NANOMATERIALS IN BIOANALYTICAL CHEMISTRY (NBC) Unit is a branch of  GABAI (Industrial, Biochemical and Environmental Analysis Group).  GABAI is located at the Laboratory of Applied Chemistry, Department of Chemical Sciences, Faculty of Pharmacy, University of Porto and is integrated in REQUIMTE (Associate Laboratory).

NBC research unit activities are focused on the development of nanomaterials, including semiconductor and carbon quantum dots, silver nanoparticles and silica nanostructures, as well as on the implementation of automated analytical methodologies involving the utilization of these nanomaterials in clinical, pharmaceutical, food and environmental analysis.

In recent years, there has been a massive interest in the use of NANOMATERIALS for biosensing, bioimaging and other bioanalytical applications due to their ability to interact with biomolecules triggering a quantifiable event.

SEMICONDUCTOR QUANTUM DOTS (QDs) have assumed a prominent role in view of their remarkable photophysical properties, such as broad excitation and narrow size-dependent emission, high photostability and improved brightness. The QDs analytical functionality is very dependent on their surface chemistry, which can be manipulated by means of functional groups or ligands to obtain specific interactions with the target providing suitable selectivity and sensitivity. Although commonly employed in solution, the immobilization of QDs on suitable solid supports could provide important operational advantages, such as re-utilization, minimization of reagents consumption, multi-parametric analysis, as well as the modulation of the photochemical properties. Several strategies for QDs immobilization have been developed, namely by using layer-by-layer electrostatic self-assembling, encapsulation into silica and polymeric nanospheres, covalent binding onto amino-functionalized surfaces and entrapment inside sol-gel materials.

NBC research Unit has a well-established background on chemical sensing using semiconductor (CdTe) QDs, including the determination of organic, inorganic species and antioxidant capacity. More recently, and as a more environmental friendly alternative to cadmium-based QDs, carbon quantum dots (or C-dots) have been the groundwork of significant advances emerging as easily obtainable fluorescent nanomaterials with appealing properties for (bio)analytical applications. The research group has already gathered expertise on C-dots hydrothermal and microwave-assisted synthesis and has beginning to exploit their analytical potential arising from advantageous features such as high aqueous solubility, facile functionalisation and the ability to act as electron donors and acceptors in photo and chemiluminescence processes.

SILVER NANOPARTICLES (AgNPs) use is widespread in diverse areas, including textile engineering, biotechnology, medicine, bioengineering, catalysis, water treatment, optics, electronics and also in food science. The control of their physicochemical properties, namely their size and specific surface area, is a key parameter to determine their application.  The research team is involved on the development of automatic methods, based on sequential injection technique to synthesize silver nanoparticles, using at the same time green reducers and UV light for the reduction process.

Quantum dots synthesised with different sizes, different emission wavelength

Quantum dots immobilized onto aminated glass - fluorescence microscopy image

Sequential injection technique as a tool for the automatic synthesis of silver nanoparticles

 Quantum dot band-gap scheme

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