Injectable Drug-Conjugated DNA Hydrogel for Local Chemotherapy to Prevent Tumor Recurrence

Development, Preparation, and Biomedical Applications of DNA-Based Hydrogels

Hydrogels have outstanding research and application prospects in the biomedical field. Among them, the design and preparation of biomedical hydrogels with deoxyribonucleic acid (DNA) as building blocks have attracted increasing research interest. DNA-based hydrogel not only has the skeleton function of hydrogel, but also retains its biological functions, including its excellent selection specificity, structural designability, precise molecular recognition ability, outstanding biocompatibility, and so on. It has shown important application prospects in the biomedical field, such as drug delivery, biosensing, and tissue engineering. In recent years, researchers have made full use of the characteristics of DNA molecules and constructed various pure DNA-based hydrogels with excellent properties through various crosslinking methods. Moreover, via introducing functional molecules or elements, or combining with other functional materials, a variety of multifunctional DNA-based hybrid hydrogels have also been constructed, which expand the breadth and depth of their applications. Here, we described the recent development trend in the area of DNA-based hydrogels and highlighted various preparation methods of DNA-based hydrogels. Representative biomedical applications are also exemplified to show the high performance of DNA-based hydrogels. Meanwhile, the existing problems and prospects are also summarized. This review provided references for the further development of DNA-based hydrogels.

DNA nanostructure-based nucleic acid probes: construction and biological applications

In recent years, DNA has been widely noted as a kind of material that can be used to construct building blocks for biosensing, in vivo imaging, drug development, and disease therapy because of its advantages of good biocompatibility and programmable properties. However, traditional DNA-based sensing processes are mostly achieved by random diffusion of free DNA probes, which were restricted by limited dynamics and relatively low efficiency. Moreover, in the application of biosystems, single-stranded DNA probes face challenges such as being difficult to internalize into cells and being easily decomposed in the cellular microenvironment. To overcome the above limitations, DNA nanostructure-based probes have attracted intense attention. This kind of probe showed a series of advantages compared to the conventional ones, including increased biostability, enhanced cell internalization efficiency, accelerated reaction rate, and amplified signal output, and thus improved in vitro and in vivo applications. Therefore, reviewing and summarizing the important roles of DNA nanostructures in improving biosensor design is very necessary for the development of DNA nanotechnology and its applications in biology and pharmacology. In this perspective, DNA nanostructure-based probes are reviewed and summarized from several aspects: probe classification according to the dimensions of DNA nanostructures (one, two, and three-dimensional nanostructures), the common connection modes between nucleic acid probes and DNA nanostructures, and the most important advantages of DNA self-assembled nanostructures in the applications of biosensing, imaging analysis, cell assembly, cell capture, and theranostics. Finally, the challenges and prospects for the future development of DNA nanostructure-based nucleic acid probes are also discussed.

Recent Advances in Improved Anticancer Efficacies of Camptothecin Nano-Formulations: A Systematic Review

Camptothecin (CPT), a natural plant alkaloid, has indicated potent antitumor activities via targeting intracellular topoisomerase I. The promise that CPT holds in therapies is restricted through factors that include lactone ring instability and water insolubility, which limits the drug oral solubility and bioavailability in blood plasma. Novel strategies involving CPT pharmacological and low doses combined with nanoparticles have indicated potent anticancer activity in vitro and in vivo. This systematic review aims to provide a comprehensive and critical evaluation of the anticancer ability of nano-CPT in various cancers as a novel and more efficient natural compound for drug development. Studies were identified through systematic searches of PubMed, Scopus, and ScienceDirect. Eligibility checks were performed based on predefined selection criteria. Eighty-two papers were included in this systematic review. There was strong evidence for the association between antitumor activity and CPT treatment. Furthermore, studies indicated that CPT nano-formulations have higher antitumor activity in comparison to free CPT, which results in enhanced efficacy for cancer treatment. The results of our study indicate that CPT nano-formulations are a potent candidate for cancer treatment and may provide further support for the clinical application of natural antitumor agents with passive targeting of tumors in the future.

DNAzyme-Triggered Sol-Gel-Sol Transition of a Hydrogel Allows Target Cell Enrichment

Enrichment of rare cancer cells from various cell mixtures for subsequent analysis or culture is essential for understanding cancer formation and progression. In particular, maintaining the viability of captured cancer cells and gently releasing them for relevant applications remain challenging for many reported methods. Here, a physically cross-linked deoxyribozyme (DNAzyme)-based hydrogel strategy was developed for the specific envelopment and release of targeted cancer cells, allowing the aptamer-guided capture, 3D envelopment, and Zn²⁺-dependent release of viable cancer cells. The DNAzyme hydrogel is constructed through the intertwinement and hybridization of two complementary DNAzyme strands located on two rolling circle amplification-synthesized ultralong DNA chains. The enveloping and separation of target cells were achieved during the formation of the DNAzyme hydrogel (sol-gel transition). Triggered by Zn²⁺, the encapsulated cells can be gently released from the dissociated DNAzyme hydrogel with high viability (gel-sol transition). Successful isolations of target cells from cancer cell mixtures and peripheral blood mononuclear cells (PBMC) were demonstrated. This method offers an attractive approach for the separation of target cancer cells for various downstream applications that require viable cells.

A Photopolymerized Semi-Interpenetrating Polymer Networks-Based Hydrogel Incorporated with Nanoparticle for Local Chemotherapy of Tumors

PURPOSE

To address the issue of local drug delivery in tumor treatment, a novel nanoparticle-hydrogel superstructure, namely semi-interpenetrating polymer networks (semi-IPNs) hydrogel composed of poly (ethylene glycol) diacrylate (PEGDA) and hyaluronic acid (HA) and incorporated with paclitaxel (PTX) loaded PLGA nanoparticles (PEGDA-HA/PLGA-PTX), was prepared by in situ UV photopolymerization for the use of local drug delivery.

METHODS

Using the gelation time, swelling rate and degradation rate as indicators, the optimal proportion of Irgacure 2959 initiator and the concentration of HA was screened and obtained for preparing hydrogels. Next, paclitaxel (PTX) loaded PLGA nanoparticles (PLGA-PTX NPs) were prepared by the emulsion solvent evaporation method.

RESULTS

The mass ratio of the initiator was 1%, and the best concentration of HA was 5 mg/mL in PEGDA-HA hydrogel. In vitro experiments showed that PLGA-PTX NPs had similar cytotoxicity to free PTX, and the cell uptake ratio on NCI-H460 cells was up to 96% by laser confocal microscopy and flow cytometry. The drug release of the PEGDA-HA/PLGA-PTX hydrogel local drug delivery system could last for 13 days. In vivo experiments proved that PEGDAHA/PLGA-PTX hydrogel could effectively inhibit the tumor growth without causing toxic effects in mice.

CONCLUSIONS

This study demonstrated that the PEGDA-HA/PLGA-PTX hydrogel is a promising local drug delivery system in future clinical applications for tumor therapy. A photopolymerized semi-interpenetrating polymer networks-based hydrogel incorporated with paclitaxel-loaded nanoparticles was fabricated by in situ UV photopolymerization, providing a promised nanoplatform for local chemotherapy of tumors.