Engineering small extracellular vesicles with multivalent DNA probes for precise tumor targeting and enhanced synergistic therapy.

Small extracellular vesicles (sEVs) have gained wide attention as efficient carriers for disease treatment. However, the proclivity of sEVs to be ingested by source cells is insufficient to accurately target specific sites, posing a challenge in realizing controlled targeting treatment. Here, we developed an engineered sEV nanocarrier capable of precise tumor targeting and enhanced synergistic therapy. Multivalent DNA probes, comprising abundant AS1411 aptamers and telomerase primers, were innovatively modified on the sEV membrane (M-D-sEV) for precise tumor targeting. To achieve synergistic therapy, gold nanorod-cerium oxide nanostructures (Au NRs-CeO2) and manganese dioxide nanosheets-doxorubicin (MnO2 NSs-DOX) were encapsulated into liposomes (Lip-Mat). Then M-D-sEV and Lip-Mat were fused together through membrane fusion to obtain nanocarriers. Owing to the multivalence of the probes, the surface of the nanocarriers was loaded with numerous aptamers, which greatly enhances their targeting ability and promotes the accumulation of drugs. When nanocarriers were ingested by tumor cells, telomerase and multivalent DNA probes triggered their aggregation, enhancing the therapeutic effect. Furthermore, under laser irradiation, Au NRs-CeO2 converted light into hyperthermia, thereby inducing the destruction of nanocarriers membrane. This process initiated a series of reactions involving glutathione and H2O2 consumption, as well as DOX release, ultimately achieving synergistic tumor therapy. In vitro and in vivo studies demonstrated the remarkable targeting ability of multivalent DNA probes and excellent therapeutic effect of this strategy. The engineered strategy of sEVs provide a promising approach for precise tumor therapy and hold great potential for the development of efficient, safe, and personalized drug delivery systems.

Timing of systemic resistance induced by local exogenous ABA application within clonal network of stoloniferous herb Centella asiatica subjected to low water availability.

Resistance traits of plants can be activated both at the damaged site and undamaged parts. Systemic resistance induced by local exogenous abscisic acid (ABA) application alleviated negative effect of low water availability on growth performance of clonal plant. However, timing of systemic resistance was poorly understood. Timing of systemic resistance refers to its activation and decay time within clonal network. Clonal fragment of Centella asiatica with four successive ramets (including first-oldest, second-older, third-old and fourth-young ramets) subjected to low water availability (20% soil moisture content) was used to explore effects of local exogenous ABA application on the timing of resistance activation and decay. Systemic resistance activated by local exogenous ABA application after 4 days remained at least 28 days. Compared with control, biomass accumulation of whole clonal fragment, root biomass and ratio of belowground to aboveground biomass significantly increased by local exogenous ABA application after 28 days. It is suggested that rapid activation and delay of resistance response induced by local exogenous ABA application within clonal network may improve fitness of clonal plant subjected to abiotic stress.