Protection and promotion of UV radiation-induced liposome leakage via DNA-directed assembly with gold nanoparticles

Plasmonic-Driven Regulation of Biomolecular Activity In Situ

Selective and remote manipulation of activity for biomolecules, including protein, DNA, and lipids, is crucial to elucidate their molecular function and to develop biomedical applications. While advances in tool development, such as optogenetics, have significantly impacted these directions, the requirement for genetic modification significantly limits their therapeutic applications. Plasmonic nanoparticle heating has brought new opportunities to the field, as hot nanoparticles are unique point heat sources at the nanoscale. In this review, we summarize fundamental engineering problems such as plasmonic heating and the resulting biomolecular responses. We highlight the biological responses and applications of manipulating biomolecules and provide perspectives for future directions in the field.

Construction Strategy of Functionalized Liposomes and Multidimensional Application

Liposomes are widely used in the biological field due to their good biocompatibility and surface modification properties. With the development of biochemistry and material science, many liposome structures and their surface functional components have been modified and optimized one by one, pushing the liposome platform from traditional to functionalized and intelligent, which will better satisfy and expand the needs of scientific research. However, a main limiting factor effecting the efficiency of liposomes is the complicated environmental conditions in the living body. Currently, in order to overcome the above problem, functionalized liposomes have become a very promising strategy. In this paper, binding strategies of liposomes with four main functional elements, namely nucleic acids, antibodies, peptides, and stimuli-responsive motif have been summarized for the first time. In addition, based on the construction characteristics of functionalized liposomes, such as drug-carrying, targeting, long-circulating, and stimulus-responsive properties, a comprehensive overview of their features and respective research progress are presented. Finally, the paper critically presents the limitations of these functionalized liposomes in the current applications and also prospectively suggests the future development directions, aiming to accelerate realization of their industrialization.

Stimuli-triggered Self-Assembly of Gold Nanoparticles: Recent Advances in Fabrication and Biomedical Applications

Gold nanoparticles have been widely used in engineering, material chemistry, and biomedical applications owing to their ease of synthesis and functionalization, localized surface plasmon resonance (LSPR), great chemical stability, excellent biocompatibility, tunable optical and electronic property. In recent years, the decoration and modification of gold nanoparticles with small molecules, ligands, surfactants, peptides, DNA/RNA, and proteins have been systematically studied. In this review, we summarize the recent approaches on stimuli-triggered self-assembly of gold nanoparticles and introduce the breakthrough of gold nanoparticles in disease diagnosis and treatment. Finally, we discuss the current challenge and future prospective of stimuli-responsive gold nanoparticles for biomedical applications.

Inorganic Nanoparticles as Radiosensitizers for Cancer Treatment

Nanotechnology has expanded what can be achieved in our approach to cancer treatment. The ability to produce and engineer functional nanoparticle formulations to elicit higher incidences of tumor cell radiolysis has resulted in substantial improvements in cancer cell eradication while also permitting multi-modal biomedical functionalities. These radiosensitive nanomaterials utilize material characteristics, such as radio-blocking/absorbing high-Z atomic number elements, to mediate localized effects from therapeutic irradiation. These materials thereby allow subsequent scattered or emitted radiation to produce direct (e.g., damage to genetic materials) or indirect (e.g., protein oxidation, reactive oxygen species formation) damage to tumor cells. Using nanomaterials that activate under certain physiologic conditions, such as the tumor microenvironment, can selectively target tumor cells. These characteristics, combined with biological interactions that can target the tumor environment, allow for localized radio-sensitization while mitigating damage to healthy cells. This review explores the various nanomaterial formulations utilized in cancer radiosensitivity research. Emphasis on inorganic nanomaterials showcases the specific material characteristics that enable higher incidences of radiation while ensuring localized cancer targeting based on tumor microenvironment activation. The aim of this review is to guide future research in cancer radiosensitization using nanomaterial formulations and to detail common approaches to its treatment, as well as their relations to commonly implemented radiotherapy techniques.

Nanotechnology enabled radioprotectants to reduce space radiation-induced reactive oxidative species

Interest in space exploration has seen substantial growth following recent launch and operation of modern space technologies. In particular, the possibility of travel beyond low earth orbit is seeing sustained support. However, future deep space travel requires addressing health concerns for crews under continuous, longer-term exposure to adverse environmental conditions. Among these challenges, radiation-induced health issues are a major concern. Their potential to induce chronic illness is further potentiated by the microgravity environment. While investigations into the physiological effects of space radiation are still under investigation, studies on model ionizing radiation conditions, in earth and micro-gravity conditions, can provide needed insight into relevant processes. Substantial formation of high, sustained reactive oxygen species (ROS) evolution during radiation exposure is a clear threat to physiological health of space travelers, producing indirect damage to various cell structures and requiring therapeutic address. Radioprotection toward the skeletal system components is essential to astronaut health, due to the high radio-absorption cross-section of bone mineral and local hematopoiesis. Nanotechnology can potentially function as radioprotectant and radiomitigating agents toward ROS and direct radiation damage. Nanoparticle compositions such as gold, silver, platinum, carbon-based materials, silica, transition metal dichalcogenides, and ceria have all shown potential as viable radioprotectants to mitigate space radiation effects with nanoceria further showing the ability to protect genetic material from oxidative damage in several studies. As research into space radiation-induced health problems develops, this review intends to provide insights into the nanomaterial design to ameliorate pathological effects from ionizing radiation exposure. This article is categorized under: Therapeutic Approaches and Drug Discovery > Emerging Technologies Nanotechnology Approaches to Biology > Nanoscale Systems in Biology Nanotechnology Approaches to Biology > Cells at the Nanoscale Therapeutic Approaches and Drug Discovery > Nanomedicine for Oncologic Disease.

Engineering Nano- and Microparticles as Oral Delivery Vehicles to Promote Intestinal Lymphatic Drug Transport

Targeted oral delivery of a drug via the intestinal lymphatic system (ILS) has the advantages of protecting against hepatic first-pass metabolism of the drug and improving its pharmacokinetic performance. It is also a promising route for the oral delivery of vaccines and therapeutic agents to induce mucosal immune responses and treat lymphatic diseases, respectively. This article describes the anatomical structures and physiological characteristics of the ILS, with an emphasis on enterocytes and microfold (M) cells, which are the main gateways for the transport of particulate delivery vehicles across the intestinal epithelium into the lymphatics. A comprehensive overview of recent advances in the rational engineering of particulate vehicles, along with the challenges and opportunities that they present for improving ILS drug delivery, is provided, and the mechanisms by which such vehicles target and transport through enterocytes or M cells are discussed. The use of naturally sourced materials, such as yeast microcapsules and their derived polymeric β-glucans, as novel ILS-targeting delivery vehicles is also reviewed. Such use is the focus of an emerging field of research. Their potential use in the oral delivery of nucleic acids, such as mRNA vaccines, is proposed.

Smart Stimuli-Responsive Liposomal Nanohybrid Systems: A Critical Review of Theranostic Behavior in Cancer

The epoch of nanotechnology has authorized novel investigation strategies in the area of drug delivery. Liposomes are attractive biomimetic nanocarriers characterized by their biocompatibility, high loading capacity, and their ability to reduce encapsulated drug toxicity. Nevertheless, various limitations including physical instability, lack of site specificity, and low targeting abilities have impeded the use of solo liposomes. Metal nanocarriers are emerging moieties that can enhance the therapeutic activity of many drugs with improved release and targeted potential, yet numerous barriers, such as colloidal instability, cellular toxicity, and poor cellular uptake, restrain their applicability in vivo. The empire of nanohybrid systems has shelled to overcome these curbs and to combine the criteria of liposomes and metal nanocarriers for successful theranostic delivery. Metallic moieties can be embedded or functionalized on the liposomal systems. The current review sheds light on different liposomal-metal nanohybrid systems that were designed as cellular bearers for therapeutic agents, delivering them to their targeted terminus to combat one of the most widely recognized diseases, cancer.

Development of a multifunctional gold nanoplatform for combined chemo-photothermal therapy against oral cancer

Aim: To design and fabricate a multifunctional drug-delivery nanoplatform for oral cancer therapy. Materials & methods: Polyethylene glycol-stabilized, PDPN antibody (PDPN Ab)- and doxorubicin (DOX)-conjugated gold nanoparticles (AuNPs) were prepared and evaluated for their cytotoxicity and antitumor efficacy in both chemotherapy and photothermal therapy. Results: The obtained (PDPN Ab)-AuNP-DOX system presents low toxicity, a high drug loading capacity and cellular uptake efficiency. Both in vitro and in vivo experiments demonstrate that (PDPN Ab)-AuNP-DOX has enhanced antitumor efficacy. Treatment with (PDPN Ab)-AuNP-DOX combined with laser irradiation exhibits superior antitumor effects. Conclusion: This (PDPN Ab)-AuNP-DOX system may be used as a versatile drug-delivery nanoplatform for targeted and combined chemo-photothermal therapy against oral cancer.

DNA Oligonucleotide-Functionalized Liposomes: Bioconjugate Chemistry, Biointerfaces, and Applications

Interfacing DNA with liposomes has produced a diverse range of programmable soft materials, devices, and drug delivery vehicles. By simply controlling liposomal composition, bilayer fluidity, lipid domain formation, and surface charge can be systematically varied. Recent development in DNA research has produced not only sophisticated nanostructures but also new functions including ligand binding and catalysis. For noncationic liposomes, a DNA is typically covalently linked to a hydrophobic or lipid moiety that can be inserted into lipid membranes. In this article, we discuss fundamental biointerfaces formed between DNA and noncationic liposomes. The methods to prepare such conjugates and the interactions at the membrane interfaces are also discussed. The effect of DNA lateral diffusion on fluid bilayer membranes and the effect of membrane on DNA assembly are emphasized. DNA hybridization can be programmed to promote fusion of lipid membranes. Representative applications of this conjugate for drug delivery, biosensor development, and directed assembly of materials are briefly described toward the end. Some future research directions are also proposed to further understand this biointerface.

Nanomaterials for Cancer Precision Medicine

Medical science has recently advanced to the point where diagnosis and therapeutics can be carried out with high precision, even at the molecular level. A new field of "precision medicine" has consequently emerged with specific clinical implications and challenges that can be well-addressed by newly developed nanomaterials. Here, a nanoscience approach to precision medicine is provided, with a focus on cancer therapy, based on a new concept of "molecularly-defined cancers." "Next-generation sequencing" is introduced to identify the oncogene that is responsible for a class of cancers. This new approach is fundamentally different from all conventional cancer therapies that rely on diagnosis of the anatomic origins where the tumors are found. To treat cancers at molecular level, a recently developed "microRNA replacement therapy" is applied, utilizing nanocarriers, in order to regulate the driver oncogene, which is the core of cancer precision therapeutics. Furthermore, the outcome of the nanomediated oncogenic regulation has to be accurately assessed by the genetically characterized, patient-derived xenograft models. Cancer therapy in this fashion is a quintessential example of precision medicine, presenting many challenges to the materials communities with new issues in structural design, surface functionalization, gene/drug storage and delivery, cell targeting, and medical imaging.

A Concise Review of Gold Nanoparticles-Based Photo-Responsive Liposomes for Controlled Drug Delivery

The focus of drug delivery is shifting toward smart drug carriers that release the cargo in response to a change in the microenvironment due to an internal or external trigger. As the most clinically successful nanosystem, liposomes naturally come under the spotlight of this trend. This review summarizes the latest development about the design and construction of photo-responsive liposomes with gold nanoparticles for the controlled drug release. Alongside, we overview the mechanism involved in this process and the representative applications.

Incorporating gold nanoclusters and target-directed liposomes as a synergistic amplified colorimetric sensor for HER2-positive breast cancer cell detection

Breast cancer is the second leading cause of cancer-related mortality in women. Successful development of sensitive nanoprobes for breast cancer cell detection is of great importance for breast cancer diagnosis and symptomatic treatment. Herein, inspired by the intrinsic peroxidase property of gold nanoclusters, high loading, and targeting ability of ErbB2/Her2 antibody functionalized liposomes, we report that gold nanoclusters-loaded, target-directed, functionalized liposomes can serve as a robust sensing platform for amplified colorimetric detection of HER2-positive breast cancer cells. This approach allows HER2-positive breast cancer cell identification at high sensitivity with high selectivity. In addition, the colorimetric “readout” offers extra advantages in terms of low-cost, portability, and easy-to-use applications. The practicality of this platform was further proved by successful detection of HER2-positive breast cancer cells in human serum samples and in breast cancer tissue, which indicated our proposed method has potential for application in cancer theranostics.

The Effects of Spacer Length and Composition on Aptamer-Mediated Cell-Specific Targeting with Nanoscale PEGylated Liposomal Doxorubicin

Aptamer-based targeted drug delivery systems have shown significant promise for clinical applications. Although much progress has been made in this area, it remains unclear how PEG coating would affect the selective binding of DNA aptamers and thus influence the overall targeting efficiency. To answer this question, we herein report a systematic investigation of the interactions between PEG and DNA aptamers on the surface of liposomes by using a series of nanoscale liposomal doxorubicin formulations with different DNA aptamer and PEG modifications. We investigated how the spatial size and composition of the spacer molecules affected the targeting ability of the liposome delivery system. We showed that a spacer of appropriate length was critical to overcome the shielding from surrounding PEG molecules in order to achieve the best targeting effect, regardless of the spacer composition. Our findings provide important guidelines for the design of aptamer-based targeted drug delivery systems.

Interfacing Zwitterionic Liposomes with Inorganic Nanomaterials: Surface Forces, Membrane Integrity, and Applications

Zwitterionic phosphocholine (PC) lipids are the main constituent of the mammalian cell membrane. PC bilayers are known for their antifouling properties, yet they are adsorbed by all tested inorganic nanoparticles. This feature article is focused on the developments in my laboratory in the past few years on this topic. The main experimental techniques include fluorescence-based liposome leakage assays, adsorption and desorption, and cryo-TEM. Different materials interact with PC liposomes differently. PC liposomes adsorb on SiO2, followed by membrane fusion with the surface forming supported lipid bilayers. TiO2 and other metal oxides adsorb only intact PC liposomes via lipid phosphate bonding; the steric effect from the choline group hinders subsequent liposome fusion onto the particles. Citrate-capped AuNPs are adsorbed very strongly via van der Waals forces, inducing local gelation. The result is transient liposome leakage upon AuNP adsorption or desorption and AuNP aggregation on the liposome surface. All carbon-based nanomaterials (graphene oxides, carbon nanotubes, and nanodiamond) are adsorbed mainly via hydrogen bonding. The oxidation level of graphene oxide strongly influences the outcome of the final hybrid material. In the context of inorganic nanoparticle adsorption, insights are given regarding the lack of protein adsorption by PC bilayers. These inorganic/lipid hybrid materials can be used for controlled release, drug delivery, and fundamental studies. A few examples of application are covered toward the end, and future perspectives are given.

Highly sensitive turn-on biosensors by regulating fluorescent dye assembly on liposome surfaces

We developed a new self-signaling sensory system built on phospholipid liposomes having H-aggregated R6G dyes on their surface. Selective molecular recognition of a target by the phospholipid displaces R6G from the liposome surface to turn on fluorescence signal. Selective and sensitive detection of neomycin down to 2.3 nM is demonstrated.

Self-healable and reversible liposome leakage by citrate-capped gold nanoparticles: probing the initial adsorption/desorption induced lipid phase transition

We herein report that the adsorption/desorption of citrate-capped gold nanoparticles (AuNPs) transiently causes leakage in fluid phase DOPC liposomes, while the liposomes do not leak with AuNPs capped with mercaptopropionic acid (MPA). Leakage also fails to occur for gel phase DPPC liposomes. Citrate-capped (but not MPA-capped) AuNPs raise the phase transition temperature of DPPC. We conclude that citrate-capped AuNPs interact with the PC liposomes very strongly, inducing a local fluid-to-gel lipid phase transition for DOPC. Leakage takes place during this transition, and the membrane integrity is resumed after the transition. Citrate-capped AuNPs allow stronger van der Waals forces than MPA-capped AuNPs with PC liposomes, since the latter are separated from the liposome surface by the ∼0.3 nm MPA layer.

Gold conjugate-based liposomes with hybrid cluster bomb structure for liver cancer therapy

Hybrid drug delivery system containing both organic and inorganic nanocarriers is expected to achieve its complementary advantages for the aim of improving the performance of antineoplastic drugs in tumor therapy. Here we report the use of liposomes and gold nanoparticles to construct a liposome with a hybrid Cluster Bomb structure and discuss its unique multi-order drug release property for liver tumor treatment. A very simple method is used for the hybrid liposome preparation and involves mixing two solutions containing liposomes loaded with either non-covalent or covalent Paclitaxel (PTX, namely free PTX or PTX-conjugated GNPs, respectively) by different ratio of volume (25:75, 50:50, 25:75, v/v). Various mixed liposomes were tested to determine the optimal conditions for maximum drug delivery. The optimized liposome was then tested using xenograft Heps tumor-bearing mice and showed the best efficacy for chemotherapeutic inhibition of tumor at PTX liposome: PTX-conjugated GNP liposome of 25:75 ratio (v/v). This system allows for simple and easy preparation while providing a more accurate site- and time-release mode for tumor treatment using antitumor drugs.

Stimuli-responsive liposomes for the delivery of nucleic acid therapeutics

Nucleic acid therapeutics (NATs) are valuable tools in the modulation of gene expression in a highly specific manner. So far, NATs have been actively pursued in both pre-clinical and clinical studies to treat diseases such as cancer, infectious and inflammatory diseases. However, the clinical application of NATs remains a considerable challenge owing to their limited cellular uptake, low biological stability, off-target effect, and unfavorable pharmacokinetics. One concept to address these issues is to deliver NATs within stimuli-responsive liposomes, which release their contents of NATs upon encountering environmental changes such as temperature, pH, and ion strength. In this case, before reaching the targeted tissue/organ, NATs are protected from degradation by enzymes and immune system. Once at the area of interest, localized and targeted delivery can be achieved with minimal influence to other parts of the body. Here, we discuss the latest developments and existing challenges in this field.

FROM THE CLINICAL EDITOR

Nucleic acid therapeutics have been shown to enhance or eliminate specific gene expression in experimental research. Unfortunately, clinical applications have so far not been realized due to problems of easy degradation and possible toxicity. The use of nanosized carriers such as liposomes to deliver nucleic acids is one solution to overcome these problems. In this review article the authors describe and discuss the potentials of various trigger-responsive "smart" liposomes, with a view to help other researchers to design better liposomal nucleic acid delivery systems.

Rapid, Reversible Release from Thermosensitive Liposomes Triggered by Near-Infra-Red Light

We present a novel drug carrier consisting of plasmonic hollow gold nanoshells (HGN) chemically tethered to liposomes made temperature sensitive with lysolipids (LTSL). Continuous-wave irradiation by physiologically friendly near infra-red light at 800 nm for 2.5 minutes at laser intensities an order of magnitude below that known to damage skin generates heating localized to the liposome membrane. The heating increases the liposome permeability in an irradiation dose-dependent, but reversible manner, resulting in rapid release of small molecules such as the self-quenching dye carboxyfluorescein or the chemotherapeutic doxorubicin, without raising the bulk temperature. The local rise in nanoshell temperature under laser irradiation was inferred by comparing dye release rates from the LTSL via bulk heating to that induced by irradiation. Laser-irradiation of LTSL enables precise control of contents release with low temperature gradients confined to areas irradiated by the laser focus. The combined effects of rapid local release and localized hyperthermia provide a synergistic effect as shown by a near doubling of androgen resistant PPC-1 prostate cancer cell toxicity compared to the same concentration of free doxorubicin.

Nanodiamond decorated liposomes as highly biocompatible delivery vehicles and a comparison with carbon nanotubes and graphene oxide

Studying interactions between nano-carbons and lipid membranes is important for multiplexed drug delivery, device fabrication and for understanding toxicity. Herein, we report that nanodiamond (ND, sp(3) carbon) forms a complex with highly biocompatible zwitterionic liposomes based on hydrogen bonding, which is confirmed by pH-dependent and urea-dependent assays. Despite such weak interaction, the complex is highly stable. Comparisons were made with two sp(2) carbons: nanoscale graphene oxide (NGO) and carbon nanotubes (CNTs), where CNT adsorption is the weakest. Adsorption of the nano-carbons does not induce liposome leakage or affect lipid phase transition temperature. Therefore, the potential toxicity of nano-carbons is unlikely to be related to direct membrane damage. ND facilitates cellular uptake of liposomes and co-delivery of negatively charged calcein and positively charged doxorubicin has been demonstrated. ND has the lowest toxicity, while CNTs and NGO are slightly more toxic. The effect of introducing fusogenic lipids and cholesterol was further studied to understand the effect of lipid formulation.

Selective Delivery of an Anticancer Drug with Aptamer-Functionalized Liposomes to Breast Cancer Cells in Vitro and in Vivo

Selective targeting of cancer cells is a critical step in cancer diagnosis and therapy. To address this need, DNA aptamers have attracted significant attention as possible targeting ligands. However, while their use in targeting cancer cells in vitro has been reported, their effectiveness has rarely been established in vivo. Here we report the development of a liposomal drug delivery system for targeted anticancer chemotherapy. Liposomes were prepared containing doxorubicin as a payload, and functionalized with AS1411, a DNA aptamer with strong binding affinity for nucleolin. AS1411 aptamer-functionalized liposomes increased cellular internalization and cytotoxicity to MCF-7 breast cancer cells as compared to non-targeting liposomes. Furthermore, targeted liposomal doxorubicin improved antitumor efficacy against xenograft MCF-7 breast tumors in athymic nude mice, attributable to their enhanced tumor tissue penetration. This study suggests that AS1411 aptamer-functionalized liposomes can recognize nucleolin overexpressed on MCF-7 cell surface, and therefore enable drug delivery with high specificity and selectivity.

Smart photothermal-triggered bilayer phase transition in AuNPs-liposomes to release drug

Novel thermosensitive liposomes with embedded Au nanoparticles (AuNPs) in the liposome bilayer were prepared by a combination method of film build and supercritical CO(2) incubation. These AuNPs-liposomes possess AuNPs that are embedded in the bilayer and a drug that is encapsulated in the central aqueous compartment. The AuNPs in the liposomes can strongly absorb light energy and efficiently convert the absorbed energy to heat. The localized heat induces a phase transition in the liposome bilayer and releases the drug. The drug release from the AuNPs-liposomes can be controlled by the irradiation time and AuNPs concentration in the AuNPs-liposomes at room temperature, where the AuNPs function as a nanoswitch for triggering drug release both spatially and temporally. The results suggest that drug release from the AuNPs-liposomes is due to a photothermic effect that induces phase transition of the liposomes rather than destruction of the liposome bilayer.

Light-activated content release from liposomes

Successful integration of diagnostic and therapeutic actions at the level of individual cells requires new materials that combine biological compatibility with functional versatility. This review focuses on the development of liposome-based functional materials, where payload release is activated by light. Methods of sensitizing liposomes to light have progressed from the use of organic molecular moieties to the use of metallic plasmon resonant structures. This development has facilitated application of near infrared light for activation, which is preferred for its deep penetration and low phototoxicity in biological tissues. Presented mechanisms of light-activated liposomal content release enable precise in vitro manipulation of minute amounts of reagents, but their use in clinical diagnostic and therapeutic applications will require demonstration of safety and efficacy.

Instantaneous and quantitative functionalization of gold nanoparticles with thiolated DNA using a pH-assisted and surfactant-free route

The attachment of thiolated DNA to gold nanoparticles (AuNPs) has enabled many landmark works in nanobiotechnology. This conjugate chemistry is typically performed using a salt-aging protocol where, in the presence of an excess amount of DNA, NaCl is gradually added to increase DNA loading over 1-2 days. To functionalize large AuNPs, surfactants need to be used, which may generate difficulties for downstream biological applications. We report herein a novel method using a pH 3.0 citrate buffer to complete the attachment process in a few minutes. More importantly, it allows for quantitative DNA adsorption, eliminating the need to quantify the number of adsorbed DNA and allowing the adsorption of multiple DNAs with different sequences at predetermined ratios. The method has been tested for various DNAs over a wide range of AuNP sizes. Our work suggests a synergistic effect between pH and salt in DNA attachment and reveals the fundamental kinetics of AuNP aggregation versus DNA adsorption, providing a novel means to modulate the interactions between DNA and AuNPs.

Biomimetic sensing based on chemically induced assembly of a signaling DNA aptamer on a fluid bilayer membrane

The adenosine aptamer was split into two halves and linked to a fluid liposome surface; addition of adenosine resulted in aptamer assembly, which did not occur if the split aptamer was attached to silica nanoparticles, demonstrating the feasibility of using aptamer probes to study diffusion within lipid membranes.