A facile, one-step nanocarbon functionalization for biomedical applications

Lipid nanoparticle mediated small interfering RNA delivery as a potential therapy for Alzheimer's disease

Alzheimer's disease (AD) is a neurodegenerative condition that exhibits a gradual decline in cognitive function and is prevalent among a significant number of individuals globally. The use of small interfering RNA (siRNA) molecules in RNA interference (RNAi) presents a promising therapeutic strategy for AD. Lipid nanoparticles (LNPs) have been developed as a delivery vehicle for siRNA, which can selectively suppress target genes, by enhancing cellular uptake and safeguarding siRNA from degradation. Numerous research studies have exhibited the effectiveness of LNP-mediated siRNA delivery in reducing amyloid beta (Aβ) levels and enhancing cognitive function in animal models of AD. The feasibility of employing LNP-mediated siRNA delivery as a therapeutic approach for AD is emphasized by the encouraging outcomes reported in clinical studies for other medical conditions. The use of LNP-mediated siRNA delivery has emerged as a promising strategy to slow down or even reverse the progression of AD by targeting the synthesis of tau phosphorylation and other genes linked to the condition. Improvement of the delivery mechanism and determination of the most suitable siRNA targets are crucial for the efficacious management of AD. This review focuses on the delivery of siRNA through LNPs as a promising therapeutic strategy for AD, based on the available literature.

A Dual-Mode Near-Infrared Optical and Photoacoustic Imaging Agent Based on a Low Energy Absorbing Ytterbium Complex

Near-infrared (NIR) luminescence and photoacoustic (PA) imaging have attracted increasing attention for the real-time monitoring of biological samples due to high sensitivity, resolution, and pronounced signal detection depth, respectively. For improved contrast, both techniques require imaging agents possessing high absorption in the red-NIR range. Herein, we took advantage of a ternary complex formed with the anionic ytterbium(III) tetrakis(2-thenoyltrifluoroacetonate) ([Yb(tta)4]-) and the cationic NIR-absorbing chromophore, 1,1'-diethyl-2,2'-dicarbocyanine (Cy+), to evaluate its potential to act as a dual-mode NIR luminescence and PA imaging agent. We demonstrated that, upon excitation with red-NIR light, Cy[Yb(tta)4] encapsulated into polystyrene nanoparticles is able to generate both NIR Yb3+ emission and a PA signal in an imaging experiment performed in a tissue-mimicking phantom.

Real-time tracking of the intracellular delivery of a 2D nanosystem using a progressively activatable fluorescence platform for cancer diagnosis

In this work, a smart nanoplatform responding to multiple biomarkers has been developed for the real-time tracking of the intracellular delivery of a 2D nanosystem. Our work provides a promising avenue for developing an optimized imaging nanoplatform for site-specific imaging and real-time tracking of the delivery process.

Levan nanoparticles with intrinsic CD44-targeting ability for tumor-targeted drug delivery

Existing anticancer therapeutics exhibit short half-lives, non-specificity, and severe side effects. To address this, active-targeting nanoparticles have been developed; however, the complex fabrication procedures, scale-up, and low reproducibility delay FDA approval, particularly for functionalized nanoparticles. We developed levan nanoparticles via simple one-pot nanoprecipitation for specific anticancer drug delivery. Levan is a plant polysaccharide which has a binding affinity to CD44 receptors and amphiphilicity. The nanoparticles are self-assembled and enable active-targeting without chemical modifications. The paclitaxel-loaded levan nanoparticles (PTX@LevNP) demonstrated a sustained PTX release and long-term stability. The LevNP can bind CD44 receptors on cancer cells, and PTX@LevNP showed enhanced anticancer activity in CD44-positive cells (SCC7 cells). In SCC7 tumor-bearing mice, the accumulation of LevNP in tumor tissue was 3.7 times higher than that of the free-dye, resulting in improved anticancer efficacy of PTX@LevNP. This new strategy using levan can produce nanoparticles for effective cancer treatment without complex fabrication procedures.

The sound of drug delivery: Optoacoustic imaging in pharmacology

Optoacoustic (photoacoustic) imaging offers unique opportunities for visualizing biological function in vivo by achieving high-resolution images of optical contrast much deeper than any other optical technique. The method detects ultrasound waves that are generated inside tissue by thermo-elastic expansion, i.e., the conversion of light absorption by tissue structures to ultrasound when the tissue is illuminated by the light of varying intensity. Listening instead of looking to light offers the major advantage of image formation with a resolution that obeys ultrasonic diffraction and not photon diffusion laws. While the technique has been widely used to explore contrast from endogenous photo-absorbing molecules, such as hemoglobin or melanin, the use of exogenous agents can extend applications to a larger range of biological and possible clinical applications, such as image-guided surgery, disease monitoring, and the evaluation of drug delivery, biodistribution, and kinetics. This review summarizes recent developments in optoacoustic agents, and highlights new functions visualized and potent pharmacology applications enabled with the use of external contrast agents.

Targeted contrast agents and activatable probes for photoacoustic imaging of cancer

Photoacoustic (PA) imaging has emerged as a powerful technique for the high resolution visualization of biological processes within deep tissue. Through the development and application of exogenous targeted contrast agents and activatable probes that can respond to a given cancer biomarker, researchers can image molecular events in vivo during cancer progression. This information can provide valuable details that can facilitate cancer diagnosis and therapy monitoring. In this tutorial review, we provide a step-by-step guide to select a cancer biomarker and subsequent approaches to design imaging agents for in vivo use. We envision this information will be a useful summary to those in the field, new members to the community, and graduate students taking advanced imaging coursework. We also highlight notable examples from the recent literature, with emphasis on the molecular designs and their in vivo PA imaging performance. To conclude, we provide our outlook and future perspective in this exciting field.

Photoacoustic Tomography Opening New Paradigms in Biomedical Imaging

After the emergence of the ultrasound, X-ray CT, PET, and MRI, photoacoustic tomography (PAT) is now in the phase of its exponential growth, with its expected full maturation being another form of mainstream clinical imaging modality. By combining the high contrast benefit of optical imaging and the high-resolution deep imaging capability of ultrasound, PAT can provide unprecedented anatomical image contrasts at clinically relevant depths as well as enable the use of a variety of functional and molecular imaging information, which is not possible with conventional imaging modalities. With these strengths, PAT has achieved numerous breakthroughs in various biomedical applications and also provided new technical platforms that may be able to resolve unmet issues in clinics. In this chapter, we provide an overview of the development of PAT technology for several major biomedical applications and provide an approximate projection of the future of PAT.

Effective Photodynamic Therapy for Colon Cancer Cells Using Chlorin e6 Coated Hyaluronic Acid-Based Carbon Nanotubes

Colon cancer is the third major cancer contributor to mortality worldwide. Nanosized particles have attracted attention due to their possible contribution towards cancer treatment and diagnosis. Photodynamic therapy (PDT) is a cancer therapeutic modality that involves a light source, a photosensitizer and reactive oxygen species. Carbon nanotubes are fascinating nanocarriers for drug delivery, cancer diagnosis and numerous potential applications due to their unique physicochemical properties. In this study, single walled carbon nanotubes (SWCNTs) were coupled with hyaluronic acid (HA) and chlorin e6 (Ce6) coated on the walls of SWCNTs. The newly synthesized nanobiocomposite was characterized using ultraviolet-visible spectroscopy, Fourier transform electron microscopy (FTIR), X-ray diffraction analysis (XRD), particle size analysis and zeta potential. The loading efficiency of the SWCNTs-HA for Ce6 was calculated. The toxicity of the nanobiocomposite was tested on colon cancer cells using PDT at a fluence of 5 J/cm² and 10 J/cm². After 24 h, cellular changes were observed via microscopy, LDH cytotoxicity assay and cell death induction using annexin propidium iodide. The results showed that the newly synthesized nanobiocomposite enhanced the ability of PDT to be a photosensitizer carrier and induced cell death in colon cancer cells.

Biodistribution Survey of Oxidized Single-Wall Carbon Nanohorns Following Different Administration Routes by Using Label-Free Multispectral Optoacoustic Tomography

Introduction

Though widely studied for biomedical applications, the lack of current systemic studies on the in vivo fate of single-walled carbon nanohorns (SWCNHs) largely restricts their further applications, as real-time monitoring of their biodistribution remains a big challenge. Here, we aim to customize a label-free multispectral optoacoustic tomography (MSOT) method and systematically survey the fate of oxidized SWCNHs (SWCNHox) following different exposure routes by whole body imaging.

Methods

Mice were given a suspension of SWCNHox with an average size of 136.4 nm via four different administration routes, and then imaged by MSOT.

Results

After oral gavage, SWCNHox were mainly distributed in the gastrointestinal tract then excreted through the gut. Compared with the observation post first dosing, the accumulation of SWCNHox in the gastrointestinal tract was not obvious even after four-time oral gavage. Almost no SWCNHox were found at detectable levels in kidney, liver, blood and spleen. Following intravenous (iv) injection, SWCNHox were mainly presented and persisted in the spleen and liver, while very little in the kidney and almost none detectable in the intestine. SWCNHox accumulated significantly in the liver and spleen after four IV administrations. Following hypodermic and intramuscular injections, almost no SWCNHox could cross biological barriers and transport to the spleen, kidney or liver, likely due to their very low absorption rate. Almost all SWCNHox remained around the injection sites. For the first time, we have systematically investigated the in vivo fate of SWCNHs in a label-free and real-time manner.

Conclusion

The findings of this study provide insights into the selection of appropriate exposure routes for potential biomedical applications of carbon nanomaterials.

Single-walled carbon nanohorns modulate tenocyte cellular response and tendon biomechanics

Subfailure ligament and tendon injury remain a significant burden to global healthcare. Here, we present the use of biocompatible single-walled carbon nanohorns (CNH) as a potential treatment for the repair of sub-failure injury in tendons. First, in vitro exposure of CNH to human tenocytes revealed no change in collagen deposition but a significant decrease in cell metabolic activity after 14 days. Additionally, gene expression studies revealed significant downregulation of collagen Types I and III mRNA at 7 days with some recovery after 14 days of exposure. Biomechanical tests with explanted porcine digitorum tendons showed the ability of CNH suspensions to modulate tendon biomechanics, most notably elastic moduli immediately after treatment. in vivo experiments demonstrated the ability of CNH to persist in the damaged matrix of stretch-injured Sprague Dawley rat Achilles tendon but not significantly modify tendon biomechanics after 7 days of treatment. Although these results demonstrate the early feasibility of utility of CNH as a potential modality for tendon subfailure injury, additional work is needed to further validate and ensure clinical efficacy.

Nanoparticle-mediated approaches for Alzheimer's disease pathogenesis, diagnosis, and therapeutics

Alzheimer's disease (AD) is an irreversible and progressive neurodegenerative disorder manifested by memory loss and cognitive impairment. Deposition of the amyloid β plaques has been identified as the most common AD pathology; however, the excessive accumulation of phosphorylated or total tau proteins, reactive oxygen species, and higher acetylcholinesterase activity are also strongly associated with Alzheimer's dementia. Several therapeutic approaches targeting these pathogenic mechanisms have failed in clinical or preclinical trials, partly due to the limited bioavailability, poor cell, and blood-brain barrier penetration, and low drug half-life of current regimens. The nanoparticles (NPs)-mediated drug delivery systems improve drug solubility and bioavailability, thus renders as superior alternatives. Moreover, NPs-mediated approaches facilitate multiple drug loading and targeted drug delivery, thereby increasing drug efficacy. However, certain NPs can cause acute toxicity damaging cellular and tissue architecture, therefore, NP material should be carefully selected. In this review, we summarize the recent NPs-mediated studies that exploit various pathologic mechanisms of AD by labeling, identifying, and treating the affected brain pathologies. The disadvantages of the select NP-based deliveries and the future aspects will also be discussed.

Hyaluronic Acid-Based Activatable Nanomaterials for Stimuli-Responsive Imaging and Therapeutics: Beyond CD44-Mediated Drug Delivery

There is a rapidly increasing interest in developing stimuli-responsive nanomaterials for treating a variety of diseases. By enabling the activation of function locally at the sites of interest, it is possible to increase therapeutic efficacy significantly while simultaneously reducing adverse side effects. While there are many sophisticated nanomaterials available, they are often highly complex and not easily transferrable to industrial scales and clinical settings. However, nanomaterials based on hyaluronic acid offer a compelling strategy for reducing their complexity while retaining several desirable benefits such as active targeting and stimuli-responsive degradation. Herein, the basic properties of hyaluronic acid, its binding partners, and natural routes for degradation by hyaluronidases-hyaluronic-acid-degrading enzymes-and oxidative stresses are discussed. Recent advances in designing hyaluronic acid-based, actively targeted, hyaluronidase- or reactive-oxygen-species-responsive nanomaterials for both diagnostic imaging and therapeutic delivery, which go beyond merely the classical targeting of CD44, are summarized.

Photoacoustic Imaging: Contrast Agents and Their Biomedical Applications

Photoacoustic (PA) imaging as a fast-developing imaging technique has great potential in biomedical and clinical applications. It is a noninvasive imaging modality that depends on the light-absorption coefficient of the imaged tissue and the injected PA-imaging contrast agents. Furthermore, PA imaging provides superb contrast, super spatial resolution, and high penetrability and sensitivity to tissue functional characteristics by detecting the acoustic wave to construct PA images. In recent years, a series of PA-imaging contrast agents are developed to improve the PA-imaging performance in biomedical applications. Here, recent progress of PA contrast agents and their biomedical applications are outlined. PA contrast agents are classified according to their components and function, and gold nanocrystals, gold-nanocrystal assembly, transition-metal chalcogenides/MXene-based nanomaterials, carbon-based nanomaterials, other inorganic imaging agents, small organic molecules, semiconducting polymer nanoparticles, and nonlinear PA-imaging contrast agents are discussed. The applications of PA contrast agents as biosensors (in the sensing of metal ions, pH, enzymes, temperature, hypoxia, reactive oxygen species, and reactive nitrogen species) and in bioimaging (lymph nodes, vasculature, tumors, and brain tissue) are discussed in detail. Finally, an outlook on the future research and investigation of PA-imaging contrast agents and their significance in biomedical research is presented.

Self-assembled hyaluronic acid nanoparticles: Implications as a nanomedicine for treatment of type 2 diabetes

Self-assembled hyaluronic acid nanoparticles (HA-NPs) have been extensively investigated for biomedical and pharmaceutical applications owing to their biocompatibility and receptor-binding properties. Here, we report that an empty HA-NP itself not bearing any drug has therapeutic effects on adipose tissue inflammation and insulin resistance. HA-NPs inhibited not only the receptor-mediated internalization of low-molecular-weight (LMW) free HA but also LMW free HA-induced pro-inflammatory gene expression in mouse primary bone marrow-derived macrophages (BMDMs) isolated from wild-type mice, but not in CD44-null (CD44-/-) BMDMs. An in vivo biodistribution study showed the distribution of HA-NPs and their co-localization with CD44 in adipose tissues including epididymal white adipose tissues (eWATs), but these were rarely observed in the eWATs of CD44-/- mice. In addition, CD44 expression and HA-NP accumulation in the eWATs were increased in mice with diet-induced obesity (DIO) compared to lean mice. Interestingly, treatment with HA-NPs in DIO mice suppressed adipose tissue inflammation as indicated by reduced macrophage content, the production of proinflammatory cytokines and NLRP3 inflammasome activity in eWATs, leading to improved insulin sensitivity and normalized blood glucose levels. Collectively, these results suggest that an empty HA-NP itself can be a therapeutic agent for the treatment of type 2 diabetes.

Highly hydrophilic carbon nanoparticles: uptake mechanism by mammalian and plant cells

As one of the carbon based materials, the potential application of carbon nanoparticles (CNPs) has emerged in the promotion of plant growth. However, knowledge on the biological mechanism of how the CNPs interact with plant cells is limited. In this study, nanostructures of CNPs were examined. The particles exhibited particulate morphology and their size distribution was in the range of 18 to 70 nm, with an average size of 30 nm. Hydrophilic groups of COOH and OH were present on the surface of CNPs, and CNPs showed the common feature of graphitic sp² hybridization carbons. The CNPs were determined to be biocompatible with these two cell lines, mammalian cells (A549 cells) and plant cells (BY-2 cells). The COOH groups on the surface of CNPs were functionalized via covalent binding with a fluorescent dye for improvement of the fluorescence. The fluorescent carbon nanoparticles (FCNPs) were found to cross the cell membrane and enter cells (A549 cells and BY-2 cells) in an energy-dependent manner. Subsequently, the mechanism of FCNPs interaction with the cell membrane was evaluated in the presence of inhibitors that specifically affect different endocytosis membrane proteins. The FCNPs mainly entered A549 cells through caveolin-mediated endocytosis and macropinocytosis, and clathrin-dependent endocytosis was also involved in the transportation of the FCNPs. Clathrin-independent endocytosis mediated in the internalization of FCNPs in BY-2 cells. The way FCNPs entering cells will provide a fundamental understanding of the influence of CNPs on cell membrane.

Carbon nanoparticles entered cells via different endocytic pathways depending on the cell type.

Theranostic Hyaluronic Acid-Iron Micellar Nanoparticles for Magnetic-Field-Enhanced in vivo Cancer Chemotherapy

The delivery of therapeutic cancer agents using nanomaterials has recently attracted much attention. Although encouraging progress with chemotherapeutics has been made, tumor treatment response remains unsatisfactory. To address this concern, we constructed a new micellar nanocomplex by covalently conjugating hyaluronic acid (HA) with an iron oxide nanoparticle (IONP). When an external magnetic field was applied to the tumor area, HA-IONP specifically accumulated in the tumor, due to the strong IONP magnetism. In addition, HA was shown to bind to cluster determinant 44 (CD44), which is overexpressed on tumor cells. With combined magnetic, CD44, and enhanced permeability retention (EPR) targeting, the efficient delivery of HA-IONP to the tumor is expected to enhance cancer treatment efficiency. After encapsulation of the chemotherapy drug homocamptothecin (HCPT), the theranostic potency of HA-IONP/HCPT (HIH) was investigated both in vitro and in vivo. The improved tumor homing behavior of HIH was observed by magnetic resonance imaging (MRI) when an external magnetic field was used. Moreover, HIH showed remarkable tumor ablation efficiency, with magnetic targeting after 3 mg kg^-1 intravenous administration (equivalent dose of free HCPT), and the tumors almost disappeared after treatment. No obvious systemic toxicity was detected. This excellent biocompatibility and tumor targetability suggests that HIH is a promising theranostic nanocomplex with great translational potency. Application of the HA-IONP platform could also be extended to delivery of other hydrophobic chemotherapy drugs or phototherapy agents.

Hyaluronan-Inorganic Nanohybrid Materials for Biomedical Applications

Nanomaterials, including gold, silver, and magnetic nanoparticles, carbon, and mesoporous materials, possess unique physiochemical and biological properties, thus offering promising applications in biomedicine, such as in drug delivery, biosensing, molecular imaging, and therapy. Recent advances in nanotechnology have improved the features and properties of nanomaterials. However, these nanomaterials are potentially cytotoxic and demonstrate a lack of cell-specific function. Thus, they have been functionalized with various polymers, especially polysaccharides, to reduce toxicity and improve biocompatibility and stability under physiological conditions. In particular, nanomaterials have been widely functionalized with hyaluronan (HA) to enhance their distribution in specific cells and tissues. This review highlights the most recent advances on HA-functionalized nanomaterials for biotechnological and biomedical applications, as nanocarriers in drug delivery, contrast agents in molecular imaging, and diagnostic agents in cancer therapy. A critical evaluation of barriers affecting the use of HA-functionalized nanomaterials is also discussed, and insights into the outlook of the field are explored.

Positron emission tomography and nanotechnology: A dynamic duo for cancer theranostics

Development of novel imaging probes for cancer diagnosis is critical for early disease detection and management. The past two decades have witnessed a surge in the development and evolution of radiolabeled nanoparticles as a new frontier in personalized cancer nanomedicine. The dynamic synergism of positron emission tomography (PET) and nanotechnology combines the sensitivity and quantitative nature of PET with the multifunctionality and tunability of nanomaterials, which can help overcome certain key challenges in the field. In this review, we discuss the recent advances in radionanomedicine, exemplifying the ability to tailor the physicochemical properties of nanomaterials to achieve optimal in vivo pharmacokinetics and targeted molecular imaging in living subjects. Innovations in development of facile and robust radiolabeling strategies and biomedical applications of such radionanoprobes in cancer theranostics are highlighted. Imminent issues in clinical translation of radiolabeled nanomaterials are also discussed, with emphasis on multidisciplinary efforts needed to quickly move these promising agents from bench to bedside.

Carbon Nanotubes as an Effective Opportunity for Cancer Diagnosis and Treatment

Despite the current progresses of modern medicine, the resistance of malignant tumors to present medical treatments points to the necessity of developing new therapeutic approaches. In recent years, numerous studies have focused their attention on the promising use of nanomaterials, like iron oxide nanowires, zinc oxide or mesoporous silica nanoparticles, for cancer and metastasis treatment with the advantage of operating directly at the bio-molecular scale. Among them, carbon nanotubes emerged as valid candidates not only for drug delivery, but also as a valuable tool in cancer imaging and physical ablation. Nevertheless, deep investigations about carbon nanotubes' potential bio-compatibility and cytotoxicity limits should be also critically addressed. In the present review, after introducing carbon nanotubes and their promising advantages and drawbacks for fighting cancer, we want to focus on the numerous and different ways in which they can assist to reach this goal. Specifically, we report on how they can be used not only for drug delivery purposes, but also as a powerful ally to develop effective contrast agents for tumors' medical or photodynamic imaging, to perform direct physical ablation of metastasis, as well as gene therapy.

Characterization of the Tumor Microenvironment and Tumor-Stroma Interaction by Non-invasive Preclinical Imaging

Tumors are often characterized by hypoxia, vascular abnormalities, low extracellular pH, increased interstitial fluid pressure, altered choline-phospholipid metabolism, and aerobic glycolysis (Warburg effect). The impact of these tumor characteristics has been investigated extensively in the context of tumor development, progression, and treatment response, resulting in a number of non-invasive imaging biomarkers. More recent evidence suggests that cancer cells undergo metabolic reprograming, beyond aerobic glycolysis, in the course of tumor development and progression. The resulting altered metabolic content in tumors has the ability to affect cell signaling and block cellular differentiation. Additional emerging evidence reveals that the interaction between tumor and stroma cells can alter tumor metabolism (leading to metabolic reprograming) as well as tumor growth and vascular features. This review will summarize previous and current preclinical, non-invasive, multimodal imaging efforts to characterize the tumor microenvironment, including its stromal components and understand tumor-stroma interaction in cancer development, progression, and treatment response.

Novel Hyaluronic Acid Conjugates for Dual Nuclear Imaging and Therapy in CD44-Expressing Tumors in Mice In Vivo

Hyaluronic acid, a natural CD44 receptor ligand, has attracted attention in the past years as a macromolecular delivery of anticancer agents to cancer. At the same time, the clinical applications of Gemcitabine (Gem) have been hindered by its short biological half-life, high dose and development of drug resistance. This work reports the synthesis of a hyaluronic acid (HA) conjugate for nuclear imaging, and in vivo Gem delivery to CD44-expressing solid tumors in mice. HA was individually conjugated, via amide coupling, to Gem (HA-Gem), 4'-(aminomethyl)fluorescein hydrochloride (HA-4'-AMF) or tris(hydroxypyridinone) amine (HA-THP) for cancer therapy, in vitro tracking or single photon emission computed tomography/computed tomography (SPECT/CT) imaging, respectively. Gem conjugation to HA was directly confirmed by nuclear magnetic resonance (¹H NMR), gel permeation chromatography (GPC) and UV-visible spectrometry, or indirectly by a nucleoside transporter inhibition study. Gem conjugation to HA improved its plasma stability, reduced blood hemolysis and resulted in delayed cytotoxicity in vitro. Uptake inhibition studies in colon CT26 and pancreatic PANC-1 cells, by flow cytometry, revealed that uptake of fluorescent HA conjugate is CD44 receptor and macropinocytosis-dependent. Gamma scintigraphy and SPECT/CT imaging confirmed the relatively prolonged blood circulation profile and uptake in CT26 (1.5 % ID/gm) and PANC-1 (1 % ID/gm) subcutaneous tumors at 24 h after intravenous injection in mice. Four injections of HA-Gem at ~15 mg/kg, over a 28-day period, resulted in significant delay in CT26 tumor growth and prolonged mice survival compared to the free drug. This study reports for the first time dual nuclear imaging and drug delivery (Gem) of HA conjugates to solid tumors in mice. The conjugates show great potential in targeting, imaging and killing of CD44-over expressing cells in vivo. This work is likely to open new avenues for the application of HA-based macromolecules in the field of image-guided delivery in oncology.

Long-Circulating Au-TiO2 Nanocomposite as a Sonosensitizer for ROS-Mediated Eradication of Cancer

Although sonodynamic therapy (SDT) has emerged as a potential alternative to conventional photodynamic therapy, the low quantum yield of the sonosensitizer such as TiO₂ nanoparticles (NPs) is still a major concern. Here, we have developed hydrophilized Au-TiO₂ nanocomposites (HAu-TiO₂ NCs) as sonosensitizers for improved SDT. The physicochemical properties of HAu-TiO₂ NCs were thoroughly studied and compared with their counterparts without gold deposition. Upon exposure of HAu-TiO₂ NCs to ultrasound, a large quantity of reactive oxygen species (ROS) were generated, leading to complete suppression of tumor growth after their systemic administration in vivo. Overall, it was evident that the composites of gold with TiO₂ NPs significantly augmented the levels of ROS generation, implying their potential as SDT agents for cancer therapy.

Contrast agents for molecular photoacoustic imaging

Photoacoustic imaging (PAI) is an emerging tool that bridges the traditional depth limits of ballistic optical imaging and the resolution limits of diffuse optical imaging. Using the acoustic waves generated in response to the absorption of pulsed laser light, it provides noninvasive images of absorbed optical energy density at depths of several centimeters with a resolution of ∼100 μm. This versatile and scalable imaging modality has now shown potential for molecular imaging, which enables visualization of biological processes with systemically introduced contrast agents. Understanding the relative merits of the vast range of contrast agents available, from small-molecule dyes to gold and carbon nanostructures to liposome encapsulations, is a considerable challenge. Here we critically review the physical, chemical and biochemical characteristics of the existing photoacoustic contrast agents, highlighting key applications and present challenges for molecular PAI.

Internalized compartments encapsulated nanogels for targeted drug delivery

Drug delivery systems inspired by natural particulates hold great promise for targeted cancer therapy. An endosome formed by internalization of plasma membrane has a massive amount of membrane proteins and receptors on the surface, which is able to specifically target the homotypic cells. Herein, we describe a simple method to fabricate an internalized compartments encapsulated nanogel with endosome membrane components (EM-NG) from source cancer cells. Following intracellular uptake of methacrylated hyaluronic acid (m-HA) adsorbed SiO2/Fe3O4 nanoparticles encapsulating a crosslinker and a photoinitiator, EM-NG was readily prepared through in situ crosslinking initiated under UV irradiation after internalization. The resulting nanogels loaded with doxorubicin (DOX) displayed enhanced internalization efficiency to the source cells through a specific homotypic affinity in vitro. However, when treated with the non-source cells, the EM-NGs exhibited insignificant difference in therapeutic efficiency compared to a bare HA nanogel with DOX. This study illustrates the potential of utilizing an internalized compartments encapsulated formulation for targeted cancer therapy, and offers guidelines for developing a natural particulate-inspired drug delivery system.

Nanotubes-Embedded Indocyanine Green-Hyaluronic Acid Nanoparticles for Photoacoustic-Imaging-Guided Phototherapy

Phototherapy is a light-triggered treatment for tumor ablation and growth inhibition via photodynamic therapy (PDT) and photothermal therapy (PTT). Despite extensive studies in this area, a major challenge is the lack of selective and effective phototherapy agents that can specifically accumulate in tumors to reach a therapeutic concentration. Although recent attempts have produced photosensitizers complexed with photothermal nanomaterials, the tedious preparation steps and poor tumor efficiency of therapy still hampers the broad utilization of these nanocarriers. Herein, we developed a CD44 targeted photoacoustic (PA) nanophototherapy agent by conjugating Indocyanine Green (ICG) to hyaluronic acid nanoparticles (HANPs) encapsulated with single-walled carbon nanotubes (SWCNTs), resulting in a theranostic nanocomplex of ICG-HANP/SWCNTs (IHANPT). We fully characterized its physical features as well as PA imaging and photothermal and photodynamic therapy properties in vitro and in vivo. Systemic delivery of IHANPT theranostic nanoparticles led to the accumulation of the targeted nanoparticles in tumors in a human cancer xenograft model in nude mice. PA imaging confirmed targeted delivery of the IHANPT nanoparticles into tumors (T/M ratio = 5.19 ± 0.3). The effect of phototherapy was demonstrated by low-power laser irradiation (808 nm, 0.8 W/cm(2)) to induce efficient photodynamic effect from ICG dye. The photothermal effect from the ICG and SWCNTs rapidly raised the tumor temperature to 55.4 ± 1.8 °C. As the result, significant tumor growth inhibition and marked induction of tumor cell death and necrosis were observed in the tumors in the tumors. There were no apparent systemic and local toxic effects found in the mice. The dynamic thermal stability of IHANPT was studied to ensure that PTT does not affect ICG-dependent PDT in phototherapy. Therefore, our results highlight imaging property and therapeutic effect of the novel IHANPT theranostic nanoparticle for CD44 targeted and PA image-guided dual PTT and PDT cancer therapy.

Hyaluronic acid for anticancer drug and nucleic acid delivery

Hyaluronic acid (HA) is widely used in anticancer drug delivery, since it is biocompatible, biodegradable, non-toxic, and non-immunogenic; moreover, HA receptors are overexpressed on many tumor cells. Exploiting this ligand-receptor interaction, the use of HA is now a rapidly-growing platform for targeting CD44-overexpressing cells, to improve anticancer therapies. The rationale underlying approaches, chemical strategies, and recent advances in the use of HA to design drug carriers for delivering anticancer agents, are reviewed. Comprehensive descriptions are given of HA-based drug conjugates, particulate carriers (micelles, liposomes, nanoparticles, microparticles), inorganic nanostructures, and hydrogels, with particular emphasis on reports of preclinical/clinical results.

The dispersion, solubilization and stabilization in “solution” of single-walled carbon nanotubes

Methods for the solubilization and dispersion of single-walled carbon nanotubes in water and organic solvents by physical and chemical methods have been reviewed.

Recent developments in hyaluronic acid-based nanomedicine for targeted cancer treatment

INTRODUCTION

Hyaluronic acid (HA) has emerged as a promising applicant for the tumor-targeted delivery of various therapeutic agents. Because of its biocompatibility, biodegradability and receptor-binding properties, HA has been extensively investigated as the drug delivery carrier. In this review, recent advances in HA-based nanomedicines are discussed.

AREAS COVERED

This review focuses on HA-based nanomedicines for the diagnosis and treatment of cancer. In particular, recent advances in HA-drug conjugates and HA-based nanoparticles for small molecular drug delivery are discussed. The bioreducible HA conjugates for small interfering ribonucleic acid delivery have been also discussed.

EXPERT OPINION

To develop a successful HA-based nanomedicine, it has to be prepared without significant deterioration of intrinsic property of HA. The chemical modification of HA with drugs or hydrophobic moieties may reduce the binding affinity of HA to the receptors. In addition, since the HA-based nanomedicines tend to accumulate in the liver after their systemic administration, new strategies to overcome this issue have to be developed.

A novel single walled carbon nanotube (SWCNT) functionalization agent facilitating in vivo combined chemo/thermo therapy

Carbon nanotubes (CNTs) have shown intriguing applications in biotechnological and biomedical fields due to their unique shape and properties. However, the fact that unmodified CNTs are prone to aggregation, stunts CNTs applications under physiological conditions. In this research, we found that as little as 1/5th the single walled carbon nanotube (SWCNT) weight of Evans Blue (EB) is capable of dispersing SWCNT as well as facilitating SWCNT functionalization. In view of the binding between EB and albumin, the yielding product (SWCNT/EB) demonstrated extreme stability for weeks under physiological conditions and it can be endowed with a therapeutic ability by simply mixing SWCNT/EB with an albumin based drug. Specifically, the formed SWCNT/EB/albumin/PTX nanocomplex exhibits strong near-infrared (NIR) absorbance, and can serve as an agent for chemo/thermal therapeutic purposes. Our in vivo result reveals that SWCNT/EB/albumin/PTX after being administered into the MDA-MB-435 tumor would effectively ablate the tumor by chemo and photothermal therapy. Such a combined treatment strategy provides remarkable therapeutic outcomes in restraining tumor growth compared to chemo or photothermal therapy alone. Overall, our strategy of dispersing SWCNTs by EB can be used as a platform for carrying other drugs or functional genes with the aid of albumin to treat diseases. The present study opens new opportunities in surface modification of SWCNTs for future clinical disease treatment.

Polymeric Micelle Platform for Multimodal Tomographic Imaging to Detect Scirrhous Gastric Cancer

Scirrhous gastric cancer (SGC) is a recalcitrant tumor, which is among the most lethal cancers. A critical issue for the improvement of SGC prognosis is the lack of an effective imaging method for accurate detection and diagnosis. Because combined nuclear medicine imaging with magnetic resonance imaging (MRI) has the ability to detect cancer with high sensitivity, and quantitation and spatial resolution, it has potential to overcome the issues with SGC detection. Herein, we designed and synthesized a new block copolymer poly(ethylene glycol)-b-poly(γ-benzyl l-glutamate) linked with a chelator 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid (DOTA-PEG-b-PBLG) to provide a platform for multimodal tomographic imaging. We then successfully prepared DOTA-functionalized polymeric micelles (DOTA/m) measuring 30 nm in diameter, which is an appropriate size to penetrate deeply into tumors with thick fibrosis, including SGC. ¹¹¹In-labeled DOTA/m highly accumulated in Colon-26 tumors (mouse colon cancer with hyperpermeability), but also in OCUM-2 M LN tumors (SGC with hypopermeability), clearly depicting both tumors by single photon emission computed tomography (SPECT). Gd-labeled DOTA/m clearly visualized OCUM-2 M LN tumors by MRI with high spatial resolution. Moreover, ¹¹¹In/Gd-labeled micelles, as well as the mixture of ¹¹¹In- and Gd-labeled DOTA/m demonstrated the capability of this system for selective multimodal SPECT/MR imaging of SCG. Our findings support ¹¹¹In/Gd-DOTA-labeled micelles as a clinical translationable modality for multimodal tomographic imaging capable of detecting SGC.

Delivery of tumor-homing TRAIL sensitizer with long-acting TRAIL as a therapy for TRAIL-resistant tumors

Tumor necrosis factor-related apoptosis inducing ligand (TRAIL) has attracted great interest as a cancer therapy because it selectively induces death receptor (DR)-mediated apoptosis in cancer cells while sparing normal tissue. However, recombinant human TRAIL demonstrates limited therapeutic efficacy in clinical trials, possibly due to TRAIL-resistance of primary cancers and its inherent short half-life. Here we introduce drug delivery approaches to maximize in vivo potency of TRAIL in TRAIL-resistant tumor xenografts by (1) extending the half-life of the ligand with PEGylated TRAIL (TRAILPEG) and (2) concentrating a TRAIL sensitizer, selected from in vitro screening, in tumors via tumor-homing nanoparticles. Antitumor efficacy of TRAILPEG with tumor-homing sensitizer was evaluated in HCT116 and HT-29 colon xenografts. Western blot, real-time PCR, immunohistochemistry and cell viability assays were employed to investigate mechanisms of action and antitumor efficacy of the combination. We discovered that doxorubicin (DOX) sensitizes TRAIL-resistant HT-29 colon cancer cells to TRAIL by upregulating mRNA expression of DR5 by 60% in vitro. Intravenously administered free DOX does not effectively upregulate DR5 in tumor tissues nor demonstrate synergy with TRAILPEG in HT-29 xenografts, but rather introduces significant systemic toxicity. Alternatively, when DOX was encapsulated in hyaluronic acid-based nanoparticles (HAC/DOX) and intravenously administered with TRAILPEG, DR-mediated apoptosis was potentiated in HT-29 tumors by upregulating DR5 protein expression by 70% and initiating both extrinsic and intrinsic apoptotic pathways with reduced systemic toxicity compared to HAC/DOX or free DOX combined with TRAILPEG (80% vs. 40% survival rate; 75% vs. 34% tumor growth inhibition). This study demonstrates a unique approach to overcome TRAIL-based therapy drawbacks using sequential administration of a tumor-homing TRAIL sensitizer and long-acting TRAILPEG.

Tunable Luminescent Carbon Nanospheres with Well-Defined Nanoscale Chemistry for Synchronized Imaging and Therapy

In this work, we demonstrate the significance of defined surface chemistry in synthesizing luminescent carbon nanomaterials (LCN) with the capability to perform dual functions (i.e., diagnostic imaging and therapy). The surface chemistry of LCN has been tailored to achieve two different varieties: one that has a thermoresponsive polymer and aids in the controlled delivery of drugs, and the other that has fluorescence emission both in the visible and near-infrared (NIR) region and can be explored for advanced diagnostic modes. Although these particles are synthesized using simple, yet scalable hydrothermal methods, they exhibit remarkable stability, photoluminescence and biocompatibility. The photoluminescence properties of these materials are tunable through careful choice of surface-passivating agents and can be exploited for both visible and NIR imaging. Here the synthetic strategy demonstrates the possibility to incorporate a potent antimetastatic agent for inhibiting melanomas in vitro. Since both particles are Raman active, their dispersion on skin surface is reported with Raman imaging and utilizing photoluminescence, their depth penetration is analysed using fluorescence 3D imaging. Our results indicate a new generation of tunable carbon-based probes for diagnosis, therapy or both.

Image-guided synergistic photothermal therapy using photoresponsive imaging agent-loaded graphene-based nanosheets

We report the image-guided synergistic photothermal antitumor effects of photoresponsive near-infrared (NIR) imaging agent, indocyanine green (ICG), by loading onto hyaluronic acid-anchored, reduced graphene oxide (HArGO) nanosheets. Loading of ICG onto either rGO (ICG/rGO) or HArGO (ICG/HArGO) substantially improved the photostability of photoresponsive ICG upon NIR irradiation. After 1min of irradiation, the NIR absorption peak of ICG almost disappeared whereas the peak of ICG on rGO or HArGO was retained even after 5min of irradiation. Compared with plain rGO, HArGO provided greater cellular delivery of ICG and photothermal tumor cell-killing effects upon laser irradiation in CD44-positive KB cells. The temperature of cell suspensions treated with ICG/HArGO was 2.4-fold higher than that of cells treated with free ICG. Molecular imaging revealed that intravenously administered ICG/HArGO accumulated in KB tumor tissues higher than ICG/rGO or free ICG. Local temperatures in tumor tissues of laser-irradiated KB cell-bearing nude mice were highest in those intravenously administered ICG/HArGO, and were sufficient to trigger thermal-induced complete tumor ablation. Immunohistologically stained tumors also showed the highest percentages of apoptotic cells in the group treated with ICG/HArGO. These results suggest that photoresponsive ICG-loaded HArGO nanosheets could serve as a potential theranostic nano-platform for image-guided and synergistic photothermal antitumor therapy.

Surface Functionalization of Chemically Reduced Graphene Oxide for Targeted Photodynamic Therapy

In this study, using chemically reduced graphene oxide (GO) as a model nanocarbon, we successfully developed a facile surface-functionalization strategy of nanocarbons to allow both biocompatibility and receptor targeted drug delivery. Polyvinylpyrrolidone (PVP) coating improves aqueous dispersibility and biocompatibility of GO, and provides anchoring sites for ACDCRGDCFCG peptide (RGD4C). Aromatic photosensitizer chlorin e6 (Ce6) can be effectively loaded into the rGO-PVP-RGD system via hydrophobic interactions and π-π stacking. The nanodelivery system can significantly increase the accumulation of Ce6 in tumor cells and lead to an improved photodynamic therapy (PDT) efficacy as compared to Ce6 alone. The facile surface functionalization strategy can be applied to other nanomaterials such as carbon nanotubes, and inorganic nanomaterials.

Water-soluble hyaluronic acid–hybridized polyaniline nanoparticles for effectively targeted photothermal therapy

Water-soluble hyaluronic acid–hybridized polyaniline nanoparticles show effective photothermal ablation of cancer with targeted specificity.

A polymeric conjugate foreignizing tumor cells for targeted immunotherapy in vivo

Antigen-specific CD8(+) cytotoxic T lymphocytes (CTLs) are key elements of immunological rejection in transplantation as well as cancer immunotherapy. Most tumors, however, are not immunologically rejected because they have self antigens, which are not recognized as the foreigner by CTLs. In this study, we hypothesized that "foreignizing" tumor cells by delivering non-self foreign antigens into the tumors would result in rejection by foreign antigen-reactive CTLs. As the model system to foreignize the tumors, we prepared a polymeric conjugate consisting of hyaluronic acid as the CD44(+) tumor-targeting ligand and ovalbumin (OVA) as a foreign antigen. When the conjugate was treated with CD44(high) TC-1 tumor cells, it was effectively taken up and allowed for displaying of antigenic OVA257-264 peptide at MHC class I on the surface of the cells. In addition, the conjugate was effectively accumulated into tumor tissue after its systemic administration to mice which are immunized with a vaccine for a vaccinia virus expressing OVA to generate OVA257-264 specific CTLs, resulting in substantial inhibition of tumor growth. Overall, these results suggest that the polymeric conjugates bearing foreign antigens may be innovative and promising cancer immunotherapeutic agents by foreignizing tumor cells, leading to immunological rejection.

Hyaluronan nanoparticles bearing γ-secretase inhibitor: in vivo therapeutic effects on rheumatoid arthritis

γ-Secretase inhibitors which prevent Notch activation are emerging as potent therapeutics for various inflammatory diseases, including ischemic stroke and rheumatoid arthritis. However, their indiscriminate distribution in the body causes serious side effects after systemic administration, since Notch proteins are ubiquitous receptors that play an important role in cellular functions such as differentiation, proliferation, and apoptosis. In this study, hyaluronan nanoparticles (HA-NPs) bearing a γ-secretase inhibitor (DAPT) were prepared as potential therapeutics for rheumatoid arthritis. In vivo biodistribution of the DAPT-loaded HA-NPs (DNPs), labeled with near-infrared dye, were observed using a non-invasive optical imaging system after systemic administration to a collagen-induced arthritis (CIA) mouse model. The results demonstrated that DNPs were effectively accumulated at the inflamed joint of the CIA mice. From the in vivo therapeutic efficacy tests, DNPs (1mg DAPT/kg) significantly attenuated the severity of RA induction compared to DAPT alone (2mg/kg), which was judged from clinical scores, tissue damage, and neutrophil infiltration. In addition, DNPs dramatically reduced the production of pro-inflammatory cytokines (TNF-α, IFN-γ, MCP-1, and IL-6, -12, -17) and collagen-specific auto-antibodies (IgG1 and IgG2a) in the serum of the CIA mice. These results suggest that DNPs have potential as therapeutics for rheumatoid arthritis.

The Aβ peptide forms non-amyloid fibrils in the presence of carbon nanotubes

Carbon nanotubes have specific properties that make them potentially useful in biomedicine and biotechnology. However, carbon nanotubes may themselves be toxic, making it imperative to understand how carbon nanotubes interact with biomolecules such as proteins. Here, we used NMR, CD, and ThT/fluorescence spectroscopy together with AFM imaging to study pH-dependent molecular interactions between single walled carbon nanotubes (SWNTs) and the amyloid-beta (Aβ) peptide. The aggregation of the Aβ peptide, first into oligomers and later into amyloid fibrils, is considered to be the toxic mechanism behind Alzheimer's disease. We found that SWNTs direct the Aβ peptides to form a new class of β-sheet-rich yet non-amyloid fibrils.

Targeted therapeutic nanotubes influence the viscoelasticity of cancer cells to overcome drug resistance

Resistance to chemotherapy is the primary cause of treatment failure in over 90% of cancer patients in the clinic. Research in nanotechnology-based therapeutic alternatives has helped provide innovative and promising strategies to overcome multidrug resistance (MDR). By targeting CD44-overexpressing MDR cancer cells, we have developed in a single-step a self-assembled, self-targetable, therapeutic semiconducting single-walled carbon nanotube (sSWCNT) drug delivery system that can deliver chemotherapeutic agents to both drug-sensitive OVCAR8 and resistant OVCAR8/ADR cancer cells. The novel nanoformula with a cholanic acid-derivatized hyaluronic acid (CAHA) biopolymer wrapped around a sSWCNT and loaded with doxorubicin (DOX), CAHA-sSWCNT-DOX, is much more effective in killing drug-resistant cancer cells compared to the free DOX and phospholipid PEG (PL-PEG)-modified sSWCNT formula, PEG-sSWCNT-DOX. The CAHA-sSWCNT-DOX affects the viscoelastic property more than free DOX and PL-PEG-sSWCNT-DOX, which in turn allows more drug molecules to be internalized. Intravenous injection of CAHA-sSWCNT-DOX (12 mg/kg DOX equivalent) followed by 808 nm laser irradiation (1 W/cm(2), 90 s) led to complete tumor eradication in a subcutaneous OVCAR8/ADR drug-resistant xenograft model, while free DOX alone failed to delay tumor growth. Our newly developed CAHA-sSWCNT-DOX nanoformula, which delivers therapeutics and acts as a sensitizer to influence drug uptake and induce apoptosis with minimal resistance factor, provides a novel effective means of counteracting the phenomenon of multidrug resistance.

Hyaluronic acid conjugates as vectors for the active targeting of drugs, genes and nanocomposites in cancer treatment

Hyaluronic acid (HA) is a naturally-occurring glycosaminoglycan and a major component of the extracellular matrix. Low levels of the hyaluronic acid receptor CD44 are found on the surface of epithelial, hematopoietic, and neuronal cells; it is overexpressed in many cancer cells, and in particular in tumor-initiating cells. HA has recently attracted considerable interest in the field of developing drug delivery systems, having been used, as such or encapsulated in different types of nanoassembly, as ligand to prepare nano-platforms for actively targeting drugs, genes, and diagnostic agents. This review describes recent progress made with the several chemical strategies adopted to synthesize conjugates and prepare novel delivery systems with improved behaviors.

In vitro and in vivo studies on the transport of PEGylated silica nanoparticles across the blood-brain barrier

Transport of PEGylated silica nanoparticles (PSiNPs) with diameters of 100, 50, and 25 nm across the blood-brain barrier (BBB) was evaluated using an in vitro BBB model based on mouse cerebral endothelial cells (bEnd.3) cultured on transwell inserts within a chamber. In vivo animal experiments were further performed by noninvasive in vivo imaging and ex vivo optical imaging after injection via carotid artery. Confocal fluorescence studies were carried out to evaluate the uptake of PSiNPs by brain endothelial cells. The results showed that PSiNPs can traverse the BBB in vitro and in vivo. The transport efficiency of PSiNPs across BBB was found to be size-dependent, with increased particle size resulting in decreased efficiency. This work points to the potential application of small sized silica nanoparticles in brain imaging or drug delivery.

Recent advances in nanoparticle-based nuclear imaging of cancers

Nuclear imaging techniques that include positron emission tomography (PET) and single-photon computed tomography have found great success in the clinic because of their inherent high sensitivity. Radionuclide imaging is the most popular form of imaging to be used for molecular imaging in oncology. While many types of molecules have been used for radionuclide-based molecular imaging, there has been a great interest in developing newer nanomaterials for use in clinic, especially for cancer diagnosis and treatment. Nanomaterials have unique physical properties which allow them to be used as imaging probes to locate and identify cancerous lesions. Over the past decade, a great number of nanoparticles have been developed for radionuclide imaging of cancer. This chapter reviews the different kinds of nanomaterials, both organic and inorganic, which are currently being researched for as potential agents for nuclear imaging of variety of cancers. Several radiolabeled multifunctional nanocarriers have been extremely successful for the detection of cancer in preclinical models. So far, significant progress has been achieved in nanoparticle structure design, in vitro/in vivo trafficking, and in vivo fate mapping by using PET. There is a great need for the development of newer nanoparticles, which improve active targeting and quantify new biomarkers for early disease detection and possible prevention of cancer.