Chiral evolution of carbon dots and the tuning of laccase activity

Abstract

Chirality has attracted extensive attention in many fields ranging from chemistry to life sciences. Carbon dots (CDs) with good biocompatibility and unique photochemical properties have become a new star in the nanocarbon family. Endowed with chirality, CDs will exhibit more marvellous properties and bridge the fields of material chemistry and life sciences tightly. Herein, we report a facile one-step alkali-assisted electrochemical method to fabricate chiral CDs from cysteine (cys). We showed the chiral evolution of CDs with highly symmetrical circular dichroism (CD) signals in the range from 205 to 350 nm. These chiral CDs have been further demonstrated to be capable of tuning the activity of laccase: the l-CDs can improve the activity of the enzyme up to 20.2%, whereas the d-CDs decrease the activity to 10.4%. A series of experiments confirm that it is the synergistic effect of nanosize and chirality of CDs that induces the change in the structure of laccase and thus leads to the tuning of the laccase activity.

Design principles of chiral carbon nanodots help convey chirality from molecular to nanoscale level

“…Such advancements could be fulfilled using properties reported here, and exploring new ones. Differently to other attempts at preparing chiral carbon nanoparticles 66 – 68 , the rationale brought forward in the present work, accompanied by proper purification and extensive investigation of the chirality, could be extended for preparing other types of carbon dots. By using our approach, chirality could be conferred from different chiral molecules 69 to different core precursors 70 .…”

Tuning residual chirality in carbon dots with anti-microbial properties

“…The observed optical properties are in accordance with other cysteine based chiral CDs, prepared using hydrothermal synthesis. [33][34][35][36][37][38] The prominent peaks of the previously reported hydrothermal cysteine-based CDs were also centred around $250 nm and $350 nm. The similarities in optical properties of CDs from the two different synthesis methods can be attributed to the use of the same precursors with similar resulting functional groups and properties.…”

“…The peaks at 250 nm and 350 nm are equivalent to previous studies that have synthesized chiral cysCDs and they correspond to the UV-Vis absorbance bands of the dots. [34][35][36][37][38] Furthermore, the unpassivated carbon dots composed of citric acid did not display any absorbance bands in the circular dichroism spectra (Fig. S1c †).…”

“…35 Chiral CDs in biological systems have also been explored, as in the work of Hu et al who synthesized CDs from enantiomers of cysteine. 36 They investigated the activity of laccase enzyme under the inuence of chiral CDs. 36 Similarly, chiral cysteine-based CDs were used by Li et al to understand its inuence on cellular energy metabolism 37 and by Zhang et al to study its effects on mung bean plant growth.…”

“…36 They investigated the activity of laccase enzyme under the inuence of chiral CDs. 36 Similarly, chiral cysteine-based CDs were used by Li et al to understand its inuence on cellular energy metabolism 37 and by Zhang et al to study its effects on mung bean plant growth. 38 While these studies have provided a wealth of information on the properties of chiral CDs, many questions remain unanswered.…”