Manipulating Immune Activation of Macrophages by Tuning the Oligonucleotide Composition of Gold Nanoparticles

Role of Surface Curvature in Gold Nanostar Properties and Applications

Gold nanostars (AuNSs) are nanoparticles with intricate three-dimensional structures and shape-dependent optoelectronic properties. For example, AuNSs uniquely display three distinct surface curvatures, i.e. neutral, positive, and negative, which provide different environments to adsorbed ligands. Hence, these curvatures are used to introduce different surface chemistries in nanoparticles. This review summarizes and discusses the role of surface curvature in AuNS properties and its impact on biomedical and chemical applications, including surface-enhanced Raman spectroscopy, contrast agent performance, and catalysis. We examine the main synthetic approaches to generate AuNSs, control their morphology, and discuss their benefits and drawbacks. We also describe the optical characteristics of AuNSs and discuss how these depend on nanoparticle morphology. Finally, we analyze how AuNS surface curvature endows them with properties distinctly different from those of other nanoparticles, such as strong electromagnetic fields at the tips and increased hydrophilic environments at the indentations, together making AuNSs uniquely useful for biosensing, imaging, and local chemical manipulation.

Preparation and Biological Properties of Oligonucleotide-Functionalized Virus-like Particles

Oligonucleotides are powerful molecules for programming function and assembly. When arrayed on nanoparticle scaffolds in high density, the resulting molecules, spherical nucleic acids (SNAs), become imbued with unique properties. We used the copper-catalyzed azide-alkyne cycloaddition to graft oligonucleotides on Qβ virus-like particles to see if such structures also gain SNA-like behavior. Copper-binding ligands were shown to promote the click reaction without degrading oligonucleotide substrates. Reactions were first optimized with a small-molecule fluorogenic reporter and were then applied to the more challenging synthesis of polyvalent protein nanoparticle-oligonucleotide conjugates. The resulting particles exhibited the enhanced cellular uptake and protection from nuclease-mediated oligonucleotide cleavage characteristic of SNAs, had similar residence time in the liver relative to unmodified particles, and were somewhat shielded from immune recognition, resulting in nearly 10-fold lower antibody titers relative to unmodified particles. Oligonucleotide-functionalized virus-like particles thus provide an interesting option for protein nanoparticle-mediated delivery of functional molecules.

The Promise of Nanoparticles-Based Radiotherapy in Cancer Treatment

Radiation has been utilized for a long time for the treatment of cancer patients. However, radiotherapy (RT) has many constraints, among which non-selectivity is the primary one. The implementation of nanoparticles (NPs) with RT not only localizes radiation in targeted tissue but also provides significant tumoricidal effect(s) compared to radiation alone. NPs can be functionalized with both biomolecules and therapeutic agents, and their combination significantly reduces the side effects of RT. NP-based RT destroys cancer cells through multiple mechanisms, including ROS generation, which in turn damages DNA and other cellular organelles, inhibiting of the DNA double-strand damage-repair system, obstructing of the cell cycle, regulating of the tumor microenvironment, and killing of cancer stem cells. Furthermore, such combined treatments overcome radioresistance and drug resistance to chemotherapy. Additionally, NP-based RT in combined treatments have shown synergistic therapeutic benefit(s) and enhanced the therapeutic window. Furthermore, a combination of phototherapy, i.e., photodynamic therapy and photothermal therapy with NP-based RT, not only reduces phototoxicity but also offers excellent therapeutic benefits. Moreover, using NPs with RT has shown promise in cancer treatment and shown excellent therapeutic outcomes in clinical trials. Therefore, extensive research in this field will pave the way toward improved RT in cancer treatment.

Recent advancements in design of nucleic acid nanocarriers for controlled drug delivery

Research of nanoscale nucleic acid carriers has garnered attention in recent years due to their distinctive and controllable properties. However, current knowledge is limited in how we can efficiently utilize these systems for clinical applications. Several researchers have pioneered new and innovative nanocarrier drug delivery systems, but understanding physiochemical properties and behavior in vivo is vital to implementing them as clinical drug delivery platforms. In this review, we outline the most significant innovations in the synthesis, physical properties, and utilization of nucleic acid nanocarriers in the past 5 years, addressing the crucial properties which improve nanocarrier characteristics, delivery, and drug release. The challenges of controlling the transport of nucleic acid nanocarriers and therapeutic release for biological applications are outlined. Barriers which inhibit effective transport into tissue are discussed with emphasis on the modifications needed to overcome such obstacles. The novel strategies discussed in this work summarize the pivotal features of modern nucleic nanocarriers and postulate where future developments could revolutionize the translation of these tools into a clinical setting.

Development of radiopharmaceuticals for targeted alpha therapy: Where do we stand?

Targeted alpha therapy is an oncological treatment, where cytotoxic doses of alpha radiation are locally delivered to tumor cells, while the surrounding healthy tissue is minimally affected. This therapeutic strategy relies on radiopharmaceuticals made of medically relevant radionuclides chelated by ligands, and conjugated to targeting vectors, which promote the drug accumulation in tumor sites. This review discusses the state-of-the-art in the development of radiopharmaceuticals for targeted alpha therapy, breaking down their key structural components, such as radioisotope, targeting vector, and delivery formulation, and analyzing their pros and cons. Moreover, we discuss current drawbacks that are holding back targeted alpha therapy in the clinic, and identify ongoing strategies in field to overcome those issues, including radioisotope encapsulation in nanoformulations to prevent the release of the daughters. Lastly, we critically discuss potential opportunities the field holds, which may contribute to targeted alpha therapy becoming a gold standard treatment in oncology in the future.

Rational Vaccinology: Harnessing Nanoscale Chemical Design for Cancer Immunotherapy

Cancer immunotherapy is a powerful treatment strategy that mobilizes the immune system to fight disease. Cancer vaccination is one form of cancer immunotherapy, where spatiotemporal control of the delivery of tumor-specific antigens, adjuvants, and/or cytokines has been key to successfully activating the immune system. Nanoscale materials that take advantage of chemistry to control the nanoscale structural arrangement, composition, and release of immunostimulatory components have shown significant promise in this regard. In this Outlook, we examine how the nanoscale structure, chemistry, and composition of immunostimulatory compounds can be modulated to maximize immune response and mitigate off-target effects, focusing on spherical nucleic acids as a model system. Furthermore, we emphasize how chemistry and materials science are driving the rational design and development of next-generation cancer vaccines. Finally, we identify gaps in the field that should be addressed moving forward and outline future directions to galvanize researchers from multiple disciplines to help realize the full potential of this form of cancer immunotherapy through chemistry and rational vaccinology.

Delivery Order of Nanoconstructs Affects Intracellular Trafficking by Endosomes

This paper reports how the endosomal pathways of nanoparticle (NP) constructs with different surface curvatures are affected by their order of delivery. Sequential incubation of cytosine-phosphate-guanine (CpG)-conjugated spiky and spherical gold NPs with macrophages resulted in different nanoconstruct ratios at the interior edges of endosomes. Application of spiky NPs after spherical NPs accelerated the formation of late-stage endosomes and resulted in larger endosomes, and the spherical NPs were enclosed by the spiky NPs. In contrast, the reverse incubation order produced an asymmetric distribution of the two nanoconstruct shapes in smaller endosomes. Macrophages with a higher proportion of the enclosed spherical NPs as well as a larger ratio of spiky to spherical NPs at the endosomal edge showed enhanced toll-like receptor 9 activation and secretion of proinflammatory cytokines and chemokines. Our results indicate that the subcellular trafficking of targeting nanoconstructs by vesicles is affected by both the delivery order and the endosomal distribution. Our study also establishes a new approach for nanoscale monitoring of intracellular therapeutics delivery with conventional electron microscopy.

Combining Nanotechnology and Gas Plasma as an Emerging Platform for Cancer Therapy: Mechanism and Therapeutic Implication

Nanomedicine and plasma medicine are innovative and multidisciplinary research fields aiming to employ nanotechnology and gas plasma to improve health-related treatments. Especially cancer treatment has been in the focus of both approaches because clinical response rates with traditional methods that remain improvable for many types of tumor entities. Here, we discuss the recent progress of nanotechnology and gas plasma independently as well as in the concomitant modality of nanoplasma as multimodal platforms with unique capabilities for addressing various therapeutic issues in oncological research. The main features, delivery vehicles, and nexus between reactivity and therapeutic outcomes of nanoparticles and the processes, efficacy, and mechanisms of gas plasma are examined. Especially that the unique feature of gas plasma technology, the local and temporally controlled deposition of a plethora of reactive oxygen, and nitrogen species released simultaneously might be a suitable additive treatment to the use of systemic nanotechnology therapy approaches. Finally, we focus on the convergence of plasma and nanotechnology to provide a suitable strategy that may lead to the required therapeutic outcomes.

Cell-Inspired Biomaterials for Modulating Inflammation

Inflammation is a crucial part of wound healing and pathogen clearance. However, it can also play a role in exacerbating chronic diseases and cancer progression when not regulated properly. A subset of current innate immune engineering research is focused on how molecules such as lipids, proteins, and nucleic acids native to a healthy inflammatory response can be harnessed in the context of biomaterial design to promote healing, decrease disease severity, and prolong survival. The engineered biomaterials in this review inhibit inflammation by releasing anti-inflammatory cytokines, sequestering proinflammatory cytokines, and promoting phenotype switching of macrophages in chronic inflammatory disease models. Conversely, other biomaterials discussed here promote inflammation by mimicking pathogen invasion to inhibit tumor growth in cancer models. The form that these biomaterials take spans a spectrum from nanoparticles to large-scale hydrogels to surface coatings on medical devices. Cell-inspired molecules have been incorporated in a variety of creative ways, including loaded into or onto the surface of biomaterials or used as the biomaterials themselves.

Oligonucleotide Therapies in the Treatment of Arthritis: A Narrative Review

Osteoarthritis (OA) and rheumatoid arthritis (RA) are two of the most common chronic inflammatory joint diseases, for which there remains a great clinical need to develop safer and more efficacious pharmacological treatments. The pathology of both OA and RA involves multiple tissues within the joint, including the synovial joint lining and the bone, as well as the articular cartilage in OA. In this review, we discuss the potential for the development of oligonucleotide therapies for these disorders by examining the evidence that oligonucleotides can modulate the key cellular pathways that drive the pathology of the inflammatory diseased joint pathology, as well as evidence in preclinical in vivo models that oligonucleotides can modify disease progression.

Gold Nanomaterial Engineering for Macrophage-Mediated Inflammation and Tumor Treatment

Macrophages play an important role in the body's immune defense process. Phenotype imbalance between M1 and M2 macrophages induced by inflammation-related disorders and tumor can also be reversibly converted to treat these diseases. As exogenous substances, a large part of gold-based nanomaterials interact with macrophages once they enter the body, which provides gold nanomaterials a huge advantage to act as imaging contrasts, active substance carriers, and therapeutic agents for macrophage modulation. By cutting off macrophage recruitment, inhibiting macrophage activities, and modulating M1/M2 polarization, gold nanomaterial engineering exerts therapeutic effects on inflammation-related diseases at target sites. In this review, biological functions of macrophages in inflammation-related diseases are introduced, the effect of physicochemical factors of gold nanomaterials including size, shape, and surface chemistry is focused on the interaction between macrophages and gold nanomaterials, and the applications of gold nanomaterials are elaborated for tracking and treating these diseases by macrophages. The rational and smart engineering of gold nanomaterials allows a promising platform for macrophage-mediated inflammation and tumor imaging and treatment.

Emerging theranostic gold nanostructures to combat cancer: Novel probes for Combinatorial Immunotherapy and Photothermal Therapy

The application of gold nanoparticles in immunotherapy has emerged as one of the most effective therapeutic strategy for eradicating cancer by releasing antigens, oligonucleotides, adjuvants, immune-stimulating agents into the body. Gold nanoparticles are found to be a superior choice, for generating attack on oncogenic cells, due to their low toxicity, better target specificity, diagnostic capabilities, and enhanced cellular uptake rate. This review focuses on the efficiency of several functionalized gold nanoparticles of diverse shapes and sizes as delivery vehicles to desired target cells through effective immunotherapy, along with a brief discussion about photothermal therapy.

Leveraging the modularity of biomaterial carriers to tune immune responses

Biomaterial carriers offer modular features to control the delivery and presentation of vaccines and immunotherapies. This tunability is a distinct capability of biomaterials. Understanding how tunable material features impact immune responses is important to improve vaccine and immunotherapy design, as well as clinical translation. Here we discuss the modularity of biomaterial properties as a means of controlling encounters with immune signals across scales - tissue, cell, molecular, and time - and ultimately, to direct stimulation or regulation of immune function. We highlight these advances using illustrations from recent literature across infectious disease, cancer, and autoimmunity. As the immune engineering field matures, informed design criteria could support more rational biomaterial carriers for vaccination and immunotherapy.

Large and Externally Positioned Ligand-Coated Nanopatches Facilitate the Adhesion-Dependent Regenerative Polarization of Host Macrophages

Macrophages can associate with extracellular matrix (ECM) demonstrating nanosequenced cell-adhesive RGD ligand. In this study, we devised barcoded materials composed of RGD-coated gold and RGD-absent iron nanopatches to show various frequencies and position of RGD-coated nanopatches with similar areas of iron and RGD-gold nanopatches that maintain macroscale and nanoscale RGD density invariant. Iron patches were used for substrate coupling. Both large (low frequency) and externally positioned RGD-coated nanopatches stimulated robust attachment in macrophages, compared with small (high frequency) and internally positioned RGD-coated nanopatches, respectively, which mediate their regenerative/anti-inflammatory M2 polarization. The nanobarcodes exhibited stability in vivo. We shed light into designing ligand-engineered nanostructures in an external position to facilitate host cell attachment, thereby eliciting regenerative host responses.

Engineering Mesoporous Silica Nanoparticles for Targeted Alpha Therapy against Breast Cancer

Targeted alpha therapy, where highly cytotoxic doses are delivered to tumor cells while sparing surrounding healthy tissue, has emerged as a promising treatment against cancer. Radionuclide conjugation with targeting vectors and dose confinement, however, are still limiting factors for the widespread application of this therapy. In the current study, we developed multifunctional silica nanoconstructs for targeted alpha therapy that show targeting capabilities against breast cancer cells, cytotoxic responses at therapeutic dosages, and enhanced clearance. The silica nanoparticles were conjugated to transferrin, which promoted particle accumulation in cancerous cells, and 3,4,3-LI(1,2-HOPO), a chelator with high selectivity and binding affinity for f-block elements. High cytotoxic effects were observed when the nanoparticles were loaded with ²²⁵Ac, a clinically relevant radioisotope. Lastly, in vivo studies in mice showed that the administration of radionuclides with nanoparticles enhanced their excretion and minimized their deposition in bones. These results highlight the potential of multifunctional silica nanoparticles as delivery systems for targeted alpha therapy and offer insight into design rules for the development of new nanotherapeutic agents.

Endosomal Organization of CpG Constructs Correlates with Enhanced Immune Activation

This Letter describes how the endosomal organization of immunostimulatory nanoconstructs can tune the in vitro activation of macrophages. Nanoconstructs composed of gold nanoparticles conjugated with unmethylated cytosine-phosphate-guanine (CpG) oligonucleotides have distinct endosomal distributions depending on the surface curvature. Mixed-curvature constructs produce a relatively high percentage of hollow endosomes, where constructs accumulated primarily along the interior edges. These constructs achieved a higher level of toll-like receptor (TLR) 9 activation along with the enhanced secretion of proinflammatory cytokines and chemokines compared to constant-curvature constructs that aggregated mostly in the center of the endosomes. Our results underscore the importance of intraendosomal interactions in regulating immune responses and targeted delivery.

Delivery of drugs, proteins, and nucleic acids using inorganic nanoparticles

Inorganic nanoparticles provide multipurpose platforms for a broad range of delivery applications. Intrinsic nanoscopic properties provide access to unique magnetic and optical properties. Equally importantly, the structural and functional diversity of gold, silica, iron oxide, and lanthanide-based nanocarriers provide unrivalled control of nanostructural properties for effective transport of therapeutic cargos, overcoming biobarriers on the cellular and organismal level. Taken together, inorganic nanoparticles provide a key addition to the arsenal of delivery vectors for fighting disease and improving human health.

In Situ Magnetic Control of Macroscale Nanoligand Density Regulates the Adhesion and Differentiation of Stem Cells

Developing materials with remote controllability of macroscale ligand presentation can mimic extracellular matrix (ECM) remodeling to regulate cellular adhesion in vivo. Herein, we designed charged mobile nanoligands with superparamagnetic nanomaterials amine-functionalized and conjugated with polyethylene glycol linker and negatively charged RGD ligand. We coupled negatively a charged nanoligand to a positively charged substrate by optimizing electrostatic interactions to allow reversible planar movement. We demonstrate the imaging of both macroscale and in situ nanoscale nanoligand movement by magnetically attracting charged nanoligand to manipulate macroscale ligand density. We show that in situ magnetic control of attracting charged nanoligand facilitates stem cell adhesion, both in vitro and in vivo, with reversible control. Furthermore, we unravel that in situ magnetic attraction of charged nanoligand stimulates mechanosensing-mediated differentiation of stem cells. This remote controllability of ECM-mimicking reversible ligand variations is promising for regulating diverse reparative cellular processes in vivo.

Transforming lanthanide and actinide chemistry with nanoparticles

Lanthanides and actinides are used in a wide variety of applications, from energy production to life sciences. To address toxicity issues due to the chemical, and often radiological, properties of these elements, methods to quantify and recover them from industrial waste are necessary. When used in biomedicine, lanthanides and actinides are incorporated in compounds that show promising therapeutic and/or bioimaging properties, but lack robust strategies to target cancer and other pathologies. Furthermore, current decorporation protocols to respond to accidental actinide exposure rely on intravenous injections of soluble chelating agents, which are inefficient for treatment of inhaled radionuclides trapped in lungs. In recent years, nanoparticles have emerged as powerful tools in both industry and clinical settings. Because some inorganic nanoparticles are sensitive to external stimuli, such as light and magnetic fields, they can be used as building blocks for sensitive bioassays and separation techniques. In addition, nanoparticles can be functionalized with multiple ligands and act as carriers for selective delivery of therapeutic and contrast agents. This review summarizes and discusses recent progress on the use of nanoparticles in lanthanide and actinide chemistry. We examine different types of nanoparticles based on composition, functionalization, and properties, and we critically analyze their performance in a comparative mode. Our focus is two-pronged, including the nanoparticles free of lanthanides and actinides that are used for the detection, separation, or decorporation of f-block elements, as well as the nanoparticles that enhance the inherent properties of lanthanides and actinides for therapeutics, imaging and catalysis.

Selective Lanthanide Sensing with Gold Nanoparticles and Hydroxypyridinone Chelators

The octadentate hydroxypyridinone chelator 3,4,3-LI(1,2-HOPO) is a promising therapeutic agent because of its high affinity for f-block elements and noncytotoxicity at medical dosages. The interaction between 3,4,3-LI(1,2-HOPO) and other biomedically relevant metals such as gold, however, has not been explored. Gold nanoparticles functionalized with chelators have demonstrated great potential in theranostics, yet thus far, no protocol that combines 3,4,3-LI(1,2-HOPO) and colloidal gold has been developed. Here, we characterize the solution thermodynamic properties of the complexes formed between 3,4,3-LI(1,2-HOPO) and Au³⁺ ions and demonstrate how under specific pH conditions the chelator promotes the growth of gold nanoparticles, acting as both reducing and stabilizing agent. 3,4,3-LI(1,2-HOPO) ligands on the nanoparticle surface remain active and selective toward f-block elements, as evidenced by gold nanoparticle selective aggregation. Finally, a new colorimetric assay capable of reaching the detection levels necessary for the quantification of lanthanides in waste from industrial processes is developed based on the inhibition of particle growth by lanthanides.

Quantifying the binding between proteins and open chromatin-like DNA sequences with gold nanorods

The binding of transcription factors to DNA is one of the main mechanisms in gene regulation. While transcription factors frequently bind to unwrapped long DNA sequences known as open chromatin structures, most bioassays that study protein-DNA binding rely on short oligonucleotide probes. In this work, we develop a gold nanorod-based colorimetric assay for the binding of transcription factors to DNA in long open chromatin-like structures. After the determination of the binding affinity and stoichiometry, we explored the effect of the probe length on the assay performance and compared it to other established techniques.

Sensing of circulating cancer biomarkers with metal nanoparticles

The analysis of circulating cancer biomarkers, including cell-free and circulating tumor DNA, circulating tumor cells, microRNA and exosomes, holds promise in revolutionizing cancer diagnosis and prognosis using body fluid analysis, also known as liquid biopsy. To enable clinical application of these biomarkers, new analytical tools capable of detecting them in very low concentrations in complex sample matrixes are needed. Metal nanoparticles have emerged as extraordinary analytical scaffolds because of their unique optoelectronic properties and ease of functionalization. Hence, multiple analytical techniques have been developed based on these nanoparticles and their plasmonic properties. The aim of this review is to summarize and discuss the present development on the use of metal nanoparticles for the analysis of circulating cancer biomarkers. We examine how metal nanoparticles can be used as (1) analytical transducers in various sensing principles, such as aggregation induced colorimetric assays, plasmon resonance energy transfer, surface enhanced Raman spectroscopy, and refractive index sensing, and (2) signal amplification elements in surface plasmon resonance spectroscopy and electrochemical detection. We critically discuss the clinical relevance of each category of circulating biomarkers, followed by a thorough analysis of how these nanoparticle-based designs have overcome some of the main challenges that gold standard analytical techniques currently face, and what new directions the field may take in the future.