Glyconanoparticles with Activatable Near-Infrared Probes for Tumor-Cell Imaging and Targeted Drug Delivery

Background

Multifunctional nanocarriers based on tumor targeting and intracellular monitoring have received much attention and been a subject of intensive study by researchers in recent years. In this study, we report multifunctional glyconanoparticles with activatable near-infrared probes for tumor imaging and targeted drug delivery.

Methods

Disulfide-functionalized dicyanomethylene-4H-pyran (DCM-SS-NH₂) and amino-functionalized lactose were modified and loaded onto the surfaces of polydopamine nanoparticles (NPs) by Michael addition or Schiff-base reaction as GSH stimulation–responsive fluorescent probes and tumor-targeting moieties, respectively. Doxorubicin (DOX), a model anticancer drug, was loaded onto polydopamine through π–π interactions directly to prepare multifunctional PLDD (PDA@Lac/DCM/DOX) NPs.

Results

Experimental results showed that PLDD NPs had been successfully prepared. DCM, the fluorescence of which was quenched in PLDD NPs, was able to restore red fluorescence in a solution with a GSH concentration of 5 mM. The amount of DOX released from PLDD NPs was 44% over 72 hours in a weak-acid environment (pH 5). The results of CLSM and flow cytometry indicated that the PLDD NPs had good HepG2-targeting ability due to the special recognition between lactose derivative of NPs and overexpressed asialoglycoprotein receptors on HepG2 cell membrane. More importantly, the disulfide bond of DCM-SS-NH₂ was broken by the high concentration of GSH inside cancer cells, activating the near-infrared fluorescence probe DCM for cancer-cell imaging. MTT assays indicated that PLDD NPs exhibited higher anticancer efficiency for HepG2 cells and had reduced side effects on normal cells compared with free DOX.

Conclusion

The fluorescence of modified DCM loaded onto PLDD NPs is able to be restored in the high-concentration GSH environment within cancer cells, while improving the effectiveness of chemotherapy with reduced side effects. It provides a good example of integration of tumor imaging and targeted drug delivery.

In situ deposition of MOF-74(Cu) nanosheet arrays onto carbon cloth to fabricate a sensitive and selective electrocatalytic biosensor and its application for the determination of glucose in human serum

A new electrocatalytic biosensor (MOF-74(Cu) NS-CC) based on the in situ deposition of MOF-74(Cu) nanosheet on carbon cloth via a bottom-up synthetic approach in a glass tube was developed. The electrocatalytic activity of the deposited MOF-74(Cu) NS was demonstrated in the oxidation of glucose to gluconate under alkaline conditions. The results revealed that the proposed method of in situ formation of MOF-74(Cu) NS onto a carbon cloth surface in a multi-layer solution is capable to generate a stable MOF-74(Cu) NS-CC electrode with excellent sensing performance. When the as-synthesized MOF-74(Cu) NS-CC was applied directly as the working electrode for glucose sensing, it showed much higher conductivity and redox activity than MOF-74(Cu) NS-GCE. With the potential applied at 0.55 V (vs. Ag/AgCl), this new electrocatalytic biosensor exhibits an excellent linear relationship between current density and concentration of glucose. Moreover, a wide linear range of detection (1.0 to 1000 μM) was observed. The limit of detection was found to be 0.41 μM (S/N = 3). The response sensitivity is 3.35 mA mM^-1 cm^-2 when the concentration of glucose is in the range 1-100 μM and 3.81 mA mM^-1 cm^-2 for the 100-1000 μM concentration range. This study provides a low-cost, easy to prepare, and reproducible methodology for the synthesis of highly redox-active nanomaterials based on the in situ formation of two-dimensional MOF-74(Cu) NS for the development of new electrocatalytic biosensors. Graphical abstract.

WS2 nanosheets-sensitized CdS quantum dots heterostructure for photoelectrochemical immunoassay of alpha-fetoprotein coupled with enzyme-mediated biocatalytic precipitation

A sensitive photoelectrochemical immunoassay for AFP was developed via signal enhancement of WS₂/CdS heterojunction and signal quenching of enzyme-mediated biocatalytic precipitation.