Zhuoxuan Lu

Enhanced chemotherapy efficacy by sequential delivery of siRNA and anticancer drugs using PEI-grafted graphene oxide.

PEI GO The RNA interference (RNAi) technique, an effective method to inhibit protein expression by targeted cleavage of messenger RNA (mRNA), has made substantial progress since the fi rst demonstration of gene knockdown in mammalian cells. [ 1 ] Short interfering RNA (siRNA) induces specifi c silencing of targeted protein, thus offering signifi cant potential in overcoming multiple drug resistance (MDR) of cancer cells. [ 2 ] For example, Bcl-2 protein, one of the main antiapoptotic defense proteins, is closely related to the MDR of cancer cells. [ 3 ] Knockdown of the Bcl-2 protein expression level in cancer cells by Bcl-2-targeted siRNA would effectively overcome the MDR of cancer cells and sensitize cancer cells to anticancer drugs. [ 3 d, 4 ] Herein, we report sequential delivery of Bcl-2-targeted siRNA and the anticancer drug doxorubicin (DOX) using polyethylenimine (PEI)-functionalized graphene oxide (PEI-GO). We demonstrate that the PEI-GO is an excellent nanocarrier for effective delivery of siRNA and chemical drugs, and that sequential delivery of the siRNA and DOX by PEI-GO into cancer cells exhibits a synergistic effect, which leads to a signifi cantly enhanced chemotherapy effi cacy. To the best of our knowledge, this is the fi rst report on applications of GO-based nanovectors for delivery of siRNA, and sequential delivery of siRNA and anticancer drugs into cancer cells. Graphene, a newly discovered 2D nanomaterial, has been studied extensively due to its fundamental importance and potential applications, [ 5 ] while exploration of its biomedical applications has just started. [ 6 ] Noncovalent adsorption through π – π stacking, electrostatic, and other molecular interactions has proven to be effective for immobilizing chemical drugs, single-stranded DNA, and RNA onto GO sheets. [ 6 a–e]

PEGylated reduced graphene oxide as a superior ssRNA delivery system

Single stranded ribonucleic acid (ssRNA) acts as a probe, antisense (AS), miRNA analog and inhibitor, and is promising for gene therapy and molecular diagnosis. However, free ssRNA exhibits poor cellular uptake due to its negative charges, and enzyme instability, which have largely limited the practical applications of ssRNA in biomedicine. To address these issues, we have developed a PEGylated reduced graphene oxide (PEG-RGO) nanovector for efficient delivery of ssRNA. We have demonstrated that PEG-RGO exhibits superior ssRNA loading and delivery capability, compared to the widely studied PEGylated graphene oxide (PEG-GO). Computational simulation further suggested that PEG-RGO binds ssRNA much stronger than PEG-GO, consistent with the experimental results. These results will have implications in designing RGO-based biocompatible and efficient ssRNA delivery systems.

Graphene oxide for rapid microRNA detection

We have developed a fluorescence quenching based approach using graphene oxide (GO) for rapid detection of miRNAs. This GO-based method has been demonstrated to be highly specific to homogenous miRNAs, and is reverse transcription free which simplifies the detection procedures and reduces the total analysis time and cost.

A Novel SNPs Detection Method Based on Gold Magnetic Nanoparticles Array and Single Base Extension

To fulfill the increasing need for large-scale genetic research, a high-throughput and automated SNPs genotyping method based on gold magnetic nanoparticles (GMNPs) array and dual-color single base extension has been designed. After amplification of DNA templates, biotinylated extension primers were captured by streptavidin coated gold magnetic nanoparticle (SA-GMNPs). Next a solid-phase, dual-color single base extension (SBE) reaction with the specific biotinylated primer was performed directly on the surface of the GMNPs. Finally, a “bead array” was fabricated by spotting GMNPs with fluorophore on a clean glass slide, and the genotype of each sample was discriminated by scanning the “bead array”. MTHFR gene C677T polymorphism of 320 individual samples were interrogated using this method, the signal/noise ratio for homozygous samples were over 12.33, while the signal/noise ratio for heterozygous samples was near 1. Compared with other dual-color hybridization based genotyping methods, the method described here gives a higher signal/noise ratio and SNP loci can be identified with a high level of confidence. This assay has the advantage of eliminating the need for background subtraction and direct analysis of the fluorescence values of the GMNPs to determine their genotypes without the necessary procedures for purification and complex reduction of PCR products. The application of this strategy to large-scale SNP studies simplifies the process, and reduces the labor required to produce highly sensitive results while improving the potential for automation.

Methoxy poly(ethylene glycol) conjugated denatured bovine serum albumin micelles for effective delivery of camptothecin

A novel nontoxic denatured bovine serum albumin (dBSA)-based platform for effectively delivering drugs was prepared. It was demonstrated that the as-prepared dBSA micelles could effectively load and deliver a water insoluble anti-cancer drug in vitro assay. The results also indicated that the denaturization of the BSA did not enhance the cytotoxicity practically, but significantly enhanced its cellular uptake.

PEGylated denatured bovine serum albumin modified water-soluble inorganic nanocrystals as multifunctional drug delivery platforms†

A novel approach of using denatured bovine serum albumin (dBSA) to modify hydrophobic nanocrystals is reported. The dBSA layer outside of nanocrystals can adsorb water insoluble drugs excellently via hydrophobic interactions. Further PEGylation of the engineered nanocrystals greatly improves their aqueous stability. PEGylated dBSA modified upconversion nanoparticles, as a model for construction of integrating imaging and drug delivery platform, were also studied. The results demonstrated the modified upconversion nanoparticles not only maintain their unique up-conversion luminescence characters but also exhibit higher drug loading ability. Thus, such novel PEGylated dBSA modification approach expands the range of biological applications of inorganic nanocrystals.