Table of Contents Table of Contents
Previous Page  44 / 280 Next Page
Information
Show Menu
Previous Page 44 / 280 Next Page
Page Background

T

he emergence of antibiotic-resistant bacteria is a major

threat to worldwide public health. Functionalised

nanoparticles can offer novel solutions for the post-

antibiotic era.

A) Ag-GQDs nanocomposite to combat drug-

resistant bacteria

In this context, we developed a nanocomposite of silver

nanoparticles decorated with graphene quantum dots (Ag GQD)

and functionalised with polyethylene glycol. This nanocomposite

inhibits the growth of Gram-positive

S. aureus

and gram-negative

P. aeruginosa

bacteria, which are commonly isolated from

microbial infections in wounds. The concentration required to

inhibit both types of bacterial strains is well below the

concentration that would affect the mammalian cell viability, being

therefore biocompatible. The effectiveness of the composite is due

to a synergistic effect in which the GQDs facilitate the

internalisation of the silver nanoparticles into the bacteria, thus

reducing the overall concentration of silver required to produce

the bactericide effect. These results suggest that Ag-GQDs can be

used in the fabrication of antibacterial ointments, self sterile

textiles, and sterile personal care products. Collaborations are

sought to expand the current study, independently validate the

results, and develop antibacterial products based on Ag-GQDs.

Contact: Dr Gerardo Morell,

gerardo.morell@upr.edu,

+1 787 282 7047

B) 1D Fe

3

O

4

-based building blocks for MRI

contrast agents

Superparamagnetic iron oxide particles (SPIO) are employed as

contrast agents in magnetic resonance imaging (MRI) due to the

fact that they exhibit clinically proven biocompatibility and high

relaxivities. As T

2

contrast agents, SPIOs alter the transverse

relaxation times of water protons, providing dark negative signal

intensity to images, and they enable the visualisation and

monitoring of cells grafted in organs due to their high sensitivity

and excellent clinical biocompatibility. In order to enhance the

relaxivity, blood circulation half-life, and homing of MRI contrast

agents to tumours, we developed 1D nanoscale core magnetite

particles with high aspect ratio. These nanoparticulate contrast

agents contain a large number of superparamagnetic molecules

that induce large relaxivities (above 100mm-

1

s

-1

) and allow the

visualisation of targets in the picomolar concentration range.

Moreover, they can cross many biological barriers and interact

with biological systems at the molecular

level.We

anticipate that

the 1D Fe

3

O

4

nanoparticles currently under development will

enhance the MRI capability to image poorly vascularised tumours

and even individual tumour cells, thus bridging a critical gap in

this research field. Collaborations are sought to expand the

current study, independently validate the results, and develop MRI

products based on 1D Fe

3

O

4

nanoparticles.

Contact: Dr Brad R Weiner,

brad@hpcf.upr.edu,

+1 787 764 8369

C) Semiconductor ferroelectrics for

photovoltaic devices

The photovoltaic (PV) effect observed in BiFeO

3

(BFO) has

received a great deal of attention due to its small band gap

(2.7eV), large open circuit voltage (Voc), and switchable diode

and photovoltaic effects. Diode-like rectifying characteristics can

be easily obtained in single crystal BFO deposited on epitaxial

substrates. The PV effects can be reversibly switched by applying

an alternating electric field, and the sign of photocurrent related

to the diode effect is opposite to the polarisation directions.

We synthesised and studied polycrystalline thin films of BFO co-

doped with La and Ta or BLFTO. They show PV effects with a high

oxygen vacancy concentration under an electric field much lower

than the coercive

field.We

have shown that the electromigration of

The University of Puerto Rico at Rio Piedras hosts a vibrant multidisciplinary

community of experts in nanoscale science and technology doing leading-edge

materials research from energy to biomedical applications

Application-driven

nanotechnology

44

I S S U E S E V E N

H O R I Z O N 2 0 2 0 P R O J E C T S : P O R TA L

www.horizon2020projects.com

P R O F I L E

S P E C I A L F E AT U R E : M AT E R I A L S