticles, which were hydrophobic and formed agglomerates in water, became fully dispersed after encapsulating into the micelles. The micelles were stable and the size remained unchanged for at least 6months.

Nanosilver rainbow: a rapid and facile method to tune different colours of nanosilver through the controlled synthesis of stable spherical silver nanoparticles

A rapid and simple one-pot reaction to synthesize stable, spherically shaped silver nanoparticles (AgNps) of different sizes producing distinct optical properties in aqueous solution at ambient temperature has been developed. Each system contains various sizes of silver nanoparticles showing rainbow colours with the peak wavelength of the absorption spectra ranging from 400 to 750 nm. Seven different colours of nano silver were developed through the controlled synthesis of spherical silver nanoparticles using silver nitrate as the metal precursor. Sodium borohydride was used as the main reducing agent and trisodium citrate and hydrazine sulphate were used as the stabilizing and auxiliary reducing agents respectively. The colour of the solution was controlled by varying the concentrations of reagents and the optimum conditions for all the colours are reported. Characterization of silver nanoparticles was carried out using UV-visible spectrophotometry and Transmission Electron Microscopy (TEM). Factors affecting the formation of different sizes of silver nanoparticles, such as silver nitrate concentration, reducing agent concentrations, reaction temperature and reaction pH are also reported. The stability of these coloured silver colloidal solutions was also investigated at different temperatures and the most stable temperature was found to be 4 °C, while the optimum pH to synthesize distinctively coloured silver nanoparticles was found to be in the range of 7–8. The outlined procedure provides a rapid, facile and reproducible synthetic route to spherical AgNps of varying size and ensuing optical properties. Thus, this method is certain to find value in the many applications where size tunability of AgNps is desired.

Magnetic Multivalent Trehalose Glycopolymer Nanoparticles for the Detection of Mycobacteria

A multivalent trehalose-grafted poly(lactic acid) is synthesized and encapsulated with iron oxide magnetic nanoparticles. The magnetic micelles interact with Mycobacterium smegmatis to form orange clusters. Very little particle interaction is found on Staphylococcus epidermidis 35984 or Escherichia coli ORN 208. The presented new approach to the detection of mycobacteria does not require molecular biology reagents or sophisticated instruments.