Engineered Fluorescent Carbon Dots and G4-G6 PAMAM Dendrimer Nanohybrids for Bioimaging and Gene Delivery

Abstract

Carbon dots (CDs) and G4-G6 (polyamidoamine)­PAMAM-NH2 dendrimers were self-assembled to produce CDs@PAMAM nanohybrids for transfection and bioimaging purposes. CDs were synthesized by the hydrothermal method, using ascorbic acid as a starting precursor and characterized by transmission electron microscopy, UV–Vis, and fluorescence (in solution and solid-state) techniques. CDs were electrostatically combined with PAMAM dendrimers at room temperature, and the UV–Vis, fluorescence, and NMR spectroscopies were used to confirm the self-assembly. When compared to pristine CDs, nanohybrids were more photostable, resisting high acidic and basic pH. Moreover, they were considerably internalized by cells, as assessed by flow cytometry and fluorescence microscopy, and, when excited, displayed multi-color emission easily quantified and visualized. These nanoscale hybrids, coined hybridplexes, can condense pDNA and transfecting cells successfully, particularly the G5 CDs@PAMAM nanohybrids. In summary, CDs prepared in mild and smooth lab conditions, showing good optical properties, were used to prepare elegantly CDs@PAMAM nanohybrids with promising biomedical applications.

Carbon dot composites for bioapplications: a review

“…196 In addition to these examples, other organics–CD composites such as (N-(2-aminoethyl)-3-aminopropyl)tris-(2-ethoxy)silane-CDs (KH791-CDs), N-isopropylacrylamide-CDs (NIPAAM-CDs), the CD–RhB core–shell nanocomposite and (polyamidoamine)-PAMAM-NH 2 -CDs have also been reported. 197–200 It is also worth mentioning that the QY of NIPAAM-CDs was as high as 94%. Interestingly, in hydrothermal reactions, the solvents used for work-up could play important roles.…”

“…12E). 199 Marina and co-workers established a CDs@HNT-DNA model through electrostatic interactions between CDs@HNT and DNA. The results showed that the model did not cause any alteration in the DNA structure and DNA was slowly released through a dialysis membrane in physiological media (Fig.…”

Intrinsic Blue Fluorescence of 2.0G PAMAM-DCM Polymer Dots and Its Applications for Fe3+ Sensing

“…Then, PAMAM (aq) and 5.0 mL dichloromethane were added into a stainless-steel autoclave (25 mL) for oil bath; the pH of the solutions was adjusted using HCl solution (0.1 M) or NaOH (0.1 M). The resulting solution was then treated by a one-step hydrothermal method under different conditions, including temperature (60-140 • C), pH (3)(4)(5)(6)(7)(8)(9)(10)(11) and concentrations (0.01-0.1 mM). The pure PDs were obtained by centrifugation and vacuum rotary evaporation, and freeze-dried.…”

“…Polyamide-amine (PAMAM) is a highly symmetrical macromolecule with an internal cavity: exhibits good compatibility, unique hydrodynamic properties, and easy modification properties [1][2][3]; receives increasing attention in bioimaging [4,5], sensors [6], catalysis [7,8], drug-delivery [9,10], etc. Previously, Wang and Imae [11] reported that PAMAM, with different terminal groups, including −NH 2 , −C=O, or −OH, could present weak and blue fluorescence.…”

Development of Tailor-Made Dendrimer Ternary Complexes for Drug/Gene Co-Delivery in Cancer

“…As literature suggests, the complexation process seems to be dependent on dendrimers physicochemical properties, such as, size, surface charge density, structural morphology or PAMAM generation [40,41]. Moreover, the surface amines exert a crucial role in DNA complexation and cellular internalization, while the tertiary amines can act as buffer to facilitate endosomal escape [40,43]. This image demonstrated that PAMAM G4-PTX dendrimer is not able to complex pDNA and, thus, immobilize it for most of the ratios under investigation.…”