Multifunctional Poly(L-lactide)-Polyethylene Glycol-Grafted Graphene Quantum Dots for Intracellular MicroRNA Imaging and Combined Specific-Gene-Targeting Agents Delivery for Improved Therapeutics

Current development of biodegradable polymeric materials for biomedical applications

In the last half-century, the development of biodegradable polymeric materials for biomedical applications has advanced significantly. Biodegradable polymeric materials are favored in the development of therapeutic devices, including temporary implants and three-dimensional scaffolds for tissue engineering. Further advancements have occurred in the utilization of biodegradable polymeric materials for pharmacological applications such as delivery vehicles for controlled/sustained drug release. These applications require particular physicochemical, biological, and degradation properties of the materials to deliver effective therapy. As a result, a wide range of natural or synthetic polymers able to undergo hydrolytic or enzymatic degradation is being studied for biomedical applications. This review outlines the current development of biodegradable natural and synthetic polymeric materials for various biomedical applications, including tissue engineering, temporary implants, wound healing, and drug delivery.

Carbon Nanomaterials in Optical Detection

Owing to their unique optical, electronic, mechanical, and chemical properties, flexible chemical modification, large surface coverage and ready cellular uptake, various carbon nanomaterials such as carbon nanotubes (CNTs), graphene and its derivatives, carbon dots (CDs), graphene quantum dots, fullerenes, carbon nanohorns (CNHs) and carbon nano-onions (CNOs), have been widely explored for use in optical detection. Most of them are based on fluorescence changes. In this chapter, we will focus on carbon nanomaterials-based optical detection applications, mainly including fluorescence sensing and bio-imaging. Moreover, perspectives on future exploration of carbon nanomaterials for optical detection are also given.

Fluorescent TPA@GQDs Probe for Sensitive Assay and Quantitative Imaging of Hydroxyl Radicals in Living Cells

A fluorescent probe TPA@GQDs is fabricated by the conjugation of terephthalic acid (TPA) on the surface of graphene quantum dots (GQDs). The TPA@GQDs probe not only has favorable dispersibility but also exhibits excellent fluorescence stability over a wide pH range and high ionic strength and favorable antiphotobleaching ability. The great fluorescence enhancement of TPA@GQDs induced by the reaction between TPA and hydroxyl radicals makes the TPA@GQDs a powerful probe for the sensitive assay of hydroxyl radicals, giving rise to a low detection limit down to 12 nmol L^-1. Meanwhile, the obtained fluorescent TPA@GQDs probe shows low cytotoxicity and favorable biocompatibility. Its potential in bioimaging is demonstrated by the quantitative fluorescent imaging of hydroxyl radicals in living HeLa cells under different circumstances, which enables the opportunities to study hydroxyl radicals dynamics in living cells.

Imaging multiple microRNAs in living cells using ATP self-powered strand-displacement cascade amplification

Herein, we design a smart autonomous ATP self-powered strand-displacement cascade amplification (SDCA) system for highly sensitive multiple intracellular miRNA detection. Rationally engineered Y-motif DNA structures are functionalized on mesoporous silica-coated copper sulfide nanoparticles loaded with numerous ATPs (CuS@mSiO2-Y/ATP) through pH stimulus-responsive disulfide bonds. The SDCA system is implemented by endogenous specific miRNA as a trigger and ATP as fuel released from the nanocarrier at acidic pH and photothermal stimuli-responsive CuS. The ATP self-powered SDCA process presents higher sensitivity compared to that without amplification for intracellular miRNA imaging. Two-color simultaneous and sensitive imaging of multiple cancer-related miRNAs in living cells is also confirmed. This enables facile and accurate differentiation between normal cells and different types of cancer cell using intracellular miRNA imaging, which improves the veracity and timeliness for early cancer diagnosis.

Recent progress in live cell mRNA/microRNA imaging probes based on smart and versatile nanomaterials

We summarize the recent progress in live cell mRNA/miRNA imaging probes based on various versatile nanomaterials, describing their structures and their working principles of bio-imaging applications.

Tumor Cell-Specific Nuclear Targeting of Functionalized Graphene Quantum Dots In Vivo

Specific targeting of tumor tissues is essential for tumor imaging and therapeutics but remains challenging. Here, we report an unprecedented method using synthetic sulfonic-graphene quantum dots (sulfonic-GQDs) to exactly target the cancer cell nuclei in vivo without any bio- ligand modification, with no intervention in cells of normal tissues. The key factor for such selectivity is the high interstitial fluid pressure (IFP) in tumor tissues, which allows the penetration of sulfonic-GQDs into the plasma membrane of tumor cells. In vitro, the sulfonic-GQDs are repelled out of the cell membrane because of the repulsive force between negatively charged sulfonic-GQDs and the cell membranes which contributes to the low distribution in normal tissues in vivo. However, the plasma membrane-crossing process can be activated by incubating cells in ultrathin film culture medium because of the attachment of sulfonic-GQDs on cell memebranes. Molecular dynamics simulations demonstrated that, once transported across the plasma membrane, the negatively charged functional groups of these GQDs will leave the membrane with a self-cleaning function retaining a small enough size to achieve penetration through the nuclear membrane into the nucleus. Our study showed that IFP is a previously unrecognized mechanism for specific targeting of tumor cell nuclei and suggested that sulfonic-GQDs may be developed into novel tools for tumor-specific imaging and therapeutics.

A DNA-Fueled and Catalytic Molecule Machine Lights Up Trace Under-Expressed MicroRNAs in Living Cells

The detection of specific intracellular microRNAs (miRNAs) in living cells can potentially provide insight into the causal mechanism of cancer metastasis and invasion. However, because of the characteristic nature of miRNAs in terms of small sizes, low abundance, and similarity among family members, it is a great challenge to monitor miRNAs in living cells, especially those with much lower expression levels. In this work, we describe the establishment of a DNA-fueled and catalytic molecule machinery in cell signal amplification approach for monitoring trace and under-expressed miRNAs in living cells. The presence of the target miRNA releases the hairpin sequences from the dsDNA (containing the fluorescence resonance energy transfer (FRET) pair-labeled and unfolded hairpin sequences)-conjugated gold nanoparticles (dsDNA-AuNPs), and the DNA fuel strands assist the recycling of the target miRNA sequences via two cascaded strand displacement reactions, leading to the operation of the molecular machine in a catalytic fashion and the release of many hairpin sequences. As a result, the liberated hairpin sequences restore the folded hairpin structures and bring the FRET pair into close proximity to generate significantly amplified signals for detecting trace miRNA targets. Besides, the dsDNA-AuNP nanoprobes have good nuclease stability and show low cytotoxicity to cells, and the application of such a molecular system for monitoring trace and under-expressed miRNAs in living cells has also been demonstrated. With the advantages of in cell signal amplification and reduced background noise, the developed method thus offers new opportunities for detecting various trace intracellular miRNA species.

Cancer-Associated, Stimuli-Driven, Turn on Theranostics for Multimodality Imaging and Therapy

Advances in bioinformatics, genomics, proteomics, and metabolomics have facilitated the development of novel anticancer agents that have decreased side effects and increased safety. Theranostics, systems that have combined therapeutic effects and diagnostic capabilities, have garnered increasing attention recently because of their potential use in personalized medicine, including cancer-targeting treatments for patients. One interesting approach to achieving this potential involves the development of cancer-associated, stimuli-driven, turn on theranostics. Multicomponent constructs of this type would have the capability of selectively delivering therapeutic reagents into cancer cells or tumor tissues while simultaneously generating unique signals that can be readily monitored under both in vitro and in vivo conditions. Specifically, their combined anticancer activities and selective visual signal respond to cancer-associated stimuli, would make these theranostic agents more highly efficient and specific for cancer treatment and diagnosis. This article focuses on the progress of stimuli-responsive turn on theranostics that activate diagnostic signals and release therapeutic reagents in response to the cancer-associated stimuli. The present article not only provides the fundamental backgrounds of diagnostic and therapeutic tools that have been widely utilized for developing theranostic agents, but also discusses the current approaches for developing stimuli-responsive turn on theranostics.

Nanotechnology in Glycomics: Applications in Diagnostics, Therapy, Imaging, and Separation Processes

This review comprehensively covers the most recent achievements (from 2013) in the successful integration of nanomaterials in the field of glycomics. The first part of the paper addresses the beneficial properties of nanomaterials for the construction of biosensors, bioanalytical devices, and protocols for the detection of various analytes, including viruses and whole cells, together with their key characteristics. The second part of the review focuses on the application of nanomaterials integrated with glycans for various biomedical applications, that is, vaccines against viral and bacterial infections and cancer cells, as therapeutic agents, for in vivo imaging and nuclear magnetic resonance imaging, and for selective drug delivery. The final part of the review describes various ways in which glycan enrichment can be effectively done using nanomaterials, molecularly imprinted polymers with polymer thickness controlled at the nanoscale, with a subsequent analysis of glycans by mass spectrometry. A short section describing an active glycoprofiling by microengines (microrockets) is covered as well.

Two-Step Assembling of Near-Infrared "OFF-ON" Fluorescent Nanohybrids for Synchronous Tumor Imaging and MicroRNA Modulation-Based Therapy

Theranostic nanoparticles with combined imaging and therapy functions show great promise in cancer precision medicine. In this study, we constructed near-infrared (NIR) "OFF-ON" fluorescent nanohybrids (F-PNDs) for synchronous tumor imaging and microRNA (miRNA) modulation therapy against esophageal cancer. Nanodiamond clusters (NDs) were first functionalized for protamine sulfate immobilization (PNDs) on their surfaces via a noncovalent self-assembling approach and simultaneous encapsulation of NIR emitting fluorescence dye cyanine 5 (Cy-5) (F-PNDs). Tumor suppressor miRNA-203 (miR-203) was then adsorbed onto the surface of F-PNDs to form miR-203/F-PNDs via electrostatic interactions. The size, morphology, photophysical and stability properties of miR-203/F-PNDs were analyzed. We found that the NIR fluorescence of miR-203/F-PNDs could be activated to the "ON" state in intracellular environment while remaining in the "OFF" state in extracellular or blood environment. Furthermore, in vivo live imaging experiments showed that miR-203/F-PNDs could be predominantly accumulated in tumor tissues and image the tumor sites 24 h postintravenous injection. In addition, intravenous and intratumoral injection of miR-203/F-PNDs could efficiently inhibit tumor growth through down-regulation of the expressions of oncogenes Ran and Δp63. Our study indicated that miRNA/F-PNDs could serve as a promising theranostic platform for synchronous tumor imaging and miRNA-based modulation therapy against cancer.

Aptamer-Conjugated Graphene Quantum Dots/Porphyrin Derivative Theranostic Agent for Intracellular Cancer-Related MicroRNA Detection and Fluorescence-Guided Photothermal/Photodynamic Synergetic Therapy

Multifunctional theranostic platform coupling diagnostic and therapeutic functions holds great promise for personalized nanomedicine. Nevertheless, integrating consistently high performance in one single agent is still challenging. This work synthesized a sort of porphyrin derivatives (P) with high singlet oxygen generation ability and graphene quantum dots (GQDs) possessing good fluorescence properties. The P was conjugated to polyethylene glycol (PEG)ylated and aptamer-functionalized GQDs to gain a multifunctional theranostic agent (GQD-PEG-P). The resulting GQD-PEG-P displayed good physiological stability, excellent biocompatibility and low cytotoxicity. The intrinsic fluorescence of the GQDs could be used to discriminate cancer cells from somatic cells, whereas the large surface facilitated gene delivery for intracellular cancer-related microRNA (miRNA) detection. Importantly, it displayed a photothermal conversion efficiency of 28.58% and a high quantum yield of singlet oxygen generation up to 1.08, which enabled it to accomplish advanced photothermal therapy (PTT) and efficient photodynamic therapy (PDT) for cancer treatment. The combined PTT/PDT synergic therapy led to an outstanding therapeutic efficiency for cancer cell treatment.

Multifunctional graphene oxide for bioimaging: emphasis on biological research

Graphene oxide (GO) nanomaterials offer a wide range of bioimaging applicability. Almost complete quenching ability of fluorescence by GO and natural interaction of GO with single stranded nucleic acid made GO a useful and intriguing multifunctional nanoplatform both as a biosensor for in vitro microplate diagnostics and as a drug delivery carrier for targeted delivery. GO’s large surface area and strong near infrared absorbance contribute to enhancement of a therapeutic effect with abundant loading of drugs for possible photothermal and photodynamic therapy. Bioimaging capability of GO made it a good theranostic tool, while enabling tracing in vivo pharmacokinetics during concurrent treatment. Fluorescence, either signal on or off, Raman and surface-enhanced Raman scattering (SERs), photoacoustic, and radionuclide imaging modalities can be used for theranostic purposes using GO nanomaterials. In this review, we highlight current applications of GO for bioimaging that are classified into in vitro microplate, in vitro cellular and in vivo bioimaging.

Graphene quantum dots: multifunctional nanoplatforms for anticancer therapy

We review the recent advances in the application of GQDs as innovative nanoplatforms for anticancer therapy and bioimaging.

Graphene-Montmorillonite Composite Sponge for Safe and Effective Hemostasis

Montmorillonite (MMT) is considered to be the most effective hemostat among natural phyllosilicates. However, there is a barrier against using MMT for the commercial hemostatics because the invaded MMT powders might cause thrombosis in vessel. Until now, it is still a challenge to manage the release of MMT and eliminate its side effect. Herein, we present a graphene-MMT composite sponge (GMCS), synthesized under a hydrothermal reaction, fixing MMT powders into the cross-linked graphene sheets. We demonstrate that only a few embedded MMT can evoke remarkable platelet stimulation at the sponge interface, while maintaining fast plasma absorbency of the innate sponge. In the synergy of the above hemostatic mechanisms, the GMCS can rapidly stop bleeding in approximately 85 s in rabbit artery injury test. More importantly, computed tomography angiography certifies that the GMCS does not cause thrombus or blood clot in vessels. Cytotoxicity assay further highlights its biocompatibility. In-depth analysis proposes that two-dimensional graphene overmatches one-dimensional linear polymers in the composite construction, and dimension transformation of blood distribution plays a crucial role for reinforcing the hemostatic performance. This GMCS hemostat not only opens a new perspective for graphene composite, but also makes a new chance of using clays for trauma therapy.

Poly(lactic acid) for delivery of bioactive macromolecules

Therapeutic biomolecules often require frequent administration and supramolecular dosing to achieve therapeutic efficiencies and direct infusion into treatment or defect sites results in inadequate physiological response and at times severe side effects or mis-targeting. Delivery systems serve several purposes such as increased circulatory time, increased biomolecule half-life, and incorporation of new innovations can enable highly specific cell targeting and improved cell and nucleus permeability. Poly(lactic acid) (PLA) has become a "material of choice" due to wide availability, reproducible synthetic route, customization, versatility, biodegradability and biocompatibility. Furthermore, PLA is amenable to a variety of fabrication methodologies and chemistries allowing an expansive library correlating physio-chemical properties, characteristics, and applications. This article discusses challenges to biomolecule delivery, and classical approaches of PLA based biomolecule delivery and targeting strategies under development and in trials.

Graphene materials as 2D non-viral gene transfer vector platforms

Advances in genomics and gene therapy could offer solutions to many diseases that remain incurable today, however, one of the critical reasons halting clinical progress is due to the difficulty in designing efficient and safe delivery vectors for the appropriate genetic cargo. Safety and large-scale production concerns counter-balance the high gene transfer efficiency achieved with viral vectors, while non-viral strategies have yet to become sufficiently efficient. The extraordinary physicochemical, optical and photothermal properties of graphene-based materials (GBMs) could offer two-dimensional components for the design of nucleic acid carrier systems. We discuss here such properties and their implications for the optimization of gene delivery. While the design of such vectors is still in its infancy, we provide here an exhaustive and up-to-date analysis of the studies that have explored GBMs as gene transfer vectors, focusing on the functionalization strategies followed to improve vector performance and on the biological effects attained.

Carboxymethyl Dextran-Stabilized Polyethylenimine-Poly(epsilon-caprolactone) Nanoparticles-Mediated Modulation of MicroRNA-34a Expression via Small-Molecule Modulator for Hepatocellular Carcinoma Therapy

MicroRNA-34a (miR-34a) modulation therapy has shown great promise to treat hepatocellular carcinoma (HCC). 2'-Hydroxy-2,4,4',5,6'-pentamethoxychalcone, termed Rubone, has been shown to specifically upregulate miR-34a expression in HCC cells and considered as novel anticancer agent. However, the extremely low aqueous solubility of Rubone hampers its use in cancer treatment. In the present study, surface-stabilized nanoparticles-based delivery strategy was engaged to overcome this impediment. In our preparation, Rubone was encapsulated in the micelles composed of polyethylenimine-poly(epsilon-caprolactone) (PEI-PCL) through hydrophobic interactions, which were subsequently stabilized with anionic carboxymethyl dextran CMD via electronic interaction. We found that Rubone-encapsulating nanoparticles are dispersed well in aqueous solution. The results further demonstrated that Rubone could be efficiently delivered in HCC cells by nanoparticles and upregulate miR-34a expression, which in turn led to inhibition of proliferation, migration, and increased apoptosis of HCC cells. In vivo experiments showed that Rubone can be preferentially delivered into tumor tissues by CMD-stabilized PEI-PCL nanoparticles after intravenous administration and significantly inhibited tumor growth. Furthermore, low cytotoxicity of the nanoparticles was observed in vitro and in vivo analyses, indicating a good compatibility of generated nanoparticles. The obtained results suggest that CMD-stabilized PEI-PCL nanoparticles may serve as a novel approach for small-molecule-modulator-mediated miR-34a restoration for HCC therapy.

Imaging Dendrimer-Grafted Graphene Oxide Mediated Anti-miR-21 Delivery With an Activatable Luciferase Reporter

MicroRNAs (miRNAs) are a class of post-transcriptional gene regulators involved in various physiological processes including carcinogenesis, and they have emerged as potential targets for tumor theranostics. However, the employment of antisense oligonucleotides, termed anti-miRs, for antagonizing miRNA functions in vivo has largely been impeded by a lack of effective delivery carriers. Here, we describe the development of polyamidoamine (PAMAM) dendrimer and polyethylene glycol (PEG)-functionalized nanographene oxide (NGO) conjugate (NGO-PEG-dendrimer) for the efficient delivery of anti-miR-21 into non-small-cell lung cancer cells. To monitor the delivery of anti-miR-21 into cells and tumors, we also constructed an activatable luciferase reporter (Fluc-3xPS) containing three perfectly complementary sequences against miR-21 in the 3' untranslated region (UTR) of the reporter. Compared with bare dendrimer and Lipofectamine 2000 (Lipo2000), NGO-PEG-dendrimer showed considerably lower cytotoxicity and higher transfection efficiency. As demonstrated by in vitro bioluminescence imaging and Western blotting assays, NGO-PEG-dendrimer effectively delivered anti-miR-21 into the cytoplasm and resulted in the upregulation of luciferase intensity and PTEN target protein expression in a dose-dependent manner. Moreover, transfection with anti-miR-21 by NGO-PEG-dendrimer led to stronger inhibition of cell migration and invasion than did bare dendrimer or Lipo2000 transfection. The intravenous delivery of anti-miR-21 via NGO-PEG-dendrimer induced a significant increase in the bioluminescence signal within the Fluc-3xPS reporter-transplanted tumor areas. These results suggest that NGO-PEG-dendrimer could be an efficient and a potential nanocarrier for delivering RNA oligonucleotides. In addition, the strategy of combining NGO-PEG-dendrimer with an activatable luciferase reporter allows the image-guided monitoring of the delivery process, which can provide insights into the RNA-based cancer treatments.

Applications and toxicity of graphene family nanomaterials and their composites

Graphene has attracted much attention of scientific community due to its enormous potential in different fields, including medical sciences, agriculture, food safety, cancer research, and tissue engineering. The potential for widespread human exposure raises safety concerns about graphene and its derivatives, referred to as graphene family nanomaterials (GFNs). Due to their unique chemical and physical properties, graphene and its derivatives have found important places in their respective application fields, yet they are being found to have cytotoxic and genotoxic effects too. Since the discovery of graphene, a number of researches are being conducted to find out the toxic potential of GFNs to different cell and animal models, finding their suitability for being used in new and varied innovative fields. This paper presents a systematic review of the research done on GFNs and gives an insight into the mode and action of these nanosized moieties. The paper also emphasizes on the recent and up-to-date developments in research on GFNs and their nanocomposites for their toxic effects.

Quantum dots in nanomedicine: recent trends, advances and unresolved issues

The review addresses the current state of progress in the use of ultra-small nanoparticles from the category of quantum dots (QDs), which presently embraces a widening range of nanomaterials of different nature, including "classical" semiconductor groups III-V and II-VI nanocrystals, along with more recently emerged carbon, silicon, gold and other types of nanoparticles falling into this class of nanomaterials due to their similar physical characteristics such as small size and associated quantum confinement effects. A diverse range of QDs applications in nanomedicine has been extensively summarised previously in numerous publications. Therefore, this review is not intended to provide an all-embracing survey of the well documented QDs uses, but is rather focused on the most recent emerging developments, concepts and outstanding unresolved problematic and sometimes controversial issues. Over 125 publications are overviewed and discussed here in the context of major nanomedicine domains, i.e. medical imaging, diagnostics, therapeutic applications and combination of them in multifunctional theranostic systems.

Establishing biodegradable single-layer MnO2 nanosheets as a platform for live cell microRNA sensing

We have established a simple and effective biosensing platform based on the non-covalent assembly of biodegradable single-layer MnO₂ nanosheet and target-specific oligonucleotide, and demonstrated its application for sensing miRNA in living cells.