Targeting the oxidative stress response has recently emerged as a promising strategy for the development of therapeutic drugs for a broad spectrum of diseases. Supporting this strategy, we have reported that chitosan nanoparticles synthesized with a controlled size had selective cytotoxicity in leukemia cells through the mechanism related to reactive oxygen species (ROS) generation. Herein, we found that the cellular uptake of chitosan nanoparticles was enhanced in a time dependent manner and inhibited the cellular proliferation of leukemia cells in a dose dependent manner with elevation of the reactive oxygen species (ROS) showing a stronger effect on apoptosis, associated with the upregulation of caspase activity and the depletion of reduced glutathione. Propidium iodide and calcein staining demonstrated the central role of the chitosan nanoparticles in triggering elevated ROS, inducing cell death and intracellular oxidative activity. The enhanced free radical scavenging activity of the chitosan nanoparticles further iterates its antioxidant activity. In vitro quantitative phase imaging studies at the single cell level further demonstrated the inhibition of cellular proliferation with significant changes in cellular behavior and this supported our hypothesis. Hemocompatibility tests demonstrated that chitosan nanoparticles could be used safely for in vivo applications. Our findings suggest that chitosan nanoparticles may be a promising redox active candidate for therapeutic applications.

Synthetic auxins such as 1-naphthalene acetic acid (NAA) and 2,4-dichlorophenoxyacetic acid (2,4-D) have been extensively used in plant tissue cultures and as herbicides because they are chemically more stable and potent than most endogenous auxins. A tool for rapid in planta detection of these compounds will enhance our knowledge about hormone distribution and signaling and facilitate more efficient usage of synthetic auxins in agriculture. In this work, we show the development of real-time and nondestructive in planta NAA and 2,4-D nanosensors based on the concept of corona phase molecular recognition (CoPhMoRe), to replace the current state-of-the-art sensing methods that are destructive and laborious. By designing a library of cationic polymers wrapped around single-walled carbon nanotubes with general affinity for chemical moieties displayed on auxins and its derivatives, we developed selective sensors for these synthetic auxins, with a particularly large quenching response to NAA (46%) and a turn-on response to 2,4-D (51%). The NAA and 2,4-D nanosensors are demonstrated in planta across several plant species including spinach, Arabidopsis thaliana (A. thaliana), Brassica rapa subsp. chinensis (pak choi), and Oryza sativa (rice) grown in various media, including soil, hydroponic, and plant tissue culture media. After 5 h of 2,4-D supplementation to the hydroponic medium, 2,4-D is seen to accumulate in susceptible dicotyledon pak choi leaves, while no uptake is observed in tolerant monocotyledon rice leaves. As such, the 2,4-D nanosensor had demonstrated its capability for rapid testing of herbicide susceptibility and could help elucidate the mechanisms of 2,4-D transport and the basis for herbicide resistance in crops. The success of the CoPhMoRe technique for measuring these challenging plant hormones holds tremendous potential to advance the plant biology study.

One of the pathological hallmarks of Alzheimer’s disease (AD) is the abnormal aggregation of amyloid beta (Aβ) peptides. Therefore the detection of Aβ peptides and imaging of amyloid plaques are considered as promising diagnostic methods for AD. Here we report a bifunctional nanoprobe prepared by conjugating gold nanoparticles (AuNPs) with Rose Bengal (RB) dye. RB is chosen due to its unique Raman fingerprints and affinity with Aβ peptides. After the conjugation, Raman signals of RB were significantly enhanced due to the surface-enhanced Raman scattering (SERS) effect. Upon binding with Aβ42 peptides, a spectrum change was detected, and the magnitude of the spectrum changes can be correlated with the concentration of target peptides. The peptide/probe interaction also induced a remarkable enhancement in the probes’ fluorescence emission. This fluorescence enhancement was further utilized to image amyloid plaques in the brain slices from transgenic mice. In this study, the RB-AuNPs were used for both SERS-based detection of Aβ42 peptides and fluorescence-based imaging of amyloid plaques. Compared to monofunctional probes, the multifunctional probe is capable to provide more comprehensive pathophysiological information, and therefore, the implementation of such multifunctional amyloid probes is expected to help the investigation of amyloid aggregation and the early diagnosis of AD.

Sweet basil (Ocimum basilicum) plants produce its characteristic phenylpropene-rich essential oil in specialized structures known as peltate glandular trichomes (PGTs). Eugenol and chavicol are the major phenylpropenes produced by sweet basil varieties whose synthetic pathways are not fully elucidated. Eugenol is derived from coniferyl acetate by a reaction catalysed by eugenol synthase. An acyltransferase is proposed to convert coniferyl alcohol to coniferyl acetate which is the first committed step towards eugenol synthesis. Here, we perform a comparative next-generation transcriptome sequencing of different tissues of sweet basil, namely PGT, leaf, leaf stripped of PGTs (leaf–PGT), and roots, to identify differentially expressed transcripts specific to PGT. From these data, we identified a PGT-enriched BAHD acyltransferase gene ObCAAT1 and functionally characterized it. In vitro coupled reaction of ObCAAT1 with eugenol synthase in the presence of coniferyl alcohol resulted in eugenol production. Analysis of ObCAAT1-RNAi transgenic lines showed decreased levels of eugenol and accumulation of coniferyl alcohol and its derivatives. Coniferyl alcohol acts as a common substrate for phenylpropene and lignin biosynthesis. No differences were found in total lignin content of PGTs and leaves of transgenic lines, indicating that phenylpropene biosynthesis is not coupled to lignification in sweet basil.