Microwave-Assisted Synthesis and Characterization of Poly(L-lysine)-Based Polymer/Carbon Quantum Dot Nanomaterials for Biomedical Purposes

Abstract

Carbon nanomaterials in the form of quantum dots have a high potential due to their luminescent properties and low cytotoxicity which allows their use in optical probes for use in bioimaging and biodetection. In this article, we present a novel type of nanomaterials and their obtainment method under microwave-assisted conditions using poly(L-lysine) as a raw material. The ready products were characterized over their chemical structure, pH-dependent fluorescence properties and cytotoxicity on human dermal fibroblasts. Moreover, their antioxidant activity as well as ability to biologically active molecules (vitamins) and heavy metal ions detection was evaluated. The results confirmed the obtainment of biocompatible nanomaterials with advanced properties and good water solubility according to sustained development principles.

Keywords: biocompatible nanomaterials; carbon quantum dots; optical probes.

Figure 1

FT-IR spectra of the prepared CQDs.

Figure 2

UV–vis characteristics of the prepared CQDs. (a) samples CQDs-1–CQDs-5; (b) samples CQDs-6–CQDs-10.

Figure 3

Fluorescence spectra of the prepared carbon quantum dots: (a) sample CQDs-1; (b) sample CQDs-2; (c) sample CQDs-3; (d) sample CQDs-4; (e) sample CQDs-5; (f) sample CQDs-6; (g) sample CQDs-7; (h) sample CQDs-8; (i) sample CQDs-9; (j) sample CQDs-10.

Figure 4

Fluorescence spectra of the prepared carbon quantum dots depending on pH value: (a) samples CQDs-1–CQDs-5; (b) samples CQDs-6–CQDs-10.

Figure 5

Fluorescence quantum yield of prepared CQDs. Violet bars—freshly after synthesis and purification. Yellow bars—fluorescence quantum yield after 2 months (photostability).

Figure 6

TEM images of the prepared CQDs: (a) CQDs-4; (b) CQDs-6.

Figure 7

Schematic presentation of CQDs synthesis. Proposed chemical and morphological structure of the CQDs.

Figure 8

Detection of metal ions and vitamins by CQDs: (a) metal ions; (b) Vitamin C; (c) Vitamin B₆.

Figure 9

Antioxidant properties of the prepared CQDs against DPPH radicals.

Figure 10

Results of the XTT assay on the prepared CQDs. (a) samples CQDs-1–CQDs-5; (b) samples CQDs-6–CQDs-10.

Figure 11

Images of the primary dermis cells (HDF) after 72h cell culture in the medium containing the CQDs. (a) sample CQDs-1; (b) sample CQDs-4; (c) sample CQDs-5; (d) sample CQDs-6; (e) sample CQDs-7; (f) sample CQDs-10.