Introduction

Silicon dioxide (silica) nanoparticles are one of the most harmful environmental agents to human health. These nanoparticles are commonly occurring as they are widespread in nature, for example silica from quartz and from the sand. Furthermore, synthetic silica is widely used in industrial application, and can be found as an additive in printing inks, cosmetics, pharmaceuticals, food products. Silicosis, characterised by inflammation of the lung tissue and the presence of nodular lesions in the upper lobes of the lungs, occurs in patients who have been exposed to silica nanoparticles. Similarly, also graphene nanoparticles have been shown to have toxic effects on human health, and means are necessary to monitor their presence, particularly in the workplace environment. Currently, multi-step processes exist on the market to monitor these nanoparticles, which involve complex procedures in sample preparation and analysis.

Technical features

Carbon dots have excellent photostability, water solubility, high sensitivity and selectivity towards analytes, high quantum yield and modulable fluorescence emission/excitation properties. Because of these characteristics, and thanks to their low toxicity and biocompatibility, carbon dot sensors can be successfully used to analyse samples or surfaces suspected of being contaminated by silica nanoparticles and/or graphene nanoplates. A method has been developed to detect the presence of silica nanoparticles or graphene nanoplatelets using a photoluminescent sensor comprising a substrate on which carbon dots (smaller than 10nm) are deposited. The invention has been shown to have good sensitivity over a wide range of average silica particle sizes (10-100nm) at a concentration between 2×10^-5 mg/mL and 1 mg/mL, whilst graphene nanoplatelets of similar size can be detected at around 0.01 mg/mL.

Possible Applications

• Environmental sample analysis;
• Air quality monitoring.

Advantages

• Very sensitive and fast method;
• Does not require complex and expensive instrumentation;
• Can be couple to existing sampling devices for monitoring dust;
• Can be incorporated in PPE.