Gene silencing by gold nanoshell-mediated delivery and laser-triggered release of antisense oligonucleotide and siRNA

Multifunctionalization of Gold Nanoshells

Gold silica nanoshells have found many applications within the field of molecular biology, including as nanoscale sensors, the detection of biomarkers, and in the treatment of solid tumors using photothermal ablation. In order for them to be targeted to specific biomarkers while also remaining stable in biological media, it is often necessary to modify their surfaces with more than one functional group. Here, we describe how to create multifunctional gold nanoshells that can be used to either target specific tumor types in vivo or for the detection of biomarkers using biological specimen.

Platinum-Coated Gold Nanorods: Efficient Reactive Oxygen Scavengers That Prevent Oxidative Damage toward Healthy, Untreated Cells during Plasmonic Photothermal Therapy

As a minimally invasive therapeutic strategy, gold nanorod (AuNR)-based plasmonic photothermal therapy (PPT) has shown significant promise for the selective ablation of cancer cells. However, the heat stress experienced by cells during the PPT treatment produces significant amounts of reactive oxygen species (ROS), which could harm healthy, untreated tissue near the point of care by inducing irreversible damage to DNA, lipids, and proteins, potentially causing cellular dysfunction or mutation. In this study, we utilized biocompatible Pt-coated AuNRs (PtAuNRs) with different platinum shell thicknesses as an alternative to AuNRs often used for the treatment. We show that the PtAuNRs maintain the efficacy of traditional AuNRs for inducing cell death while scavenging the ROS formed as a byproduct during PPT treatment, thereby protecting healthy, untreated cells from indirect death resulting from ROS formation. The synergistic effect of PtAuNRs in effectively killing cancer cells through hyperthermia with the simultaneous removal of heat stress induced ROS during PPT was validated in vitro using cell viability and fluorescence assays. Our results suggest that the high photothermal efficiency and ROS-scavenging activity of PtAuNRs makes them ideal candidates to improve the therapeutic efficacy of PPT treatment while reducing the risk of undesired side effects due to heat-stress-induced ROS formation.

Understanding Resonant Light-Triggered DNA Release from Plasmonic Nanoparticles

Nanoparticle-based platforms for gene therapy and drug delivery are gaining popularity for cancer treatment. To improve therapeutic selectivity, one important strategy is to remotely trigger the release of a therapeutic cargo from a specially designed gene- or drug-laden near-infrared (NIR) absorbing gold nanoparticle complex with NIR light. While there have been multiple demonstrations of NIR nanoparticle-based release platforms, our understanding of how light-triggered release works in such complexes is still limited. Here, we investigate the specific mechanisms of DNA release from plasmonic nanoparticle complexes using continuous wave (CW) and femtosecond pulsed lasers. We find that the characteristics of nanoparticle-based DNA release vary profoundly from the same nanoparticle complex, depending on the type of laser excitation. CW laser illumination drives the photothermal release of dehybridized single-stranded DNA, while pulsed-laser excitation results in double-stranded DNA release by cleavage of the Au-S bond, with negligible local heating. This dramatic difference in DNA release from the same DNA-nanoparticle complex has very important implications in the development of NIR-triggered gene or drug delivery nanocomplexes.

Nanoparticle delivery of Wnt-1 siRNA enhances photodynamic therapy by inhibiting epithelial–mesenchymal transition for oral cancer

A combination of nanoparticle delivery of Wnt-1 siRNA with photodynamic therapy was realized by inhibiting epithelial–mesenchymal transition.

Changes in Optical Properties of Plasmonic Nanoparticles in Cellular Environments are Modulated by Nanoparticle PEGylation and Serum Conditions

When plasmonic nanoparticles (NPs) are internalized by cells and agglomerate within intracellular vesicles, their optical spectra can shift and broaden as a result of plasmonic coupling of NPs in close proximity to one another. For such optical changes to be accounted for in the design of plasmonic NPs for light-based biomedical applications, quantitative design relationships between designable factors and spectral shifts need to be established. Here we begin building such a framework by investigating how functionalization of gold NPs (AuNPs) with biocompatible poly(ethylene) glycol (PEG), and the serum conditions in which the NPs are introduced to cells impact the optical changes exhibited by NPs in a cellular context. Utilizing darkfield hyperspectral imaging, we find that PEGylation decreases the spectral shifting and spectral broadening experienced by 100 nm AuNPs following uptake by Sk-Br-3 cells, but up to a 33 ± 12 nm shift in the spectral peak wavelength can still occur. The serum protein-containing biological medium also modulates the spectral changes experienced by cell-exposed NPs through the formation of a protein corona on the surface of NPs that mediates NP interactions with cells: PEGylated AuNPs exposed to cells in serum-free conditions experience greater spectral shifts than in serum-containing environments. Moreover, increased concentrations of serum (10, 25, or 50 %) result in the formation of smaller intracellular NP clusters and correspondingly reduced spectral shifts after 5 and 10 h NP-cell exposure. However, after 24 h, NP cluster size and spectral shifts are comparable and become independent of serum concentration. By elucidating the impact of PEGylation and serum concentration on the spectral changes experienced by plasmonic NPs in cells, this study provides a foundation for the optical engineering of plasmonic NPs for use in biomedical environments.

Nanoparticles for siRNA-Based Gene Silencing in Tumor Therapy

Gene silencing through RNA interference (RNAi) has emerged as a potential strategy in manipulating cancer causing genes by complementary base-pairing mechanism. Small interfering RNA (siRNA) is an important RNAi tool that has found significant application in cancer therapy. However due to lack of stability, poor cellular uptake and high probability of loss-of-function due to degradation, siRNA therapeutic strategies seek safe and efficient delivery vehicles for in vivo applications. The current review discusses various nanoparticle systems currently used for siRNA delivery for cancer therapy, with emphasis on liposome based gene delivery systems. The discussion also includes various methods availed to improve nanoparticle based-siRNA delivery with target specificity and superior efficiency. Further this review describes challenges and perspectives on the development of safe and efficient nanoparticle based-siRNA-delivery systems for cancer therapy.

Smart Carbon Nanotubes with Laser-Controlled Behavior in Gene Delivery and Therapy through a Non-Digestive Trafficking Pathway

Near-infrared (NIR) laser-controlled gene delivery presents some benefits in gene therapy, inducing enhanced gene transfection efficiency. In this study, a "photothermal transfection" agent is obtained by wrapping poly(ethylenimine)-cholesterol derivatives (PEI-Chol) around single-walled carbon nanotubes (SWNTs). The PEI-Chol modified SWNTs (PCS) are effective in compressing DNA molecules and protecting them from DNaseI degradation. Compared to the complexes formed by PEI with DNA (PEI/DNA), complexes of PCS and DNA that are formed (PCS/DNA) exhibit a little lower toxicity to HEK293 and HeLa cells under the same PEI molecule weight and weight ratios. Notably, caveolae-mediated cellular uptake of PCS/DNA occurs, which results in a safer intracellular transport of the gene due to the decreased lysosomal degradation in comparison with that of PEI/DNA whose internalization mainly depends on clathrin rather than caveolae. Furthermore, unlike PEI/DNA, PCS/DNA exhibits a photothermal conversion ability, which promotes DNA release from PCS under NIR laser irradiation. The NIR laser-mediated photothermal transfection of PCS_10K /plasmid TP53 (pTP53) results in more apoptosis and necrosis of HeLa cells in vitro than other groups, and achieves a higher tumor-growth inhibition in vivo than naked pTP53, PEI_25K /pTP53, and PCS_10K /pTP53 alone. The enhanced transfection efficiency of PCS/DNA can be attributed to more efficient DNA internalization into the tumor cells, promotes detachment of DNA from PCS under the mediation of NIR laser and higher DNA stability in the cells due to caveolae-mediated cellular uptake of the complexes.

Biomaterials in siRNA Delivery: A Comprehensive Review

With the dearth of effective treatment options for prominent diseases including Ebola and cancer, RNA interference (RNAi), a sequence-specific mechanism for genetic regulation that can silence nearly any gene, holds the promise of unlimited potential in treating illness ever since its discovery in 1999. Given the large size, unstable tertiary structure in physiological conditions and negative charge of small interfering RNAs (siRNAs), the development of safe and effective delivery vehicles is of critical importance in order to drive the widespread use of RNAi therapeutics into clinical settings. Immense amounts of time and billions of dollars have been devoted into the design of novel and diverse delivery strategies, and there are a handful of delivery systems that have been successfully translated into clinic. This review provides an introduction to the in vivo barriers that need to be addressed by siRNA delivery systems. We also discuss the progress up to the most effective and clinically advanced siRNA delivery systems including liposomal, polymeric and siRNA conjugate delivery systems, as well as their design to overcome the challenges.

Gold nanoprism-nanorod face off: comparing the heating efficiency, cellular internalization and thermoablation capacity

AIM

This work compares the synthesis, heating capability, cellular internalization and thermoablation capacity of two different types of anisotropic gold nanoparticles: gold nanorods (NRs) and nanoprisms (NPrs).

METHODS

Both particles possess surface plasmon resonance absorption bands in the near-IR, and their heating efficiency upon irradiation with a continuous near-IR laser (1064 nm) was evaluated. The cellular internalization, location and toxicity of these PEG-stabilized NPrs and NRs were then assessed in the Vero cell line by transmission electron microscopy and inductively coupled plasma mass spectrometry analysis, and their ability to induce cell death upon laser irradiation was then evaluated and compared.

RESULTS & CONCLUSION

Although both nanoparticles are highly efficient photothermal converters, NRs possessed a more efficient heating capability, yet the in vitro thermoablation studies clearly demonstrated that NPrs were more effective at inducing cell death through photothermal ablation due to their greater cellular internalization.

Structural-Engineering Rationales of Gold Nanoparticles for Cancer Theranostics

Personalized theranostics of cancer is increasingly desired, and can be realized by virtue of multifunctional nanomaterials with possible high performances. Gold nanoparticles (GNPs) are a type of especially promising candidate for cancer theranostics, because their synthesis and modification are facile, their structures and physicochemical properties are flexibly controlled, and they are also biocompatible. Especially, the localized surface plasmon resonance and multivalent coordination effects on the surface endow them with NIR light-triggered photothermal imaging and therapy, controlled drug release, and targeted drug delivery. Although the structure, properties, and theranostic application of GNPs are considerably plentiful, no expert review systematically explains the relationships among their structure, property. and application and induces the engineering rationales of GNPs for cancer theranostics. Hence, there are no clear rules to guide the facile construction of optimal GNP structures aiming at a specific theranostic application. A series of structural-engineering rationales of GNPs for cancer theranostics is proposed through digging out the deep relationships between the structure and properties of GNPs. These rationales will be inspiring for guiding the engineering of specific and advanced GNPs for personalized cancer theranostics.

Imaging-guided delivery of RNAi for anticancer treatment

The RNA interference (RNAi) technique is a new modality for cancer therapy, and several candidates are being tested clinically. In the development of RNAi-based therapeutics, imaging methods can provide a visible and quantitative way to investigate the therapeutic effect at anatomical, cellular, and molecular level; to noninvasively trace the distribution; to and study the biological processes in preclinical and clinical stages. Their abilities are important not only for therapeutic optimization and evaluation but also for shortening of the time of drug development to market. Typically, imaging-functionalized RNAi therapeutics delivery that combines nanovehicles and imaging techniques to study and improve their biodistribution and accumulation in tumor site has been progressively integrated into anticancer drug discovery and development processes. This review presents an overview of the current status of translating the RNAi cancer therapeutics in the clinic, a brief description of the biological barriers in drug delivery, and the roles of imaging in aspects of administration route, systemic circulation, and cellular barriers for the clinical translation of RNAi cancer therapeutics, and with partial content for discussing the safety concerns. Finally, we focus on imaging-guided delivery of RNAi therapeutics in preclinical development, including the basic principles of different imaging modalities, and their advantages and limitations for biological imaging. With growing number of RNAi therapeutics entering the clinic, various imaging methods will play an important role in facilitating the translation of RNAi cancer therapeutics from bench to bedside.

Recent Advances of Using Hybrid Nanocarriers in Remotely Controlled Therapeutic Delivery

The development of hybrid biomaterials has been attracting great attention in the design of materials for biomedicine. The nanosized level of inorganic and organic or even bioactive components can be combined into a single material by this approach, which has created entirely new advanced compositions with truly unique properties for drug delivery. The recent advances in using hybrid nanovehicles as remotely controlled therapeutic delivery carriers are summarized with respect to different nanostructures, including hybrid host-guest nanoconjugates, micelles, nanogels, core-shell nanoparticles, liposomes, mesoporous silica, and hollow nanoconstructions. In addition, the controlled release of guest molecules from these hybrid nanovehicles in response to various remote stimuli such as alternating magnetic field, near infrared, or ultrasound triggers is further summarized to introduce the different mechanisms of remotely triggered release behavior. Through proper chemical functionalization, the hybrid nanovehicle system can be further endowed with many new properties toward specific biomedical applications.

Gold Nanoantenna-Mediated Photothermal Drug Delivery from Thermosensitive Liposomes in Breast Cancer

In this work, we demonstrate controlled drug delivery from low-temperature-sensitive liposomes (LTSLs) mediated by photothermal heating from multibranched gold nanoantennas (MGNs) in triple-negative breast cancer (TNBC) cells in vitro. The unique geometry of MGNs enables the generation of mild hyperthermia (∼42 °C) by converting near-infrared light to heat and effectively delivering doxorubicin (DOX) from the LTSLs in breast cancer cells. We confirmed the cellular uptake of MGNs by using both fluorescence confocal Z-stack imaging and transmission electron microscopy (TEM) imaging. We performed a cellular viability assay and live/dead cell fluorescence imaging of the combined therapeutic effects of MGNs with DOX-loaded LTSLs (DOX-LTSLs) and compared them with free DOX and DOX-loaded non-temperature-sensitive liposomes (DOX-NTSLs). Imaging of fluorescent live/dead cell indicators and MTT assay outcomes both demonstrated significant decreases in cellular viability when cells were treated with the combination therapy. Because of the high phase-transition temperature of NTSLs, no drug delivery was observed from the DOX-NTSLs. Notably, even at a low DOX concentration of 0.5 μg/mL, the combination treatment resulted in a higher (33%) cell death relative to free DOX (17% cell death). The results of our work demonstrate that the synergistic therapeutic effect of photothermal hyperthermia of MGNs with drug delivery from the LTSLs can successfully eradicate aggressive breast cancer cells with higher efficacy than free DOX by providing a controlled light-activated approach and minimizing off-target toxicity.

Controlled drug release to cancer cells from modular one-photon visible light-responsive micellar system

We present a one-photon visible light-responsive micellar system for efficient, on-demand delivery of small molecules. Release is mediated by a novel class of photochromic material - donor-acceptor Stenhouse adducts (DASAs). We demonstrate controlled delivery of small molecules such as the chemotherapeutic agent (paclitaxel) to human breast cancer cells triggered by micellar switching with low intensity, visible light.

Sub-wavelength Unidirectional Antenna Realized by Stacked Spoof Localized Surface Plasmon Resonators

The use of resonant structures to control scattering strength and directionality is of importance in various electromagnetic systems. Here we propose and demonstrate sub-wavelength unidirectional scattering by two nearby spoof localized surface plasmon resonators for microwave. The principle is that metal surfaces corrugated by grooves can support magnetic dipolar modes, as well as electric dipolar modes. The resonance is essentially dictated by the geometric parameter of the structure, enabling extremely high degrees of freedom for tuning the scattering properties of the resonator. Particularly, by adjusting the thickness of the resonators, we can make the magnetic dipole mode of one resonator have nearly the same resonant frequency with that of the electric dipole mode of the other resonator. We show that nearly zero backscattering happens when the distance between the two resonators is subwavelenght but larger than a certain value, otherwise strong vertical coupling and mode splitting occur. The results can be extended to other frequency bands and might find application in unique resonant devices as a radio frequency (RF) antenna, filter and metasurface.

Synthesis and characterization of extremely small gold nanoshells, and comparison of their photothermal conversion capacity with gold nanorods

The current methods for preparing gold nanoshells (AuNSs) produce shells with a diameter of approximately 40 nm or larger, with a relatively large polydispersity. However, AuNSs with smaller diameters and more monodispersity are better suited for biomedical applications. In this work, we present a modified method for the preparation of AuNSs, based on the use of sacrificial silver nanoparticles (AgNPs). We customized the Lee-Meisel method to prepare small and monodisperse AgNPs that were used as sacrificial nanoparticles to prepare extremely small monodispersed AuNSs with an average diameter from 17 to 25 ± 4 nm. We found that these AuNSs are faceted, and that the oxidized silver likely dissolves out of the nanoparticles through some of the facets on the AuNSs. This leads to a silver oxide plug on the surface of the AuNSs, which has not been reported before. The smaller AuNSs, prepared under the best conditions, absorb in the near infrared region (NIR) that is appropriate for applications, such as photothermal therapy or medical imaging. The AuNSs showed absorption peaks in the NIR similar to those of gold nanorods (AuNRs) but with better photothermal capacity. In addition, because of their negative charge, these AuNSs are more biocompatible than the positively charged AuNRs. The synthesis of small, monodisperse, stable and biocompatible nanoparticles, like the ones presented in this work, is of prime importance in biomedical applications.

Rational Design of Plasmonic Nanoparticles for Enhanced Cavitation and Cell Perforation

Metallic nanoparticles are routinely used as nanoscale antenna capable of absorbing and converting photon energy with subwavelength resolution. Many applications, notably in nanomedicine and nanobiotechnology, benefit from the enhanced optical properties of these materials, which can be exploited to image, damage, or destroy targeted cells and subcellular structures with unprecedented precision. Modern inorganic chemistry enables the synthesis of a large library of nanoparticles with an increasing variety of shapes, composition, and optical characteristic. However, identifying and tailoring nanoparticles morphology to specific applications remains challenging and limits the development of efficient nanoplasmonic technologies. In this work, we report a strategy for the rational design of gold plasmonic nanoshells (AuNS) for the efficient ultrafast laser-based nanoscale bubble generation and cell membrane perforation, which constitute one of the most crucial challenges toward the development of effective gene therapy treatments. We design an in silico rational design framework that we use to tune AuNS morphology to simultaneously optimize for the reduction of the cavitation threshold while preserving the particle structural integrity. Our optimization procedure yields optimal AuNS that are slightly detuned compared to their plasmonic resonance conditions with an optical breakdown threshold 30% lower than randomly selected AuNS and 13% lower compared to similarly optimized gold nanoparticles (AuNP). This design strategy is validated using time-resolved bubble spectroscopy, shadowgraphy imaging and electron microscopy that confirm the particle structural integrity and a reduction of 51% of the cavitation threshold relative to optimal AuNP. Rationally designed AuNS are finally used to perforate cancer cells with an efficiency of 61%, using 33% less energy compared to AuNP, which demonstrate that our rational design framework is readily transferable to a cell environment. The methodology developed here thus provides a general strategy for the systematic design of nanoparticles for nanomedical applications and should be broadly applicable to bioimaging and cell nanosurgery.

Fabrication of photoactive heterostructures based on quantum dots decorated with Au nanoparticles

Silica based multifunctional heterostructures, exhibiting near infrared (NIR) absorption (650-1200 nm) and luminescence in the visible region, represent innovative nanosystems useful for diagnostic or theranostic applications. Herein, colloidal synthetic procedures are applied to design a photoactive multifunctional nanosystem. Luminescent silica (SiO2) coated quantum dots (QDs) have been used as versatile nanoplatforms to assemble on their surface gold (Au) seeds, further grown into Au spackled structures. The synthesized nanostructures combine the QD emission in the visible region, and, concomitantly, the distinctive NIR absorption of Au nanodomains. The possibility of having multiple QDs in a single heterostructure, the SiO2 shell thickness, and the extent of Au deposition onto SiO2 surface have been carefully controlled. The work shows that a single QD entrapped in 16 nm thick SiO2 shell, coated with Au speckles, represents the most suitable geometry to preserve the QD emission in the visible region and to generate NIR absorption from metal NPs. The resulting architectures present a biomedical potential as an effective optical multimodal probes and as promising therapeutic agents due to the Au NP mediated photothermal effect.

Rational design of a comprehensive cancer therapy platform using temperature-sensitive polymer grafted hollow gold nanospheres: simultaneous chemo/photothermal/photodynamic therapy triggered by a 650 nm laser with enhanced anti-tumor efficacy

Combining multi-model treatments within one single system has attracted great interest for the purpose of synergistic therapy. In this paper, hollow gold nanospheres (HAuNs) coated with a temperature-sensitive polymer, poly(oligo(ethylene oxide) methacrylate-co-2-(2-methoxyethoxy)ethyl methacrylate) (p(OEGMA-co-MEMA)), co-loaded with DOX and a photosensitizer Chlorin e6 (Ce6) were successfully synthesized. As high as 58% DOX and 6% Ce6 by weight could be loaded onto the HAuNs-p(OEGMA-co-MEMA) nanocomposites. The grafting polymer brushes outside the HAuNs play the role of "gate molecules" for controlled drug release by 650 nm laser radiation owing to the temperature-sensitive property of the polymer and the photothermal effect of HAuNs. The HAuNs-p(OEGMA-co-MEMA)-Ce6-DOX nanocomposites with 650 nm laser radiation show effective inhibition of cancer cells in vitro and enhanced anti-tumor efficacy in vivo. In contrast, control groups without laser radiation show little cytotoxicity. The nanocomposite demonstrates a way of "killing three birds with one stone", that is, chemotherapy, photothermal and photodynamic therapy are triggered simultaneously by the 650 nm laser stimulation. Therefore, the nanocomposites show the great advantages of multi-modal synergistic effects for cancer therapy by a remote-controlled laser stimulus.

Near Infrared-Guided Smart Nanocarriers for MicroRNA-Controlled Release of Doxorubicin/siRNA with Intracellular ATP as Fuel

In chemotherapy, it is a great challenge to recruit endogenous stimuli instead of external intervention for targeted delivery and controlled release; microRNAs are the most promising candidates due to their vital role during tumorigenesis and significant expression difference. Herein, to amplify the low abundant microRNAs in live cells, we designed a stimuli-responsive DNA Y-motif for codelivery of siRNA and Dox, in which the cargo release was achieved via enzyme-free cascade amplification with endogenous microRNA as trigger and ATP (or H(+)) as fuel through toehold-mediated strand displacement. Furthermore, to realize controlled release in tumor cells, smart nanocarriers were constructed with stimuli-responsive Y-motifs, gold nanorods, and temperature-sensitive polymers, whose surfaces could be reversibly switched between PEG and RGD states via photothermal conversion. The PEG corona kept the nanocarriers stealth during blood circulation to protect the Y-motifs against nuclease digestion and enhance passive accumulation, whereas the exposed RGD shell under near-infrared (NIR) irradiation at tumor sites facilitated the specific receptor-mediated endocytosis by tumor cells. Through modulating NIR laser, microRNA, or ATP expressions, the therapy efficacies to five different cell lines were finely controlled, presenting NIR-guided accumulation, massive release, efficient gene silence, and severe apoptosis in HeLa cells; in vivo study showed that a low dosage of nanocarriers synergistically inhibited the tumor growth by silencing gene expression and inducing cell apoptosis under mild NIR irradiation, though they only brought minimum damage to normal organs. The combination of nanomaterials, polymers, and DNA nanomachines provided a promising tool for designing smart nanodevices for disease therapy.

Synthesis of gold Nanoshells through Improved Seed-Mediated Growth Approach: Brust-like, in Situ Seed Formation

Gold nanoshells have shown great potentials in various fields. However, the widely used seed-mediated growth method based on a silica template for gold nanoshells is a complex and time-consuming procedure. In this work, mercaptosilica was first used as a template to synthesize gold nanoshells through improved seed-mediated growth method. It is verified that gold seeds were formed and attached onto the mercaptosilica nanospheres through Brust-like, in situ process, which makes this method extremely time-saving and easy to manipulate. Importantly, the key factors affecting the in situ process were demonstrated, allowing fine control on the synthesis in a highly reproducible manner. The as-synthesized nanoshells are monodisperse with well-defined morphology and tunable near-IR plasmon resonance. Furthermore, other metal nanoparticles such as Pt and Pd could be grafted onto the surface of mercaptosilica nanospheres through the same Brust-like, in situ process. These provide new insights into seed attachment, and the improved seed-mediated growth approach based on Brust-like, in situ seed formation will take an important step forward toward the widespread application of gold nanoshells.

Synergistic nanomedicine by combined gene and photothermal therapy

To date, various nanomaterials with the ability for gene delivery or photothermal effect have been developed in the field of biomedicine. The therapeutic potential of these nanomaterials has raised considerable interests in their use in potential next-generation strategies for effective anticancer therapy. In particular, the advancement of novel nanomedicines utilizing both therapeutic strategies of gene delivery and photothermal effect has generated much optimism regarding the imminent development of effective and successful cancer treatments. In this review, we discuss current research progress with regard to combined gene and photothermal therapy. This review focuses on synergistic therapeutic systems combining gene regulation and photothermal ablation as well as logically designed nano-carriers aimed at enhancing the delivery efficiency of therapeutic genes using the photothermal effect. The examples detailed in this review provide insight to further our understanding of combinatorial gene and photothermal therapy, thus paving the way for the design of promising nanomedicines.

Overcoming Gene-Delivery Hurdles: Physiological Considerations for Nonviral Vectors

With the use of contemporary tools and techniques, it has become possible to more precisely tune the biochemical mechanisms associated with using nonviral vectors for gene delivery. Consequently, nonviral vectors can incorporate numerous vector compositions and types of genetic cargo to develop diverse genetic therapies. Despite these advantages, gene-delivery strategies using nonviral vectors have poorly translated into clinical success due to preclinical experimental design considerations that inadequately predict therapeutic efficacy. Furthermore, the manufacturing and distribution processes are critical considerations for clinical application that should be considered when developing therapeutic platforms. In this review, we evaluate potential avenues towards improving the transition of gene-delivery technologies from in vitro assessment to human clinical therapy.

Hyperthermia using nanoparticles--Promises and pitfalls

An ever-increasing body of literature affirms the physical and biological basis for sensitisation of tumours to conventional therapies such as chemotherapy and radiation therapy by mild temperature hyperthermia. This knowledge has fuelled the efforts to attain, maintain, measure and monitor temperature via technological advances. A relatively new entrant in the field of hyperthermia is nanotechnology which capitalises on locally injected or systemically administered nanoparticles that are activated by extrinsic energy sources to generate heat. This review describes the kinds of nanoparticles available for hyperthermia generation, their activation sources, their characteristics, and the unique opportunities and challenges with nanoparticle-mediated hyperthermia.

Hyaluronic Acid Modified Hollow Prussian Blue Nanoparticles Loading 10-hydroxycamptothecin for Targeting Thermochemotherapy of Cancer

This paper reported the fabrication of a multifunctional nanoplatform by modifying hollow Prussian blue nanoparticles with hyaluronic acid grafting polyethylene glycol, followed by loading 10-hydroxycamptothecin for tumor-targeted thermochemotherapy. It was found that the surface modification of hollow Prussian blue nanoparticles with hyaluronic acid grafting polyethylene endowed a great colloidal stability, long blood circulation time and the capability for targeting Hela cells over-expressing the CD44 receptor. The obtained nanoagent exhibited efficient photothermal effect and a light triggered and stepwise release behavior of 10-hydroxycamptothecin due to the strong optical absorption in the near-infrared region. The investigations on the body weight change, histological injury and blood biochemical indexes showed that such nanoagent had excellent biocompatibility for medical application. Both in vitro and in vivo experiments proved that the combination of chemotherapy and photothermal therapy through the agent of hyaluronic acid modified Prussian blue nanoparticles loading 10-hydroxycamptothecin could significantly improve the therapeutic efficacy compared with either therapy alone because of a good synergetic effect.

Nucleic Acid Bioconjugates in Cancer Detection and Therapy

Nucleoside- and nucleotide-based chemotherapeutics have been used to treat cancer for more than 50 years. However, their inherent cytotoxicities and the emergent resistance of tumors against treatment has inspired a new wave of compounds in which the overall pharmacological profile of the bioactive nucleic acid component is improved by conjugation with delivery vectors, small-molecule drugs, and/or imaging modalities. In this manner, nucleic acid bioconjugates have the potential for targeting and effecting multiple biological processes in tumors, leading to synergistic antitumor effects. Consequently, tumor resistance and recurrence is mitigated, leading to more effective forms of cancer therapy. Bioorthogonal chemistry has led to the development of new nucleoside bioconjugates, which have served to improve treatment efficacy en route towards FDA approval. Similarly, oligonucleotide bioconjugates have shown encouraging preclinical and clinical results. The modified oligonucleotides and their pharmaceutically active formulations have addressed many weaknesses of oligonucleotide-based drugs. They have also paved the way for important advancements in cancer diagnosis and treatment. Cancer-targeting ligands such as small-molecules, peptides, and monoclonal antibody fragments have all been successfully applied in oligonucleotide bioconjugation and have shown promising anticancer effects in vitro and in vivo. Thus, the application of bioorthogonal chemistry will, in all likelihood, continue to supply a promising pipeline of nucleic acid bioconjugates for applications in cancer detection and therapy.

Near-IR responsive nanostructures for nanobiophotonics: emerging impacts on nanomedicine

Nanobiophotonics is an emerging field at the intersection of nanoscience, photonics, and biotechnology. Harnessing interactions of light with nanostructures enables new types of bioimaging, sensing, and light-activated therapy which can make a major impact on nanomedicine. Low penetration through tissue limits the use of visible light in nanomedicine. Near infrared (NIR) light (~780-1100 nm) can penetrate significantly further, enabling free-space delivery into deep tissues. This review focuses on interactions of NIR light with nanostructures to produce three effects: direct photoactivation, photothermal effects, and photochemical effects. Applications of direct photoactivation include bioimaging and biosensing using NIR-emitting quantum dots, materials with localized surface plasmon resonance (LSPR) in the NIR, and upconverting nanoparticles. Two key nanomedicine applications using photothermal effects are photothermal therapy (PTT), and photoacoustic (PA) imaging. For photochemical effects, we present the latest advances in in-situ upconversion and upconverting nanostructures for NIR activation of photodynamic therapy (PDT).

FROM THE CLINICAL EDITOR

Nanobiophotonics is a relatively new field applying light for the interactions with nanostructures, which can be used in bioimaging, sensing, and therapy. As near infrared (NIR) light (~780-1100 nm) can have better tissue penetration, its clinical potential is far greater. In this review, the authors discussed the latest research on the applications of NIR light in imaging and therapeutics.

Efficient RNA delivery by integrin-targeted glutathione responsive polyethyleneimine capped gold nanorods

RNA interference (RNAi) mediated gene silencing holds significant promises in gene therapy. A major obstacle to efficient RNAi is the systemic delivery of the therapeutic RNAs into the cytoplasmon without being trapped in intracellular endo-/lyso-somes. Herein we report the development of a PEGylated, RGD peptide modified, and disulfide cross-linked short polyethylenimines (DSPEIs) functionalized gold nanorod (RDG) for targeted small hairpin (sh)RNA delivery. The RDG effectively condensed shRNAs into stable nanoparticles, allowing for highly specific targeting of model human brain cancer cells (U-87 MG-GFP) via the αvβ3 integrins-mediated endocytosis. The combined effects of endosomal escape (via the proton-sponge effect of the PEIs) and efficient cleavage of the disulfide-cross-linked DSPEIs by the high intracellular glutathione content triggered rapid cytoplasma shRNAs release resulting in excellent RNAi efficiency and low cytotoxicity. Furthermore, the high stability and prolonged blood circulation afforded by PEGylation allowed for highly effective, targeted tumor accumulation and internalization of the carriers, resulting in outstanding intra-tumor gene silencing efficiency in U-87 MG-GFP tumor bearing BALB/c mice. Combining the capabilities of both passive and active targeting, intracellular glutathione-triggered "off-on" release and endosomal escape, the RDG nanocarrier developed herein appears to be a highly promising non-viral vector for efficient RNAi.

Multifunctional gold nanostars for molecular imaging and cancer therapy

Plasmonics-active gold nanoparticles offer excellent potential in molecular imaging and cancer therapy. Among them, gold nanostars (AuNS) exhibit cross-platform flexibility as multimodal contrast agents for macroscopic X-ray computer tomography (CT), magnetic resonance imaging (MRI), positron emission tomography (PET), as well as nanoprobes for photoacoustic tomography (PAT), two-photon photoluminescence (TPL), and surface-enhanced Raman spectroscopy (SERS). Their surfactant-free surface enables versatile functionalization to enhance cancer targeting, and allow triggered drug release. AuNS can also be used as an efficient platform for drug carrying, photothermal therapy, and photodynamic therapy (PDT). This review paper presents the latest progress regarding AuNS as a promising nanoplatform for cancer nanotheranostics. Future research directions with AuNS for biomedical applications will also be discussed.

Synthesis and design of biologically inspired biocompatible iron oxide nanoparticles for biomedical applications

During the last couple of decades considerable research efforts have been directed towards the synthesis and coating of iron oxide nanoparticles (IONPs) for biomedical applications. To address the current limitations, recent studies have focused on the design of new generation nanoparticle systems whose internalization and targeting capabilities have been improved through surface modifications. This review covers the most recent challenges and advances in the development of IONPs with enhanced quality, and biocompatibility for various applications in biotechnology and medicine.

Personalizing Biomaterials for Precision Nanomedicine Considering the Local Tissue Microenvironment

New advances in (nano)biomaterial design coupled with the detailed study of tissue-biomaterial interactions can open a new chapter in personalized medicine, where biomaterials are chosen and designed to match specific tissue types and disease states. The notion of a "one size fits all" biomaterial no longer exists, as growing evidence points to the value of customizing material design to enhance (pre)clinical performance. The complex microenvironment in vivo at different tissue sites exhibits diverse cell types, tissue chemistry, tissue morphology, and mechanical stresses that are further altered by local pathology. This complex and dynamic environment may alter the implanted material's properties and in turn affect its in vivo performance. It is crucial, therefore, to carefully study tissue context and optimize biomaterials considering the implantation conditions. This practice would enable attaining predictable material performance and enhance clinical outcomes.

Photoresponsive nanoparticles for drug delivery

Externally triggerable drug delivery systems provide a strategy for the delivery of therapeutic agents preferentially to a target site, presenting the ability to enhance therapeutic efficacy while reducing side effects. Light is a versatile and easily tuned external stimulus that can provide spatiotemporal control. Here we will review the use of nanoparticles in which light triggers drug release or induces particle binding to tissues (phototargeting).

Clean Photothermal Heating and Controlled Release from Near-Infrared Dye Doped Nanoparticles without Oxygen Photosensitization

The photothermal heating and release properties of biocompatible organic nanoparticles, doped with a near-infrared croconaine (Croc) dye, were compared with analogous nanoparticles doped with the common near-infrared dyes ICG and IR780. Separate formulations of lipid-polymer hybrid nanoparticles and liposomes, each containing Croc dye, absorbed strongly at 808 nm and generated clean laser-induced heating (no production of (1)O2 and no photobleaching of the dye). In contrast, laser-induced heating of nanoparticles containing ICG or IR780 produced reactive (1)O2, leading to bleaching of the dye and also decomposition of coencapsulated payload such as the drug doxorubicin. Croc dye was especially useful as a photothermal agent for laser-controlled release of chemically sensitive payload from nanoparticles. Solution state experiments demonstrated repetitive fractional release of water-soluble fluorescent dye from the interior of thermosensitive liposomes. Additional experiments used a focused laser beam to control leakage from immobilized liposomes with very high spatial and temporal precision. The results indicate that fractional photothermal leakage from nanoparticles doped with Croc dye is a promising method for a range of controlled release applications.

Dual targeted immunotherapy via in vivo delivery of biohybrid RNAi-peptide nanoparticles to tumour-associated macrophages and cancer cells

Lung cancer is associated with very poor prognosis and considered one of the leading causes of death worldwide. Here, we present highly potent and selective bio-hybrid RNAi-peptide nanoparticles that can induce specific and long-lasting gene therapy in inflammatory tumour associated macrophages (TAMs), via an immune modulation of the tumour milieu combined with tumour suppressor effects. Our data prove that passive gene silencing can be achieved in cancer cells using regular RNAi NPs. When combined with M2 peptide-based targeted immunotherapy that immuno-modulates TAMs cell-population, a synergistic effect and long-lived tumour eradication can be observed along with increased mice survival. Treatment with low doses of siRNA (ED50 0.0025-0.01 mg/kg) in a multi and long-term dosing system substantially reduced the recruitment of inflammatory TAMs in lung tumour tissue, reduced tumour size (∼95%) and increased animal survival (∼75%) in mice. Our results suggest that it is likely that the combination of silencing important genes in tumour cells and in their supporting immune cells in the tumour microenvironment, such as TAMs, will greatly improve cancer clinical outcomes.

Gold nanoparticles for photothermally controlled drug release

In this article, we describe how nanoparticles work in photothermally triggered drug delivery, starting with a description of the plasmon resonance and the photothermal effect, and how this is used to release a drug. Then, we describe the four major functionalization strategies and each of their different applications. Finally, we discuss the biodistribution and toxicity of these systems and the necessary requirements for the use of gold nanoparticles for spatially and temporally controlling drug release through the photothermal effect.

Quantitative study of the photothermal properties of metallic nanowire networks

In this article, we present a comprehensive investigation of the photothermal properties of plasmonic nanowire networks. We measure the local steady-state temperature increase, heat source density, and absorption in Ag, Au, and Ni metallic nanowire networks under optical illumination. This allows direct experimental confirmation of increased heat generation at the junction between two metallic nanowires and stacking-dependent absorption of polarized light. Due to thermal collective effects, the local temperature distribution in a network is shown to be completely delocalized on a micrometer scale, despite the nanoscale features in the heat source density. Comparison of the experimental temperature profile with numerical simulation allows an upper limit for the effective thermal conductivity of a Ag nanowire network to be established at 43 Wm(-1) K(-1) (0.1 κbulk).

Superior plasmon absorption in iron-doped gold nanoparticles

Although the excitation of localized surface plasmons is associated with enhanced scattering and absorption of incoming photons, only the latter is relevant for the efficient conversion of light into heat. Here we show that the absorption cross section of gold nanoparticles is sensibly increased when iron is included in the lattice as a substitutional dopant, i.e. in a gold-iron nanoalloy. Such an increase is size and shape dependent, with the best performance observed in nanoshells where a 90-190% improvement is found in a size range that is crucial for practical applications. Our findings are unexpected according to the common belief and previous experimental observations that alloys of Au with transition metals show a depressed plasmonic response. These results are promising for the design of efficient plasmonic converters of light into heat and pave the way to more in-depth investigations of the plasmonic properties in noble metal nanoalloys.

Strategy for selecting nanotechnology carriers to overcome immunological and hematological toxicities challenging clinical translation of nucleic acid-based therapeutics

INTRODUCTION

Clinical translation of nucleic acid-based therapeutics (NATs) is hampered by assorted challenges in immunotoxicity, hematotoxicity, pharmacokinetics, toxicology and formulation. Nanotechnology-based platforms are being considered to help address some of these challenges due to the nanoparticles' ability to change drug biodistribution, stability, circulation half-life, route of administration and dosage. Addressing toxicology and pharmacology concerns by various means including NATs reformulation using nanotechnology-based carriers has been reviewed before. However, little attention was given to the immunological and hematological issues associated with nanotechnology reformulation.

AREAS COVERED

This review focuses on application of nanotechnology carriers for delivery of various types of NATs, and how reformulation using nanoparticles affects immunological and hematological toxicities of this promising class of therapeutic agents.

EXPERT OPINION

NATs share several immunological and hematological toxicities with common nanotechnology carriers. In order to avoid synergy or exaggeration of undesirable immunological and hematological effects of NATs by a nanocarrier, it is critical to consider the immunological compatibility of the nanotechnology platform and its components. Since receptors sensing nucleic acids are located essentially in all cellular compartments, a strategy for developing a nanoformulation with reduced immunotoxicity should first focus on precise delivery to the target site/cells and then on optimizing intracellular distribution.

shRNA-Mediated Silencing of Y-Box Binding Protein-1 (YB-1) Suppresses Growth of Neuroblastoma Cell SH-SY5Y In Vitro and In Vivo

Y-box binding protein-1 (YB-1), a member of cold-shock protein superfamily, has been demonstrated to be associated with tumor malignancy, and is proposed as a prognostic marker in multiple carcinomas. However, the role of YB-1 in neuroblastoma has not been well studied. To investigate the functional role of YB-1 in neuroblastoma, we established a YB-1-silenced neuroblastoma cell strain by inhibiting YB-1 expression using a shRNA knockdown approach. YB-1-silenced neuroblastoma SH-SY5Y cells exhibited a pronounced reduction in cell proliferation and an increased rate of apoptosis in vitro and in vivo xenograft tumor model. At molecular level, YB-1 silencing resulted in downregulation of Cyclin A, Cyclin D1 and Bcl-2, as well as upregulated levels of Bax, cleaved caspase-3 and cleaved PARP-1. We further demonstrated that YB-1 transcriptionally regulated Cyclin D1 expression by chromatin-immunoprecipitation and luciferase reporter assays. In addition, xenograft tumors derived from neuroblastoma SH-SY5Y cell line were treated with YB-1 shRNA plasmids by intra-tumor injection, and YB-1 targeting effectively inhibited tumor growth and induced cell death. In summary, our findings suggest that YB-1 plays a critical role in neuroblastoma development, and it may serve as a potential target for neuroblastoma therapy.

Thermoplasmonic ssDNA Dynamic Release from Gold Nanoparticles Examined with Advanced Fluorescence Microscopy

Plasmon excitation of spherical gold nanoparticles carrying a fluorescent labeled 30 bp dsDNA cargo, with one chain covalently attached through two S-Au bonds to the surface, results in release of the complementary strand as ssDNA that can be examined in situ using high-resolution fluorescence microscopy. The release is dependent on the total energy delivered, but not the rate of delivery, an important property for plasmonic applications in medicine, sensors, and plasmon-induced PCR.