Carrier‐Free Delivery of Precise Drug–Chemogene Conjugates for Synergistic Treatment of Drug‐Resistant Cancer

Chemistries and applications of DNA-natural product conjugate

Natural products and their derivatives have made great contributions to chemotherapy, especially for the treatment of tumors and infections. Despite the achievements, natural product-based small molecule drugs usually suffer from side effects, short circulation time, and solubility issue. To overcome these drawbacks, a common approach is to integrate another bio-functional motif into a natural product compound, enabling targeted or synergistic therapy. One of the most promising strategies is to form a DNA-natural product conjugate to improve therapeutic purposes. The incorporated DNA molecules can serve as an aptamer, a nucleic-acid-based congener of antibody, to specifically bind to the disease target of interest, or function as a gene therapy agent, such as immuno-adjuvant or antisense, to enable synergistic chemo-gene therapy. DNA-natural product conjugate can also be incorporated into other DNA nanostructures to improve the administration and delivery of drugs. This minireview aims to provide the chemistry community with a brief overview on this emerging topic of DNA-natural product conjugates for advanced therapeutics. The basic concepts to use the conjugation, the commonly used robust conjugation chemistries, as well as applications in targeted therapy and synergistic therapy of using DNA-natural product conjugates, are highlighted in this minireview. Future perspectives and challenges of this field are also discussed in the discussion and perspective section.

Light-Harvesting Fluorescent Spherical Nucleic Acids Self-Assembled from a DNA-Grafted Conjugated Polymer for Amplified Detection of Nucleic Acids

The ultralow concentration of nucleic acids in complex biological samples requires fluorescence probes with high specificity and sensitivity. Herein, a new kind of spherical nucleic acids (SNAs) is developed by using fluorescent π-conjugated polymers (FCPs) as a light-harvesting antenna to enhance the signal transduction of nucleic acid detection. Specifically, amphiphilic DNA-grafted FCPs are synthesized and self-assemble into FCP-SNA structures. Tuning the hydrophobicity of the graft copolymer can adjust the size and light-harvesting capability of the FCP-SNAs. We observe that more efficient signal amplification occurs in larger FCP-SNAs, as more chromophores are involved, and the energy transfer can go beyond the Förster radius. Accordingly, the optimized FCP-SNA shows an antenna effect of up to 37-fold signal amplification and the limit of detection down to 1.7 pM in microRNA detection. Consequently, the FCP-SNA is applied to amplified in situ nucleic acid detecting and imaging at the single-cell level.

Cation-Free siRNA Micelles as Effective Drug Delivery Platform and Potent RNAi Nanomedicines for Glioblastoma Therapy

Nanoparticle-based small interfering RNA (siRNA) therapy shows great promise for glioblastoma (GBM). However, charge associated toxicity and limited blood-brain-barrier (BBB) penetration remain significant challenges for siRNA delivery for GBM therapy. Herein, novel cation-free siRNA micelles, prepared by the self-assembly of siRNA-disulfide-poly(N-isopropylacrylamide) (siRNA-SS-PNIPAM) diblock copolymers, are prepared. The siRNA micelles not only display enhanced blood circulation time, superior cell take-up, and effective at-site siRNA release, but also achieve potent BBB penetration. Moreover, due to being non-cationic, these siRNA micelles exert no charge-associated toxicity. Notably, these desirable properties of this novel RNA interfering (RNAi) nanomedicine result in outstanding growth inhibition of orthotopic U87MG xenografts without causing adverse effects, achieving remarkably improved survival benefits. Moreover, as a novel type of polymeric micelle, the siRNA micelle displays effective drug loading ability. When utilizing temozolomide (TMZ) as a model loading drug, the siRNA micelle realizes effective synergistic therapy effect via targeting the key gene (signal transducers and activators of transcription 3, STAT3) in TMZ drug resistant pathways. The authors' results show that this siRNA micelle nanoparticle can serve as a robust and versatile drug codelivery platform, and RNAi nanomedicine and for effective GBM treatment.

Exquisite Vesicular Nanomedicine by Paclitaxel Mediated Co-assembly with Camptothecin Prodrug

We report that the self-assembly of drug amphiphiles, Evans blue conjugated camptothecin prodrug (EB-CPT), can be modulated by another anticancer drug paclitaxel (PTX), resulting in ultrahigh quality of nanovesicles (NVs) with uniform shape and diameters of around 80 nm with the EB-CPT:PTX weight ratio of 1:1, 1:2, and 1:3, denoted as ECX NVs. Significantly, the co-assembly of EB-CPT and PTX without adding other excipients has nearly 100 % drug loading efficiency (DLE) and ultrahigh drug loading content (DLC) of PTX alone of up to 72.3±1.7 wt % which, to our best knowledge, is among the highest level reported in literature. Moreover, the ECX NVs with the EB-CPT:PTX weight ratio of 1:2 showed remarkable combination index of 0.59 at a level of 50 % efficacy against HCT116 cells in vitro and greatly improved tumor inhibition effect in vivo compared with two clinically approved CPT- and PTX-based anticancer nanomedicines (Onivyde and Abraxane) individually and their combinations.