Sunscreen agents derived from plants have been regarded as promising alternatives to artificial compounds. In this work

carbon dots (CDs) were prepared from carrot juice

via

a continuous microflow-based approach

where the influence of process parameters was studied and optimized. Complimentary characterization revealed the CDs not only have small size

narrow size distribution

and good water solubility

but also have abundant functional groups as well as excellent UV absorption performance. Relying on these properties

the CDs were used as UV absorbers

suggesting they have strong long-term UV absorption ability over a broad pH range. The UV-absorption properties of the CDs were confirmed by incorporating the CDs in polyvinyl alcohol (PVA) to get C-CDs@PVA films of different thickness

in which significantly enhanced UV absorption performance was observed. Besides

the sun protection performance is also related to the film thickness. Afterwards

the practical application of the CDs was evaluated by adding them in a typical skin cream. With the addition of the CDs

the cream has drastically reduced UV transmittance in both UVA and UVB regions

and exhibits better UV absorption performance than commercial sunscreen agents. The CDs also demonstrated low cytotoxicity and high DPPH radical scavenging activity

making them promising as green sunscreen absorbers. This work is expected to provide a guidance for the development of green and effective natural sunscreen agents

via

micr

oflow-based method.