Smart DNA nanogel coated polydopamine nanoparticle with high drug loading for chemo-photothermal therapy of cancer.

A smart deoxyribose nucleic acid nanogel coated polydopamine nanosphere hybrid was designed for chemo-photothermal therapy of cancer. The nanohybrid showed good colloid stability, narrow size distribution, high drug loading, good biocompatibility, and high photothermal conversion efficiency, and could release the drug on desired tumor sites.

High-Throughput and Real-Time Monitoring of Single-Cell Extracellular pH Based on Polyaniline Microarrays.

Real-time monitoring of extracellular pH (pHe) at the single-cell level is critical for elucidating the mechanisms of disease development and investigating drug effects, with particular importance in cancer cells. However, there are still some challenges for analyzing and measuring pHe due to the strong heterogeneity of cancer cells. Thus, it is necessary to develop a reliable method with good selectivity, reproducibility, and stability for achieving the pHe heterogeneity of cancer cells. In this paper, we report a high-throughput, real-time measuring technique based on polyaniline (PANI) microelectrode arrays for monitoring single-cell pHe. The PANI microelectrode array not only has a high sensitivity (57.22 mV/pH) ranging from pH 6.0 to 7.6 but also exhibits a high reliability (after washing, the PANI film was still smooth, dense, and with a sensitivity of 55.9 mV/pH). Our results demonstrated that the pHe of the cancer cell region is lower than that of the surrounding blank region, and pHe changes of different cancer cells exhibit significant cellular heterogeneity during cellular respiration and drug stimulation processes.

Polydopamine with Tailorable Photoelectrochemical Activities for the Highly Sensitive Immunoassay of Tumor Markers.

A simple and highly sensitive photoelectrochemical (PEC) immunoassay sensor was fabricated by using the two forms of polydopamine (PDA), the thin film and nanosphere, to serve as the photoelectrode-modified material and signal reporting label, respectively. The two forms of PDA show similar light absorption behavior but totally different PEC activities. The PDA film can extend the light absorption from the ultraviolet to near infrared light range, transfer a photoelectron to TiO2 nanoparticles and the underlying photoelectrode, and largely amplify the photocurrent response. However, the PDA nanospheres have insignificant photoelectron transport ability. When they are brought close to the PDA film and TiO2 nanocomposite-modified electrode via the sandwich immunoreaction, they function like a black hole to compete with the PDA film for light absorption, resist the access of the electron donor to regenerate the photoactive material, and capture the photoelectron generated from the PDA film. Besides, the heat generated from the PDA nanospheres also contributes to the photocurrent decrease. The PDA nanospheres with multiple quenching effects on the PDA film greatly decrease the photocurrent signal and lead to a highly sensitive PEC immunosensing strategy. Under optimal conditions, a wide linear range from 0.1 to 106 pg·mL-1 is obtained toward carcinoembryonic antigen, with a low limit of detection of 40 fg·mL-1. Besides, the PDA with excellent biosafety can be readily assembled with proteins, which thus simplifies the preparation procedures and decreases the costs. All these features indicate that the whole PDA-based PEC sensing strategy may have great application prospects for the point-of-care assay of various kinds of tumor markers.

Polydopamine nanospheres with multiple quenching effect on TiO2/CdS:Mn for highly sensitive photoelectrochemical assay of tumor markers.

A photoelectrochemical (PEC) immunosensing strategy based on the multiple quenching of polydopamine nanoparticles (PDA NPs) to Mn2+-doped CdS-modified TiO2 nanoparticles (TiO2/CdS:Mn) was designed for the highly sensitive detection of carcinoembryonic antigen (CEA). The uniform PDA NPs possessed good dispersibility, good biocompatibility, and abundant functional groups for biomolecule assembly. They also had unique photophysical properties, with light absorption spanning the visible to infrared light range. When the immune-recognition brought the PDA NPs close to the TiO2/CdS:Mn interface, the PDA NPs competed with TiO2/CdS:Mn to absorb light, consumed photoelectrons generated in the TiO2/CdS:Mn, and hindered the access of electron donors to photoactive materials. The contribution from these aspects thus led to a significant decrease in photocurrent. Benefiting from the multiple quenching mechanism, the PEC immunosensor showed high sensitivity for CEA detection. Under optimal conditions, a low detection limit of 0.02 pg/mL and a wide linear relationship from 0.1 pg/mL to 100 ng/mL were obtained. The immunoassay showed good reproducibility and stability, and good selectivity and high accuracy in serum sample analysis. In this regard, PEC immunosensors may have great application potential for screening tumor markers and the prevention and monitoring of serious diseases.