Fluorescent folic acid-chitosan/carbon dot for pH-responsive drug delivery and bioimaging

Nanodroplets Engineered with Folate Carbon Dots for Enhanced Cancer Cell Uptake toward Theranostic Application

The research in nanotherapeutics is rapidly advancing, particularly in the realm of nanoconstructs for drug delivery. This study introduces folate-based carbon dot-decorated nanodroplets (f-Dnm), synthesized from a binary mixture of negatively charged folic acid carbon dots (f-CDs) and cationic-branched polyethylenimine (PEI). The uniformly spherical nanodroplets with an average diameter of 115 ± 15 nm exhibit notable photoluminescence. Surface potential analysis reveals a significant change upon coacervation, attributed to strong electrostatic interactions between f-CD and PEI. The engineered nanodroplets show excellent colloidal and photostability even after 6 months of storage at room temperature. The pH-dependent self-assembly and disassembly properties of f-Dnm are explored for drug loading and release studies using doxorubicin (DOX) as a model anticancer drug. Moreover, the f-Dnm nanocarrier demonstrates significantly higher drug loading capabilities (∼90%). In vitro release studies of doxorubicin-loaded f-Dnm [f-Dnm(DOX)] reveal 5 times higher drug release at lysosomal pH 5.4 compared to that at physiological blood pH 7.4. Cytocompatibility assessments using the MTT assay on HeLa, A549, and NIH-3T3 cells confirm the nontoxic nature of f-Dnm, even at high concentrations. Additionally, f-Dnm(DOX) exhibits higher cytotoxicity in HeLa cells compared to f-CD(DOX) at similar DOX concentrations. Cellular uptake studies show an increased uptake of f-Dnm in folate receptor-positive HeLa and MDA-MB 231 cells. Hemolysis assay validated the biocompatibility of the developed formulation. Overall, these engineered nanodroplets represent a class of nontoxic nanocarriers that offer promising potential as nanotherapeutics for folate receptor-positive cells.

Preparation of multi-functional active packaging film of Galla chinensis waste CDs/pullulan

In this study, multifunctional green carbon dots (CDs) have been synthesized using Galla chinensis waste (GCW) via hydrothermal method for the first time. An active packaging film has been developed in this work by combining CDs and pullulan (PL), using the solution-casting method. The microscopic morphology revealed that the CDs that were prepared using GCW exhibited good compatibility with PL. In addition, it also led to improvement in the toughness of the PL film (14.01 % to 20.26 %), along with its water vapor permeability value [1.31 to 0.53 (g·mm)/(kPa·h·m2)]. The composite films consisting of CDs exhibited good UV blocking rates for the UVA (90.41 %-7.87 %), UVB (87.76 %-0.08 %), and UVC (83.39 %-0 %) spectral ranges. The composite films exhibited strong antioxidant activity, and the clearance of ABTS and DPPH were obtained to be 93.61 % and 86.30 %, respectively. In addition, the composite films showed good antibacterial activity for E. coli and S. aureus, with a high antibacterial rate of up to 99.99 %. Finally, the non-contact preservation of strawberries over a duration of 10 d at room temperature confirmed that the prepared composite film can help preserve the quality of strawberries, as well as extended their shelf-life.

Tunable Release of Calcium from Chitosan-Coated Bioglass

Bioglass presents a standard biomaterial for regeneration of hard tissues in orthopedics and dentistry. The notable osteo-inductive properties of bioglass are largely due to the release of calcium ions from it. However, this release is not easily controllable and can often be excessive, especially during the initial interaction of the biomaterial with the surrounding tissues. Consequently, this excessive release can deplete the calcium content of the bioglass, ultimately reducing its overall bioactivity. In this study, we have tested if applying biopolymer chitosan coatings of different thicknesses would be able to mitigate and regulate the calcium ion release from monodisperse bioglass nanoparticles. Calcium release was assessed for four different chitosan coating thicknesses at different time points over the period of 28 days using a fluorescence quencher. Expectedly, chitosan-coated particles released less calcium as the concentration of chitosan in the coating solution increased, presumably due to the increased thickness of the chitosan coating around the bioglass particles. The mechanism of release remained constant for each coating thickness, corresponding to anomalous, non-Fickian diffusion, but the degree of anomalousness increased with the deposition of chitosan. Zeta potential testing showed an expected increase in the positive double layer charge following the deposition of the chitosan coating due to the surface exposure of the amine groups of chitosan. Less intuitively, the zeta potential became less positive as thickness of the chitosan coating increased, attesting to the lower density of the surface charges within thicker coatings than within the thinner ones. Overall, the findings of this study demonstrate that chitosan coating efficiently prevents the early release of calcium from bioglass. This coating procedure also allows for the tuning of the calcium release kinetics by controlling the chitosan concentration in the parent solution.