Enhanced Lysosomal Escape of pH-Responsive Polyethylenimine-Betaine Functionalized Carbon Nanotube for the Codelivery of Survivin Small Interfering RNA and Doxorubicin

Tumor Microenvironment-Responsive Polymer-Based RNA Delivery Systems for Cancer Treatment

Ribonucleic acid (RNA) therapeutics offer a broad prospect in cancer treatment. However, their successful application requires overcoming various physiological barriers to effectively deliver RNAs to the target sites. Currently, a number of RNA delivery systems based on polymeric nanoparticles are developed to overcome these barriers in RNA delivery. This work provides an overview of the existing RNA therapeutics for cancer gene therapy, and particularly summarizes those that are entering the clinical phase. This work then discusses the core features and latest research developments of tumor microenvironment-responsive polymer-based RNA delivery carriers which are designed based on the pathological characteristics of the tumor microenvironment. Finally, this work also proposes opportunities for the transformation of RNA therapies into cancer immunotherapy methods in clinical applications.

Understanding the Novel Approach of Nanoferroptosis for Cancer Therapy

As a new form of regulated cell death, ferroptosis has unraveled the unsolicited theory of intrinsic apoptosis resistance by cancer cells. The molecular mechanism of ferroptosis depends on the induction of oxidative stress through excessive reactive oxygen species accumulation and glutathione depletion to damage the structural integrity of cells. Due to their high loading and structural tunability, nanocarriers can escort the delivery of ferro-therapeutics to the desired site through enhanced permeation or retention effect or by active targeting. This review shed light on the necessity of iron in cancer cell growth and the fascinating features of ferroptosis in regulating the cell cycle and metastasis. Additionally, we discussed the effect of ferroptosis-mediated therapy using nanoplatforms and their chemical basis in overcoming the barriers to cancer therapy.

Ligand Phase Separation-Promoted, "Squeezing-Out" Mode Explaining the Mechanism and Implications of Neutral Nanoparticles That Escaped from Lysosomes

Neutral nanomaterials functionalized with PEG or similar molecules have been popularly employed as nanomedicines. Compared to positive counterparts that are capable of harnessing the well-known proton sponge effect to facilitate their escape from lysosomes, it is yet unclear how neutral substances got their entry into the cytosol. In this study, by taking PEGylated, neutral Au nanospheres as an example, we systematically investigated their time-dependent translocation postuptake. Specifically, we harnessed dissipative particle dynamics simulations to uncover how nanospheres bypass lysosomal entrapment, wherein a mechanism termed as "squeezing-out" mode was discovered. We next conducted a comprehensive investigation on how nanomaterials implicate lysosomes in terms of integrity and functionality. By using single-molecule imaging, specific preservation of PEG-terminated with targeting moieties in lysosomes supports the "squeezing-out" mode as the mechanism underlying the lysosomal escape of nanomaterials. All evidence points out that such a process is benign to lysosomes, wherein the escape of nanomaterials proceeds at the expense of targeting moieties loss. Furthermore, we proved that by fine-tuning of the efficacy of nanomaterials escaping from lysosomes, modulation of distinct pathways and metabolic machinery can be achieved readily, thereby offering us a simple and robust tool to implicate cells.

Recent advances in modification of novel carbon-based composites: Synthesis, properties, and biotechnological/ biomedical applications

Nowadays, carbon-based materials owing to great interest in biomedical science/biotechnology and applied for effective diagnosis and treatment of disease. To enhance the effectiveness of carbon nanotubes (CNTs)/graphene-based materials for bio-medical science/technology applications, different kinds of surface modification/functionalization were developed for the attachment of metal oxides nanostructures, biomolecules and polymers. The attachment of pharmaceutical agents with CNTs/graphene, make it a favorable candidate in research field of bio-medical science/technology applications. Surface modified/functionalized CNTs and graphene derivatives materials integrated with pharmaceutical agents has been developed for the purpose of cancer therapy, antibacterial action, pathogens bio detection, drug and gene delivery. Surface modification or functionalization of CNT/graphene materials provides good platform for pharmaceutical agents attachment with improved surface Raman scattering, fluorescence and its quenching capability. Graphene-based biosensing and bioimaging technologies are widely applied to identify numerous trace level analytes. These fluorescent and electrochemical sensors are utilized primarily for detecting organic, inorganic, and biomolecules. In this article, we highlights and summarized overview of the current research progress concerned on the CNTs/graphene-based materials as a new generation materials for detection and treatment of diseases.

Enhanced lysosomal escape of cell penetrating peptide-functionalized metal-organic frameworks for co-delivery of survivin siRNA and oridonin

In recent years, small interfering RNA (siRNA) has been widely used in the treatment of human diseases, especially tumors, and has shown great appeal. However, the clinical application of siRNA faces several challenges. Insufficient efficacy, poor bioavailability, poor stability, and lack of responsiveness to a single therapy are the main problems affecting tumor therapy. Here, we designed a cell-penetrating peptide (CPP)-modified metal organic framework nanoplatform (named PEG-CPP33@ORI@survivin siRNA@ZIF-90, PEG-CPP33@NPs) for targeted co-delivery of oridonin (ORI), a natural anti-tumor active ingredient) and survivin siRNA in vivo. This can improve the stability and bioavailability of siRNA and the efficacy of siRNA monotherapy. The high drug-loading capacity and pH-sensitive properties of zeolite imidazolides endowed the PEG-CPP33@NPs with lysosomal escape abilities. The Polyethylene glycol (PEG)-conjugated CPP (PEG-CPP33) coating significantly improved the uptake in the PEG-CPP33@NPs in vitro and in vivo. The results showed that the co-delivery of ORI and survivin siRNA greatly enhanced the anti-tumor effect of PEG-CPP33@NPs, demonstrating the synergistic effect between ORI and survivin siRNA. In summary, the novel targeted nanobiological platform loaded with ORI and survivin siRNA presented herein showed great advantages in cancer therapy, and provides an attractive strategy for the synergistic application of chemotherapy and gene therapy.

Carbon-Based Nanomaterials as Drug Delivery Agents for Colorectal Cancer: Clinical Preface to Colorectal Cancer Citing Their Markers and Existing Theranostic Approaches

Colorectal cancer (CRC) is one of the universally established cancers with a higher incidence rate. Novel progression toward cancer prevention and cancer care among countries in transition should be considered seriously for controlling CRC. Hence, several cutting edge technologies are ongoing for high performance cancer therapeutics over the past few decades. Several drug-delivery systems of the nanoregime are relatively new in this arena compared to the previous treatment modes such as chemo- or radiotherapy to mitigate cancer. Based on this background, the epidemiology, pathophysiology, clinical presentation, treatment possibilities, and theragnostic markers for CRC were revealed. Since the use of carbon nanotubes (CNTs) for the management of CRC has been less studied, the present review analyzes the preclinical studies on the application of carbon nanotubes for drug delivery and CRC therapy owing to their inherent properties. It also investigates the toxicity of CNTs on normal cells for safety testing and the clinical use of carbon nanoparticles (CNPs) for tumor localization. To conclude, this review recommends the clinical application of carbon-based nanomaterials further for the management of CRC in diagnosis and as carriers or therapeutic adjuvants.

Lysosomal-mediated drug release and activation for cancer therapy and immunotherapy

The development of carrier systems that are able to transport and release therapeutics to target cells is an emergent strategy to treat cancer; however, they following endocytosis are usually trapped in the endo/lysosomal compartments. The efficacy of drug conjugates and nanotherapeutics relies critically on their intracellular drug release ability, for which advanced systems responding to the unique lysosomal environment such as acidic pH and abundant enzymes (e.g. cathepsin B, sulfatase and β-glucuronidase) or equipped with photochemical internalization property have been energetically pursued. In this review, we highlight the recent designs of smart systems that promote efficient lysosomal release and/or escape of anticancer agents including chemotherapeutics (e.g. doxorubicin, platinum, chloroquine and hydrochloroquine) and biotherapeutics (e.g. proteins, siRNA, miRNA, mRNA and pDNA) to cancer cells or immunotherapeutic agents (e.g. antigens, mRNA and immunoadjuvants) to antigen-presenting cells (APCs), thereby boosting cancer therapy and immunotherapy. Lysosomal-mediated drug release presents an appealing approach to develop innovative cancer therapeutics and immunotherapeutics.

Carbon Nanotubes as Carriers in Drug Delivery for Non-Small Cell Lung Cancer, Mechanistic Analysis of Their Carcinogenic Potential, Safety Profiling and Identification of Biomarkers

Non-small cell lung cancer (NSCLC) is a global burden leading to millions of deaths worldwide every year. Nanomedicine refers to the use of materials at the nanoscale for drug delivery and subsequent therapeutic approaches in cancer. Carbon nanotubes (CNTs) are widely used as nanocarriers for therapeutic molecules such as plasmids, siRNAs, antisense agents, aptamers and molecules related to the immunotherapy for several cancers. They are usually functionalized and loaded with standard drug molecules to improve their therapeutic efficiency. Functionalization and drug loading possibly decrease the genotoxic and carcinogenic potential of CNTs. In addition, the targeted cytotoxic properties of the drug improve and undesired toxicity decreases after drug loading and/or conjugation with proteins, including antibodies. For intended drug delivery, a lysosomal pH of 5.5 is more suitable and effective for the slow and extended release of cytotoxic drugs than a physiological of pH 7.4. Remarkably, CNTs possess intrinsic antitumor properties and are usually internalized by endocytosis. After being internalized, several mechanisms are involved in the therapeutic and carcinogenic effects of CNTs. They are generally safe for therapy, and their toxicity profile remains dependent on their physicochemical properties. Moreover, the dose, route, duration of exposure, surface properties and degradative potential determine the toxicity outcomes of CNTs locally or systemically. In summary, the use of CNTs in drug delivery and NSCLC therapy, as well as their genotoxic and carcinogenic potential and the possible mechanisms, has been discussed in this review. The therapeutic index is generally high for NSCLC cells treated with drug-loaded CNTs; therefore, they are effective carriers in implementing targeted therapy for NSCLC.

Design of double functionalized carbon nanotube for amphotericin B and genetic material delivery

In the present work, single wall carbon nanotubes (SWCNT) were successively functionalized with phospholipid DSPE-PEG carboxylic acid, and then, with ethylenediamine (EDA), to obtain double functionalized single wall carbon nanotube (DFSWCNT). Then, DFSWCNT was applied as a carrier for delivering amphotericin B (Amb) and EGFP plasmid. FSWCNT's concentration obtained via UV-visible analysis was 0.99 mg/mL. The TGA analysis results provided the lost weights of DSPE-PEG-COOH, EDA, Amb and SWCNT impurities. XPS results showed that carbon atoms' percentage decreased during the functionalization processes from 97.2% (SWCNT) to 76.4% (FSWCNT) and 69.9% (DFSWNCT). Additionally, the oxygen atoms' percentage increased from 2.3% (SWCNT) to 21% and 22.5% for FSWCNT and DFSWCNT, respectively. New bonds such as C-N and N-C=O appeared in the synthesized nanocarrier. The I_G/I_D ratio in Raman analysis decreased from 7.15 (SWCNT) to 4.08 (FSWCNT). The amount of Amb released to phosphate buffer saline medium was about 33% at pH = 5.5 and 75% at pH = 7.4 after 48 h. CCK8 results confirmed that the toxicity of functionalized SWCNT had decreased. In a 2:1 ratio of DFSWCNT/EGFP plasmid, the cell viability (87%) and live transfected cells (56%) were at their maximum values. The results indicate that carbon nanotubes have the potential to be applied as drug/gene delivery systems with outstanding properties such as high loading capacity and easy penetration to cell membrane.

Recent Advancements in the Design of Nanodelivery Systems of siRNA for Cancer Therapy

RNA interference (RNAi) has increased the possibility of restoring RNA drug targets for cancer treatment. Small interfering RNA (siRNA) is a promising therapeutic RNAi tool that targets the defective gene by inhibiting its mRNA expression and stopping its translation. However, siRNAs have flaws like poor intracellular trafficking, RNase degradation, rapid kidney filtration, off-targeting, and toxicity, which limit their therapeutic efficiency. Nanocarriers (NCs) have been designed to overcome such flaws and increase antitumor activity. Combining siRNA and anticancer drugs can give synergistic effects in cancer cells, making them a significant gene-modification tool in cancer therapy. Our discussion of NCs-mediated siRNA delivery in this review includes their mechanism, limitations, and advantages in comparison with naked siRNA delivery. We will also discuss organic NCs (polymers and lipids) and inorganic NCs (quantum dots, carbon nanotubes, and gold) that have been reported for extensive delivery of therapeutic siRNA to tumor sites. Finally, we will conclude by discussing the studies based on organic and inorganic NCs-mediated siRNA drug delivery systems conducted in the years 2020 and 2021.

Biocompatible Iron Oxide Nanoparticles for Targeted Cancer Gene Therapy: A Review

In recent years, gene therapy has made remarkable achievements in tumor treatment. In a successfully cancer gene therapy, a smart gene delivery system is necessary for both protecting the therapeutic genes in circulation and enabling high gene expression in tumor sites. Magnetic iron oxide nanoparticles (IONPs) have demonstrated their bright promise for highly efficient gene delivery target to tumor tissues, partly due to their good biocompatibility, magnetic responsiveness, and extensive functional surface modification. In this review, the latest progress in targeting cancer gene therapy is introduced, and the unique properties of IONPs contributing to the efficient delivery of therapeutic genes are summarized with detailed examples. Furthermore, the diagnosis potentials and synergistic tumor treatment capacity of IONPs are highlighted. In addition, aiming at potential risks during the gene delivery process, several strategies to improve the efficiency or reduce the potential risks of using IONPs for cancer gene therapy are introduced and addressed. The strategies and applications summarized in this review provide a general understanding for the potential applications of IONPs in cancer gene therapy.

Combretastatin A4-loaded Poly (Lactic-co-glycolic Acid)/Soybean Lecithin Nanoparticles with Enhanced Drug Dissolution Rate and Antiproliferation Activity

OBJECTIVE

This study aimed to prepare combretastatin A4 (CA4)-loaded nanoparticles (CA4 NPs) using poly(lactic-co-glycolic acid) (PLGA) and soybean lecithin (Lipoid S100) as carriers, and further evaluate the physicochemical properties and cytotoxicities of CA4 NPs against cancer cells.

METHODS

CA4 NPs were prepared using a solvent evaporation technique. The effects of formulations on CA4 NPs were investigated in terms of particle size, zeta potential, encapsulation efficacy, and drug loading. The physicochemical properties of CA4 NPs were characterized using transmission electron microscopy, X-ray powder diffraction, differential scanning calorimetry, and Fourier transform infrared spectra. The drug release from CA4NPs was performed using a dialysis method. In addition, the cytotoxicity of CA4NPs against human alveolar basal epithelial (A549) cells was also evaluated.

RESULTS

CA4 NPs prepared with a low organic/water phase ratio (1:20) and high drug/PLGA mass ratio (1:2.5) exhibited a uniform hydrodynamic particle size of 142 nm, the zeta potential of -1.66 mV, and encapsulation efficacy and drug loading of 92.1% and 28.3%, respectively. CA4 NPs showed a significantly higher release rate than pure CA4 in pH 7.4 phosphate-buffered solution with 0.5% Tween 80. It was found that the drug molecules could change from the crystal state to an amorphous form when loaded into the PLGA/Lipoid S100 matrix, and some molecular interactions could also occur between the drug and PLGA. Importantly, CA4 NPs showed a remarkably higher antiproliferation activity against A549 cancer cells compared to pure CA4.

CONCLUSION

These results suggested the promising potential of PLGA/Lipoid S100 nanoparticles as the drug delivery system of CA4 for effective cancer therapy.

Nanocapping-enabled charge reversal generates cell-enterable endosomal-escapable bacteriophages for intracellular pathogen inhibition

Bacteriophages (phages) are widely explored as antimicrobials for treating infectious diseases due to their specificity and potency to infect and inhibit host bacteria. However, the application of phages to inhibit intracellular pathogens has been greatly restricted by inadequacy in cell entry and endosomal escape. Here, we describe the use of cationic polymers to selectively cap negatively charged phage head rather than positively charged tail by electrostatic interaction, resulting in charge-reversed phages with uninfluenced vitality. Given the positive surface charge and proton sponge effect of the nanocapping, capped phages are able to enter intestinal epithelial cells and subsequently escape from endosomes to lyse harbored pathogens. In a murine model of intestinal infection, oral ingestion of capped phages significantly reduces the translocation of pathogens to major organs, showing a remarkable inhibition efficacy. Our work proposes that simple synthetic nanocapping can manipulate phage bioactivity, offering a facile platform for preparing next-generation antimicrobials.

Cancer Targeting and Diagnosis: Recent Trends with Carbon Nanotubes

Cancer belongs to a category of disorders characterized by uncontrolled cell development with the potential to invade other bodily organs, resulting in an estimated 10 million deaths globally in 2020. With advancements in nanotechnology-based systems, biomedical applications of nanomaterials are attracting increasing interest as prospective vehicles for targeted cancer therapy and enhancing treatment results. In this context, carbon nanotubes (CNTs) have recently garnered a great deal of interest in the field of cancer diagnosis and treatment due to various factors such as biocompatibility, thermodynamic properties, and varied functionalization. In the present review, we will discuss recent advancements regarding CNT contributions to cancer diagnosis and therapy. Various sensing strategies like electrochemical, colorimetric, plasmonic, and immunosensing are discussed in detail. In the next section, therapy techniques like photothermal therapy, photodynamic therapy, drug targeting, gene therapy, and immunotherapy are also explained in-depth. The toxicological aspect of CNTs for biomedical application will also be discussed in order to ensure the safe real-life and clinical use of CNTs.

Carbon Graphitization: Towards Greener Alternatives to Develop Nanomaterials for Targeted Drug Delivery

Carbon nanomaterials have attracted great interest for their unique physico-chemical properties for various applications, including medicine and, in particular, drug delivery, to solve the most challenging unmet clinical needs. Graphitization is a process that has become very popular for their production or modification. However, traditional conditions are energy-demanding; thus, recent efforts have been devoted to the development of greener routes that require lower temperatures or that use waste or byproducts as a carbon source in order to be more sustainable. In this concise review, we analyze the progress made in the last five years in this area, as well as in their development as drug delivery agents, focusing on active targeting, and conclude with a perspective on the future of the field.

Mannan-decorated pathogen-like polymeric nanoparticles as nanovaccine carriers for eliciting superior anticancer immunity

Using nanotechnology for cancer vaccine design holds great promise because of the intrinsic feature of nanoparticles in being captured by antigen-presenting cells (APCs). However, there are still obstacles in current nanovaccine systems in achieving efficient tumor therapeutic effects, which could partially be attributed to the unsatisfactory vaccine carrier design. Herein, we report a mannan-decorated pathogen-like polymeric nanoparticle as a protein vaccine carrier for eliciting robust anticancer immunity. This nanovaccine was constructed as a core-shell structure with mannan as the shell, polylactic acid-polyethylenimine (PLA-PEI) assembled nanoparticle as the core, and protein antigens and Toll-like receptor 9 (TLR9) agonist CpG absorbed onto the PLA-PEI core via electrostatic interactions. Compared to other hydrophilic materials, mannan decoration could greatly enhance the lymph node draining ability of the nanovaccine and promote the capturing by the CD8⁺ dendritic cells (DCs) in the lymph node, while PLA-PEI as the inner core could enhance antigen endosome escape thus promoting the antigen cross-presentation. In addition, mannan itself as a TLR4 agonist could synergize with CpG for maximally activating the DCs. Excitingly, we observed in several murine tumor models that using this nanovaccine alone could elicit robust immune response in vivo and result in superior anti-tumor effects with 50% of mice completely cured. This study strongly evidenced that mannan decoration and a rationally designed nanovaccine system could be quite robust in tumor vaccine therapy.

Self-assembled RNA nanocarrier-mediated chemotherapy combined with molecular targeting in the treatment of esophageal squamous cell carcinoma

Background

Esophageal cancer is the fifth most common cancer affecting men in China. The primary treatment options are surgery and traditional radio-chemotherapy; no effective targeted therapy exists yet. Self-assembled RNA nanocarriers are highly stable, easily functionally modified, and have weak off-tumor targeting effects. Thus, they are among the most preferred carriers for mediating the targeted delivery of anti-tumor drugs. miR-375 was found to be significantly down-regulated in esophageal squamous cell carcinoma (ESCC) tissues and its overexpression effectively inhibits the proliferation, migration, and invasion of ESCC cells. Moreover, epidermal growth factor receptor (EGFR) was overexpressed in ESCC cells, and accumulation of RNA nanoparticles in ESCC tumors was enhanced by EGFR-specific aptamer (EGFR_apt) modification.

Results

Herein, a novel four-way junction RNA nanocarrier, 4WJ-EGFR_apt-miR-375-PTX simultaneously loaded with miR-375, PTX and decorated with EGFR_apt, was developed. In vitro analysis demonstrated that 4WJ-EGFR_apt-miR-375-PTX possesses strong thermal and pH stabilities. EGFR_apt decoration facilitated tumor cell endocytosis and promoted deep penetration into 3D-ESCC spheroids. Xenograft mouse model for ESCC confirmed that 4WJ-EGFR_apt-miR-375-PTX was selectively distributed in tumor sites via EGFR_apt-mediating active targeting and targeted co-delivery of miR-375 and PTX exhibited more effective therapeutic efficacy with low systemic toxicity.

Conclusion

This strategy may provide a practical approach for targeted therapy of ESCC.

Graphical Abstract

Supplementary Information

The online version contains supplementary material available at 10.1186/s12951-021-01135-5.

Self-assembled ternary hybrid nanodrugs for overcoming tumor resistance and metastasis

Traditional chemotherapy exhibits a certain therapeutic effect toward malignant cancer, but easily induce tumor multidrug resistance (MDR), thereby resulting in the progress of tumor recurrence or metastasis. In this work, we deigned ternary hybrid nanodrugs (PEI/DOX@CXB-NPs) to simultaneously combat against tumor MDR and metastasis. In vitro results demonstrate this hybrid nanodrugs could efficiently increase cellular uptake at pH 6.8 by the charge reversal, break lysosomal sequestration by the proton sponge effect and trigger drugs release by intracellular GSH, eventually leading to higher drugs accumulation and cell-killing in drug-sensitive/resistant cells. In vivo evaluation revealed that this nanodrugs could significantly inhibit MDR tumor growth and simultaneously prevent A549 tumor liver/lung metastasis owing to the specifically drugs accumulation. Mechanism studies further verified that hybrid nanodrugs were capable of down-regulating the expression of MDR or metastasis-associated proteins, lead to the enhanced anti-MDR and anti-metastasis effect. As a result, the multiple combination strategy provided an option for effective cancer treatment, which could be potentially extended to other therapeutic agents or further use in clinical test.

Delivery of small interfering RNAs by nanovesicles for cancer therapy

Small interfering ribonucleic acids (siRNAs) are originally recognized as an intermediate of the RNA interference (RNAi) pathway. They can inhibit or silence various cellular pathways by knocking down specific messenger RNA molecules. In cancer cells, siRNAs can suppress the expression of several multidrug-resistant genes, leading to the increased deposition of chemotherapeutic drugs at the tumor site. siRNA therapy can be used to selectively increase apoptosis of cancer cells or activate an immune response to the cancer. However, delivering siRNAs to the targeted location is the main limitation in achieving safe and effective delivery of siRNAs. This review highlights some representative examples of nonviral delivery systems, especially nanovesicles such as exosomes, liposomes, and niosomes. Nanovesicles can improve the delivery of siRNAs by increasing their intracellular delivery, and they have demonstrated excellent potential for cancer therapy. This review focuses on recent discoveries of siRNA targets for cancer therapy and the use of siRNAs to successfully silence these targets. In addition, this review summarizes the recent progress in designing nanovesicles (liposomes or niosomes) for siRNA delivery to cancer cells and the effects of a combination of anticancer drugs and siRNA therapy in cancer therapy.

Multifunctional Size-Expandable Nanomedicines Enhance Tumor Accumulation and Penetration for Synergistic Chemo-Photothermal Therapy

Size expansion can effectively improve tumor accumulation of nanocarriers where precise control is required. A dual-responsive nanocarrier stimulated by both endogenous pH and exogenous heat stimuli can change its size. Herein, a nanoparticle composed of poly(N,N-diethyl acrylamide) (PDEAA) and poly(2-(diisopropylamino) ethyl methacrylate) (PDPA) is developed. The antitumor drug celastrol (CLT) and the photosensitizer indocyanine green (ICG) are then loaded in it to form CIPP. ICG generates heat under near-infrared (NIR) stimulation to kill tumor cells and enhance CIPP penetration. Meanwhile, CIPP expands in response to hyperthermia and acid tumor microenvironments, preventing itself from returning to the blood flow, thus accumulating in tumor sites. Ultimately, the acidic lysosomal environment in tumor cells disintegrates CIPP to release CLT, directly inducing immunogenic cell death and sensitizing tumor cells for hyperthermia by disrupting the interaction of heat shock protein 90 and P50cdc37. Most of the tumors in B16F10-bearing mice are eradicated after single laser irradiation. The dual-responsive CIPP with multiple functions and simple design displays a synergistic antitumor effect. This study provides a basis for developing size-expandable stimulus-responsive drug delivery systems against tumors.

Application of Non-Viral Vectors in Drug Delivery and Gene Therapy

Vectors and carriers play an indispensable role in gene therapy and drug delivery. Non-viral vectors are widely developed and applied in clinical practice due to their low immunogenicity, good biocompatibility, easy synthesis and modification, and low cost of production. This review summarized a variety of non-viral vectors and carriers including polymers, liposomes, gold nanoparticles, mesoporous silica nanoparticles and carbon nanotubes from the aspects of physicochemical characteristics, synthesis methods, functional modifications, and research applications. Notably, non-viral vectors can enhance the absorption of cargos, prolong the circulation time, improve therapeutic effects, and provide targeted delivery. Additional studies focused on recent innovation of novel synthesis techniques for vector materials. We also elaborated on the problems and future research directions in the development of non-viral vectors, which provided a theoretical basis for their broad applications.

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.

Carbon nanotubes as an emerging nanocarrier for the delivery of doxorubicin for improved chemotherapy

Carbon nanotubes (CNTs), a versatile nanocarrier for doxorubicin (DOX) delivery had attracted significant attention in drug delivery of pharmaceuticals. Several properties such as high surface area, high drug loading capacity, stability, ease of functionalization, ultrahigh length to diameter ratio and good cellular uptake make them preferred nanocarrier as multipurpose drug delivery system. Several surface properties of CNTs can be easily modified by covalent/noncovalent functionalization, which can make CNTs a profound nanomaterial. Hydrophobic surface of CNTs facilitated π-π stacking interactions, with several drugs and therapeutic agents having aromatic ring in their structure, for example anthracyclines. In case some drug molecules, electrostatic interaction between drug and CNTs comes into the picture. DOX, an anthracycline anticancer drug, can easily adsorb on the surface of CNTs by π-π stacking interactions. In present article, we have reviewed various CNTs based drug delivery systems for the delivery of DOX alone or in combination with genetic materials and other drug molecules. In addition, we described recent updates in CNTs based drug delivery system for the delivery of DOX, we covered adsorption and desorption, different types of functionalization, to alter the properties of CNTs in vitro and in vivo. CNT attached many targeting ligands for the targeted delivery of DOX have also been discussed.

A tumor-activatable peptide supramolecular nanoplatform for the delivery of dual-gene targeted siRNAs for drug-resistant cancer treatment

Combinatorial short interference RNA (siRNA) technology for the silencing of multiple genes is expected to provide an effective therapeutic approach for cancer with complex genetic mutation and dysregulation. Herein we present a tumor-activatable supramolecular nanoplatform for the delivery of siRNAs to target telomerase and telomeres for paclitaxel-resistant non-small-cell lung cancer (A549/PTX) treatment. Two different sequences of siRNA are incorporated in a single nanoparticle, which is obtained by self-assembly from a peptide dendrimer. The siRNA stability is improved by the nanoparticle in the presence of serum compared to free siRNA, and these siRNAs are protected from RNA enzyme degradation. In the tumor extracellular acid environment, the PEG corona of the nanoparticle is removed to promote the internalization of siRNAs into tumor cells. The disulfide linkages between the nanoparticle and siRNAs are cleared in the reductive environment of the tumor cells, and the siRNAs are released in the cytoplasm. In vitro experiments show that the gene expression of hTERT and TRF2 at the mRNA and protein levels of A549/PTX tumor cells is down-regulated, which results in cooperative restraining proliferation and invasion of A549/PTX tumor cells. For the tumor cell-targeting function of the MUC1 aptamer and the EPR effect, sufficient tumor accumulation of nanoparticles was observed. Meanwhile, a shift of negative surface charge of nanoparticles to positive charge in the tumor extracellular microenvironment enhances deep penetration of siRNA-incorporating nanoparticles into tumor tissues. In vivo animal studies support that successful down-regulation of hTERT and TRF2 gene expression achieves effective inhibition of the growth and neovascularization of drug-resistant tumor cells. This work has provided a new avenue for drug-resistant cancer treatment by designing and synthesizing a tumor-activatable nanoplatform to achieve the delivery of dual-gene targeted combinatorial siRNAs.

Cancer Nanopharmaceuticals: Physicochemical Characterization and In Vitro/In Vivo Applications

Physicochemical, pharmacokinetic, and biopharmaceutical characterization tools play a key role in the assessment of nanopharmaceuticals' potential imaging analysis and for site-specific delivery of anti-cancers to neoplastic cells/tissues. If diagnostic tools and therapeutic approaches are combined in one single nanoparticle, a new platform called nanotheragnostics is generated. Several analytical technologies allow us to characterize nanopharmaceuticals and nanoparticles and their properties so that they can be properly used in cancer therapy. This paper describes the role of multifunctional nanoparticles in cancer diagnosis and treatment, describing how nanotheragnostics can be useful in modern chemotherapy, and finally, the challenges associated with the commercialization of nanoparticles for cancer therapy.

Carbon Nanotubes: Smart Drug/Gene Delivery Carriers

The unique properties of carbon nanotubes (CNTs) (such as their high surface to volume ratios, enhanced conductivity and strength, biocompatibility, ease of functionalization, optical properties, etc.) have led to their consideration to serve as novel drug and gene delivery carriers. CNTs are effectively taken up by many different cell types through several mechanisms. CNTs have acted as carriers of anticancer molecules (including docetaxel (DTX), doxorubicin (DOX), methotrexate (MTX), paclitaxel (PTX), and gemcitabine (GEM)), anti-inflammatory drugs, osteogenic dexamethasone (DEX) steroids, etc. In addition, the unique optical properties of CNTs have led to their use in a number of platforms for improved photo-therapy. Further, the easy surface functionalization of CNTs has prompted their use to deliver different genes, such as plasmid DNA (PDNA), micro-RNA (miRNA), and small interfering RNA (siRNA) as gene delivery vectors for various diseases such as cancers. However, despite all of these promises, the most important continuous concerns raised by scientists reside in CNT nanotoxicology and the environmental effects of CNTs, mostly because of their non-biodegradable state. Despite a lack of widespread FDA approval, CNTs have been studied for decades and plenty of in vivo and in vitro reports have been published, which are reviewed here. Lastly, this review covers the future research necessary for the field of CNT medicine to grow even further.

DNA interfaces with dimensional materials for biomedical applications

DNA interfaces with nano, micro, and macro materials have gained widespread attention for various applications. Such interfaces exhibit distinct functions and properties not only due to the unique properties of interfacing materials but also sequence- and conformation-dependent characteristics of the DNA. Therefore, DNA interfaces with diverse dimensional materials have advanced our understanding of the interaction mechanisms and the properties of such interfaces. The unique interfacial properties of such novel materials have applications in nanotechnology, biophysics, cell biology, biosensing, and bioelectronics. The field is growing rapidly with the frequent emergence of new interfaces carrying remarkable interfacial character. In this review article, we have classified the DNA interfaces into 0D, 1D, 2D, and 3D categories based on the types of dimensional materials. We review the key efforts made in the last five years and focus on types of interfaces, interfacing mechanisms, and their state-of-the-art applications. This review will draw a general interest because of the diversity in the DNA materials science but also the unique applications that will play a cutting-edge role in biomedical and biosensing research.

DNA interfaces with 0–3 dimensional materials through physisorption and chemisorption mechanisms acquire unique interfacial character for novel biomedical applications.

Precise design strategies of nanomedicine for improving cancer therapeutic efficacy using subcellular targeting

Therapeutic efficacy against cancer relies heavily on the ability of the therapeutic agents to reach their final targets. The optimal targets of most cancer therapeutic agents are usually biological macromolecules at the subcellular level, which play a key role in carcinogenesis. Therefore, to improve the therapeutic efficiency of drugs, researchers need to focus on delivering not only the therapeutic agents to the target tissues and cells but also the drugs to the relevant subcellular structures. In this review, we discuss the most recent construction strategies and release patterns of various cancer cell subcellular-targeting nanoformulations, aiming at providing guidance in the overall design of precise nanomedicine. Additionally, future challenges and potential perspectives are illustrated in the hope of enhancing anticancer efficacy and accelerating the translational progress of precise nanomedicine.

The Applications of Carbon Nanotubes in the Diagnosis and Treatment of Lung Cancer: A Critical Review

The importance of timely diagnosis and the complete treatment of lung cancer for many people with this deadly disease daily increases due to its high mortality. Diagnosis and treatment with helping the nanoparticles are useful, although they have reasonable harms. This article points out that the side effects of using carbon nanotube (CNT) in this disease treatment process such as inflammation, fibrosis, and carcinogenesis are very problematic. Toxicity can reduce to some extent using the techniques such as functionalizing to proper dimensions as a longer length, more width, and greater curvature. The targeted CNT sensors can be connected to various modified vapors. In this regard, with helping this method, screening makes non-invasive diagnosis possible. Researchers have also found that nanoparticles such as CNTs could be used as carriers to direct drug delivery, especially with chemotherapy drugs. Most of these carriers were multi-wall carbon nanotubes (MWCNT) used for cancerous cell targeting. The results of laboratory and animal researches in the field of diagnosis and treatment became very desirable and hopeful. The collection of researches summarized has highlighted the requirement for a detailed assessment which includes CNT dose, duration, method of induction, etc., to achieve the most controlled conditions for animal and human studies. In the discussion section, 4 contradictory issues are discussed which are invited researchers to do more research to get clearer results.

Recent Advances in Nanocarrier-Assisted Therapeutics Delivery Systems

Nanotechnologies have attracted increasing attention in their application in medicine, especially in the development of new drug delivery systems. With the help of nano-sized carriers, drugs can reach specific diseased areas, prolonging therapeutic efficacy while decreasing undesired side-effects. In addition, recent nanotechnological advances, such as surface stabilization and stimuli-responsive functionalization have also significantly improved the targeting capacity and therapeutic efficacy of the nanocarrier assisted drug delivery system. In this review, we evaluate recent advances in the development of different nanocarriers and their applications in therapeutics delivery.

pH-Responsive charge switchable PEGylated ε-poly-l-lysine polymeric nanoparticles-assisted combination therapy for improving breast cancer treatment

Stimuli-responsive nanotechnology-mediated drug co-delivery system is a notable strategy to improve access of the systemically administered chemotherapeutics to the tumors. Herein, a tailor-made 2,3-dimethylmaleic-anhydride-poly(ethylene glycol)-ε-poly-l-lysine-doxorubicin /lapatinib polymeric nanoplatform (DMMA-P-DOX/LAP) for synergistically eliminating breast cancer is developed by encapsulating lapatinib into dual-pH responsive charge switchable biopolymer-doxorubicin conjugate nanoparticles. The physicochemical properties of polymeric nanoparticles are conducive to their stable circulation in the physiological condition, but reverse the surface charge from negative to positive ultrasensitively in slightly acidic tumor microenvironment, facilitating cell internalization and deep tumor penetration. Subsequently, DOX and LAP are synchronously released into the cytoplasm in response to the significantly increased acidity of intracellular environment. As a result, the combination therapy by DMMA-P-DOX/LAP nanoparticles compels the solid tumors to contract significantly or even vanish completely in the MCF-7 tumor model, moreover, the structural composition with amino acid and bioinert PEG ensures the favorable biosecurity of the co-delivery system in vivo. This dual-pH responsive nanotechnology-mediated drug co-delivery system provides great potentials for safe and effective cancer therapy.

Far-reaching advances in the role of carbon nanotubes in cancer therapy

Cancer includes a group of diseases involving unregulated cell growth with the potential to invade or expand to other parts of the body, resulting in an estimate of 9.6 million deaths worldwide in 2018. Manifold studies have been conducted to design more efficacious techniques for cancer therapy due to the inadequacy of conventional treatments including chemotherapy, surgery, and radiation therapy. With the advances in the biomedical applications of nanotechnology-based systems, nanomaterials have gained increasing attention as promising vehicles for targeted cancer therapy and optimizing treatment outcomes. Owing to their outstanding thermal, electrical, optical and chemical properties, carbon nanotubes (CNTs) have been profoundly studied to explore the various perspectives of their application in cancer treatment. The current study aims to review the role of CNTs whether as a carrier or mediator in cancer treatment for enhancing the efficacy as well as the specificity of therapy and reducing adverse side effects. This comprehensive review indicates that CNTs have the capability to be the next generation nanomaterials to actualize noninvasive targeted eradication of tumors. However, further studies are needed to evaluate the consequences of their biomedical application before the transition into clinical trials, since possible adverse effects of CNTs on biological systems have not been clearly understood.

Co-delivery of doxorubicin and DNAzyme using ZnO@polydopamine core-shell nanocomposites for chemo/gene/photothermal therapy

Multi-modal nanomedicines that synergistically combine chemo-, gene-, and photothermal therapy have shown great potential for cancer treatment. In this study, a core-shell nanosystem-based on a zinc oxide (ZnO) nanocore and a polydopamine (PDA) shell was constructed to integrate chemo- (doxorubicin, DOX), gene- (DNAzyme, DZ), and photothermal (PDA layer) therapy in one system. Instead of small interfering RNAs, we employed DZ for tumor-related gene (survivin) regulation owing to its higher stability, biocompatibility, and predictable activity. DOX and amino-modified DZ were loaded onto the PDA shell via physisorption and covalent conjugation, respectively. Specifically, the ZnO nanocore was designed as a metal cofactor reservoir to release Zn²⁺ in response to intracellular stimuli, which triggered the activation of DZ for gene silencing after endocytosis into cells. Both in vitro and in vivo experiments demonstrated the enhanced anti-tumor efficacy of these multifunctional nanocomposites and highlighted the advantages of these nano-drug delivery systems to alleviate the side effects of DOX. This study provides a strategy for synergistic cancer therapy via chemo/gene/photothermal combination and offers a strategy to harness DZ as a gene-silencing tool for disease treatment in combination with other therapeutic modalities. STATEMENT OF SIGNIFICANCE: In this work, we constructed a core-shell nanosystem containing a zinc oxide (ZnO) nanocore and a polydopamine (PDA) outer layer, which integrated chemo- (doxorubicin, DOX), gene- (DNAzyme, DZ), and photothermal (PDA layer) therapies for multimodal cancer therapy. Specifically, the ZnO core was incorporated to solve the key issue of DZ for gene silencing applications, which acted as the metal cofactor reservoir to release Zn²⁺ inside cells for effective DZ activation. In addition, the PDA shell could detoxify the ZnO by scavenging the reactive oxygen species produced by ZnO, thus increasing the biocompatibility of the nanocarrier. This work solves the key issue of DZ for RNAi-based applications, offers a platform to combine DZ with other therapeutic modalities, and also provides a smart strategy to achieve triggered activation of biocatalytic reactions for therapeutic applications.

Evaluation the synergistic antitumor effect of methotrexate-camptothecin codelivery prodrug from self-assembly process to acid-catalyzed both drugs release: A comprehensive theoretical study

Therapeutic efficiency of amphiphilic methotrexate-camptothecin (MTX-CPT) prodrug compared to free drug mixture (MTX/CPT) has been investigated using all-atom molecular dynamics simulation and first principles density functional theory calculations. This comparison revealed that MTX-CPT prodrug tends to form spherical self-assembled nanoparticle (NP), while free MTX/CPT mixture forms rod-shape NP. These observations are attributed to a structural defect in the MTX-CPT prodrug and solvation free energies of MTX, CPT and MTX-CPT molecules. The results provided evidence that noncovalent interactions (NCIs) among the pharmaceutical drugs play a very important role in anticancer agents aggregation process, leading to enhanced stability of the self-assembled NPs. It is found that the stability of MTX-CPT self-assembled NP is greater than the MTX/CPT NP due to the synergistic effect of hydrogen bonding between monomers and solvent (water). Moreover, the noncatalyzed as well as catalyzed hydrolysis reactions of MTX-CPT prodrug are theoretically studied at the PCM(water)//M06-2X/6-31G(d,p) computational level to shed additional light on the role of acidic condition in tumor tissues. We found that the ester hydrolysis in mild acidic solutions is a concerted reaction. In an agreement between theory and experiment, we also confirmed that the activation energies of the catalyzed-hydrolysis steps are much lower than the activation energies of the corresponding steps in the noncatalyzed reaction. Thus, the MTX-CPT prodrug reveals very promising properties as a pH-controlled drug delivery system.

The effects of functionalization of carbon nanotubes on toxicological parameters in mice

Carbon nanotubes (CNTs) have emerged as a new class of multifunctional nanoparticles in biomedicine, but their multiple in vivo effects remain unclear. Also, the impact of various functionalization types and duration of exposures are still unidentified. Herein, we report a complete toxicological study to evaluate the effects of single- and multiwalled carbon nanotubes (SWCNTs and MWCNTs) with either amine or carboxylic acid (COOH) surface functional groups. The results showed that significant oxidative stress and the subsequent cell apoptosis could be resulted in both acute and, mainly, in chronic intravenous administrations. Also, male reproductive parameters were altered during these exposures. The amino-functionalized CNTs had more toxic properties compared with the COOH functionalized group, and also, in some groups, the multiwalled nanotubes were more active in eliciting cytotoxicity than the single-walled nanotubes. Interestingly, the SWCNTs-COOH had the least alterations in most of the parameters. Evidently, it is concluded that the toxicity of CNTs in specific organs can be minimized through particular surface functionalizations.

Targeting the undruggable in pancreatic cancer using nano-based gene silencing drugs

Pancreatic cancer is predicted to be the second leading cause of cancer-related death by 2025. The best chemotherapy only extends survival by an average of 18 weeks. The extensive fibrotic stroma surrounding the tumor curbs therapeutic options as chemotherapy drugs cannot freely penetrate the tumor. RNA interference (RNAi) has emerged as a promising approach to revolutionize cancer treatment. Small interfering RNA (siRNA) can be designed to inhibit the expression of any gene which is important given the high degree of genetic heterogeneity present in pancreatic tumors. Despite the potential of siRNA therapies, there are hurdles limiting their clinical application such as poor transport across biological barriers, limited cellular uptake, degradation, and rapid clearance. Nanotechnology can address these challenges. In fact, the past few decades have seen the conceptualization, design, pre-clinical testing and recent clinical approval of a RNAi nanodrug to treat disease. In this review, we comment on the current state of play of clinical trials evaluating siRNA nanodrugs and review pre-clinical studies investigating the efficacy of siRNA therapeutics in pancreatic cancer. We assess the physiological barriers unique to pancreatic cancer that need to be considered when designing and testing new nanomedicines for this disease.

Co-Delivery Of Dihydroartemisinin And HMGB1 siRNA By TAT-Modified Cationic Liposomes Through The TLR4 Signaling Pathway For Treatment Of Lupus Nephritis

Background and purpose

Systemic lupus erythematous (SLE) is an autoimmune disease caused by many factors. Lupus nephritis (LN) is a common complication of SLE and represents a major cause of morbidity and mortality. Previous studies have shown the advantages of multi-targeted therapy for LN and that TLR4 signaling is a target of anti-LN drugs. High-mobility group box 1 (HMGB1), a nuclear protein with a proinflammatory cytokine activity, binds specifically to TLR4 to induce inflammation. We aimed to develop PEGylated TAT peptide-cationic liposomes (TAT-CLs) to deliver anti-HMGB1 siRNA and dihydroartemisinin (DHA) to increase LN therapeutic efficiency and explore their treatment mechanism.

Methods

We constructed the TAT-CLs-DHA/siRNA delivery system using the thin film hydration method. The uptake and localization of Cy3-labeled siRNA were detected by confocal microscopy and flow cytometry. MTT assays were used to detect glomerular mesangial cell proliferation. Real-time PCR, Western blot analysis, and ELISA evaluated the anti-inflammatory mechanism of TAT-CLs-DHA/siRNA.

Results

We constructed the TAT-CLs-DHA/siRNA delivery system measuring approximately 140 nm with superior storage and serum stabilities. In vitro, it showed significantly greater uptake compared with unmodified liposomes and significant inhibition of glomerular mesangial cell proliferation. TAT-CLs-DHA/siRNA inhibited NF-κB activation in a concentration-dependent manner. Real-time PCR and Western blot analysis showed that TAT-CLs-DHA/siRNA downregulated expression of HMGB1 mRNA and protein. TAT-CLs-DHA/siRNA markedly diminished Toll-like receptor 4 (TLR4) expression and subsequent activation of MyD88, IRAK4, and NF-κB.

Conclusion

TAT-CLs-DHA/siRNA may have the potential for treatment of inflammatory diseases such as LN mediated by the TLR4 signaling pathway.

Cancer therapeutics using survivin BIRC5 as a target: what can we do after over two decades of study?

Survivin (also named BIRC5) is a well-known cancer therapeutic target. Since its discovery more than two decades ago, the use of survivin as a target for cancer therapeutics has remained a central goal of survivin studies in the cancer field. Many studies have provided intriguing insight into survivin's functional role in cancers, thus providing promise for survivin as a cancer therapeutic target. Despite this, moving survivin-targeting agents into and through the clinic remains a challenge. In order to address this challenge, we may need to rethink current strategies in order to develop a new mindset for targeting survivin. In this Review, we will first summarize the current survivin mechanistic studies, and then review the status of survivin cancer therapeutics, which is classified into five categories: (i) survivin-partner protein interaction inhibitors, (ii) survivin homodimerization inhibitors, (iii) survivin gene transcription inhibitors, (iv) survivin mRNA inhibitors and (v) survivin immunotherapy. We will then provide our opinions on cancer therapeutics using survivin as a target, with the goal of stimulating discussion that might facilitate translational research for discovering improved strategies and/or more effective anticancer agents that target survivin for cancer therapy.

Cell-penetrating peptide: a means of breaking through the physiological barriers of different tissues and organs

The selective infiltration of cell membranes and tissue barriers often blocks the entry of most active molecules. This natural defense mechanism prevents the invasion of exogenous substances and limits the therapeutic value of most available molecules. Therefore, it is particularly important to find appropriate ways of membrane translocation and therapeutic agent delivery to its target site. Cell penetrating peptides (CPPs) are a group of short peptides harnessed in this condition, possessing a significant capacity for membrane transduction and could be exploited to transfer various biologically active cargoes into the cells. Since their discovery, CPPs have been employed for delivery of a wide variety of therapeutic molecules to treat various disorders including cranial nerve involvement, ocular inflammation, myocardial ischemia, dermatosis and cancer. The promising results of CPPs-derived therapeutics in various tumor models demonstrated a potential and worthwhile scope of CPPs in chemotherapy. This review describes the detailed description of CPPs and CPPs-assisted molecular delivery against various tissues and organs disorders. An emphasis is focused on summarizing the novel insights and achievements of CPPs in surmounting the natural membrane barriers during the last 5 years.

Theranostic Nanoparticles for RNA-Based Cancer Treatment

Certain genetic mutations lead to the development of cancer through unchecked cell growth and division. Cancer is typically treated through surgical resection, radiotherapy, and small-molecule chemotherapy. A relatively recent approach to cancer therapy involves the use of a natural process wherein small RNA molecules regulate gene expression in a pathway known as RNA interference (RNAi). RNA oligomers pair with a network of proteins to form an RNA-induced silencing complex, which inhibits the translation of mRNA into proteins, thereby controlling the expression of gene products. Synthetically produced RNA oligomers may be designed to target and silence specific oncogenes to provide cancer therapy. The primary challenges facing the use of the RNAi pathway for cancer therapy are the safe and efficacious delivery of RNA payloads and their release at pertinent sites within disease-causing cells. Nucleases are abundant in the bloodstream and intracellular environment, and therapeutic RNA sequences often require a suitable carrier to provide protection from degradation prior to reaching their site of action in the body. The use of metal core nanoparticles (NPs) serving as targeted delivery vehicles able to shield and direct RNA payloads to their intended destinations have recently gained favor. Biological barriers present in the body establish a size prerequisite for drug delivery vehicles; to overcome recognition by the body's immune system and to gain access to intracellular environments, drug carriers must be small (< 100 nm). Iron oxide and gold core NPs can be synthesized with a high degree of control to create uniform ultrasmall drug delivery vehicles capable of bypassing key biological barriers. While progress is being made in size control of liposomal and polymer NPs, such advances still lag in comparison to the exquisite tunability and time stability of size engineering achievable with metal core NPs at bulk scales. Further, unlike lipid- and viral-based transfection agents, the biodistribution of metal core NPs can be traced using noninvasive imaging techniques that capitalize on the interaction of electromagnetic radiation and the inorganic atoms at the core of the NPs. Finally, metal core NPs have been shown to match the transfection efficiency of conventional RNA-delivery vehicles while also providing less immunogenicity and minimal side effects through the addition of tumor-targeting ligands on their surface. This Account reviews recent advances in the use of iron oxide and gold NPs for RNAi therapy. An overview of the different types of RNA-based therapies is provided along with a discussion of the advantages and current limitations of the technique. We highlight design considerations for the use of iron oxide and gold NP carriers in RNAi, including a discussion of the importance of size and its role in traversing biological barriers, NP surface modifications required for targeted delivery and RNA payload release, and auxiliary properties supporting imaging functionality for treatment monitoring. Applications of NPs for combination therapies including the pairing of RNAi with chemotherapy, photothermal therapy, immunotherapy, and radiotherapy are explored through examples. Finally, future perspectives are provided with a focus on the current limitations and the potential for clinical translation of iron oxide and gold NPs in RNAi therapy.

pH-Responsive polyelectrolyte coated gadolinium oxide-doped mesoporous silica nanoparticles (Gd2O3@MSNs) for synergistic drug delivery and magnetic resonance imaging enhancement

Theranostic platforms that combine therapeutic and imaging modalities have received increasing interest.