Facile synthesis of semi-library of low charge density cationic polyesters from poly(alkylene maleate)s for efficient local gene delivery

Recent Advances in Engineering Carriers for siRNA Delivery

RNA interference (RNAi) technology has been a promising treatment strategy for combating intractable diseases. However, the applications of RNAi in clinical are hampered by extracellular and intracellular barriers. To overcome these barriers, various siRNA delivery systems have been developed in the past two decades. The first approved RNAi therapeutic, Patisiran (ONPATTRO) using lipids as the carrier, for the treatment of amyloidosis is one of the most important milestones. This has greatly encouraged researchers to work on creating new functional siRNA carriers. In this review, the recent advances in siRNA carriers consisting of lipids, polymers, and polymer-modified inorganic particles for cancer therapy are summarized. Representative examples are presented to show the structural design of the carriers in order to overcome the delivery hurdles associated with RNAi therapies. Finally, the existing challenges and future perspective for developing RNAi as a clinical modality will be discussed and proposed. It is believed that the addressed contributions in this review will promote the development of siRNA delivery systems for future clinical applications.

A Trojan Horse Delivery Vehicle Carrying siRNA Nanotherapeutics with Multiple Tumor Microenvironment Responsiveness Elicits Robust Antitumor Immune Responses In Situ via a "Self-Synergistic" Approach

The potential of small interfering RNAs (siRNAs) in the treatment of malignant tumors has attracted increasing attention due to their inherent advantages. However, their therapeutic performance strongly depends on the efficiency of their cytoplasmic delivery in vivo by the delivery vehicle with good cellular permeability and histocompatibility. Herein, a polycationic carrier camouflaged with macrophage membrane (MPM) is constructed biomimetically, which is condensed from endogenous spermine monomers through diselenide bonds. The developed Trojan horse delivery vehicle has desirable compression efficacy for siRNA oligo against PD-L1 (siPDL1) as well as intracytoplasmic release properties derived from its sequential degradation triggered by redox microenvironment in tumor cells. Furthermore, the coloading of photosensitizer can mediate photodynamic therapy (PDT) accompanied by the generation of reactive oxygen species (ROS) upon light irradiation applied, which accelerated the degradation of the carrier as well as the release of cargoes while enhancing the PD-L1 blockage-mediated immunotherapy by inducing in-situ immunogenic cell death. Moreover, the synchronously delivered siPDL1 attenuated the ROS-induced increase in immunosuppressive PD-L1 expression, thereby effectively eliciting a robust antitumor immune response with a "self-synergistic" manner in the xenograft breast cancer mouse model.

Pyrene-Labeled and Quaternized Chitosan: Synthesis, Characterization, and Its Potential Application for Fluorescently Trackable Nucleic Acid Delivery into Cells

A chitosan derivative (Pyr-CS-HTAP) having pyrene (Pyr) and N-[(2-hydroxyl-3-trimethylammonium)] propyl (HTAP) units conjugated at C6 and C2 positions, respectively, was synthesized and characterized. Dynamic light scattering and scanning electron microscopy revealed that Pyr-CS-HTAP self-assembled into spherical nanoparticles with a hydrodynamic diameter of 211 ± 5 nm and a ζ-potential of +49 mV. The successful binding of Pyr-CS-HTAP with nucleic acid was ascertained by fluorescence resonance energy-transfer analysis and gel electrophoresis. Pyr-CS-HTAP facilitated the cellular uptake of nucleic acid up to 99%. Co-localization analysis using fluorescence microscopy revealed the endosomal escape of the Pyr-CS-HTAP/nucleic acid complexes and the successful release of the nucleic acid cargoes from the polyplexes into the nucleus. It is strongly believed that Pyr-CS-HTAP can potentially be developed into a fluorescently trackable gene delivery system in the future.

Biodegradable nanomaterials for diagnosis and therapy of tumors

Although degradable nanomaterials have been widely designed and applied for cancer bioimaging and various cancer treatments, few reviews of biodegradable nanomaterials have been reported. Herein, we have summarized the representative research advances of biodegradable nanomaterials with respect to the mechanism of degradation and their application in tumor imaging and therapy. First, four kinds of tumor microenvironment (TME) responsive degradation are presented, including pH, glutathione (GSH), hypoxia and matrix metalloproteinase (MMP) responsive degradation. Second, external stimulation degradation is summarized briefly. Next, we have outlined the applications of nanomaterials in bioimaging. Finally, we have focused on some typical examples of biodegradable nanomaterials in radiotherapy (RT), photothermal therapy (PTT), starvation therapy, photodynamic therapy (PDT), chemotherapy, chemodynamic therapy (CDT), sonodynamic therapy (SDT), gene therapy, immunotherapy and combination therapy.

Tailoring biomimetic dual-redox-responsive nanoplexes for enhanced RNAi-synergized photodynamic cancer immunotherapy

Despite the strong potential of RNA interference (RNAi) therapies, critical issues, such as poor permeability across biological membranes and efficacy of their delivery into the cytoplasm, remain to be addressed before their successful clinical application. The current study aimed to address these issues by constructing a biomimetic nanoplex with dual redox responsiveness, which is derived from a cationic polymer formed by the condensation of endogenous spermine monomers via diselenide bonds. The developed nanoplexes decomposed in response to the redox microenvironment in cancer cells, thereby avoiding accumulation toxicity and poor transfection efficiency owing to incomplete siRNA release. When co-delivered with siPDL1 and a photosensitizer, the reactive oxygen species generated by irradiated nanoplexes accelerated the cytoplasmic release of siPDL1, which was expected to alleviate the PDT-induced increase in immunosuppressive PD-L1 expression. In a murine model of 4T1 xenografted breast cancer, the fabricated macrophage membrane (MPM)-camouflaged nanoplexes with payloads boosted antitumor immune responses in situ through a "self-synergistic" immunogenic cell death induced by photodynamic therapy (PDT). Overall, the study reported a new strategy for harnessing photodynamic immunotherapy for treating immunologically cold tumors. STATEMENT OF SIGNIFICANCE: This study provides a biomimetic nanoplex with dual redox responsiveness, which is derived from a novel cationic polymer formed by the condensation of endogenous spermine monomers through diselenide bonds. The developed nanoplex disassembles according to the redox microenvironment in cancer cells, thereby avoiding accumulation toxicity and poor transfection efficiency due to incomplete siRNA release. When co-delivery of siPDL1 and photosensitizer in vivo, the ROS generated by irradiated nanoplexes accelerated the cytoplasmic release of siPDL1, and which is expected to alleviate PDT-induced increase in immunosuppressive PD-L1 expression, thereby boosting antitumor immune responses in situ through a "self-synergistic" immunogenic cell death induced by PDT. Our findings reveal a new strategy of harnessing photodynamic immunotherapy therapy toward immunologically cold tumors.

Designing Synthetic Polymers for Nucleic Acid Complexation and Delivery: From Polyplexes to Micelleplexes to Triggered Degradation

Gene delivery as a therapeutic tool continues to advance toward impacting human health, with several gene therapy products receiving FDA approval over the past 5 years. Despite this important progress, the safety and efficacy of gene therapy methodology requires further improvement to ensure that nucleic acid therapeutics reach the desired targets while minimizing adverse effects. Synthetic polymers offer several enticing features as nucleic acid delivery vectors due to their versatile functionalities and architectures and the ability of synthetic chemists to rapidly build large libraries of polymeric candidates equipped for DNA/RNA complexation and transport. Current synthetic designs are pursuing challenging objectives that seek to improve transfection efficiency and, at the same time, mitigate cytotoxicity. This Perspective will describe recent work in polymer-based gene complexation and delivery vectors in which cationic polyelectrolytes are modified synthetically by introduction of additional components─including hydrophobic, hydrophilic, and fluorinated units─as well as embedding of degradable linkages within the macromolecular structure. As will be seen, recent advances employing these emerging design strategies are promising with respect to their excellent biocompatibility and transfection capability, suggesting continued promise of synthetic polymer gene delivery vectors going forward.

Copper (Ⅱ)/cis-platinum -loaded nanogels as an adjuvant potentiate disulfiram antitumor efficacy

Disulfiram (DSF) is nontoxic and exerts anticancer activity by forming highly toxic chelate via its metabolite diethyldithiocarbamate with transition metal ions. However, there are not enough such ions in the...

Influence of the chirality of carbon nanodots on their interaction with proteins and cells

Carbon nanodots with opposite chirality possess the same major physicochemical properties such as optical features, hydrodynamic diameter, and colloidal stability. Here, a detailed analysis about the comparison of the concentration of both carbon nanodots is carried out, putting a threshold to when differences in biological behavior may be related to chirality and may exclude effects based merely on differences in exposure concentrations due to uncertainties in concentration determination. The present study approaches this comparative analysis evaluating two basic biological phenomena, the protein adsorption and cell internalization. We find how a meticulous concentration error estimation enables the evaluation of the differences in biological effects related to chirality.

Degradable cationic polyesters via ring-opening copolymerization of valerolactones as nanocarriers for the gene delivery

The development of cationic polymers as non-viral gene vectors has been hurdled by their high toxicity, thus degradable and biocompatible polymers are urgently demanded. Herein, five polyesters (B3a-B3e) were synthesized based on the ring-opening copolymerization between α-allyl-δ-valerolactone and δ-valerolactone derivatives decorated with alkyl or alkoxyl chains of different lengths, followed by the modification with 1,5,9-triazacyclododecyl ([12]aneN₃) through thiol-ene click reactions. The five polyesters effectively condensed DNA into nanoparticles. Of them, B3a with a shorter alkyl chain and B3d with more positive charged units showed stronger DNA condensing performance and can completely retard the migration of DNA at N/P = 1.6 in the presence of DOPE. B3b/DOPE with a longer alkyl chain exhibited the highest transfection efficiency in HeLa cells with 1.8 times of 25 kDa PEI, while B3d/DOPE with more positive charged units exhibited highest transfection efficiency in A549 cells with 2.3 times of 25 kDa PEI. B3b/DOPE and B3d/DOPE successfully delivered pEGFP into zebrafish, which was superior to 25 kDa PEI (1.5 folds and 1.1 folds, respectively). The cytotoxicity measurements proved that the biocompatibility of these polyesters was better than 25 kDa PEI, due to their degradable property in acid environment. The results indicated that these cationic polyesters can be developed as potential non-viral gene vectors for DNA delivery.

Influence of the Modulation of the Protein Corona on Gene Expression Using Polyethylenimine (PEI) Polyplexes as Delivery Vehicle

The protein corona can significantly modulate the physicochemical properties and gene delivery of polyethylenimine (PEI)/DNA complexes (polyplexes). The effects of the protein corona on the transfection have been well studied in terms of averaged gene expression in a whole cell population. Such evaluation methods give excellent and reliable statistics, but they in general provide the final transfection efficiency without reflecting the dynamic process of gene expression. In this regard the influence of bovine serum albumin (BSA) on the gene expression of PEI polyplexes also on a single cell level via live imaging is analyzed. The results reveal that although the BSA corona causes difference in the overall gene expression and mRNA transcription, the gene expression behavior on the level of individual cell is similar, including the mitosis-dependent expression, distributions of onset time, expression pattern in two daughter cells, and expression kinetics in successfully transfected cells. Comparison of single cell and ensemble data on whole cell cultures indicate that the protein corona does not alter the transfection process after nuclear entry, including cell division, polyplex dissociation, and protein expression. Its influence on other steps of in vitro gene delivery before nuclear entry shall render the difference in the overall transfection.

Dose-Independent Transfection of Hydrophobized Polyplexes

Cationic polymers dynamically complex DNA into complexes (polyplexes). So, upon dilution, polyplexes easily dissociate and lose transfection ability, limiting their in vivo systemic gene delivery. Herein, it is found that polyplex's stability and endocytosis pathway determine its transfection dose-dependence. The polyplexes of hydrophilic polycations have dose-dependent integrity and lysosome-trafficking endocytosis; at low doses, most of these polyplexes dissociate, and the remaining few are internalized and trapped in lysosomes, abolishing their transfection ability. In contrast, the polyplexes of the polycations with optimal hydrophobicity remain integrated even at low concentrations and enter cells via macropinocytosis directly into the cytosol evading lysosomes, so each polyplex can accomplish its infection process, leading to dose-independent DNA transfection like viral vectors. Furthermore, the tuned hydrophobicity balancing the affinity of anionic poly(γ-glutamic acid) (γ-PGA) to the polyplex surface enables γ-PGA to stick on the polyplex surface as a shielding layer but peel off on the cell membrane to release the naked polyplexes for dose-independent transfection. These findings may provide guidelines for developing polyplexes that mimick a viral vector's dose-independent transfection for effective in vivo gene delivery.

Polymeric Delivery of Therapeutic Nucleic Acids

The advent of genome editing has transformed the therapeutic landscape for several debilitating diseases, and the clinical outlook for gene therapeutics has never been more promising. The therapeutic potential of nucleic acids has been limited by a reliance on engineered viral vectors for delivery. Chemically defined polymers can remediate technological, regulatory, and clinical challenges associated with viral modes of gene delivery. Because of their scalability, versatility, and exquisite tunability, polymers are ideal biomaterial platforms for delivering nucleic acid payloads efficiently while minimizing immune response and cellular toxicity. While polymeric gene delivery has progressed significantly in the past four decades, clinical translation of polymeric vehicles faces several formidable challenges. The aim of our Account is to illustrate diverse concepts in designing polymeric vectors towards meeting therapeutic goals of in vivo and ex vivo gene therapy. Here, we highlight several classes of polymers employed in gene delivery and summarize the recent work on understanding the contributions of chemical and architectural design parameters. We touch upon characterization methods used to visualize and understand events transpiring at the interfaces between polymer, nucleic acids, and the physiological environment. We conclude that interdisciplinary approaches and methodologies motivated by fundamental questions are key to designing high-performing polymeric vehicles for gene therapy.

Nanoparticles as Drug Delivery Systems of RNAi in Cancer Therapy

RNA interference (RNAi) can mediate gene-silencing by knocking down the expression of a target gene via cellular machinery with much higher efficiency in contrast to other antisense-based approaches which represents an emerging therapeutic strategy for combating cancer. Distinct characters of nanoparticles, such as distinctive size, are fundamental for the efficient delivery of RNAi therapeutics, allowing for higher targeting and safety. In this review, we present the mechanism of RNAi and briefly describe the hurdles and concerns of RNAi as a cancer treatment approach in systemic delivery. Furthermore, the current nanovectors for effective tumor delivery of RNAi therapeutics are classified, and the characteristics of different nanocarriers are summarized.

Automation and data-driven design of polymer therapeutics

Polymers are uniquely suited for drug delivery and biomaterial applications due to tunable structural parameters such as length, composition, architecture, and valency. To facilitate designs, researchers may explore combinatorial libraries in a high throughput fashion to correlate structure to function. However, traditional polymerization reactions including controlled living radical polymerization (CLRP) and ring-opening polymerization (ROP) require inert reaction conditions and extensive expertise to implement. With the advent of air-tolerance and automation, several polymerization techniques are now compatible with well plates and can be carried out at the benchtop, making high throughput synthesis and high throughput screening (HTS) possible. To avoid HTS pitfalls often described as "fishing expeditions," it is crucial to employ intelligent and big data approaches to maximize experimental efficiency. This is where the disruptive technologies of machine learning (ML) and artificial intelligence (AI) will likely play a role. In fact, ML and AI are already impacting small molecule drug discovery and showing signs of emerging in drug delivery. In this review, we present state-of-the-art research in drug delivery, gene delivery, antimicrobial polymers, and bioactive polymers alongside data-driven developments in drug design and organic synthesis. From this insight, important lessons are revealed for the polymer therapeutics community including the value of a closed loop design-build-test-learn workflow. This is an exciting time as researchers will gain the ability to fully explore the polymer structural landscape and establish quantitative structure-property relationships (QSPRs) with biological significance.

pH-Sensitive Polycations for siRNA Delivery: Effect of Asymmetric Structures of Tertiary Amine Groups

pH-sensitive polyelectrolytes provide enormous opportunity for siRNA delivery. Especially, their tertiary amine structures can not only bind genes but also act as pH-sensitive hydrophobic structure to control genes release. However, the influence of molecular structures on siRNA delivery still remains elusive, especially for the asymmetric alkyl substituents of the tertiary amine groups. Herein, a library of N-methyl-N-alkyl aminoethyl methacrylate monomers (MsAM) with asymmetric alkyl substituents on the tertiary amine group is synthesized and used to prepare a series of tri-block polycationic copolymers poly(aminoethyl methacrylate)-block-poly (N-methyl-N-alkyl aminoethyl methacrylate)-block-poly(ethylene glycol methacrylate) (PAMA-PMsMA-PEG). And the properties of these polycations and their self-assembled micelles are characterized, including molecular structure, proton buffering capacity, pH-sensitivity, size, and zeta potential. With the length increase of one alkyl substituent, the proton buffering capacity of both monomers and polycations is demonstrated to be narrowed down. The siRNA delivery efficiency and cytotoxicity of these micelles are also evaluated on HepG2 cells. In particular, poly(aminoethyl methacrylate)-block-poly(N-methyl-N-ethyl aminoethyl methacrylate)-block-poly(ethylene glycol methacrylate) (PAMA-PMEMA-PEG) elicited the best luciferase knockdown efficiency and low cytotoxicity. Besides, PAMA-PMEMA-PEG/siRRM2 also induced significant anti-tumor activity in vitro. These results indicated PAMA-PMEMA-PEG has potential for further use in the design of gene vehicles with the improved efficiency of siRNA delivery.

Recent advances in development of nanomedicines for multiple sclerosis diagnosis

Multiple sclerosis (MS) is a neurodegenerative disease with a high morbidity and disease burden. It is characterized by the loss of the myelin sheath, resulting in the disruption of neuron electrical signal transmissions and sensory and motor ability deficits. The diagnosis of MS is crucial to its management, but the diagnostic sensitivity and specificity are always a challenge. To overcome this challenge, nanomedicines have recently been employed to aid the diagnosis of MS with an improved diagnostic efficacy. Advances in nanomedicine-based contrast agents in magnetic resonance imaging scanning of MS lesions, and nanomedicine-derived sensors for detecting biomarkers in the cerebrospinal fluid biopsy, or analyzing the composition of exhaled breath gas, have demonstrated the potential of using nanomedicines in the accurate diagnosis of MS. This review aims to provide an overview of recent advances in the application of nanomedicines for the diagnosis of MS and concludes with perspectives of using nanomedicines for the development of safe and effective MS diagnostic nanotools.

Vanadium-based nanomaterials for cancer diagnosis and treatment

In the past few decades, various vanadium compounds have displayed potential in cancer treatment. However, fast clearness in the body and possible toxicity of vanadium compounds has hindered their further development. Vanadium-based nanomaterials not only overcome these limitations, but take advantage of the internal properties of vanadium in photics and magnetics, which enable them as a multimodal platform for cancer diagnosis and treatment. In this paper, we first introduced the basic biological and pharmacological functions of vanadium compounds in treating cancer. Then, the synthesis routes of three vanadium-based nanomaterials were discussed, including vanadium oxides, 2D vanadium sulfides, carbides and nitrides: V_mX_n (X = S, C, N) and water-insoluble vanadium salts. Finally, we highlighted the applications of these vanadium-based nanomaterials as tumor therapeutic and diagnostic agents.

Efficient Polymer-Mediated Delivery of Gene-Editing Ribonucleoprotein Payloads through Combinatorial Design, Parallelized Experimentation, and Machine Learning

Chemically defined vectors such as cationic polymers are versatile alternatives to engineered viruses for the delivery of genome-editing payloads. However, their clinical translation hinges on rapidly exploring vast chemical design spaces and deriving structure-function relationships governing delivery performance. Here, we discovered a polymer for efficient intracellular ribonucleoprotein (RNP) delivery through combinatorial polymer design and parallelized experimental workflows. A chemically diverse library of 43 statistical copolymers was synthesized via combinatorial RAFT polymerization, realizing systematic variations in physicochemical properties. We selected cationic monomers that varied in their pK_a values (8.1-9.2), steric bulk, and lipophilicity of their alkyl substituents. Co-monomers of varying hydrophilicity were also incorporated, enabling elucidation of the roles of protonation equilibria and hydrophobic-hydrophilic balance in vehicular properties and performance. We screened our multiparametric vector library through image cytometry and rapidly uncovered a hit polymer (P38), which outperforms state-of-the-art commercial transfection reagents, achieving nearly 60% editing efficiency via nonhomologous end-joining. Structure-function correlations underlying editing efficiency, cellular toxicity, and RNP uptake were probed through machine learning approaches to uncover the physicochemical basis of P38's performance. Although cellular toxicity and RNP uptake were solely determined by polyplex size distribution and protonation degree, respectively, these two polyplex design parameters were found to be inconsequential for enhancing editing efficiency. Instead, polymer hydrophobicity and the Hill coefficient, a parameter describing cooperativity-enhanced polymer deprotonation, were identified as the critical determinants of editing efficiency. Combinatorial synthesis and high-throughput characterization methodologies coupled with data science approaches enabled the rapid discovery of a polymeric vehicle that would have otherwise remained inaccessible to chemical intuition. The statistically derived design rules elucidated herein will guide the synthesis and optimization of future polymer libraries tailored for therapeutic applications of RNP-based genome editing.

Advances of Nanoparticles for Leukemia Treatment

Leukemia is a liquid tumor caused by a hematopoietic stem cell malignant clone, which seriously affects the normal function of the hematopoietic system. Conventional drugs have poor therapeutic effects due to their poor specificity and stability. With the development of nanotechnology, nonviral nanoparticles bring hope for the efficient treatment of leukemia. Nanoparticles are easily modified. They can be designed to target lesion sites and control drug release. Thereby, nanoparticles can improve the effects of drugs and reduce side effects. This review mainly focuses on and summarizes the current research progress of nanoparticles to deliver different leukemia therapeutic drugs, as to demonstrate the potential of nanoparticles in leukemia treatment.

Quantitative Assessment of Endosomal Escape of Various Endocytosed Polymer-Encapsulated Molecular Cargos upon Photothermal Heating

Encapsulated molecular cargos are efficiently endocytosed by cells. For cytosolic delivery, understanding the dynamic process of cargos release from the carrier vehicles used for encapsulation and the lysosomes where the carrier vehicles are trapped (which in general is the bottleneck), followed by diffusion in the cytosol is important for improving drug/gene delivery strategies. A methodology is reported to image this process on a millisecond scale and to quantitatively analyze the data. Polyelectrolyte capsules with embedded gold nanostars to encapsulate 43 fluorescent molecular cargos with diverse properties, ranging from small fluorophores to fluorescently labeled proteins, siRNA, etc., are used. By short laser irradiation intracellular release of the molecular cargos from endocytosed capsules into the cytosol is triggered, and their intracellular spreading is imaged. Most of the released molecular cargos evenly distribute inside the entire cell, while others are enriched in certain cell compartments. The time the different molecular cargos take to distribute within cells, i.e., the spreading time, is used as a quantifier. Quantitative analysis reveals that intracellular spread cannot be described by free diffusion, but is determined by interaction of the molecular cargo with intracellular components.

Glycodendron/pyropheophorbide-a (Ppa)-functionalized hyaluronic acid as a nanosystem for tumor photodynamic therapy

To enhance the drug delivery efficiency of hyaluronic acid (HA), we designed and prepared glycodendron and pyropheophorbide-a (Ppa)-functionalized HA (HA-Ppa-Dendron) as a nanosystem for cancer photodynamic therapy. Linear Ppa-modified HA (HA-Ppa) was also prepared as a control. Cellular uptake of both polymers by MDA-MB-231 cells led to mitochondrial dysfunction and generation of reactive oxygen species under the irradiation of a laser. Compared to the linear polymer, HA-Ppa-Dendron had higher molecular weight, a more compact nanoscale particle size, and a dendritic structure, resulting in a much longer blood circulation time and higher tumor accumulation. HA-Ppa-Dendron outperformed HA-Ppa in inhibiting cell growth, with 60 % of tumors was eradicated under laser irradiation. Tumor growth inhibition (TGI) up to 99.2 % was achieved from HA-Ppa-Dendron, which was much higher than that of HA-Ppa (50.6 %). Therefore, glycodendron-functionalized HAs by integration of HA and dendritic polymers may act as efficient anti-cancer nanomedicine.

Functional gadolinium-based nanoscale systems for cancer theranostics

Cancer theranostics is a new strategy for combating cancer that integrates cancer imaging and treatment through theranostic agents to provide an efficient and safe way to improve cancer prognosis. Design and synthesis of these cancer theranostic agents are crucial since these agents are required to be biocompatible, tumor-specific, imaging distinguishable and therapeutically efficacious. In this regard, several types of gadolinium (Gd)-based nanomaterials have been introduced to combine different therapeutic agents with Gd to enhance the efficacy of therapeutic agents. At the same time, the entire treatment procedure could be monitored via imaging tools due to incorporation of Gd ions, Gd chelates and Gd/other imaging probes in the theranostic agents. This review aims to overview recent advances in the Gd-based nanomaterials for cancer theranostics and perspectives for Gd nanomaterial-based cancer theranostics are provided.

Drug Delivery System in the Treatment of Diabetes Mellitus

Diabetes mellitus has been described as a chronic endocrine and metabolic disease, which is characterized by hyperglycemia and the coexistence of multiple complications. At present, the drugs widely applied in clinical treatment of diabetes mellitus mainly include insulin, insulin analogs, non-insulin oral hypoglycemic drugs and genetic drugs. Nevertheless, there is still no complete therapy strategy for diabetes mellitus management by far due to the intrinsic deficiencies of drugs and limits in administration routes such as the adverse reactions caused by long-term subcutaneous injection and various challenges in oral administration, such as enzymatic degradation, chemical instability and poor gastrointestinal absorption. Therefore, it is remarkably necessary to develop appropriate delivery systems and explore complete therapy strategies according to the characters of drugs and diabetes mellitus. Delivery systems have been found to be potentially beneficial in many aspects for effective diabetes treatment, such as improving the stability of drugs, overcoming different biological barriers in vivo to increase bioavailability, and acting as an intelligent automatized system to mimic endogenous insulin delivery and reduce the risk of hypoglycemia. This review aims to provide an overview related with the research advances, development trend of drug therapy and the application of delivery systems in the treatment diabetes mellitus, which could offer reference for the application of various drugs in the field of diabetes mellitus treatment.

Surface Modification of Iron Oxide-Based Magnetic Nanoparticles for Cerebral Theranostics: Application and Prospection

Combining diagnosis with therapy, magnetic iron oxide nanoparticles (INOPs) act as an important vehicle for drug delivery. However, poor biocompatibility of INOPs limits their application. To improve the shortcomings, various surface modifications have been developed, including small molecules coatings, polymers coatings, lipid coatings and lipopolymer coatings. These surface modifications facilitate iron nanoparticles to cross the blood-brain-barrier, which is essential for diagnosis and treatments of brain diseases. Here we focus on the characteristics of different coated INOPs and their application in brain disease, particularly gliomas, Alzheimer's disease (AD) and Parkinson's disease (PD). Moreover, we summarize the current progress and expect to provide help for future researches.

Reactive mesoporous silica nanoparticles loaded with limonene for improving physical and mental health of mice at simulated microgravity condition

Astronauts are under high stress for a long time because of the microgravity condition, which leads to anxiety, affects their learning and memory abilities, and seriously impairs the health of astronauts. Aromatherapy can improve the physical and mental health of astronauts in a way that moisturizes them softly and silently. However, the strong volatility of fragrances and inconvenience of aroma treatment greatly limit their application in the field of spaceflight. In this study, reactive mesoporous silica nanoparticles were prepared to encapsulate and slowly release limonene. The limonene loaded nanoparticles were named limonene@mesoporous silica nanoparticles-cyanuric chloride (LE@MSNs-CYC). LE@MSNs-CYC were then applied to wallpaper to improve the convenience of aromatherapy. LE@MSNs-CYC could chemically react with the wallpaper, thus firmly adsorbed on the wallpaper. In the following, the mice were treated with hindlimb unloading (HU) to simulate a microgravity environment. The results showed that 28-day HU led to an increase in the level of anxiety and declines in learning, memory, and physical health in mice. LE@MSNs-CYC showed significant relief effects on anxiety, learning, memory, and physical health of HU treated mice. Subsequently, the molecular mechanisms were explored by hypothalamic-pituitary-adrenal axis related hormones, immune-related cytokines, learning, and memory-related neurotransmitters and proteins.

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Large-scale industrial production and cost-effective fabrication of reactive nanofragrance.

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Strong adhesion of nanofragrance on substrate through covalent bonds.

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Improvement of physical and mental health under simulated microgravity condition in moisten things softly and silently.

Glutathione-Specific and Intracellularly Labile Polymeric Nanocarrier for Efficient and Safe Cancer Gene Delivery

Cationic polymers condense nucleic acids into nanosized complexes (polyplexes) that are widely explored for nonviral gene delivery, but their strong electrostatic binding with DNA causes inefficient intracellular gene release and translation and thereby unsatisfactory gene transfection efficiencies. Facilitated intracellular dissociation of polyplexes by making the polymer undergo positive-to-negative/neutral charge reversal can effectively solve these problems, but they must be sufficiently stable during the delivery. Herein, we report the first glutathione (GSH)-specific intracellular labile polyplexes for cancer-targeted gene delivery. The polymers are made from p-(2,4-dinitrophenyloxybenzyl)-ammonium cationic moieties, whose p-2,4-dinitrophenyl ether is cleaved specifically by GSH, rather than other biological thiols, triggering the conversion of the ammonium cation into the carboxylate anion and thus the fast intracellular DNA release of the polyplexes. Furthermore, the polyplexes coated with PEG-functionalized lipids are stable in biological fluids to gain long blood circulation for tumor accumulation. Thus, the efficient tumor accumulation and cell transfection of the polyplexes loaded with the tumor suicide gene tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) give rise to potent antitumor activity similar to that of the first-line chemotherapy drug paclitaxel but with much less adverse effects.

PEGylated Amine-Functionalized Poly(ε-caprolactone) for the Delivery of Plasmid DNA

As a promising strategy for the treatment of various diseases, gene therapy has attracted increasing attention over the past decade. Among various gene delivery approaches, non-viral vectors made of synthetic biomaterials have shown significant potential. Due to their synthetic nature, non-viral vectors can have tunable structures and properties by using various building units. In particular, they can offer advantages over viral vectors with respect to biosafety and cytotoxicity. In this study, a well-defined poly(ethylene glycol)-block-poly(α-(propylthio-N,N-diethylethanamine hydrochloride)-ε-caprolactone) diblock polymer (PEG-b-CPCL) with one poly(ethylene glycol) (PEG) block and one tertiary amine-functionalized cationic poly(ε-caprolactone) (CPCL) block, as a novel non-viral vector in the delivery of plasmid DNA (pDNA), was synthesized and studied. Despite having a degradable polymeric structure, the polymer showed remarkable hydrolytic stability over multiple weeks. The optimal ratio of the polymer to pDNA for nanocomplex formation, pDNA release from the nanocomplex with the presence of heparin, and serum stability of the nanocomplex were probed through gel electrophoresis. Nanostructure of the nanocomplexes was characterized by DLS and TEM imaging. Relative to CPCL homopolymers, PEG-b-CPCL led to better solubility over a wide range of pH. Overall, this work demonstrates that PEG-b-CPCL possesses a range of valuable properties as a promising synthetic vector for pDNA delivery.

Endosomolytic and Tumor-Penetrating Mesoporous Silica Nanoparticles for siRNA/miRNA Combination Cancer Therapy

Combination therapies consisting of multiple short therapeutic RNAs, such as small interfering RNA (siRNA) and microRNA (miRNA), have enormous potential in cancer treatment as they can precisely silence a specific set of oncogenes and target multiple disease-related pathways. However, clinical use of siRNA/miRNA combinations is limited by the availability of safe and efficient systemic delivery systems with sufficient tumor penetrating and endosomal escaping capabilities. This study reports on the development of multifunctional tumor-penetrating mesoporous silica nanoparticles (iMSNs) for simultaneous delivery of siRNA (siPlk1) and miRNA (miR-200c), using encapsulation of a photosensitizer indocyanine green (ICG) to facilitate endosomal escape and surface conjugation of the iRGD peptide to enable deep tumor penetration. Increased cell uptake of the nanoparticles was observed in both 3D tumor spheroids in vitro and in orthotopic MDA-MB-231 breast tumors in vivo. Using a galectin-8 recruitment assay, we showed that reactive oxygen species generated by ICG upon light irradiation functioned as an endosomolytic stimulus that caused release of the siRNA/miRNA combination from endosomes. Co-delivery of the therapeutic RNAs displayed combined cell killing activity in cancer cells. Systemic intravenous treatment of metastatic breast cancer with the iMSNs loaded with siPlk1 and miR-200c resulted in a significant suppression of the primary tumor growth and in marked reduction of metastasis upon short light irradiation of the primary tumor. This work demonstrates that siRNA-miRNA combination assisted by the photodynamic effect and tumor penetrating delivery system may provide a promising approach for metastatic cancer treatment.

Two new approaches based on dynamic carboxyl–hydroxyl or hydroxyl–carboxyl transformation for high molecular weight poly(butylene maleate)

Synthesis of high molecular weight maleic acid-based polyesters via a green approach is of great significance but also a huge challenge.

Synergistic MicroRNA Therapy in Liver Fibrotic Rat Using MRI-Visible Nanocarrier Targeting Hepatic Stellate Cells

Liver fibrosis, as one of the leading causes of liver-related morbidity and mortality, has no Food and Drug Administration (FDA)-approved antifibrotic therapy yet. Although microRNA-29b (miRNA-29b) and microRNA-122 (miRNA-122) have great potential in treating liver fibrosis via regulating profibrotic genes in hepatic stellate cells (HSCs), it is still a challenge to achieve a HSC-targeted and meanwhile noninvasively trackable delivery of miRNAs in vivo. Herein, a pH-sensitive and vitamin A (VA)-conjugated copolymer VA-polyethylene glycol-polyethyleneimine-poly(N-(N',N'-diisopropylaminoethyl)-co-benzylamino) aspartamide (T-PBP) is synthesized and assembled into superparamagnetic iron oxide (SPIO)-decorated cationic micelle for miRNA delivery. The T-PBP micelle efficiently transports the miRNA-29b and miRNA-122 to HSC in a magnetic resonance imaging-visible manner, resulting in a synergistic antifibrosis effect via downregulating the expression of fibrosis-related genes, including collagen type I alpha 1, α-smooth muscle actin, and tissue inhibitor of metalloproteinase 1. Consequently, the HSC-targeted combination therapy with miRNA-29b and miRNA-122 demonstrates a prominent antifibrotic efficacy in terms of improving liver function and relieving hepatic fibrosis.

Enhancing the In Vitro and In Vivo Stabilities of Polymeric Nucleic Acid Delivery Nanosystems

Gene therapy holds great promise for various medical and biomedical applications. Nonviral gene delivery systems formed by cationic polymer and nucleic acids (e.g., polyplexes) have been extensively investigated for targeted gene therapy; however, their in vitro and in vivo stability is affected by both their intrinsic properties such as chemical compositions (e.g., polymer molecular weight and structure, and N/P ratio) and a number of environmental factors (e.g., shear stress during circulation in the bloodstream, interaction with the serum proteins, and physiological ionic strength). In this review, we surveyed the effects of a number of important intrinsic and environmental factors on the stability of polymeric gene delivery systems, and discussed various strategies to enhance the stability of polymeric gene delivery systems, thereby enabling efficient gene delivery into target cells. Future opportunities and challenges of polymeric nucleic acid delivery nanosystems were also briefly discussed.

A PEG-b-poly(disulfide-l-lysine) based redox-responsive cationic polymer for efficient gene transfection

Gene therapy is concerned with the transfer of complement genes to functionally defective cells in a safe and directed manner for the treatment of the most challenging diseases. But safety issues and low transfection efficiency of the gene vectors are the major challenges, which need to be overcome. Recently, redox-responsive bioreducible polymers containing disulfide linkages have been considered as efficient gene vectors, owing to the selective degradation of the disulfide bond in the reducing environment of the cells. This enables spatiotemporal release of pDNA with no or minimum toxicity. Herein, we reported a bioreducible poly(ethyleneglycol)-b-poly(disulfide-l-lysine) cationic polymer (denoted as PEG-SSL) via a Michael addition reaction of poly(ethyleneglycol)tetraacrylate PEG(Ac)₄ and the terminal amine group of poly(disulfide-l-lysine). PEG-SSL efficiently condensed the plasmid ZNF580 gene (pZNF580) forming nano-sized polyplexes (155 ± 4 to 285 ± 3 nm) with zeta potentials of 1.9 ± 0.1 to 26.7 ± 0.4 mV. PEG-SSL successfully retarded pZNF580 at a small polymer/pDNA weight ratio of 10/1 and higher. When exposed to a reducing environment of 5 mM DTT, it rapidly released genes even at higher weight ratios of the PEG-SSL polymer in the PEG-SSL/pDNA complexes. The PEG-SSL/pZNF580 complexes exhibited good stability when exposed to DNase I and efficiently protected pDNA from degradation. In vitro transfection and cytotoxicity were investigated in EA.hy926 cells. The results showed that PEG-SSL successfully delivered pZNF580 into the cells with less cytotoxicity compared to PEI25kDa. The flow cytometry and confocal scanning laser microscopy results indicated that PEG-SSL polyplexes exhibited good cellular uptake and nuclear co-localization rates. All these results implied that PEG-SSL had the potential as a non-viral vector for gene transfection.

Differentially Branched Ester Amine Quadpolymers with Amphiphilic and pH-Sensitive Properties for Efficient Plasmid DNA Delivery

Development of highly effective nonviral gene delivery vectors for transfection of diverse cell populations remains a challenge despite utilization of both rational and combinatorial driven approaches to nanoparticle engineering. In this work, multifunctional polyesters are synthesized with well-defined branching structures via A2 + B2/B3 + C1 Michael addition reactions from small molecule acrylate and amine monomers and then end-capped with amine-containing small molecules to assess the influence of polymer branching structure on transfection. These Branched poly(Ester Amine) Quadpolymers (BEAQs) are highly effective for delivery of plasmid DNA to retinal pigment epithelial cells and demonstrate multiple improvements over previously reported leading linear poly(beta-amino ester)s, particularly for volume-limited applications where improved efficiency is required. BEAQs with moderate degrees of branching are demonstrated to be optimal for delivery under high serum conditions and low nanoparticle doses further relevant for therapeutic gene delivery applications. Defined structural properties of each polymer in the series, including tertiary amine content, correlated with cellular transfection efficacy and viability. Trends that can be applied to the rational design of future generations of biodegradable polymers are elucidated.

Remotely controlled opening of delivery vehicles and release of cargo by external triggers

Tremendous efforts have been devoted to the development of future nanomedicines that can be specifically designed to incorporate responsive elements that undergo modification in structural properties upon external triggers. One potential use of such stimuli-responsive materials is to release encapsulated cargo upon excitation by an external trigger. Today, such stimuli-response materials allow for spatial and temporal tunability, which enables the controlled delivery of compounds in a specific and dose-dependent manner. This potentially is of great interest for medicine (e.g. allowing for remotely controlled drug delivery to cells, etc.). Among the different external exogenous and endogenous stimuli used to control the desired release, light and magnetic fields offer interesting possibilities, allowing defined, real time control of intracellular releases. In this review we highlight the use of stimuli-responsive controlled release systems that are able to respond to light and magnetic field triggers for controlling the release of encapsulated cargo inside cells. We discuss established approaches and technologies and describe prominent examples. Special attention is devoted towards polymer capsules and polymer vesicles as containers for encapsulated cargo molecules. The advantages and disadvantages of this methodology in both, in vitro and in vivo models are discussed. An overview of challenges associate with the successful translation of those stimuli-responsive materials towards future applications in the direction of potential clinical use is given.

Reactive Oxygen Species (ROS)-Responsive Charge-Switchable Nanocarriers for Gene Therapy of Metastatic Cancer

The application of nonviral gene vectors has been limited by their insufficient transfection efficiency because of poor serum stability, high endosomal entrapment, limited intracellular release, and low accumulation in the targeted organelle. It is still challenging to design gene carriers with properties that can overcome all of the barriers. We previously developed a reactive oxygen species (ROS)-responsive cationic polymer, poly[(2-acryloyl)ethyl( p-boronic acid benzyl) diethylammonium bromide] (B-PDEAEA), which switches the charge at high concentrations of intracellular ROS to promote intracellular DNA release. However, its gene-delivery efficiency has been limited by serum instability and lysosomal trapping, and coating with an anionic PEGylated lipid only showed mild enhancement. Herein, we coated the ROS-responsive B-PDEAEA polymer with two cationic lipids to form ROS-responsive lipopolyplexes with integrated properties to overcome multiple delivery barriers. The surface cationic lipids endowed the nanocarrier with improved serum stability, effective cellular uptake, and lysosomal evasion. The interior B-PDEAEA/DNA polyplexes, which were highly stable in the extracellular environment, but quickly dissociated, released DNA, promoted nuclei localization, and achieved efficient transcription. The mechanisms of the ROS-responsive and charge-switchable properties of B-PDEAEA were quantitatively studied. The transfection efficiency and antitumor activity of lipopolyplexes were studied in vitro and in vivo. We found that the ROS-responsive lipopolyplexes effectively delivered therapeutic genes into cell nuclei and caused high tumor inhibition in mice bearing peritoneal or lung metastases.