Ultrasound Triggered Tumor Oxygenation with Oxygen-Shuttle Nanoperfluorocarbon to Overcome Hypoxia-Associated Resistance in Cancer Therapies

Tumor hypoxia is known to be one of critical reasons that limit the efficacy of cancer therapies, particularly photodynamic therapy (PDT) and radiotherapy (RT) in which oxygen is needed in the process of cancer cell destruction. Herein, taking advantages of the great biocompatibility and high oxygen dissolving ability of perfluorocarbon (PFC), we develop an innovative strategy to modulate the tumor hypoxic microenvironment using nano-PFC as an oxygen shuttle for ultrasound triggered tumor-specific delivery of oxygen. In our experiment, nanodroplets of PFC stabilized by albumin are intravenously injected into tumor-bearing mice under hyperoxic breathing. With a low-power clinically adapted ultrasound transducer applied on their tumor, PFC nanodroplets that adsorb oxygen in the lung would rapidly release oxygen in the tumor under ultrasound stimulation, and then circulate back into the lung for reoxygenation. Such repeated cycles would result in dramatically enhanced tumor oxygenation and thus remarkably improved therapeutic outcomes in both PDT and RT treatment of tumors. Importantly, our strategy may be applied for different types of tumor models. Hence, this work presents a simple strategy to promote tumor oxygenation with great efficiency using agents and instruments readily available in the clinic, so as to overcome the hypoxia-associated resistance in cancer treatment

Drug-Induced Self-Assembly of Modified Albumins as Nano-theranostics for Tumor-Targeted Combination Therapy

Paclitaxel (PTX) can bind to human serum albumin (HSA) <i>via</i> hydrophobic interaction, forming Abraxane, which is a U.S. Food and Drug Administration (FDA) approved effective antitumor nanomedicine drug. Herein, the effective antitumor drug PTX is used to induce the self-assembly of HSA modified with either a photosensitizer chlorin e6 (Ce6), which at the same time serves as a chelating agent for Mn²⁺ to enable magnetic resonance imaging, or acyclic Arg-Gly-Asp (cRGDyK) peptide that targets αvβ3-integrin overexpressed on tumor angiogenic endothelium. Two types of tumor-targeting theranostic nanoparticles are constructed, either by coassembly of both HSA-Ce6 and HSA-RGD simultaneously or by forming an HSA-Ce6@HSA-RGD core–shell structure, with the assistance of PTX-induced albumin aggregation. Such albumin-based nanoparticles on one hand could targetαvβ3-integrin, as evidenced by both <i>in vitro</i> and <i>in vivo</i> experiments, and on the other hand enable combined photodynamic/chemotherapy, which offers remarkably improved therapeutic efficacy to kill cancer in comparison to the respective monotherapies. Our work presents a new type of tumor-targeted multifunctional albumin-based nanoparticles by drug-induced self-assembly, which is a rather simple method without any sophisticated chemistry or materials engineering and is promising for multimodel imaging-guided combination therapy of cancer

Patterned Substrates of Nano-Graphene Oxide Mediating Highly Localized and Efficient Gene Delivery

A facile approach was developed to fabricate patterned substrates of nano-graphene oxide, demonstrating highly localized and efficient gene delivery to multiple cell lines in a substrate-mediated manner. The GO substrates served as a valid platform to preconcentrate PEI/pDNA complexes and maintain their gradual releasing for a relatively long period of time. Our approach allowed successful gene delivery in selected groups of cells on the stripe-patterned GO substrates, without transfecting their neighbor cells directly cultured on glass. These GO substrates exhibited excellent biocompatibility and enabled effective gene transfection for various cell lines including stem cells, thus promising important applications in stem cell research and tissue engineering

Photosensitizer Decorated Red Blood Cells as an Ultrasensitive Light-Responsive Drug Delivery System

Red blood cells (RBCs) have been widely explored as a natural drug delivery system (DDS) owing to their inherent biocompatibility and large internal cavities to load various types of functional molecules. Herein, we uncover that a photosensitizer, chlorin e6 (Ce6), could be decorated into the membrane of RBCs upon simple mixing, without affecting the membrane integrity and stability in dark. Upon light irradiation with a rather low power density, the singlet oxygen generated by Ce6 would lead to rather efficient disruption of RBC membrane. With doxorubicin (DOX), a typical chemotherapy drug, as the model, we engineer a unique type of light-responsive RBC-based DDS by decorating Ce6 on the cell membrane and loading DOX inside cells. The light triggered cell membrane breakdown would thus trigger instant release of DOX, enabling light-controlled chemotherapy with great specificity. Beyond that our RBC system could also be utilized for loading of larger biomolecules such as enzymes, whose release as well as catalytic function is also controlled by light. Our work thus presents a unique type of biocompatible cell-based DDS that can be precisely controlled by mild external stimuli, promising not only for cancer therapy but also for other potential applications in biotechnologies

Functionalization of Graphene Oxide Generates a Unique Interface for Selective Serum Protein Interactions

Potential toxicity and risk of inducing allergy and inflammation have always been a great concern of using nanomaterials in biomedicine. In this work, we investigate the serum behaviors of graphene oxide (GO) and how such behaviors are affected by its surface modification such as PEGylation. The results show that, when incubated with human sera, unfunctionalized GO adsorbs a significant amount of serum proteins and strongly induces complement C3 cleavage (part of the complement activation cascade), generating C3a/C3a­(des-Arg), an anaphylatoxin involved in local inflammatory responses, whereas PEGylated nano-GO (nGO-PEG) exhibits dramatic reductions in both protein binding in general and complement C3 activation. Moreover, we uncover that PEGylation on GO nanosheets apparently generates an interesting nanointerface, evidenced by the acquired certain selectivity and increased binding capacities of nGO-PEG toward a few serum proteins. Further mass spectrometry analysis identifies six nGO-PEG binding proteins, four of which are immune-related factors, including C3a/C3a­(des-Arg). A series of Western blot analysis demonstrate that nGO-PEG binds up to 2-fold amount of C3a/C3a­(des-Arg) than unfunctionalized GO, and can efficiently decrease the level of C3a/C3a­(des-Arg) in treated sera, preventing the normal interaction of C3a with its receptor. In a proof-of-concept experiment, we demonstrate that nGO-PEG may serve to help eliminate the C3a/C3a­(des-Arg) induced by other nanomaterials such as as-made GO, indicating a new strategy to modulate the immune responses evoked by one nanomaterial through the addition of another type of nanomaterial. Our results highlight the great importance of nanobio interface in regulating the biological effects of nanomaterials

Graphene Oxide Selectively Enhances Thermostability of Trypsin

In the past few years, graphene and its derivative, graphene oxide (GO), have been extensively studied for their applications in biotechnology. In our previous work, we reported certain PEGylated GOs (GO-PEGs) can selectively promote trypsin activity and enhance its thermostability. To further explore this, here we synthesized a series of GO-PEGs with varying PEGylation degrees. Enzymatic activity assay shows that both GO and GO-PEGs can protect trypsin, but not chymotrypsin, from thermal denaturation at high temperature. Surprisingly, the lower the PEGylation degree, the better the protection, and GO as well as the GO-PEG with the lowest PEGylation degree show the highest protection efficiency (∼70% retained activity at 70 °C). Fluorescence spectroscopy analysis shows that GO/GO-PEGs have strong interactions with trypsin. Molecular Dynamics (MD) simulation results reveal that trypsin is adsorbed onto the surface of GO through its cationic residues and hydrophilic residues. Different from chymotrypsin adsorbed on GO, the active site of trypsin is covered by GO. MD simulation at high temperature shows that, through such interaction with GO, trypsin’s active site is therefore stabilized and protected by GO. Our work not only illustrates the promising potential of GO/GO-PEGs as efficient, selective modulators for trypsin, but also provides the interaction mechanism of GO with specific proteins at the nano–bio interface

Theranostic Liposomes with Hypoxia-Activated Prodrug to Effectively Destruct Hypoxic Tumors Post-Photodynamic Therapy

Photodynamic therapy (PDT), a noninvasive cancer therapeutic method triggered by light, would lead to severe tumor hypoxia after treatment. Utilizing a hypoxia-activated prodrug, AQ4N, which only shows toxicity to cancer cells under hypoxic environment, herein, a multipurpose liposome is prepared by encapsulating hydrophilic AQ4N and hydrophobic hexadecylamine conjugated chlorin e6 (<i>h</i>Ce6), a photosensitizer, into its aqueous cavity and hydrophobic bilayer, respectively. After chelating a ⁶⁴Cu isotope with Ce6, the obtained AQ4N-⁶⁴Cu-<i>h</i>Ce6-liposome is demonstrated to be an effective imaging probe for <i>in vivo</i> positron emission tomography, which together with <i>in vivo</i> fluorescence and photoacoustic imaging uncovers efficient passive homing of those liposomes after intravenous injection. After being irradiated with the 660 nm light-emitting diode light, the tumor bearing mice with injection of AQ4N-<i>h</i>Ce6-liposome show severe tumor hypoxia, which in turn would trigger activation of AQ4N, and finally contributes to remarkably improved cancer treatment outcomes <i>via</i> sequential PDT and hypoxia-activated chemotherapy. This work highlights a liposome-based theranostic nanomedicine that could utilize tumor hypoxia, a side effect of PDT, to trigger chemotherapy, resulting in greatly improved efficacy compared to conventional cancer PDT

Antigen-Loaded Upconversion Nanoparticles for Dendritic Cell Stimulation, Tracking, and Vaccination in Dendritic Cell-Based Immunotherapy

A dendritic cell (DC) vaccine, which is based on efficient antigen delivery into DCs and migration of antigen-pulsed DCs to draining lymph nodes after vaccination, is an effective strategy in initiating CD8⁺ T cell immunity for immunotherapy. Herein, antigen-loaded upconversion nanoparticles (UCNPs) are used to label and stimulate DCs, which could be precisely tracked after being injected into animals and induce an antigen-specific immune response. It is discovered that a model antigen, ovalbumin (OVA), could be adsorbed on the surface of dual-polymer-coated UCNPs <i>via</i> electrostatic interaction, forming nanoparticle–antigen complexes, which are efficiently engulfed by DCs and induce DC maturation and cytokine release. Highly sensitive <i>in vivo</i> upconversion luminescence (UCL) imaging of nanoparticle-labeled DCs is successfully carried out, observing the homing of DCs to draining lymph nodes after injection. In addition, strong antigen-specific immune responses including enhanced T cell proliferation, interferon gamma (IFN-γ) production, and cytotoxic T lymphocyte (CTL)-mediated responses are induced by a nanoparticle-pulsed DC vaccine, which is promising for DC-based immunotherapy potentially against cancer

Graphene Oxide–Silver Nanocomposite As a Highly Effective Antibacterial Agent with Species-Specific Mechanisms

Recently, graphene oxide (GO) based nanocomposites have raised significant interests in many different areas, one of which being antibacterial agents where sliver nanoparticle (AgNPs) anchored GO (GO–Ag) has shown promising potential. However, to our best knowledge, factors affecting its antibacterial activity as well as the underlying mechanism remain unclear. In this study, we fabricate GO–Ag nanocomposites with different AgNPs to GO ratios and carefully investigate their antibacterial activities against both the Gram-negative (G−) bacteria Escherichia coli (E. coli) and the Gram-positive (G+) bacteria Staphylococcus aureus (S. aureus). We discover that, compared to AgNPs, GO–Ag nanocomposite with an optimal ratio of AgNPs to GO is much more effective and shows synergistically enhanced, strong antibacterial activities at rather low dose (2.5 μg/mL). The GO–Ag nanocomposite is more toxic to E. coli than that to S. aureus. The antibacterial effects of GO–Ag nanocomposite are further investigated, revealing distinct, species-specific mechanisms. The results demonstrate that GO–Ag nanocomposite functions as a bactericide against the G– E. coli through disrupting bacterial cell wall integrity, whereas it exhibits bacteriostatic effect on the G+ S. aureus by dramatically inhibiting cell division. Our work not only highlights the great promise of using GO–Ag as a highly effective antibacterial agent but also provides more in-depth understandings of the interactions between microorganisms and GO-based nanocomposites

Seeded Growth of Cu_2–<i>x</i>Se Nanocrystals and Their Size-Dependent Phototherapeutic Effect

Doped semiconductors supporting localized surface plasmon resonances, such as nonstoichiometric copper chalcogenides Cu_2–<i>x</i>Se, have been intensively researched for their potential applications in photoacoustic imaging and photothermal therapy. For these self-doped nanoparticles, their physicochemical attributes such as size and surface chemistry will not only affect their cellular uptake and biodistribution but also influence their own optical properties. Thus, optimization of the physicochemical properties is crucial for their nanobio-applications. Through a seeded growth approach, aqueous phase synthesis of monodisperse Cu_2–<i>x</i>Se with various sizes has been developed for the first time. Taking three different sized Cu_2–<i>x</i>Se NPs (35, 65, and 105 nm in diameter) as examples, their size-dependent optical cross-section, photothermal property, and cellular cytotoxicity have been investigated, and the 65 nm one displays the largest optical cross-section at 21.57 L g^–1 cm^–1 and best photothermal property per unit mass. In addition, Cu_2–<i>x</i>Se exhibits a size-dependent reactive oxygen species generation effect that is inversely proportional to their diameters. Finally, on the basis of optical property and cytotoxicity optimizations, the photothermal cancer cell ablation ability and potential use of Cu_2–<i>x</i>Se NPs as photoacoustic contrast enhancing agent has been demonstrated in vivo