Direct Monitoring of Cancer-Associated mRNAs in Living Cells to Evaluate the Therapeutic RNAi Efficiency Using Fluorescent Nanosensor

Stat3 shRNA delivery with folate receptor-modified multi-functionalized graphene oxide particles for combined infrared radiation and gene therapy in hepatocellular carcinoma

As a vital oncogene, a variety of inhibitors targeting Stat3 and its various upstream signaling pathways has been explored. Since small molecules, peptidomimetics and other peptide inhibitors usually lead to side effects and difficult administration, gene therapeutics that have characteristics of low toxicity and high targeting, make them an attractive alternative for targeting Stat3. A major challenge to this approach is the lack of safe delivery systems for in-vivo applications. Among the various siRNA delivery systems, nanoparticles emerge as a new tool for gene delivery with high biocompatibility, low cost, and minimal toxicity. In this study, we developed a graphene oxide (GO)-based nanocarrier, GO-polyethyleneimine (PEI)-polyethylene glycol (PEG)-folic acid (FA), as a tool targeting for Stat3-specific shRNA to mouse hepatoma cells in vitro and in vivo . Infrared photothermal therapy was combined in vivo since GO has the characteristic of infrared absorbability. Our results suggest a significant tumor growth inhibition after treatment with GO-PEI-PEG-FA- sh-Stat3 combined with infrared photothermal therapy. Thus, GO-PEI-PEG-FA appears to be a novel nano-transformer that could be used in the clinics in future.

Graphene oxide for photonics, electronics and optoelectronics

Graphene oxide (GO) was initially developed to emulate graphene, but it was soon recognized as a functional material in its own right, addressing an application space that is not accessible to graphene and other carbon materials. Over the past decade, research on GO has made tremendous advances in material synthesis and property tailoring. These, in turn, have led to rapid progress in GO-based photonics, electronics and optoelectronics, paving the way for technological breakthroughs with exceptional performance. In this Review, we provide an overview of the optical, electrical and optoelectronic properties of GO and reduced GO on the basis of their chemical structures and fabrication approaches, together with their applications in key technologies such as solar energy harvesting, energy storage, medical diagnosis, image display and optical communications. We also discuss the challenges of this field, together with exciting opportunities for future technological advances.

Enhancing Peptide Nucleic Acid-Nanomaterial Interaction and Performance Improvement of Peptide Nucleic Acid-Based Nucleic Acid Detection by Using Electrostatic Effects

Single-stranded peptide nucleic acid (PNA) probes interact strongly with several nanomaterials, and the interaction was diminished in the presence of complementary nucleic acid targets which forms the basis of many nucleic acid sensing platforms. As opposed to the negatively charged DNA probes, the charges on the PNA probes may be fine-tuned by incorporating amino acids with charged side chains. The contribution of electrostatic effects to the interaction between PNA probes and nanomaterials has been largely overlooked. This work reveals that electrostatic effects substantially enhanced the quenching of dye-labeled conformationally constrained pyrrolidinyl PNA probes by several nanomaterials including graphene oxide (GO), reduced graphene oxide, gold nanoparticles (AuNPs), and silver nanoparticles. The fluorescence quenching and the color change from red to purple in the case of AuNPs because of aggregation were inhibited in the presence of complementary nucleic acid targets. Thus, fluorescence and colorimetric assays for DNA and RNA that can distinguish even single-base-mismatched nucleic acids with improved sensitivity over conventional DNA probes were established. Both the GO- and AuNP-based sensing platforms have been successfully applied for the detection of real DNA and RNA samples in vitro and in living cells. This study emphasizes the active roles of electrostatic effects in the PNA-nanomaterial interactions, which paves the way toward improving the performance of PNA-nanomaterial based assays of nucleic acids.

Graphene oxide-based fluorescent biosensors and their biomedical applications in diagnosis and drug discovery

Graphene oxide (GO), an oxidized derivative of graphene, has received much attention for developing novel fluorescent bioanalytic platforms due to its remarkable optical properties and biocompatibility. The reliable performance and robustness of GO-based biosensors have enabled various applications in the biomedical field including diagnosis and drug discovery. Here, recent advances in the development of GO-based fluorescent biosensors are overviewed, particularly nucleic acid detection and enzyme activity assay. In addition, practical applications in biomarker detection and high-throughput screening are also examined. Lastly, basic design principles and remaining challenges of these types of biosensors are discussed for further progress.

Fluorometric Viral miRNA Nanosensor for Diagnosis of Productive (Lytic) Human Cytomegalovirus Infection in Living Cells

A human cytomegalovirus (HCMV) causes a persistent asymptomatic infection in healthy individuals and possesses unexpected dangers to newborn babies, immunocompromised people, and organ transplant recipients because of stealth transmission. Thus, an early and accurate diagnosis of HCMV infection is crucial for prevention of unexpected transmission and progression of the severe diseases. The standard method of HCMV diagnosis depends on serology, antigen test, and polymerase chain reaction-based nucleic acid detection, which have advantages for each target molecule. However, the serological test for an antibody is an indirect method assuming the past virus infection, and antigen and viral nucleic acid testing demand laborious, complex multistep procedures for direct virus detection. Herein, we present an alternative simple and facile fluorometric biosensor composed of a graphene oxide nanocolloid and fluorescent peptide nucleic acid (PNA) probe to detect the HCMV infection by simply monitoring the virally encoded microRNA as a new biomarker of lytic virus infection. We verify the sensing of HCMV-derived microRNA accumulated within 72 h after HCMV infection and examine the diagnosis of HCMV in living cells. We proceed with the time course and concentration-dependent investigation of hcmv-miRNA sensing in living cells as a direct method of HCMV detection at the molecular level on the basis of an intracellular hcmv-miRNA expression profile and graphene oxide nanocolloid-based simple diagnostic platform. The fluorometric biosensor enables the sequence-specific binding to the target HCMV miRNAs in HCMV-infected fibroblasts and shows the quantitative detection capability of HCMV infection to be as low as 4.15 × 10⁵ immunofluorescence focus unit (IFU)/mL of the virus titer at 48 h post-infection with picomolar sensitivity for HCMV miRNA.