Tuning the Drug Loading and Release of DNA-Assembled Gold-Nanorod Superstructures

Multi-drug sequential release systems: Construction and application for synergistic tumor treatment

In tumor treatment, the sequence and timing of drug action have a large influence on therapeutic efficacy. Multi-drug sequential release systems (MDSRS) enable the sequential and/or on-demand release of multiple drugs following the single administration of a therapeutic agent. Several researchers have explored MDSRS, providing fresh strategies for synergistic cancer therapy. This review article first introduces the main characteristics of MDSRS. It then elaborates on the design principles of MDSRS. Subsequently, it summarizes the various structures of carriers used for constructing MDSRS, including core-shell structure, Layer-by-layer structure, Janus structure and hydrogel. Next, through specific examples, the article emphasizes the application of MDSRS in cancer treatment, focusing on their role in remodeling the tumor microenvironment (TME) and enhancing therapeutic effects through multiple mechanisms. Finally, the article discusses the current limitations and challenges of these systems and proposes potential future solutions. Overall, this review underscores the importance of the sequence and timing of drug therapy in cancer treatment, providing valuable theoretical and technical guidance for pharmaceutical research.

Gold nanorod-based smart platform for efficient cellular uptake and combination therapy

Gold nanorods (GNRs) have received much attention as potential drug-delivery vehicles because of their various advantages such as good biocompatibility, passive targeting, responsiveness to stimuli, and easy post-functionalization by surface modification. However, the drug structure might be changed for loading into GNRs, making it difficult to load various drugs, and the space to contain drugs is small, making it difficult to deliver sufficient drugs required for treatment compared with other porous materials. Herein, we report an amphiphilic polymer-coated GNR platform for chemo- and photothermal combination therapy. Amphiphilic polymers comprise hydrophobic alkyl chains for drug encapsulation, polyethylene glycol for biocompatibility, and folic acid for cancer targeting. GNRs generate heat energy under near-infrared light irradiation, promoting controlled drug release, and inducing cellular uptake by deforming the cell membrane. On-demand release behavior was traced with Nile red, and targeting and delivery efficiency were confirmed with paclitaxel through cellular experiments. This GNR-based platform enables combination therapy with passive and active targeting to enhance the efficacy of cancer treatment.

Efficient Poly-Adenine-Tailed DNA Functionalization of Gold Nanorods for Tailored Nanostructure Assembly

Gold nanorods (AuNRs) with unique optical properties play a pivotal role in applications in plasmonic imaging, small molecule detection, and photothermal therapy. However, challenges in DNA functionalization of AuNRs hinder their full potential due to the presence of a dense cetyltrimethylammonium bromide (CTAB) bilayer, impeding close DNA contact. In this study, we introduced a convenient approach for the rapid assembly of polyadenine (polyA) tailed DNA on AuNRs with control of DNA density, rigidity, and valence. We explored the impact of DNA with designed properties on the construction of core-satellite structures by employing AuNRs as cores and spherical gold nanoparticles (AuNSs) as satellites. Density, rigidity, and valence are identified as crucial factors for efficient construction. Specifically, polyA-tailed DNA modulated DNA density and reduced spatial hindrance and electrostatic repulsion, thereby facilitating the construction. Enhancing the rigidity of DNA and incorporating multiple binding sites can further improve the efficiency.

Mode-Selective Plasmon Coupling between Au Nanorods and Au Nanospheres

Plasmons play a central role in the properties of gold nanoparticles (AuNPs). Plasmons in a AuNP are influenced by neighboring ones, resulting in hybridized bonding dipole modes and red-shifted resonance peaks in the extinction spectra. Previous studies have mainly focused on plasmon coupling among spherical AuNPs (AuNSs). Here, we explore plasmonic interactions between AuNSs and anisotropic gold nanorods (AuNRs), which have longitudinal (LO) and transverse (TR) plasmon modes. We successfully assemble AuNSs around AuNRs ("AuNR@AuNS"), observing shifts in both the LO and TR modes in the extinction spectra due to directional coupling. Selectively binding AuNSs to the ends of AuNRs ("AuNR═AuNS") leads to predominant plasmon coupling along the LO direction. Our simulation studies reveal that exclusive LO or TR coupling occurs only when AuNSs attach to the center of either the end or the side of AuNRs. This study provides a valuable guideline for selectively exciting plasmons in desired nanogaps when multiple nanogaps are present.

Nanoclays: Promising Materials for Vaccinology

Clay materials and nanoclays have gained recent popularity in the vaccinology field, with biocompatibility, simple functionalization, low toxicity, and low-cost as their main attributes. As elements of nanovaccines, halloysite nanotubes (natural), layered double hydroxides and hectorite (synthetic) are the nanoclays that have advanced into the vaccinology field. Until now, only physisorption has been used to modify the surface of nanoclays with antigens, adjuvants, and/or ligands to create nanovaccines. Protocols to covalently attach these molecules have not been developed with nanoclays, only procedures to develop adsorbents based on nanoclays that could be extended to develop nanovaccine conjugates. In this review, we describe the approaches evaluated on different nanovaccine candidates reported in articles, the immunological results obtained with them and the most advanced approaches in the preclinical field, while describing the nanomaterial itself. In addition, complex systems that use nanoclays were included and described. The safety of nanoclays as carriers is an important key fact to determine their true potential as nanovaccine candidates in humans. Here, we present the evaluations reported in this field. Finally, we point out the perspectives in the development of vaccine prototypes using nanoclays as antigen carriers.

Electrostatically Directed Long-Range Self-Assembly of Nucleotides with Cationic Nanoparticles To Form Multifunctional Bioplasmonic Networks

Precise control over interparticle interactions is essential to retain the functions of individual components in a self-assembled superstructure. Here, we report the design of a multifunctional bioplasmonic network via an electrostatically directed self-assembly process involving adenosine 5'-triphosphate (ATP). The present study unveils the ability of ATP to undergo a long-range self-assembly in the presence of cations and gold nanoparticles (AuNP). Modelling and NMR studies gave a qualitative insight into the major interactions driving the bioplasmonic network formation. ATP-Ca²⁺ coordination helps in regulating the electrostatic interaction, which is crucial in transforming an uncontrolled precipitation into a kinetically controlled aggregation process. Remarkably, ATP and AuNP retained their inherent properties in the multifunctional bioplasmonic network. The generality of electrostatically directed self-assembly process was extended to different nucleotide-nanoparticle systems.

Modular super-assembly of hierarchical superstructures from monomicelle building blocks

Manipulating the super-assembly of polymeric building blocks still remains a great challenge due to their thermodynamic instability. Here, we report on a type of three-dimensional hierarchical core-satellite SiO₂@monomicelle spherical superstructures via a previously unexplored monomicelle interfacial super-assembly route. Notably, in this superstructure, an ultrathin single layer of monomicelle subunits (~18 nm) appears in a typically hexagon-like regular discontinuous distribution (adjacent micelle distance of ~30 nm) on solid spherical interfaces (SiO₂), which is difficult to achieve by conventional super-assembled methods. Besides, the number of the monomicelles on colloidal SiO₂ interfaces can be quantitatively controlled (from 76 to 180). This quantitative control can be precisely manipulated by tuning the interparticle electrostatic interactions (the intermicellar electrostatic repulsion and electrostatic attractions between the monomicelle units and the SiO₂ substrate). This monomicelle interfacial super-assembly strategy will enable a controllable way for building multiscale hierarchical regular micro- and/or macroscale materials and devices.

Aptamer-engineered gold nanorod driven an absorbance enhanced strategy for sensitive biomacromolecule profiling

Gold nanorods (AuNRs)-based plasmonic biosensor offers new opportunity for quantification of biomacromolecules due to their high designability and low technical demands. However, existing methods for the optical detection of biomacromolecule require the targets to induce the aggregation or etching of AuNRs. This limits the range of targets that can be detected, because molecules at extremely low concentration are difficult to arouse aggregation or etching of AuNRs. Thus, it is still challenge to design a scheme for the biomacromolecules at extremely low concentration which can't arouse aggregation or etching of AuNRs based on their plasmonic property. This study proposes a universal absorbance enhanced strategy for biomacromolecule detection with aptamers engineered AuNRs. The biosensor assay (Apts/AuNRs) is designed through assembly of two aptamers on AuNRs to specified recognize the target biomacromolecules, forming closed-loop conformation based on the proximity-dependent ligation, producing absorbance enhancement in the plasmonic peak of AuNRs. It is interesting that the absorbance enhancement increases gradually with increasing protein concentration within a certain range, whereas no aggregation or etching of AuNRs was observed compared with the typical AuNRs based LSPR sensor. Taking advantage of the excellent near infrared light absorption of AuNRs, Apts/AuNRs could be utilized to detect red protein such as cytochrome C, which exhibited better performance than AuNPs based plasmonic sensor. On this basis, the selectivity detection of cytochrome C with the detection of limit down to picomole level was demonstrated. By changing the type of aptamers on AuNRs, the sensitive and credible method was also utilized for the analysis of telomerase activity in nerve cell lysate. Telomerase activity in 4 × 10⁴ neuroblastoma cell was determined to be about 3.575 U/L, which was close to the result of ELISA kit. Good recovery was achieved using standard samples recovery. This study broadens the scope of AuNRs based plasmonic ‬‬‬‬‬‬property ‬‬‬‬and offer a simple, sensitive and selective strategy for biomacromolecules detection in complexed biofluid.

Dynamic nanoassembly-based drug delivery system (DNDDS): Learning from nature

Dynamic nanoassembly-based drug delivery system (DNDDS) has evolved from being a mere curiosity to emerging as a promising strategy for high-performance diagnosis and/or therapy of various diseases. However, dynamic nano-bio interaction between DNDDS and biological systems remains poorly understood, which can be critical for precise spatiotemporal and functional control of DNDDS in vivo. To deepen the understanding for fine control over DNDDS, we aim to explore natural systems as the root of inspiration for researchers from various fields. This review highlights ingenious designs, nano-bio interactions, and controllable functionalities of state-of-the-art DNDDS under endogenous or exogenous stimuli, by learning from nature at the molecular, subcellular, and cellular levels. Furthermore, the assembly strategies and response mechanisms of tailor-made DNDDS based on the characteristics of various diseased microenvironments are intensively discussed. Finally, the current challenges and future perspectives of DNDDS are briefly commented.

Recent near-infrared light-activated nanomedicine toward precision cancer therapy

Light has been present throughout the history of mankind and even the universe. It is of great significance to human life, contributing to energy, agriculture, communication, and much more. In the biomedical field, light has been developed as a switch to control medical processes with minimal invasion and high spatiotemporal selectivity. During the past three years, near-infrared (NIR) light as long-wavelength light has been applied to more than 3000 achievements in biological applications due to its deep penetration depth and low phototoxicity. Remotely controlled cancer therapy usually involves the conversion of biologically inert NIR light. Thus, various materials, especially nanomaterials that can generate reactive oxygen species (ROS), ultraviolet (UV)/visual light, or thermal energy and so on under NIR illumination achieve great potential for the research of nanomedicine. Here, we offered an overview of recent advances in NIR light-activated nanomedicine for cancer therapeutic applications. NIR-light-conversion nanotechnologies for both directly triggering nanodrugs and smart drug delivery toward tumor therapy were discussed emphatically. The challenges and future trends of the use of NIR light in biomedical applications were also provided as a conclusion. We expect that this review will spark inspiration for biologists, materials scientists, pharmacologists, and chemists to fight against diseases and boost the future clinical-translational applications of NIR technology-based precision nanomedicine.

Rationally Programming Nanomaterials with DNA for Biomedical Applications

DNA is not only a carrier of genetic information, but also a versatile structural tool for the engineering and self-assembling of nanostructures. In this regard, the DNA template has dramatically enhanced the scalability, programmability, and functionality of the self-assembled DNA nanostructures. These capabilities provide opportunities for a wide range of biomedical applications in biosensing, bioimaging, drug delivery, and disease therapy. In this review, the importance and advantages of DNA for programming and fabricating of DNA nanostructures are first highlighted. The recent progress in design and construction of DNA nanostructures are then summarized, including DNA conjugated nanoparticle systems, DNA-based clusters and extended organizations, and DNA origami-templated assemblies. An overview on biomedical applications of the self-assembled DNA nanostructures is provided. Finally, the conclusion and perspectives on the self-assembled DNA nanostructures are presented.

Nonspherical Metal-Based Nanoarchitectures: Synthesis and Impact of Size, Shape, and Composition on Their Biological Activity

Metal-based nanoentities, apart from being indispensable research tools, have found extensive use in the industrial and biomedical arena. Because their biological impacts are governed by factors such as size, shape, and composition, such issues must be taken into account when these materials are incorporated into multi-component ensembles for clinical applications. The size and shape (rods, wires, sheets, tubes, and cages) of metallic nanostructures influence cell viability by virtue of their varied geometry and physicochemical interactions with mammalian cell membranes. The anisotropic properties of nonspherical metal-based nanoarchitectures render them exciting candidates for biomedical applications. Here, the size-, shape-, and composition-dependent properties of nonspherical metal-based nanoarchitectures are reviewed in the context of their potential applications in cancer diagnostics and therapeutics, as well as, in regenerative medicine. Strategies for the synthesis of nonspherical metal-based nanoarchitectures and their cytotoxicity and immunological profiles are also comprehensively appraised.

Near-Infrared-Triggered Photothermal Aggregation of Polymer-Grafted Gold Nanorods in a Simulated Blood Fluid

Gold nanorods were decorated with thermoresponsive copolymers of tailored architecture and constructed from N-isopropyl acrylamide and acrylamide. The copolymers were prepared via reversible addition-fragmentation chain transfer polymerization (RAFT) and immobilized on the gold nanorod surface taking advantage of the aurophilicity of its inherently formed trithiocarbonate groups. The topology as well as the average molecular weight of the copolymers was altered using either a monofunctional or 3-arm star RAFT agent. Two-dimensional arrays of the self-assembled core-shell nanostructures were fabricated by drop-casting showing tunable interparticle spacings. In a simulated blood fluid, the lower critical solution temperature of the nanohybrids could be modified over a significant temperature range around body temperature by adjusting the copolymer composition, the architecture, and/or the size of the polymer. The intrinsic photothermal properties of the gold nanorods were utilized to trigger particle aggregation by irradiation at 808 nm in the optical window of human tissues. In effect, a new nanohybrid system with remotely controllable aggregation via an external NIR-light stimulus for nanomedical applications was developed.

Understanding and advancement in gold nanoparticle targeted photothermal therapy of cancer

The present communication summarizes the importance, understanding and advancement in the photothermal therapy of cancer using gold nanoparticles. Photothermal therapy was used earlier as a single line therapy, but using a combination of photothermal therapy with other therapies like immunotherapy, chemotherapy, photodynamic therapy; efficient therapy management can be achieved. As it was discussed in many studies that gold nanoparticles are treated as idyllic photothermal transducers due to their structural dimensions, which enables them to strongly absorb near infrared light. Gold nanoparticles which are mediated for photothermal therapy can warn cancer cells to chemotherapy, regulate genes and immunotherapy by enhancing the cell permeability and intracellular delivery. The necrosis process and apoptosis depend on the power of laser and temperature within the cancerous tissues which are reached during irradiation. Cells death mechanism is also important because the cells which died through the process of necrosis can endorse secondary tumor growth while the cells which died through apoptosis may provoke the immune response to inhibit the development of secondary tumor growth. To decrease the in vivo barriers, gold nanostructures are again modified with targeting ligand and bio-responsive linker. The manuscript summarizes that the use of gold nanoparticles is capable of inhibiting the growth of cancerous cells by using photothermal therapy which has lesser adverse effects compared to other line therapies.

Dynamics of Human Serum Albumin Corona Formation on Gold Nanorods with Different Surface Ligands In Silico

The interaction between human serum albumin (HSA) and nanoparticles (NPs) to form HSA corona has widely been studied since endogenous functions of albumin are highly attractive for drug delivery. However, a full understanding of the molecular dynamics and factors behind the formation of HSA corona, including interactions between HSA and different surface ligands and between neighboring HSA molecules, resulting in conformational change of HSA is presently lacking. Here, we assembled 14 HSA molecules around gold nanorods (AuNRs) with different surface chemistries (bare gold surface, cetyltrimethylammonium bromide (CTAB), polystyrene sulfonate (PSS), and polydiallyldimethylammonium chloride (PDADMAC)) in silico and examined the dynamics of HSA corona formation using coarse-grained molecular dynamics for 300 ns of simulation. We observed that PDADMAC, being more flexible than PSS, resulted in all HSA molecules moving toward AuNR-PDADMAC, while the instability of CTAB on AuNR resulted in fewer HSA molecules moving toward AuNR-CTAB compared to AuNR-PSS. HSA molecules around AuNR-PDADMAC also exhibited the largest conformational change in terms of their radius of gyration (R_g) and root mean square deviation (RMSD). In the absence of surface ligands, HSA molecules around the bare AuNR were susceptible to steric hindrance with conformational change observed in terms of their RMSD but not their R_g unlike that of HSA molecules around AuNR-PDADMAC. The insights gained from the inclusion of neighboring HSA molecules in the simulation of corona formation could be more representative than examining a single adsorbed HSA molecule on AuNRs with different surface passivations.

Cascade Drug-Release Strategy for Enhanced Anticancer Therapy

Chemotherapy serves as one of the most effective approaches in numerous tumor treatments but also suffers from the limitations of low bioavailability and adverse side effects due to premature drug leakage. Therefore, it is crucial to realize accurate on-demand drug release for promoting the application of chemotherapeutic agents. To achieve this, stimuli-responsive nanomedicines that can be activated by delicately designed cascade reactions have been developed in recent years. In general, the nanomedicines are triggered by an internal or external stimulus, generating an intermediate stimulus at tumor site, which can intensify the differences between tumor and normal tissues; the drug release process is then further activated by the intermediate stimulus. In this review, the latest progress made in cascade reactions-driven drug-release modes, based on the intermediate stimuli of heat, hypoxia, and reactive oxygen species, is systematically summarized. The perspectives and challenges of cascade strategy for drug delivery are also discussed.

DNA Nanostructures and DNA-Functionalized Nanoparticles for Cancer Theranostics

In the last two decades, DNA has attracted significant attention toward the development of materials at the nanoscale for emerging applications due to the unparalleled versatility and programmability of DNA building blocks. DNA-based artificial nanomaterials can be broadly classified into two categories: DNA nanostructures (DNA-NSs) and DNA-functionalized nanoparticles (DNA-NPs). More importantly, their use in nanotheranostics, a field that combines diagnostics with therapy via drug or gene delivery in an all-in-one platform, has been applied extensively in recent years to provide personalized cancer treatments. Conveniently, the ease of attachment of both imaging and therapeutic moieties to DNA-NSs or DNA-NPs enables high biostability, biocompatibility, and drug loading capabilities, and as a consequence, has markedly catalyzed the rapid growth of this field. This review aims to provide an overview of the recent progress of DNA-NSs and DNA-NPs as theranostic agents, the use of DNA-NSs and DNA-NPs as gene and drug delivery platforms, and a perspective on their clinical translation in the realm of oncology.

Pathological Mechanism of Photodynamic Therapy and Photothermal Therapy Based on Nanoparticles

The ultimate goal of phototherapy based on nanoparticles, such as photothermal therapy (PTT) which generates heat and photodynamic therapy (PDT) which not only generates reactive oxygen species (ROS) but also induces a variety of anti-tumor immunity, is to kill tumors. In addition, due to strong efficacy in clinical treatment with minimal invasion and negligible side effects, it has received extensive attention and research in recent years. In this paper, the generations of nanomaterials in PTT and PDT are described separately. In clinical application, according to the different combination pathway of nanoparticles, it can be used to treat different diseases such as tumors, melanoma, rheumatoid and so on. In this paper, the mechanism of pathological treatment is described in detail in terms of inducing apoptosis of cancer cells by ROS produced by PDT, immunogenic cell death to provoke the maturation of dendritic cells, which in turn activate production of CD4+ T cells, CD8+T cells and memory T cells, as well as inhibiting heat shock protein (HSPs), STAT3 signal pathway and so on.

Femtosecond Laser Pulse Excitation of DNA-Labeled Gold Nanoparticles: Establishing a Quantitative Local Nanothermometer for Biological Applications

Femtosecond (fs) laser pulsed excitation of plasmonic nanoparticle (NP)-biomolecule conjugates is a promising method to locally heat biological materials. Studies have demonstrated that fs pulses of light can modulate the activity of DNA or proteins when attached to plasmonic NPs; however, the precision over subsequent biological function remains largely undetermined. Specifically, the temperature the localized biomolecules "experience" remains unknown. We used 55 nm gold nanoparticles (AuNPs) displaying double-stranded (ds) DNA to examine how, for dsDNA with different melting temperatures, the laser pulse energy fluence and bulk solution temperature affect the rate of local DNA denaturation. A universal "template" single-stranded DNA was attached to the AuNP surface, and three dye-labeled probe strands, distinct in length and melting temperature, were hybridized to it creating three individual dsDNA-AuNP bioconjugates. The dye-labeled probe strands were used to quantify the rate and amount of DNA release after a given number of light pulses, which was then correlated to the dsDNA denaturation temperature, resulting in a quantitative nanothermometer. The localized DNA denaturation rate could be modulated by more than threefold over the biologically relevant range of 8-53 °C by varying pulse energy fluence, DNA melting temperature, and surrounding bath temperature. With a modified dissociation equation tailored for this system, a "sensed" temperature parameter was extracted and compared to simulated AuNP temperature profiles. Determining actual biological responses in such systems can allow researchers to design precision nanoscale photothermal heating sources.

Hyperthermia-Triggered On-Demand Biomimetic Nanocarriers for Synergetic Photothermal and Chemotherapy

Nanoparticle-based drug delivery systems with low side effects and enhanced efficacy hold great potential in the treatment of various malignancies, in particular cancer; however, they are still challenging to attain. Herein, an anticancer drug delivery system based on a cisplatin (CDDP) containing nanogel, functionalized with photothermal gold nanorods (GNRs) which are electrostatically decorated with doxorubicin (DOX) is reported. The nanoparticles are formed via the crosslinking reaction of hyaluronic acid with the ancillary anticarcinogen CDDP in the presence of DOX-decorated GNRs. The nanogel is furthermore cloaked with a cancer cell membrane, and the resulting biomimetic nanocarrier (4T1-HANG-GNR-DC) shows efficient accumulation by homologous tumor targeting and possesses long-time retention in the tumor microenvironment. Upon near-infrared (NIR) laser irradiation, in situ photothermal therapy is conducted which further induces hyperthermia-triggered on-demand drug release from the nanogel reservoir to achieve a synergistic photothermal/chemo-therapy. The as-developed biomimetic nanocarriers, with their dual-drug delivery features, homotypic tumor targeting and synergetic photothermal/chemo-therapy, show much promise as a potential platform for cancer treatment.

DNA-directed arrangement of soft synthetic compartments and their behavior in vitro and in vivo

DNA has been widely used as a key tether to promote self-organization of super-assemblies with emergent properties. However, control of this process is still challenging for compartment assemblies and to date the resulting assemblies have unstable membranes precluding in vitro and in vivo testing. Here we present our approach to overcome these limitations, by manipulating molecular factors such as compartment membrane composition and DNA surface density, thereby controlling the size and stability of the resulting DNA-linked compartment clusters. The soft, flexible character of the polymer membrane and low number of ssDNA remaining exposed after cluster formation determine the interaction of these clusters with the cell surface. These clusters exhibit in vivo stability and lack of toxicity in a zebrafish model. To display the breadth of therapeutic applications attainable with our system, we encapsulated the medically established enzyme laccase within the inner compartment and demonstrated its activity within the clustered compartments. Most importantly, these clusters can interact selectively with different cell lines, opening a new strategy to modify and expand cellular functions by attaching such pre-organized soft DNA-mediated compartment clusters on cell surfaces for cell engineering or therapeutic applications.

Acid-Switchable DNAzyme Nanodevice for Imaging Multiple Metal Ions in Living Cells

Metal-assisted deoxyribozyme catalysis (DNAzyme) has been a general platform for constructing highly sensitive and selective detection sensors of metal ions. However, the "always on" mode of the traditional DNAzyme sensors greatly limits their application in the visual analysis of endogenous metal ions in a complex physiological microenvironment. To overcome this obstacle, a smart acid-switchable DNAzyme nanodevice is designed to control the DNAzyme activity in living cells and achieve simultaneous visualization of metal ions (Zn²⁺ and Pb²⁺) in situ. This nanodevice is built on DNAzyme precursors (DPs) and acid-switchable DNA (SW-DNA), precisely responding to pH variations in the range of 4.5-7.0, and the state of the three-strand hybridization of DPs successfully renders the DNAzymes inactive before being transported into cells. Once the nanodevice is taken up into living cells, the SW-DNA will change the configuration from linear to triplex in the acidic intracellular compartments (lysosomes, pH ∼4.5 to 5.0) and then the strands hybridized with the SW-DNA are liberated and subsequently react with DPs to form the active DNAzyme, which can further realize multi-imaging of intracellular metal ions. Moreover, this strategy has broad prospects as a powerful platform for constructing various acid-switchable nanodevices for visual analysis of multiple biomolecules in living cells.

Attaching DNA to Gold Nanoparticles With a Protein Corona

DNA-functionalized gold nanoparticles (AuNPs) have been widely used in directed assembly of materials, biosensors, and drug delivery. This conjugate may encounter proteins in these applications and proteins may affect not only DNA adsorption but also the function of the attached DNA. Bovine serum albumin (BSA) with many cysteine residues can strongly adsorb on AuNPs and this conjugate showed high colloidal stability against salt, acid and base. Similar protection effects were also observed with a few other common proteins including catalase, hemoglobin, glucose oxidase, and horseradish peroxidase. DNA oligonucleotides without a thiol label can hardly displace adsorbed BSA, and BSA cannot displace pre-adsorbed DNA either, indicating a strongly kinetically controlled system. Thiolated DNA can be attached at a low density on the AuNPs with a BSA corona. The BSA corona did not facilitate the hybridization of the conjugated DNA, while a smaller peptide, glutathione allowed faster hybridization. Overall, proteins increase the colloidal stability of AuNPs, and they do not perturb the gold-thiol bond in the DNA conjugate, although a large protein corona may inhibit the hybridization function of DNA.

The impact of size and surface ligand of gold nanorods on liver cancer accumulation and photothermal therapy in the second near-infrared window

Gold nanorods (GNRs) with longitudinal surface plasmon resonance (LSPR) peaks in second near-infrared (NIR-II) window have attracted a great amount of attention as photothermal transducer because of their inherently excellent photothermal transition efficiency, high biocompatibility and versatile surface functionalization. One key question for the application of these GNRs against tumors in vivo is which size/shape and surface ligand conjugation are promising for circulation and tumor targeting. In this study, we prepared a series of gold nanorods (GNRs) of similar aspect ratio and LSPR peaks, and thus similar photothermal transfer efficiency under irradiation of 980 nm laser, but with tunable size in width and length. The obtained GNRs were subjected to surface modification with PEG and tumor targeting ligand lactoferrin. With these tailor-designed GNRs in hand, we have the chance to study the impact of dimension and surface property of the GNRs on their internalization via tumor cells, photothermal cytotoxicity in vitro, blood circulation and tissue distribution pattern in vivo. As a result, the GNRs with medium size (70 nm in length and 11.5 nm in width) and surface PEG/LF modification (GNR70@PEG-LF) exhibit the fastest cell internalization via HepG2 cells and best photothermal outcome in vitro. The GNR70@PEG-LF also display long circulation time and the highest tumor accumulation in vivo, due to the synergetic effect of surface coating and dimension. Finally, tumor ablation ability of the GNRs under irradiation of 980 nm light were validated on mice xenograft model, suggesting their potential photothermal therapy against cancer in NIR-II window.

A tumor-microenvironment-responsive nanomaterial for cancer chemo-photothermal therapy

Taxol (TAX) is a typical anticancer drug that is widely used in clinical treatment of cancer, while gold nanorods (AuNRs) are a kind of well-known material applied for photothermal therapy (PTT). The therapeutic outcome of TAX in chemotherapy is however limited by drug resistance, while AuNRs often show poor accuracy in PTT. To optimize the functions of TAX and AuNRs, we developed a hydrogen peroxide (H₂O₂)-triggered nanomaterial (LV–TAX/Au@Ag) for combined chemo-photothermal therapy. In normal tissues, TAX is protected in the lipid bilayer and isolated from the surrounding normal cells, while AuNRs are coated with silver shells and show low photothermal capacity. However, after reaching the tumor tissues, the silver shells can be etched by endogenous H₂O₂ in the tumor microenvironment, and the photothermal properties of AuNRs are then recovered. Meanwhile, the generated oxygen destabilizes the LV, which makes the 100 nm sized nanosystems disassemble into the smaller sized TAX and AuNRs, leading to the deep penetration and direct interaction with tumor tissues. The related in vitro experiments proved the validity of this “turn off/on” effect. Extensive necrosis and apoptosis were observed in the tumor tissues and the proliferation of solid tumor was greatly suppressed due to this combined chemo-photothermal therapy. In addition, no significant damage was found in normal tissues after the treatment of LV–TAX/Au@Ag. Therefore, the strategy to achieve environmental response by modifying the photothermal agents enhanced the efficiency and safety of nanomedicine, which may help improve cancer treatment.

Endogenous hydrogen peroxide was utilized to control the release of agents for better tumor therapeutic effect and safety.

Dynamic supraparticles for the treatment of age-related diseases

Age-related diseases (ARDs) are arising as a major threat to public health in our fast-aging society. Current development of nanomedicine has sparked much optimism toward ARDs management by improving drug delivery and controlled drug release. However, effective treatments for ARDs, such as cancer and Alzheimer's diseases (AD), are still lacking, due to the complicated pathological features of ARDs including multifactorial pathogenesis, intricate disease microenvironment, and dynamic symptom manifestation. Recently, dynamic supraparticles (DS), which are reversibly self-assembled functional nanoparticles, have provided a novel strategy for combating ARDs. Besides the intrinsic advantages of nanomedicine including multifunctional and multitarget, DS are capable of dynamic structural reconfiguration upon certain stimulation, creating another layer of maneuverability that allows programmed response to the spatiotemporal alterations of ARDs during progression and treatment. In this review, we will overview the challenges faced by ARDs management, and discuss the unique opportunities brought by DS. Then, we will summarize the designed synthesis of DS for ARDs treatment. Finally, we will dissect the therapeutic targets in ARDs that can be exploited by DS, and present the encouraging advances in this field. Hopefully, this review will bridge our knowledge of the design principle of DS and ARDs management, which may inspire the future development of potent theranostic agents to improve the healthcare.

SERS and plasmonic heating efficiency from anisotropic core/satellite superstructures

The optical properties of nanoparticle assemblies can be tailored via hybridization of plasmon modes. Isotropic core/satellite superstructures made of spherical nanoparticles are known to exhibit coupled modes with a strongly scattering (radiative) character, and provide hot spots yielding high activity in surface-enhanced Raman scattering (SERS). However, to complement this functionality with plasmonic heating, additional absorbing (non-radiative) modes are required. We introduce herein anisotropic superstructures formed by decorating a central nanorod with spherical satellite nanoparticles, which feature two coupled modes that allow application for both SERS and heating. On the basis of diffuse reflectance spectroscopy, small-angle X-ray scattering (SAXS), and electromagnetic simulations, the origin of the coupled modes is disclosed and thus serves as a basis toward alternative designs of functional superstructures. This work represents a proof-of-principle for the combination of high SERS efficiency with efficient plasmonic heating by near-infrared irradiation.

Development of Multifunctional Clay-Based Nanomedicine for Elimination of Primary Invasive Breast Cancer and Prevention of Its Lung Metastasis and Distant Inoculation

Cancer recurrence and metastasis are worldwide challenges but current bimodular strategies such as combined radiotherapy and chemotherapy (CTX), and photothermal therapy (PTT) and immunotherapy have succeeded only in some limited cases. Thus in the present study, a multifunctional nanomedicine has been rationally designed via elegantly integrating three FDA-approved therapeutics, that is, indocyanine green (for PTT), doxorubicin (for CTX), and CpG (for immunotherapy) into the structure of layered double hydroxide (LDH) nanoparticles, aiming to completely prevent the recurrence and metastasis of invasive breast cancer. This multifunctional hybrid nanomedicine has been demonstrated to eliminate the primary tumor and efficiently prevent tumor recurrence and lung metastasis through combined PTT/CTX and induction of specific and strong immune responses mediated by the hybrid nanomedicine in a 4T1 breast cancer mouse model. Furthermore, the promoted in situ immunity has significantly inhibited the growth of reinoculated distant tumors. Altogether, our multifunctional LDH-based nanomedicine has showed an excellent efficacy in invasive cancer treatment using much lower doses of three FDA-approved therapeutics, providing a preclinical/clinical alternative to cost-effectively treat invasive breast cancer.

Near-infrared photothermally activated nanomachines for cancer theragnosis

Near-infrared photothermal-activated nanomaterials are emerging as a promising tool in precise cancer theranostics. This Frontier article highlights the recent advances of photothermal-activated nanoagents in biomedical applications, namely photothermal-initiated drug/contrast agent release, gene silencing, programmed targeting and gas theranostics. In the end, we give a perspective on the further development of photothermal-sensitive nanomedicines.

Triplex DNA Nanoswitch for pH-Sensitive Release of Multiple Cancer Drugs

A DNA-based stimulus-responsive drug delivery system for synergetic cancer therapy has been developed. The system is built on a triplex-DNA nanoswitch capable of precisely responding to pH variations in the range of ∼5.0-7.0. In extracellular neutral pH space, the DNA nanoswitch keeps a linear conformation, immobilizing multiple therapeutics such as small molecules and antisense compounds simultaneously. Following targeted cancer cell uptake via endocytosis, the nanoswitch inside acidic intracellular compartments goes through a conformational change from linear to triplex, leading to smart release of the therapeutic combination. This stimuli-responsive drug delivery system does not rely on artificial responsive materials, making it biocompatible. Furthermore, it enables simultaneous delivery of multiple therapeutics for enhanced efficacy. Using tumor-bearing mouse models, we show efficient gene silencing and significant inhibition of tumor growth upon intravenous administration of the smart nanoswitch, providing opportunities for combinatorial cancer therapy.

Dynamic Nanostructures from DNA-Coupled Molecules, Polymers, and Nanoparticles

Dynamic and reconfigurable systems that can sense and react to physical and chemical signals are ubiquitous in nature and are of great interest in diverse areas of science and technology. DNA is a powerful tool for fabricating such smart materials and devices due to its programmable and responsive molecular recognition properties. For the past couple of decades, DNA-based self-assembly is actively explored to fabricate various DNA-organic and DNA-inorganic hybrid nanostructures with high-precision structural control. Building upon past development, researchers have recently begun to design and assemble dynamic nanostructures that can undergo an on-demand transformation in the structure, properties, and motion in response to various external stimuli. In this Review, recent advances in dynamic DNA nanostructures, focusing on hybrid structures fabricated from DNA-conjugated molecules, polymers, and nanoparticles, are introduced, and their potential applications and future perspectives are discussed.

Recent progress in nanoscale metal-organic frameworks for drug release and cancer therapy

Nanoscale metal-organic frameworks (MOFs) have been widely used as controlled drug delivery vehicles and cancer therapy agents due to their intrinsic superior properties. Scientists have made remarkable achievements in the field of nanomedicine by using the MOFs and MOF-based multifunctional nanomaterials due to the easy synthesis into nanoscale and functionalization. In this review, we highlight the recent progress of nanoscale MOFs as drug delivery vehicles for cancer theranostics. We divide the discussion into three parts. The first and second parts focus on the drug delivery of unmodified MOF and modified MOFs, respectively, while the third part focuses on porphyrin MOFs as photosensitizers for photodynamic therapy. Finally, we conclude by identifying areas of research that we believe will propel the translation and application of MOFs.

Biomedical applications of nanoflares: Targeted intracellular fluorescence probes

Nanoflares are intracellular probes consisting of oligonucleotides immobilized on various nanoparticles that can recognize intracellular nucleic acids or other analytes, thus releasing a fluorescent reporter dye. Single-stranded DNA (ssDNA) complementary to mRNA for a target gene is constructed containing a 3'-thiol for binding to gold nanoparticles. The ssDNA "recognition sequence" is prehybridized to a shorter DNA complement containing a fluorescent dye that is quenched. The functionalized gold nanoparticles are easily taken up into cells. When the ssDNA recognizes its complementary target, the fluorescent dye is released inside the cells. Different intracellular targets can be detected by nanoflares, such as mRNAs coding for genes over-expressed in cancer (epithelial-mesenchymal transition, oncogenes, thymidine kinase, telomerase, etc.), intracellular levels of ATP, pH values and inorganic ions can also be measured. Advantages include high transfection efficiency, enzymatic stability, good optical properties, biocompatibility, high selectivity and specificity. Multiplexed assays and FRET-based systems have been designed.

Gold nanorods with a noncovalently tailorable surface for multi-modality image-guided chemo-photothermal cancer therapy

Cucurbit[7]uril functionalized Au nanorods allowed noncovalently tailorable surface modification for image-guided, targeted chemo-photothermal cancer therapy in vitro and in vivo.

MicroRNA detection based on duplex-specific nuclease-assisted target recycling and gold nanoparticle/graphene oxide nanocomposite-mediated electrocatalytic amplification

DNA technology based bio-responsive nanomaterials have been widely studied as promising tools for biomedical applications. Gold nanoparticles (AuNPs) and graphene oxide (GO) sheets are representative zero- and two-dimensional nanomaterials that have long been combined with DNA technology for point-of-care diagnostics. Herein, a cascade amplification system based on duplex-specific nuclease (DSN)-assisted target recycling and electrocatalytic water-splitting is demonstrated for the detection of microRNA. Target microRNAs can form DNA: RNA heteroduplexes with DNA probes on the surface of AuNPs, which can be hydrolyzed by DSN. MicroRNAs are preserved during the reaction and released into the suspension for the digestion of multiple DNA probes. After the DSN-based reaction, AuNPs are collected and mixed with GO to form AuNP/GO nanocomposite on an electrode for the following electrocatalytic amplification. The utilization of AuNP/GO nanocomposite offers large surface area, exceptional affinity to water molecules, and facilitated mass diffusion for the water-splitting reaction. For let-7b detection, the proposed biosensor achieved a limit detection of 1.5 fM in 80 min with a linear detection range of approximately four orders of magnitude. Moreover, it has the capability of discriminating non-target microRNAs containing even single-nucleotide mismatches, thus holding considerable potential for clinical diagnostics.

Enhancing Antitumor Efficacy by Simultaneous ATP-Responsive Chemodrug Release and Cancer Cell Sensitization Based on a Smart Nanoagent

The exploitation of smart nanoagents based drug delivery systems (DDSs) has proven to be a promising strategy for fighting cancers. Hitherto, such nanoagents still face challenges associated with their complicated synthesis, insufficient drug release in tumors, and low cancer cell chemosensitivity. Here, the engineering of an adenosine triphosphate (ATP)-activatable nanoagent is demonstrated based on self-assembled quantum dots-phenolic nanoclusters to circumvent such challenges. The smart nanoagent constructed through a one-step assembly not only has high drug loading and low cytotoxicity to normal cells, but also enables ATP-activated disassembly and controlled drug delivery in cancer cells. Particularly, the nanoagent can induce cell ATP depletion and increase cell chemosensitivity for significantly enhanced cancer chemotherapy. Systematic in vitro and in vivo studies further reveal the capabilities of the nanoagent for intracellular ATP imaging, high tumor accumulation, and eventual body clearance. As a result, the presented multifunctional smart nanoagent shows enhanced antitumor efficacy by simultaneous ATP-responsive chemodrug release and cancer cell sensitization. These findings offer new insights toward the design of smart nanoagents for improved cancer therapeutics.

Site-Selective Nucleation and Size Control of Gold Nanoparticle Photothermal Antennae on the Pore Structures of a Virus

In this Article, we show that the surface of the bacteriophage Qβ is equipped with natural ligands for the synthesis of small gold nanoparticles (AuNPs). By exploiting disulfides in the protein secondary structure and the geometry formed from the capsid quaternary structure, we find that we can produce regularly arrayed patterns of ∼6 nm AuNPs across the surface of the virus-like particle. Experimental and computational analyses provide insight into the formation and stability of this composite. We further show that the entrapped genetic material can hold upward of 500 molecules of the anticancer drug Doxorubicin without leaking and without interfering with the synthesis of the AuNPs. This direct nucleation of nanoparticles on the capsid allows for exceptional conduction of photothermal energy upon nanosecond laser irradiation. As a proof of principle, we demonstrate that this energy is capable of rapidly releasing the drug from the capsid without heating the bulk solution, allowing for highly targeted cell killing in vitro.

Programmable Metal/Semiconductor Nanostructures for mRNA-Modulated Molecular Delivery

Cytotoxic chemotherapeutics are important tools for the clinical treatment of a variety of solid tumors. However, their use is often complicated by multidrug resistance that can develop in patients, limiting the potencies of these agents. New strategies are needed to provide versatile systems that can respond to and disable resistance mechanisms. We demonstrate the use of a new family of materials, programmable metal/semiconductor nanostructures, for drug delivery and mRNA sensing in drug-resistant cells. These materials are composed of a central core gold nanoparticle surrounded by a layer of DNA-capped quantum dots. The modularity of these "core-satellite" assemblies allows for the construction of superstructures with controlled size and the incorporation of multiple functionalities for drug delivery. The DNA sequence within the nanoparticle specifically binds to an mRNA encoding an important drug resistance factor, MRP1, inside cancer cells, releasing a potent anticancer drug doxorubicin. This event triggers a turn-on fluorescence emission along with a downregulation of the MRP1 drug efflux pump, a main resistance factor for doxorubicin, yielding a remarkable improvement in therapeutic efficacy against drug-resistant cancer cells. This work paves the way for the development of programmable materials with multiple synergistic functionalities for biomedical applications.

TiO2-Capped Gold Nanorods for Plasmon-Enhanced Production of Reactive Oxygen Species and Photothermal Delivery of Chemotherapeutic Agents

Near infrared (NIR)-absorbing noble metal nanostructures are being extensively studied as theranostic agents, in particular for photoacoustic imaging and photothermal therapy. Because of the electric field enhancement at the tips of anisotropic metal nanostructures, positioning photoactive species at these sites can lead to increased energy absorption. Herein, we show the site-specific placement of NIR-active photosensitizers at the ends of gold nanorods (AuNRs) by growing porous TiO2 caps. The surface plasmon resonance of the AuNRs was carefully tuned to overlap with the exciton absorption of indocyanine green (ICG), a NIR photosensitizer with low quantum yields and poor photostability. In conjugating high amounts of ICG to the TiO2 caps, increased amounts of singlet oxygen (1O2) were generated as compared to when ICG was attached to sidewalls of the AuNRs. Because the AuNRs also cause local increases in temperature upon NIR excitation, DNA strands were next attached to the AuNRs sidewalls and loaded with doxorubicin (DOX). We found that the synergistic effect of increased 1O2 and photothermal-induced drug delivery led to significant improvements in tumor cell killing. This work demonstrates that with careful design over hybrid nanostructure synthesis, higher levels of tumor therapy may be achieved.

Polyvalent Spherical Nucleic Acids for Universal Display of Functional DNA with Ultrahigh Stability

For nanomaterials that are difficult to functionalize by covalent attachment of DNA, we herein communicate a general method taking advantage of the high avidity of polyvalent binding and the 3D structure of densely functionalized spherical nucleic acids (SNAs). Using DNA-functionalized gold nanoparticles, simple mixing leads to the formation of highly stable conjugates on 11 different materials including metals, metal oxides, metal-organic frameworks, transition-metal dichalcogenides, nanocarbons, and polymers. The adsorption affinity of SNAs can be over thousand-fold higher than that of free DNA of the same sequence, and practically irreversible conjugates are formed withstanding various denaturing agents. The surface attachment and molecular recognition functions of DNA are spatially separated, showing a key advantage of SNAs. The functionalized materials possess the properties of both the substrate and the SNA, allowing specific DNA hybridization in buffer and in serum.