Tumor site-specific silencing of NF-kappaB p65 by targeted hollow gold nanosphere-mediated photothermal transfection

The Application of Nanoparticle-Based Imaging and Phototherapy for Female Reproductive Organs Diseases

Various female reproductive disorders affect millions of women worldwide and bring many troubles to women's daily life. Let alone, gynecological cancer (such as ovarian cancer and cervical cancer) is a severe threat to most women's lives. Endometriosis, pelvic inflammatory disease, and other chronic diseases-induced pain have significantly harmed women's physical and mental health. Despite recent advances in the female reproductive field, the existing challenges are still enormous such as personalization of disease, difficulty in diagnosing early cancers, antibiotic resistance in infectious diseases, etc. To confront such challenges, nanoparticle-based imaging tools and phototherapies that offer minimally invasive detection and treatment of reproductive tract-associated pathologies are indispensable and innovative. Of late, several clinical trials have also been conducted using nanoparticles for the early detection of female reproductive tract infections and cancers, targeted drug delivery, and cellular therapeutics. However, these nanoparticle trials are still nascent due to the body's delicate and complex female reproductive system. The present review comprehensively focuses on emerging nanoparticle-based imaging and phototherapies applications, which hold enormous promise for improved early diagnosis and effective treatments of various female reproductive organ diseases.

TME-Responsive Nanoplatform with Glutathione Depletion for Enhanced Tumor-Specific Mild Photothermal/Gene/Ferroptosis Synergistic Therapy

Background

Triple negative breast cancer (TNBC) is one of the worst prognosis types of breast cancer that urgently needs effective therapy methods. However, cancer is a complicated disease that usually requires multiple treatment modalities.

Methods

A tumor microenvironment (TME)-responsive PFC/TRIM37@Fe-TA@HA (abbreviated as PTFTH) nanoplatform was constructed by coating Fe3+ and tannic acid (TA) on the surface of TRIM37-siRNA loaded phase-transition perfluorocarbon (PFC) nanodroplets and further modifying them with hyaluronic acid (HA) to achieve tumor-specific mild photothermal/gene/ferroptosis synergistic therapy (MPTT/GT/ Ferroptosis) in vitro. Once internalized into tumor cells through CD44 receptor-mediated active targeting, the HA shell of PTFTH would be preliminarily disassembled by hyaluronidase (HAase) to expose the Fe-TA metal-phenolic networks (MPNs), which would further degrade in response to an acidic lysosomal environment, leading to HAase/pH dual-responsive release of Fe3+ and PFC/TRIM37.

Results

PTFTH showed good biocompatibility in vitro. On the one hand, the released Fe3+ could deplete the overexpressed glutathione (GSH) through redox reactions and produce Fe2+, which in turn converts endogenous H2O2 into highly cytotoxic hydroxyl radicals (•OH) for chemodynamic therapy (CDT). On the other hand, the local hyperthermia generated by PTFTH under 808 nm laser irradiation could not only improve CDT efficacy through accelerating the Fe2+-mediated Fenton reaction, but also enhance TRIM37-siRNA delivery for gene therapy (GT). The consumption of GSH and accumulation of •OH synergistically augmented intracellular oxidative stress, resulting in substantial tumor cell ferroptosis. Moreover, PTFTH possessed outstanding contrast enhanced ultrasound (CEUS), photoacoustic imaging (PAI) and magnetic resonance imaging (MRI) ability.

Conclusion

This PTFTH based multiple-mode therapeutic strategy has successfully achieved a synergistic anticancer effect in vitro and has the potential to be translated into clinical application for tumor therapy in future.

Metal-based nanoparticle in cancer treatment: lessons learned and challenges

Cancer, being one of the deadliest diseases, poses significant challenges despite the existence of traditional treatment approaches. This has led to a growing demand for innovative pharmaceutical agents that specifically target cancer cells for effective treatment. In recent years, the use of metal nanoparticles (NPs) as a promising alternative to conventional therapies has gained prominence in cancer research. Metal NPs exhibit unique properties that hold tremendous potential for various applications in cancer treatment. Studies have demonstrated that certain metals possess inherent or acquired anticancer capabilities through their surfaces. These properties make metal NPs an attractive focus for therapeutic development. In this review, we will investigate the applicability of several distinct classes of metal NPs for tumor targeting in cancer treatment. These classes may include gold, silver, iron oxide, and other metals with unique properties that can be exploited for therapeutic purposes. Additionally, we will provide a comprehensive summary of the risk factors associated with the therapeutic application of metal NPs. Understanding and addressing these factors will be crucial for successful clinical translation and to mitigate any potential challenges or failures in the translation of metal NP-based therapies. By exploring the therapeutic potential of metal NPs and identifying the associated risk factors, this review aims to contribute to the advancement of cancer treatment strategies. The anticipated outcome of this review is to provide valuable insights and pave the way for the advancement of effective and targeted therapies utilizing metal NPs specifically for cancer patients.

Lactate/GPR81 recruits regulatory T cells by modulating CX3CL1 to promote immune resistance in a highly glycolytic gastric cancer

Lactate plays an important role in shaping immune tolerance in tumor microenvironment (TME) and correlates with poor prognosis in various solid tumors. Overcoming the immune resistance in an acidic TME may improve the anti-tumor immunity. Here, this study elucidated that via G-protein-coupled receptor 81 (GPR81), lactate could modulate immune tolerance in TME by recruiting regulatory T cells (Tregs) in vitro and in vivo. A high concentration of lactate was detected in cell supernatant and tissues of gastric cancer (GC), which was modulated by lactic dehydrogenase A (LDHA). GPR81 was the natural receptor of lactate and was overexpressed in different GC cell lines and samples, which correlated with poor outcomes in GC patients. Lactate/GPR81 signaling could promote the infiltration of Tregs into TME by inducing the expression of chemokine CX3CL1. GPR81 deficiency could decrease the infiltration of Tregs into TME, thereby inhibiting GC progression by weakening the inhibition of CD8+T cell function in a humanized mouse model. In conclusion, targeting the lactate/GPR81 signaling may potentially serve as a critical process to overcome immune resistance in highly glycolytic GC.

Biological Applications of Thermoplasmonics

Thermoplasmonics has emerged as an extraordinarily versatile tool with profound applications across various biological domains ranging from medical science to cell biology and biophysics. The key feature of nanoscale plasmonic heating involves remote activation of heating by applying laser irradiation to plasmonic nanostructures that are designed to optimally convert light into heat. This unique capability paves the way for a diverse array of applications, facilitating the exploration of critical biological processes such as cell differentiation, repair, signaling, and protein functionality, and the advancement of biosensing techniques. Of particular significance is the rapid heat cycling that can be achieved through thermoplasmonics, which has ushered in remarkable technical innovations such as accelerated amplification of DNA through quantitative reverse transcription polymerase chain reaction. Finally, medical applications of photothermal therapy have recently completed clinical trials with remarkable results in prostate cancer, which will inevitably lead to the implementation of photothermal therapy for a number of diseases in the future. Within this review, we offer a survey of the latest advancements in the burgeoning field of thermoplasmonics, with a keen emphasis on its transformative applications within the realm of biosciences.

A detailed insight of the tumor targeting using nanocarrier drug delivery system

Human struggle against the deadly disease conditions is continued since ages. The contribution of science and technology in fighting against these diseases cannot be ignored exclusively due to the invention of novel procedure and products, extending their size ranges from micro to nano. Recently nanotechnology has been gaining more consideration for its ability to diagnose and treat different cancers. Different nanoparticles have been used to evade the issues related with conservative anticancer delivery systems, including their nonspecificity, adverse effects and burst release. These nanocarriers including, solid lipid nanoparticles (SLNs), liposomes, nano lipid carriers (NLCs), nano micelles, nanocomposites, polymeric and magnetic nanocarriers, have brought revolutions in antitumor drug delivery. Nanocarriers improved the therapeutic efficacy of anticancer drugs with better accumulation at the specific site with sustained release, improved bioavailability and apoptosis of the cancer cells while bypassing the normal cells. In this review, the cancer targeting techniques and surface modification on nanoparticles are discussed briefly with possible challenges and opportunities. It can be concluded that understanding the role of nanomedicine in tumor treatment is significant, and therefore, the modern progressions in this arena is essential to be considered for a prosperous today and an affluent future of tumor patients.

Remodeling the tumor immune microenvironment via siRNA therapy for precision cancer treatment

How to effectively transform the pro-oncogenic tumor microenvironments (TME) surrounding a tumor into an anti-tumoral never fails to attract people to study. Small interfering RNA (siRNA) is considered one of the most noteworthy research directions that can regulate gene expression following a process known as RNA interference (RNAi). The research about siRNA delivery targeting tumor cells and TME has been on the rise in recent years. Using siRNA drugs to silence critical proteins in TME was one of the most efficient solutions. However, the manufacture of a siRNA delivery system faces three major obstacles, i.e., appropriate cargo protection, accurately targeted delivery, and site-specific cargo release. In the following review, we summarized the pharmacological actions of siRNA drugs in remolding TME. In addition, the delivery strategies of siRNA drugs and combination therapy with siRNA drugs to remodel TME are thoroughly discussed. In the meanwhile, the most recent advancements in the development of all clinically investigated and commercialized siRNA delivery technologies are also presented. Ultimately, we propose that nanoparticle drug delivery siRNA may be the future research focus of oncogene therapy. This summary offers a thorough analysis and roadmap for general readers working in the field.

Role of Tunable Gold Nanostructures in Cancer Nanotheranostics: Implications on Synthesis, Toxicity, Clinical Applications and Their Associated Opportunities and Challenges

The existing diagnosis and treatment modalities have major limitations related to their precision and capability to understand several stages of disease development. A superior therapeutic system consists of a multifunctional approach in early diagnosis of the disease with a simultaneous progressive cure, using a precise medical approach towards complex treatment. These challenges can be addressed via nanotheranostics and explore suitable approaches to improve health care. Nanotechnology in combination with theranostics as an unconventional platform paved the way for developing novel strategies and modalities leading to diagnosis and therapy for complex disease conditions, ranging from acute to chronic levels. Among the metal nanoparticles, gold nanoparticles are being widely used for theranostics due to their inherent non-toxic nature and plasmonic properties. The unique optical and chemical properties of plasmonic metal nanoparticles along with theranostics have led to a promising era of plausible early detection of disease conditions, and they enable real-time monitoring with enhanced non-invasive or minimally invasive imaging of several ailments. This review aims to highlight the improvement and advancement brought to nanotheranostics by gold nanoparticles in the past decade. The clinical use of the metal nanoparticles in nanotheranostics is explained, along with the future perspectives on addressing the key applications related to diagnostics and therapeutics, respectively. The scope of gold nanoparticles and their realistic potential to design a sophisticated theranostic system is discussed in detail, along with their implications in clinical advancements which are the needs of the hour. The review concluded with the challenges, opportunities, and implications on translational potential of using gold nanoparticles in nanotheranostics.

A rationally designed cancer vaccine based on NIR-II fluorescence image-guided light-triggered remote control of antigen cross-presentation and autophagy

Cancer vaccines represent a promising immunotherapeutic treatment modality. The promotion of cross-presentation of extracellular tumor-associated antigens on the major histocompatibility complex (MHC) class I molecules and dendritic cell maturation at the appropriate time and place is crucial for cancer vaccines to prime cytolytic T cell response with reduced side effects. Current vaccination strategies, however, are not able to achieve the spatiotemporal control of antigen cross-presentation. Here, we report a liposomal vaccine loading the second near-infrared window (NIR-II, 1000-1700 nm) fluorophore BPBBT with an efficient photothermal conversion effect that offers an NIR-light-triggered endolysosomal escape under the imaging guidance. The NIR-II image-guided vaccination strategy specifically controls the cytosolic delivery of antigens for cross-presentation in the draining lymph nodes (DLNs). Moreover, the photothermally induced endolysosomal rupture initiates autophagy. We also find that the adjuvant simvastatin acts as an autophagy activator through inhibiting the PI3K/AKT/mTOR pathway. The light-induced autophagy in the DLNs together with simvastatin treatment cooperatively increase MHC class II expression by activating autophagy machinery for dendritic cell maturation. This study presents a paradigm of NIR-II image-guided light-triggered vaccination. The approach for remote control of antigen cross-presentation and autophagy represents a new strategy for vaccine development.

Physically stimulus-responsive nanoparticles for therapy and diagnosis

Nanoparticles offer numerous advantages in various fields of science, particularly in medicine. Over recent years, the use of nanoparticles in disease diagnosis and treatments has increased dramatically by the development of stimuli-responsive nano-systems, which can respond to internal or external stimuli. In the last 10 years, many preclinical studies were performed on physically triggered nano-systems to develop and optimize stable, precise, and selective therapeutic or diagnostic agents. In this regard, the systems must meet the requirements of efficacy, toxicity, pharmacokinetics, and safety before clinical investigation. Several undesired aspects need to be addressed to successfully translate these physical stimuli-responsive nano-systems, as biomaterials, into clinical practice. These have to be commonly taken into account when developing physically triggered systems; thus, also applicable for nano-systems based on nanomaterials. This review focuses on physically triggered nano-systems (PTNSs), with diagnostic or therapeutic and theranostic applications. Several types of physically triggered nano-systems based on polymeric micelles and hydrogels, mesoporous silica, and magnets are reviewed and discussed in various aspects.

Thermal Sensitivity on Eccentric Gold Hollow Nanoparticles: A Perspective from Atomistic Simulations

Eccentricity is a common feature consequence of several synthesis protocols of hollow nanoshells. Despite the crescent interest in these nanoparticles, it is still unclear how an irregular layer on the nanoparticle impacts the macroscopic properties. Here, we study the thermal stability of eccentric hollow nanoparticles (hNPs) for different sizes and eccentricity values by means of classical molecular dynamics simulations. Our results reveal that eccentricity displays a significant role in the thermal stability of hNPs. We attribute this behavior to the irregular shell contour, which collapses due to the thermal-activated diffusive process from the nanoparticle shell's most thin region. The mechanism is driven at low temperature by the nucleation of stacking faults until the amorphization for larger temperature values. Besides, for some particular eccentric hNPs, the shell suffers a surface reconstruction process, transforming the eccentric hNP into a concentric hNP. We believe that our study on thermal effects in eccentric hNPs has relevance because of their outstanding applications for plasmonic and sensing.

Comparative Study on Inhibition of Pancreatic Cancer Cells by Resveratrol Gold Nanoparticles and a Resveratrol Nanoemulsion Prepared from Grape Skin

Resveratrol, a phenolic compound possessing vital biological activities such as anti-cancer, is present abundantly in grape skin, a waste produced during the processing of grape juice. The objectives of this study were to prepare resveratrol-gold nanoparticles and a resveratrol nanoemulsion from grape skin and study their inhibition effects on pancreatic cancer cells BxPC-3. The spherical-shaped citrate gold nanoparticles (GNPs) and resveratrol-gold nanoparticles (R-GNPs) were, respectively, prepared with a surface plasmon resonance peak at 528 and 538 nm, mean particle size of 20.8 and 11.9 nm, and zeta-potential at −32.7 and −66.7 mV, by controlling an appropriate concentration of citrate/resveratrol and gold chloride as well as stirring time and temperature. The resveratrol nanoemulsion, composed of soybean oil, Tween 80, and sucrose fatty acid ester in glycerol and water, possessed a high storage stability with a mean particle size of 14.1 nm, zeta-potential of −49.7 mV, and encapsulation efficiency of 95.5%. An antiproliferation study revealed that both R-GNPs and resveratrol nanoemulsion could effectively inhibit the growth of pancreatic cancer cells BxPC-3, with the latter showing a higher inhibition effect. Western blot analysis implied that both can down-regulate expressions of cyclin A, cyclin B, CDK1, and CDK2 and up-regulate expressions of p53 and p21, accompanied by enhancing cytochrome C expression, decreasing BcL-2 expression, increasing Bax expression, and leading to the elevation of caspase-8, caspase-9, and caspase-3 activities for cell apoptosis execution. Future research is needed to study the inhibition of pancreatic tumors in vivo by R-GNPs and resveratrol nanoemulsions.

Polydopamine nanoparticles with different sizes for NIR-promoted gene delivery and synergistic photothermal therapy

The combination of photothermal therapy and gene therapy has received increasing attention in tumor treatment. However, how to improve synergistic efficacy has become a new challenge. NIR light has a great potential in tumor treatment because of its considerable penetration depth and spatiotemporal controllability. Polydopamine is a popular photothermal conversion agent, which has desirable photothermal conversion ability and good biocompatibility. In this research, polydopamine-polyethyleneimine nanoparticles with diameters of 13 nm (SPPNPs) and 236 nm (LPPNPs) were prepared as gene carriers. The size of polydopamine nanoparticles had great effect on the complexes formation, photothermal conversion ability and gene transfection efficiency. After loading gene, the SPPNPs/gene and LPPNPs/gene complexes were about 60-80 nm and 240 nm respectively, indicating different styles of complexes formation. Both SPPNPs/gene and LPPNPs/gene complexes without NIR irradiation could achieve similar gene transfection efficiency as commercial lipofectamine 2000, while with lower cytotoxicity. Due to better photothermal conversion ability, the transfection level of LPPNPs/pGL-3 complexes increased to 4.5 times after NIR irradiation (2.6 W/cm², 15 min), which ascribed to the quick escape of gene complexes from the endosome. The produced heat under NIR irradiation could also ablate tumor cells. So LPPNPs were chosen to deliver tumor suppressor gene p53 DNA to investigate the synergistic efficacy of gene/photothermal therapy. The tumor in KB tumor-bearing mice was almost eliminated after intratumoral injection, and the tumor inhibition efficacy of gene/photothermal synergistic therapy achieved to 99%. By combining NIR-promoted gene transfection and gene/photothermal synergistic therapy, the LPPNPs hold great promise in practical tumor treatment.

Nanoscale Au@SiO2-drug/VEGF as an in vivo probe for osteosarcoma diagnosis and therapy

Osteosarcoma is a common primary bone malignancy, with a 5-year survival rate of only 20–30% in patients undergoing surgical treatment. Thus, it is important to identify novel methods for diagnosing and treating osteosarcoma, which was the aim of the present study. Vascular endothelial growth factor (VEGF) was used as the tumor-targeting protein to synthesize a multifunctional core-shell nanostructure, Au@SiO₂-drug/VEGF, in which the drug can be indocyanine green (ICG; as an optical tracer) or doxorubicin (DOX; as a chemotherapeutic agent). With VEGF as the osteosarcoma-targeting protein, Au exhibited optimal photothermal transformation performance, while SiO₂ served as the carrier for the drug. Au@SiO₂-ICG/VEGF nanoparticles (NPs) were evaluated for imaging and for the monitoring of drug accumulation in a tumor region in mice. Once the optimal drug accumulation was achieved, combined treatment of osteosarcoma (chemotherapy and photothermal therapy) was assessed. In the perioperative period associated with minimal invasive embolization of osteosarcoma, photothermal therapy and chemotherapy were applied for osteosarcoma diagnosis using Au@SiO₂-DOX/VEGF NPs. Taken together, the results of the present study provide a promising strategy for tumor detection prior to surgical treatment to improve the survival outcome of patients with osteosarcoma.

Nanotechnology-Assisted RNA Delivery: From Nucleic Acid Therapeutics to COVID-19 Vaccines

In recent years, the main quest of science has been the pioneering of the groundbreaking biomedical strategies needed for achieving a personalized medicine. Ribonucleic acids (RNAs) are outstanding bioactive macromolecules identified as pivotal actors in regulating a wide range of biochemical pathways. The ability to intimately control the cell fate and tissue activities makes RNA-based drugs the most fascinating family of bioactive agents. However, achieving a widespread application of RNA therapeutics in humans is still a challenging feat, due to both the instability of naked RNA and the presence of biological barriers aimed at hindering the entrance of RNA into cells. Recently, material scientists' enormous efforts have led to the development of various classes of nanostructured carriers customized to overcome these limitations. This work systematically reviews the current advances in developing the next generation of drugs based on nanotechnology-assisted RNA delivery. The features of the most used RNA molecules are presented, together with the development strategies and properties of nanostructured vehicles. Also provided is an in-depth overview of various therapeutic applications of the presented systems, including coronavirus disease vaccines and the newest trends in the field. Lastly, emerging challenges and future perspectives for nanotechnology-mediated RNA therapies are discussed.

Effective tools for RNA-derived therapeutics: siRNA interference or miRNA mimicry

The approval of the first small interfering RNA (siRNA) drug Patisiran by FDA in 2018 marks a new era of RNA interference (RNAi) therapeutics. MicroRNAs (miRNA), an important post-transcriptional gene regulator, are also the subject of both basic research and clinical trials. Both siRNA and miRNA mimics are ~21 nucleotides RNA duplexes inducing mRNA silencing. Given the well performance of siRNA, researchers ask whether miRNA mimics are unnecessary or developed siRNA technology can pave the way for the emergence of miRNA mimic drugs. Through comprehensive comparison of siRNA and miRNA, we focus on (1) the common features and lessons learnt from the success of siRNAs; (2) the unique characteristics of miRNA that potentially offer additional therapeutic advantages and opportunities; (3) key areas of ongoing research that will contribute to clinical application of miRNA mimics. In conclusion, miRNA mimics have unique properties and advantages which cannot be fully matched by siRNA in clinical applications. MiRNAs are endogenous molecules and the gene silencing effects of miRNA mimics can be regulated or buffered to ameliorate or eliminate off-target effects. An in-depth understanding of the differences between siRNA and miRNA mimics will facilitate the development of miRNA mimic drugs.

A Review of pH-Responsive Organic-Inorganic Hybrid Nanoparticles for RNAi-Based Therapeutics

RNA interference (RNAi) shows great potential in the treatment of varying cancer and genetic disorders. The lack of safe and effective delivery methods is an ongoing challenge to realize the full potential of RNAi-based therapeutics. pH-responsive hybrid nanoparticle is a promising non-virus platform for small interfering RNA (siRNA) delivery with unique properties including the robust response to the acidic microenvironment and the capability of theranostic and combined therapeutics. The mechanism of RNAi and the delivery barriers for RNAi-based therapeutics are first discussed. Then, the general patterns of pH-response and the typical construction of hybrid nanoparticles are demonstrated. The recent advances in pH-responsive organic-inorganic hybrid nanoparticles for siRNA delivery are highlighted, in particular, how pH-response of ionizable groups, acid-labile bonds, and decomposition of inorganic components affect the physicochemical properties of hybrid nanoparticles and benefit the cellular uptake and intracellular trafficking of siRNA payloads are discussed. At last, the remaining problems and the prospects for pH-responsive hybrid nanoparticles for siRNA delivery are analyzed.

Delivery Systems for Nucleic Acids and Proteins: Barriers, Cell Capture Pathways and Nanocarriers

Gene therapy has been used as a potential approach to address the diagnosis and treatment of genetic diseases and inherited disorders. In this line, non-viral systems have been exploited as promising alternatives for delivering therapeutic transgenes and proteins. In this review, we explored how biological barriers are effectively overcome by non-viral systems, usually nanoparticles, to reach an efficient delivery of cargoes. Furthermore, this review contributes to the understanding of several mechanisms of cellular internalization taken by nanoparticles. Because a critical factor for nanoparticles to do this relies on the ability to escape endosomes, researchers have dedicated much effort to address this issue using different nanocarriers. Here, we present an overview of the diversity of nanovehicles explored to reach an efficient and effective delivery of both nucleic acids and proteins. Finally, we introduced recent advances in the development of successful strategies to deliver cargoes.

Nanocarrier-delivered small interfering RNA for chemoresistant ovarian cancer therapy

Ovarian cancer is the fifth leading cause of cancer-related death in women in the United States. Because success in early screening is limited, and most patients with advanced disease develop resistance to multiple treatment modalities, the overall prognosis of ovarian cancer is poor. Despite the revolutionary role of surgery and chemotherapy in curing ovarian cancer, recurrence remains a major challenge in treatment. Thus, improving our understanding of the pathogenesis of ovarian cancer is essential for developing more effective treatments. In this review, we analyze the underlying molecular mechanisms leading to chemotherapy resistance. We discuss the clinical benefits and potential challenges of using nanocarrier-delivered small interfering RNA to treat chemotherapy-resistant ovarian cancer. We aim to elicit collaborative studies on nanocarrier-delivered small interfering RNA to improve the long-term survival rate and quality of life of patients with ovarian cancer. This article is categorized under: RNA Methods > RNA Nanotechnology Regulatory RNAs/RNAi/Riboswitches > RNAi: Mechanisms of Action.

The Use of Alternative Strategies for Enhanced Nanoparticle Delivery to Solid Tumors

Nanomaterial (NM) delivery to solid tumors has been the focus of intense research for over a decade. Classically, scientists have tried to improve NM delivery by employing passive or active targeting strategies, making use of the so-called enhanced permeability and retention (EPR) effect. This phenomenon is made possible due to the leaky tumor vasculature through which NMs can leave the bloodstream, traverse through the gaps in the endothelial lining of the vessels, and enter the tumor. Recent studies have shown that despite many efforts to employ the EPR effect, this process remains very poor. Furthermore, the role of the EPR effect has been called into question, where it has been suggested that NMs enter the tumor via active mechanisms and not through the endothelial gaps. In this review, we provide a short overview of the EPR and mechanisms to enhance it, after which we focus on alternative delivery strategies that do not solely rely on EPR in itself but can offer interesting pharmacological, physical, and biological solutions for enhanced delivery. We discuss the strengths and shortcomings of these different strategies and suggest combinatorial approaches as the ideal path forward.

Photoresponsive miR-34a/Nanoshell Conjugates Enable Light-Triggered Gene Regulation to Impair the Function of Triple-Negative Breast Cancer Cells

Triple-negative breast cancer (TNBC) is an aggressive disease that requires new interventions. A promising approach to improve patient prognosis is to introduce tumor suppressive miR-34a into TNBC cells. Unfortunately, naked miR-34a is not effective therapeutically because it is degraded by nucleases and cannot passively enter cells. Nanocarriers designed to increase miR-34a stability and cellular entry have lacked specificity and potency. To overcome these limitations, we conjugated miR-34a to photoresponsive gold nanoshells (NS), which can release tethered miR-34a upon excitation with continuous wave (CW) or nanosecond (ns) pulsed near-infrared light to facilitate on-demand gene regulation. We demonstrate that miR-34a/NS can regulate downstream miR-34a targets following irradiation to reduce TNBC cell viability, proliferation, and migration. Further, we show ns pulsed light releases miRNA more effectively than CW light, and that released miR-34a is as potent as transfected miR-34a. These findings signify miR-34a/NS as promising tools for precisely controlled gene regulation of TNBC.

Hollow micro and nanostructures for therapeutic and imaging applications

Hollow particles have been extensively used in bioanalytical and biomedical applications for almost two decades due to their unique and tunable optoelectronic properties as well as their significantly high loading capacities. These intrinsic properties led them to be used in various bioimaging applications as contrast agents, controlled delivery (i.e. drugs, nucleic acids and other biomolecules) platforms and photon-triggered therapies (e.g. photothermal and photodynamic therapies). Since recent studies showed that imaging-guided targeted therapeutics have higher success rates, multimodal theranostic platforms (combination of one or more therapy and diagnosis modality) have been employed more often and hollow particles (i.e. nanoshells) have been one of the most efficient candidates to be used in multiple-purpose platforms, owing to their intrinsic properties that enable synergistic multimodal performance. In this review, recent advances in the applications of such hollow particles fabricated with various routes (either inorganic or organic based) were summarized to delineate strategies for tuning their properties for more efficient biomedical performance by overcoming common biological barriers. This review will pave the ways for expedited progress in design of next generation of hollow particles for clinical applications.

NIR light-triggered nanomaterials-based prodrug activation towards cancer therapy

Nanomaterials-based prodrug activation systems have been widely explored in cancer therapy, aiming at overcoming limited dosage formulation, systemic toxicity, and insufficient pharmacokinetic performance of parent drugs. For better delivery control, various stimuli systems, especially nanomaterials-based ones, have come to the forefront. Among them, near-infrared (NIR) light takes advantage of on-demand/site-specific regulation and non-invasiveness. In this review, we will address the developments of nanomaterials-based prodrug over the last decade, the activation mechanisms, and bioapplications under NIR light triggering. The advantages and limitations of NIR-triggered prodrug activation strategies and the perspectives of the next-generation prodrug nanomedicine will also be summarized. This article is categorized under: Therapeutic Approaches and Drug Discovery > Nanomedicine for Oncologic Disease Therapeutic Approaches and Drug Discovery > Emerging Technologies.

Gold Nanoparticles in Glioma Theranostics

Despite many endeavors to treat malignant gliomas in the last decades, the median survival of patients has not significantly improved. The infiltrative nature of high-grade gliomas and the impermeability of the blood-brain barrier to the most therapeutic agents remain major hurdles, impeding an efficacious treatment. Theranostic platforms bridging diagnosis and therapeutic modalities aim to surmount the current limitations in diagnosis and therapy of glioma. Gold nanoparticles (AuNPs) due to their biocompatibility and tunable optical properties have widely been utilized for an assortment of theranostic purposes. In this Review, applications of AuNPs as imaging probes, drug/gene delivery systems, radiosensitizers, photothermal transducers, and multimodal theranostic agents in malignant gliomas are discussed. This Review also aims to provide a perspective on cancer theranostic applications of AuNPs in future clinical trials.

Engineered Gold Nanoshells Killing Tumor Cells: New Perspectives

The current strategies to treat different kinds of cancer are mainly based on chemotherapy, surgery and radiation therapy. Unfortunately, these approaches are not specific and rather invasive as well. In this scenario, metal nano-shells, in particular gold-based nanoshells, offer interesting perspectives in the effort to counteract tumor cells, due to their unique ability to tune Surface Plasmon Resonance in different light-absorbing ranges. In particular, the Visible and Near Infrared Regions of the electromagnetic spectrum are able to penetrate through tissues. In this way, the light absorbed by the gold nanoshell at a specific wavelength is converted into heat, inducing photothermal ablation in treated cancer cells. Furthermore, inert gold shells can be easily functionalized with different types of molecules in order to bind cellular targets in a selective manner. This review summarizes the current state-of-art of nanosystems embodying gold shells, regarding methods of synthesis, bio-conjugations, bio-distribution, imaging and photothermal effects (in vitro and in vivo), providing new insights for the development of multifunctional antitumor drugs.

Polymer-Graphene Nanoassemblies and their Applications in Cancer Theranostics

BACKGROUND AND OBJECTIVE

Graphene-based nanomaterials have received increasing attention due to their unique physical-chemical properties including two-dimensional planar structure, large surface area, chemical and mechanical stability, superconductivity and good biocompatibility. On the other hand, graphene-based nanomaterials have been explored as theranostics agents, the combination of therapeutics and diagnostics. In recent years, grafting hydrophilic polymer moieties have been introduced as an efficient approach to improve the properties of graphene-based nanomaterials and obtain new nanoassemblies for cancer therapy.

METHODS AND RESULTS

This review would illustrate biodistribution, cellular uptake and toxicity of polymergraphene nanoassemblies and summarize part of successes achieved in cancer treatment using such nanoassemblies.

CONCLUSION

The observations showed successful targeting functionality of the polymer-GO conjugations and demonstrated a reduction of the side effects of anti-cancer drugs for normal tissues.

Nitrone-Modified Gold Nanoparticles: Synthesis, Characterization, and Their Potential as 18F-Labeled Positron Emission Tomography Probes via I-SPANC

A novel bioorthogonal gold nanoparticle (AuNP) template displaying interfacial nitrone functional groups for bioorthogonal interfacial strain-promoted alkyne-nitrone cycloaddition reactions has been synthesized. These nitrone-AuNPs were characterized in detail using 1H nuclear magnetic resonance spectroscopy, transmission electron microscopy, thermogravimetric analysis, and X-ray photoelectron spectroscopy, and a nanoparticle raw formula was calculated. The ability to control the conjugation of molecules of interest at the molecular level onto the nitrone-AuNP template allowed us to create a novel methodology for the synthesis of AuNP-based radiolabeled probes.

Pulsed-laser irradiation of multifunctional gold nanoshells to overcome trastuzumab resistance in HER2-overexpressing breast cancer

Background

HER2-overexpressing metastatic breast cancers are challenging practice in oncology when they become resistant to anti-HER2 therapies such as trastuzumab. In these clinical situations, HER2-overexpression persists in metastatic localizations, and can thus be used for active targeting using innovative therapeutic approaches. Functionalized gold nanoparticles with anti-HER2 antibody can be stimulated by near-infrared light to induce hyperthermia.

Methods

Here, hybrid anti-HER2 gold nanoshells were engineered for photothermal therapy to overcome trastuzumab resistance in HER2-overexpressing breast cancer xenografts.

Results

When gold nanoshells were administered in HER2-tumor xenografts, no toxicity was observed. A detailed pharmacokinetic study showed a time-dependent accumulation of gold nanoshells within the tumors, significantly greater with functionalized gold nanoshells at 72 h. This enabled us to optimize the treatment protocol and irradiate the mice when the anti-HER2 gold nanoshells had accumulated most in the tumors. After weekly injections of anti-HER2 gold nanoshells, and repeated irradiations with a femtosecond-pulsed laser over four weeks, tumor growth was significantly inhibited. Detailed tissue microscopic analyses showed that the tumor growth inhibition was due to an anti-angiogenic effect, coherent with a preferential distribution of the nanoshells in tumor microvessels. We also showed a direct tumor cell effect with apoptosis and inhibition of proliferation, coherent with an immune-mediated targeting of tumor cells by anti-HER2 nanoshells.

Conclusion

This preclinical study thus supports the use of anti-HER2 gold nanoshells and photothermal therapy to overcome trastuzumab resistance in HER2-overexpressing breast cancer.

Electronic supplementary material

The online version of this article (10.1186/s13046-019-1305-x) contains supplementary material, which is available to authorized users.

Current Applications of Nanoemulsions in Cancer Therapeutics

Nanoemulsions are pharmaceutical formulations composed of particles within a nanometer range. They possess the capacity to encapsulate drugs that are poorly water soluble due to their hydrophobic core nature. Additionally, they are also composed of safe gradient excipients, which makes them a stable and safe option to deliver drugs. Cancer therapy has been an issue for several decades. Drugs developed to treat this disease are not always successful or end up failing, mainly due to low solubility, multidrug resistance (MDR), and unspecific toxicity. Nanoemulsions might be the solution to achieve efficient and safe tumor treatment. These formulations not only solve water-solubility problems but also provide specific targeting to cancer cells and might even be designed to overcome MDR. Nanoemulsions can be modified using ligands of different natures to target components present in tumor cells surface or to escape MDR mechanisms. Multifunctional nanoemulsions are being studied by a wide variety of researchers in different research areas mainly for the treatment of different types of cancer. All of these studies demonstrate that nanoemulsions are efficiently taken by the tumoral cells, reduce tumor growth, eliminate toxicity to healthy cells, and decrease migration of cancer cells to other organs.

Folic acid functionalized nanoparticles as pharmaceutical carriers in drug delivery systems

Conventional chemotherapeutic approaches in cancer therapy such as surgery, chemotherapy, and radiotherapy have several disadvantages due to their nontargeted distributions in the whole body. On the other hand, nanoparticles (NPs) based therapies are remarkably progressing to solve several limitations of conventional drug delivery systems (DDSs) including nonspecific biodistribution and targeting, poor water solubility, weak bioavailability and biodegradability, low pharmacokinetic properties, and so forth. The enhanced permeability and retention effect escape from P-glycoprotein trap in cancer cells as a passive targeting mechanism, and active targeting strategies are also other most important advantages of NPs in cancer diagnosis and therapy. Folic acid (FA) is one of the biologic molecules which has been targeted overexpressed-folic acid receptor (FR) on the surface of cancer cells. Therefore, conjugation of FA to NPs most easily enhances the FR-mediated targeting delivery of therapeutic agents. Here, the recent works in FA which have been decorated NPs-based DDSs are discussed and cancer therapy potency of these NPs in clinical trials are presented.

Light-induced mechanisms for nanocarrier's cargo release

Nanomaterials have been the focus of attention in several fields, including biomedicine, electronics, or catalysis, mainly due to the novel properties of the materials at the nanoscale. In the field of diagnosis, nanomaterials have been contemplated as an opportunity to improve sensitivity and time of response, therefore, facilitating early treatment and monitoring of the disease. For therapeutic applications, new drug delivery nanosystems aiming to provide enhanced efficiency have been proposed often addressing selective or controlled delivery of therapeutic agents to particular cells to maximize treatment efficacy minimizing adverse effects. The therapeutic agents can be dissolved, adsorbed, entrapped, encapsulated or attached on the surface or inside the nanocarriers. Given the context of the different generations of nanocarriers and their wide range of applications, the present article aims to discuss the nature of external stimuli which will trigger the controlled release of different biomolecules. For each class, a brief description of the physical principle, basic concepts, as well as some examples, are reported. A final discussion focused on the real implications and needs for optimal drug delivery system is presented, altogether with some considerations and prospects in the trends that diagnostics applications could follow in the next years.

Recent Advances in Functional-Polymer-Decorated Transition-Metal Nanomaterials for Bioimaging and Cancer Therapy

In this review, we focus on recent advances in the synthesis of polymer-functionalized transition-metal-based nanomaterials and follow this up by discussing their applications in bioimaging diagnosis and cancer therapy. Transition-metal-based nanomaterials show great potential in cancer therapy owing to their intensive near-IR absorption, excellent photothermal conversion efficiency, strong X-ray attenuation, and magnetic properties. Functional polymers are usually introduced by a one-step or multistep method to further endow these nanomaterials with great biocompatibility and physiological stability. Polymer-decorated transition-metal nanomaterials show great potential in multimodal imaging diagnosis (photoacoustic imaging, computed tomography, photoluminescence imaging, positron emission tomography, etc.) and cancer therapy (chemotherapy, photothermal therapy, microwave therapy, radiotherapy, photodynamic therapy). At the end of this review, the prospects of these polymer-decorated transition-metal-based nanomaterials are also discussed.

Correlating quantitative tumor accumulation and gene knockdown using SPECT/CT and bioluminescence imaging within an orthotopic ovarian cancer model

Using an orthotopic model of ovarian cancer, we studied the delivery of siRNA in nanoparticles of tri-block copolymers consisting of hyperbranched polyethylenimine-graft-polycaprolactone-block-poly(ethylene glycol) (hyPEI-g-PCL-b-PEG) with and without a folic acid targeting ligand. A SKOV-3/LUC FRα overexpressing cell line was employed to mimic the clinical manifestations of ovarian cancer. Both targeted and non-targeted micelleplexes were able to effectively deliver siRNA to the primary tumor and its metastases, as measured by gamma scintillation counting and confocal microscopy. Stability of the micelleplexes was demonstrated with a serum albumin binding study. Regarding biodistribution, intravenous (I.V.) administration showed a slight advantage of FRα targeted over non-targeted micelleplex accumulation within the tumor. However, both formulations displayed significant liver uptake. On the other hand, intraperitoneally (I.P.) injected mice showed a modest 6% of the injected dose per gram (ID/g) uptake within the primary and most interestingly also in the metastatic lesions which subsequently resulted in a 62% knockdown of firefly luciferase expression in the tumor after a single injection. While this is, to the best of our knowledge, the first paper that correlates quantitative tumor accumulation in an orthotopic tumor model with in vivo gene silencing, these data demonstrate that PEI-g-PCL-b-PEG-Fol conjugates are a promising option for gene knockdown in ovarian cancer.

Rational design of multimodal therapeutic nanosystems for effective inhibition of tumor growth and metastasis

Simultaneous inhibition of both tumor growth and metastasis is the key to treating metastatic cancer, yet the development of effective drug delivery systems represents a great challenge since multimodal therapeutic agents must be rationally combined to overcome the biological mechanisms underpinning tumor cell proliferation and invasion. In this context, we report a hybrid therapeutic nanoscale platform that incorporates an anti-proliferative drug, doxorubicin (DOX), and an anti-NF-κB agent, p65-shRNA, for effective treatment of metastatic breast cancer. In our design, we first conjugated DOX via an acid-labile linker onto gold nanorods that were pre-modified with the tumor targeting peptide RGD and a positively charged, disulfide cross-linked short polyethylenimines (DSPEI), and then incorporated shRNA through electrostatic complexation with DSPEI. We show that this "all in one" nanotherapeutic system (RDG/shRNA@DOX) can be effectively internalized through RGD-mediated endocytosis, followed by stimuli-responsive intracellular co-release of DOX and shRNA. Our in vitro experiments suggest that this multimodal system can significantly inhibit cell proliferation, angiogenesis, and invasion of metastatic MDA-MB-435 cancer cells. Systemic administration of RDG/shRNA@DOX into a metastatic mouse model led to enhanced tumor accumulation, and, most importantly, significant inhibition of in situ tumor growth and almost complete suppression of tumor metastasis. We believe this hybrid multimodal nanotherapeutic system provides important insight into the rational design of therapeutic systems for the effective treatment of metastatic carcinoma.

STATEMENT OF SIGNIFICANCE

The key to successfully treat metastatic cancer is the simultaneous inhibition of both tumor growth and metastasis. This represents a great challenge for the design of drug delivery systems since multimodal therapeutic agents must be rationally combined to overcome the respective biological mechanisms underpinning tumor cell proliferation and invasion. Toward this end, we developed a hybrid nanomedicine platform that incorporates an anti-proliferative drug, doxorubicin (DOX), and an anti-NF-κB agent, p65-shRNA, for effective treatment of metastatic breast cancer. We showed that this multimodal system (RDG/shRNA@DOX) enhanced tumor accumulation, led to prolonged circulation, and most importantly, significant inhibition of in situ tumor growth and almost complete suppression of tumor metastasis. We believe this hybrid multimodal nanotherapeutic system provides significant insight into the rational design of therapeutic systems for the effective treatment of metastatic cancer.

Cisplatin-loaded hollow gold nanoparticles for laser-triggered release

Background

Hollow gold nanoparticles (HGNPs) exposed to near-infrared (NIR) light yield photothermal effects that can trigger a variety of biological effects for potential biomedical applications. However, the mechanism of laser-triggered drug release has not been studied before.

Methods

A tripeptide Ac-Glu-Glu-Cys-NH₂ (Ac-EEC) was directly linked to the surface of HGNPs. The EEC-HGNPs conjugate was then complexed with cisplatin Pt(II) to give Ac-EEC(Pt)-HGNPs. Folic acid was introduced to the gold surface of Ac-EEC-HGNPs through a thioctic acid-terminated polyethylene glycol linker (F-PEG-TA) followed by complexation with Pt(II) to give F-Ac-EEC(Pt)-HGNPs. Laser treatment was instituted with a 15-ns pulsed laser at a repetition rate of 10 Hz. The released Pt(II) was quantified by inductively coupled plasma mass spectroscopy, and the nature of the released Pt-containing species was characterized by liquid chromatography-mass spectroscopy. The cytotoxicity was studied using the MTT assay.

Results

Pt(II) was released from Ac-EEC(Pt)-HGNPs via two modes: (1) sustained release through an inverse ligand exchange reaction with chloride ions and (2) rapid release through cleavage of the Au-S bond between the tripeptide linker and Au surface upon NIR laser irradiation. The folate (F) conjugate of the nanoconstruct, F-Ac-EEC(Pt)-HGNPs, in combination with laser treatment showed a significantly greater effect on cell mortality against folate-overexpressing human epidermoid carcinoma KB cells than F-Ac-ECC(Pt)-HGNPs alone after 24 h of incubation.

Conclusions

These results demonstrate that the photothermal property of HGNPs can be used for dual-modality photothermal therapy and NIR laser-triggered platinum-based chemotherapy.

The Role of the Nuclear Factor κB Pathway in the Cellular Response to Low and High Linear Energy Transfer Radiation

Astronauts are exposed to considerable doses of space radiation during long-term space missions. As complete shielding of the highly energetic particles is impracticable, the cellular response to space-relevant radiation qualities has to be understood in order to develop countermeasures and to reduce radiation risk uncertainties. The transcription factor Nuclear Factor κB (NF-κB) plays a fundamental role in the immune response and in the pathogenesis of many diseases. We have previously shown that heavy ions with a linear energy transfer (LET) of 100–300 keV/µm have a nine times higher potential to activate NF-κB compared to low-LET X-rays. Here, chemical inhibitor studies using human embryonic kidney cells (HEK) showed that the DNA damage sensor Ataxia telangiectasia mutated (ATM) and the proteasome were essential for NF-κB activation in response to X-rays and heavy ions. NF-κB’s role in cellular radiation response was determined by stable knock-down of the NF-κB subunit RelA. Transfection of a RelA short-hairpin RNA plasmid resulted in higher sensitivity towards X-rays, but not towards heavy ions. Reverse Transcriptase real-time quantitative PCR (RT-qPCR) showed that after exposure to X-rays and heavy ions, NF-κB predominantly upregulates genes involved in intercellular communication processes. This process is strictly NF-κB dependent as the response is completely absent in RelA knock-down cells. NF-κB’s role in the cellular radiation response depends on the radiation quality.

Enhanced endosomal escape by photothermal activation for improved small interfering RNA delivery and antitumor effect

BACKGROUND

Effective endosomal escape is still a critical bottleneck for intracellular delivery of small interfering RNAs (siRNAs) to maximize their therapeutic efficacy. To overcome this obstacle, we have developed a photothermally triggered system by using the near-infrared (NIR) irradiation to achieve "on-demand" endosomal escape and subsequent siRNA release into cytoplasm.

MATERIALS AND METHODS

Herein, the poly-L-lysine (PLL) was successfully conjugated with melanin to obtain melanin-poly-L-lysine (M-PLL) polymer as a siRNA vehicle. The melanin was an efficient photothermal sensitizer, and the positive pendant amino groups of PLL could condense siRNAs to form stable complexes by electrostatic interactions.

RESULTS AND DISCUSSION

Inspired by its excellent photothermal conversion efficiency, the melanin was first involved in the siRNA delivery system. Confocal laser scanning microscopic observation revealed that after cellular uptake the photothermally induced endosomal escape could facilitate siRNAs to overcome endosomal barrier and be delivered into cytoplasm, which resulted in significant silence in the luciferase expression over the NIR- and melanin-free controls. Moreover, the anti-survivin siRNA-loaded M-PLL nanoparticles displayed great inhibitory effect on 4T1 tumor growth in vitro and in vivo.

CONCLUSION

These findings suggest that the M-PLL-mediated siRNA delivery is a promising candidate for therapeutic siRNA delivery and shows improved effect for cancer therapy via enhanced endosomal escape.

Light-responsive Drug Delivery Systems

Materials that interact with light and subsequently change their physicochemical properties are of great interest for drug delivery. The human body is semitransparent to light of the near-infrared (NIR) region, which makes it possible to use light as an external stimulus to trigger drug release. In this chapter, we review light-triggered drug release systems of both photochemical and photothermal mechanisms. We explore recent literature on a variety of light-responsive materials for drug delivery, including organic, inorganic, and hybrid systems, which collectively embody the strategies for synergizing light responsiveness for controlled drug release/activation with other drug delivery techniques.

Triptolide exhibits antitumor effects by reversing hypermethylation of WIF‑1 in lung cancer cells

Triptolide (TP) exhibits numerous biological activities, including immunosuppressive, anti‑inflammatory and antitumor effects. The aim of the present study was to investigate the role of TP as a potent therapeutic drug for the treatment of lung cancer and to investigate the underlying therapeutic mechanisms. Western blot analyses and reverse transcription‑quantitative polymerase chain reaction (PCR) were performed to investigate the expression of genes at transcriptional and translational levels, respectively. Methylation‑specific PCR assays were conducted to investigate whether TP affects the Wnt inhibitory factor‑1 (WIF‑1) methylation status and subsequently affects apoptosis, migration or the invasion of lung cancer cells. The results of the present study revealed that the methylation status of WIF‑1 in lung cancer cell lines A549 and H460 was significantly enhanced compared with the human normal bronchial epithelial cell line HBE, whereas treatment with TP was revealed to induce the demethylation of WIF‑1. The present study aimed to investigate whether the biological activities of TP are regulated by inhibiting the Wnt signaling pathway via an increase in WIF‑1 expression levels. The results of the present study revealed that Wnt signaling was suppressed in cells following treatment with TP, which was concluded by the downregulation of Axin 2 and β‑catenin expression. Further investigation demonstrated that the silencing of WIF‑1 expression with small interfering RNA reversed the TP‑induced upregulation of WIF‑1 expression, upregulated Axin 2 and β‑catenin expression and enhanced the activation of Wnt signaling. Notably, an upregulation of cellular tumor antigen p53 expression, and downregulation of matrix metalloproteinase‑9 (MMP‑9) and phosphorylated‑nuclear factor‑κB (NF‑κB) P65 (p‑P65) levels was observed following TP treatment. These results suggest that the Wnt, p53 and NF‑κB signaling pathways mediate the potent antitumor effects of TP. Notably, the silencing of WIF‑1 did not completely recover the levels of p53, MMP‑9 and p‑P65 in cells treated with TP compared with the control cells, thus suggesting that TP exhibits further functions in addition to the targeting of WIF‑1.

Metallic Nanoparticles for Cancer Immunotherapy

Cancer immunotherapy, or the utilization of the body's immune system to attack tumor cells, has gained prominence over the past few decades as a viable cancer treatment strategy. Recently approved immunotherapeutics have conferred remission upon patients with previously bleak outcomes and have expanded the number of tools available to treat cancer. Nanoparticles -including polymeric, liposomal, and metallic formulations - naturally traffic to the spleen and lymph organs and the relevant immune cells therein, making them good candidates for delivery of immunotherapeutic agents. Metallic nanoparticle formulations in particular are advantageous because of their potential for dense surface functionalization and their capability for optical or heat based therapeutic methods. Many research groups have investigated the potential of nanoparticle-mediated delivery platforms to improve the efficacy of immunotherapies. Despite the significant preclinical successes demonstrated by many of these platforms over the last twenty years, few metallic nanoparticles have successfully entered clinical trials with none achieving FDA approval for cancer therapy. In this review, we will discuss preclinical research and clinical trials involving metallic nanoparticles (MNPs) for cancer immunotherapy applications and discuss the potential for clinical translation of MNPs.

Evaluating the Mechanisms of Light-Triggered siRNA Release from Nanoshells for Temporal Control Over Gene Regulation

The ability to regulate intracellular gene expression with exogenous nucleic acids such as small interfering RNAs (siRNAs) has substantial potential to improve the study and treatment of disease. However, most transfection agents and nanoparticle-based carriers that are used for the intracellular delivery of nucleic acids cannot distinguish between diseased and healthy cells, which may cause them to yield unintended widespread gene regulation. An ideal delivery system would only silence targeted proteins in diseased tissue in response to an external stimulus. To enable spatiotemporal control over gene silencing, researchers have begun to develop nucleic acid-nanoparticle conjugates that keep their nucleic acid cargo inactive until it is released from the nanoparticle on-demand by externally applied near-infrared laser light. This strategy can overcome several limitations of other nucleic acid delivery systems, but the mechanisms by which these platforms operate remain ill understood. Here, we perform a detailed investigation of the mechanisms by which silica core/gold shell nanoshells (NSs) release conjugated siRNA upon excitation with either pulsed or continuous wave (CW) near-infrared (NIR) light, with the goal of providing insight into how these nanoconjugates can enable on-demand gene regulation. We demonstrate that siRNA release from NSs upon pulsed laser irradiation is a temperature-independent process that is substantially more efficient than siRNA release triggered by CW irradiation. Contrary to literature, which suggests that only pulsed irradiation releases siRNA duplexes, we found that both modes of irradiation release a mixture of siRNA duplexes and single-stranded oligonucleotides, but that pulsed irradiation results in a higher percentage of released duplexes. To demonstrate that the siRNA released from NSs upon pulsed irradiation remains functional, we evaluated the use of NSs coated with green fluorescent protein (GFP)-targeted siRNA (siGFP-NS) for on-demand knockdown of GFP in cells. We found that GFP-expressing cells treated with siGFP-NS and irradiated with a pulsed laser experienced a 33% decrease in GFP expression compared to cells treated with no laser. Further, we observed that light-triggered gene silencing mediated by siGFP-NS is more potent than using commercial transfection agents to deliver siRNA into cells. This work provides unprecedented insight into the mechanisms by which plasmonic NSs release siRNA upon light irradiation and demonstrates the importance of thoroughly characterizing photoresponsive nanosystems for applications in triggered gene regulation.

The influence of tumor-induced immune dysfunction on the immune cell distribution of gold nanoparticles in vivo

Gold nanoparticles (AuNPs) have been extensively explored as a drug carrier and have been widely used to provide advanced biomedical research tools in diagnostic imaging and therapy for cancer. Although the mononuclear phagocyte system and immune system are known to play the main roles in the clearance of AuNPs during the circulation, the particle distribution within the immune cells under the condition of immune dysfunction caused by tumor growth has not been thoroughly studied. Here, the cellular distribution of Cy5 labeled AuNPs with diameters of 5, 30 and 50 nm is characterized within the immune populations of the blood, spleen and bone marrow from tumor free and tumor bearing mice using flow cytometry. Tumor-associated immune dysfunction was observed in all immune organs and cell lineages, and it changed with tumor growth. Furthermore, the particle cellular distribution significantly changed in the tumor bearing mice compared with the tumor free mice. Finally, the particle distribution in the immune cells was also different at different stages of the tumor. Overall, these results can help inform and influence future AuNP design criteria including the future applications for nanoparticle-mediated cancer therapy.

Non-viral Gene Delivery

Although viral vectors comprise the majority of gene delivery vectors, their various safety, production, and other practical concerns have left a research gap to be addressed. The non-viral vector space encompasses a growing variety of physical and chemical methods capable of gene delivery into the nuclei of target cells. Major physical methods described in this chapter are microinjection, electroporation, and ballistic injection, magnetofection, sonoporation, optical transfection, and localized hyperthermia. Major chemical methods described in this chapter are lipofection, polyfection, gold complexation, and carbon-based methods. Combination approaches to improve transfection efficiency or reduce immunological response have shown great promise in expanding the scope of non-viral gene delivery.