Polymer Precursor Strategy Toward the Precise Synthesis of Uniform Hairy Carbon Dots with Tunable Sizes and Size Effects over Their Fluorescence

Abstract

A polymeric precursor strategy was developed toward precise synthesis of uniform and size-tunable hairy fluorescent carbon dots (C-dots, CDs). The strategy was achieved by (i) the synthesis of core−shell 6-arm starlike block copolymers of PGMA-b-PMMA (poly(glucosyl methyacrylate), PGMA; poly-(methyl methacrylate), PMMA), serving as a precursor using atom transfer radical polymerization (ATRP) and (ii) selective carbonization of the inner PGMA chains to generate hairy C-dots with PMMA blocks attaching on the surfaces. The resultant C-dots with tunable sizes showed blue to green fluorescence depending on the excitation, size, and concentration. The large size of the C-dots led to a significant red shift of fluorescence emission, which was attributed to enhanced intra-C-dot Forster resonance energy transfer (FRET) between the emitter homologues in a single C-dot. In addition, the FRET effect between C-dots was further confirmed by the aggregation-caused quenching characteristics and red shift of emission at high concentrations. Interestingly, different from the traditional fluorophores with photobleaching characteristics, C-dots showed recoverable photoabsorption capacity and enhanced fluorescence after the long-time exposure to UV light.

A universal polymer precursor strategy for precise synthesis of uniform hairy carbon dots and polymer dots

“…17 In our recent work, it was found that FRET effect could happen between different C-dots at high concentrations in addition to FRET pairs formed by sub-fluorophores in a single C-dots. 33 As expected, as the concentration increased gradually until it reached 3.0 mg mL −1 , the fluorescence intensity at λ em = 535 nm began to increase gradually and reached the maximum. In such a range, the concentration did not show any significant effect on the optimal emission wavelength.…”

“…The sizes of C-dots were easily controlled by molecular weight of inner block in the polymer precursor. 33 In this strategy, 6-arm star-like diblock copolymers with a pendent glucosyl group in the inner block were pre-synthesized and the star-like copolymers were one-to-one transformed into C-dots by carbonizing the glucosyl group.…”

Carbon dots as a new class of multifunctional nanomaterial in mesenchymal stem cells: opportunities and challenges

“…The core–shell polymer can be used as an ideal nanoreactor for the synthesis of inorganic nanomaterials with uniform and adjustable structure. 258 The nanospace of molecular sieves provides an ideal rigid microenvironment for the growth of CDs, thus leading to uniform size. 259 Similarly, the significant difference in carbonization temperature between metal–organic framework (MOF) and glucose (precursor) is used to realize the composite of CDs and MOF.…”

Comprehensive advances in the synthesis, fluorescence mechanism and multifunctional applications of red-emitting carbon nanomaterials

“…They showed that the emission wavelength shifted from blue to red when increasing the size of the carbon dots from small to large. 275 Liu et al described the size-dependent fluorescence of carbon dots. The team showed that increasing the size of the carbon dots resulted in red-shifted fluorescence.…”