Gold nanoparticles capped with polyethyleneimine for enhanced siRNA delivery

Influence of synthesis methods on the internalization of fluorescent gold nanoparticles into glioblastoma stem-like cells

Glioblastoma (GBM) is an aggressive disease with currently no satisfying treatment option available. GBM cells with stem cell properties are thought to be responsible for the initiation and propagation of the disease, as well as main contributors to the emergence of therapy resistance. In this work, we developed a novel method to synthesize fluorescent gold nanoparticles as potential drug and gene delivery systems for GBM therapy, able to penetrate three-dimensional stem cell selected patient-derived GBM neurosphere systems in vitro. By using polyethylene imine (PEI) as a stabilizer and reducing agent, as well as fluorescein isothiocyanate (FITC) as a fluorescent marker, our fully in-house developed fluorescent gold nanoparticles (AuPEI-FITC NPs) with core sizes between 3 and 6 nm were obtained via a fast microwave-assisted reaction. Cytotoxicity, adsorption and internalization of AuPEI-FITC NPs into the cell lines JHH520, 407 and GBM1 were investigated using the cellular growth assay and fluorescence-activated cell sorting (FACS) analysis. AuPEI-FITC NPs showed no apparent cytotoxicity and an uptake in cells of up to ~80%. A differentiation between surface-bound and internalized AuPEI-FITC NPs was possible by quenching extracellular signals. This resulted in a maximal internalization degree of 61%, which depends highly on the synthesis method of the nanoparticles and the cell type tested. The best internalization was found for AuPEI-FITC1 which was prepared in a one pot reaction from KAuCl₄, PEI and FITC. Thus, appropriately synthesized AuPEI-FITC NPs show great potential as vehicles to transport DNA or drugs in GBM cells.

Role of Cholesterol Conjugation in the Antibacterial Photodynamic Therapy of Branched Polyethylenimine-Containing Nanoagents

Photodynamic therapy is a promising approach for fighting bacterial infections because it can induce few side effects, develop no drug resistance, and realize precise treatment. However, most photosensitizers (PSs) have the disadvantages of poor water-solubility, severe self-quenching, and potential toxicity. Here, the cationic polymer polyethyleneimine (PEI) was used to prepare a cholesterol- and chlorin e6 (Ce6, a common PS)-conjugated compound via the carboxyl-amine reaction or the acyl chloride-amine reaction (abbreviated as Chol-PEI-Ce6). The as-prepared Chol-PEI-Ce6 molecules can self-assemble into close-to-spherical nanoparticles (NPs) with an average diameter of ∼15 nm and can bind to the bacterial surfaces via the synergistic hydrophobic insertion of the cholesterol moieties and electrostatic interaction between the cationic amine groups of PEI and the bacterial surfaces. Upon light irradiation, the NPs can effectively inactivate both Gram-positive and Gram-negative bacteria. Besides, the interaction between Chol-PEI-Ce6 NPs and bacteria markedly enhances the production of intracellular reactive oxygen species after light irradiation, which may account for the excellent antibacterial performance of the NPs. More importantly, the NPs possess negligible dark cytotoxicity and good hemocompatibility. Therefore, the present work may have strong implications for developing novel antibacterial agents to fight against bacterial infections.

Electrocatalytic synthesis of black tin oxide nanomaterial as photothermal agent for cancer therapy

Photothermal therapy (PTT) is among the popular approach for treating solid tumours. The rapid killing of cancer cells under the influence of infrared radiation by a rapid increase in the temperature of the remote area now demands external agents with high photothermal transduction efficiency (PTE). Despite their improved PTE, black nanomaterials such as black phosphorus and titanium oxide are unable to meet the challenges in the physiological conditions. To address this major concern, we have developed black tin oxide (bSnO) with enhanced capabilities to respond in the physiological milieu. To make the synthesis cost-effective and eco-friendly, we have used electrochemical oxidation at 5 V and 100 mA to achieve ∼15 nm nanoparticle of bSnO. The as-synthesized bSnO exhibited high NIR absorption as well as high photothermal transduction efficiency. To circumvent the low aqueous solubility and photostability, bSnO was functionalized with polyethyleneimine (PEI). Upon exposure to 808 nm laser for ∼8-10 min, the temperature of the bSnO@PEI solution reached ∼58.5 °C. PTE of bSnO@PEI was calculated to be 51.2%. Owing to its high biological compatibility, tin offers relatively better stability when exposed to cancer cells in vitro and in vivo. In comparison to other black nanomaterials, bSnO@PEI was found to exhibit better response under NIR irradiance for non-invasive photothermal therapy of cancer.

Biofriendly and Regenerable Emotional Monitor from Interfacial Ultrathin 2D PDA/AuNPs Cross-linking Films

Well-designed 2D materials with ultrathin structures show great potential for humidity-sensing performance owing to their high surface-volume ratio and a great number of exposed atoms on the surface. However, some sensing elements employed for healthcare applications may be considered as potentially risky, such as inflammation, granuloma formation, and carcinogenesis. Herein, we explored biofriendly humidity-sensing characteristics inspired by the great biocompatibility and conductivity of hyperbranched polyethyleneimine-capped gold nanoparticles and cross-linked with polydopamine from the adhesive proteins in mussels. It was successfully employed into two kinds of wearable devices, sports watches and breathing masks, for real-time recording humidity's fluctuation in expiration and sweat with changes of individual's crying, laughing, nervous, sleeping, training, and cold states. The wearable devices allow us to monitor individual's physical activities and emotional states well, suggesting a promising prospect in safe, reusable, long term, and noncontact human health monitoring applications.

Multifunctionality of gold nanoparticles: Plausible and convincing properties

In a couple of decades, nanotechnology has become a trending area in science due to it covers all subject that combines diverse range of fields including but not limited to chemistry, physics and medicine. Various metal and metal oxide nanomaterials have been developed for wide range applications. However, the application of gold nanostructures and nanoparticles has been received more attention in various biomedical applications. The unique property of gold nanoparticles (AuNPs) is surface plasmon resonance (SPR) that determine the size, shape and stability. The wide surface area of AuNPs eases the proteins, peptides, oligonucleotides, and many other compounds to tether and enhance the biological activity of AuNPs. AuNPs have multifunctionality including antimicrobial, anticancer, drug and gene delivery, sensing applications and imaging. This state-of-the-art review is focused on the role of unique properties of AuNPs in multifunctionality and its various applications.

Triggered RNAi Therapy Using Metal Inorganic Nanovectors

The administration of small interfering RNA (siRNA) is a very interesting therapeutic option to treat genetic diseases such as Alzheimer's or some types of cancer, but its effective delivery still remains a challenge. Herein, Au nanorod (GNR)-based platforms functionalized with polyelectrolyte layers were developed and analyzed as potential siRNA nanocarriers. The polymeric layers were successfully assembled on the particle surfaces by means of the layer-by-layer assembly technique through the alternating deposition of oppositely charged poly(styrene)sulfonate, PSS, poly(lysine), PLL, and siRNA biopolymers, with a final hyaluronic acid layer in order to provide the nanoconstructs with a potential targeting ability as well as colloidal stability in physiological medium. Once the hybrid nanocarriers were obtained, the cargo release, their colloidal stability in physiological-relevant media, cytotoxicity, cellular internalization and uptake, and knockdown activity were studied. The present hybrid particles release the genetic material inside cells by means of a protease-assisted and/or a light-triggered release mechanism in order to control the delivery of the oligonucleotides on demand. In addition, the hybrid nanovectors were observed to be nontoxic to cells and could efficiently deliver the genetic material in the cell cytoplasms. The GNR-based nanocarriers proposed here can provide a suitable environment to load and protect a sufficient amount of the genetic material to allow an efficient and sustained knockdown gene expression for long (up to 93% for 72 h), thanks to the slow degradation of PLL, without the observation of adverse side toxic effects. It was also found that the silencing activity was enhanced with the number of siRNA layers assembled in the nanoplatforms.

Challenges of gene delivery to the central nervous system and the growing use of biomaterial vectors

Gene therapy is a promising form of treatment for those suffering from neurological disorders or central nervous system (CNS) injury, however, obstacles remain that limit its translational potential. The CNS is protected by the blood brain barrier, and this barrier blocks genes from traversing into the CNS if administered outside of the CNS. Viral and non-viral gene delivery vehicles, commonly referred to as vectors, are modified to enhance delivery efficiency to target locations in the CNS. Still, there are few gene therapy approaches approved by the FDA for CNS disease or injury treatment. The lack of viable clinical approaches is due, in part, to the unpredictable nature of many vector systems. In particular, safety concerns exist with the use of viral vectors for CNS gene delivery. To seek some alternatives to viral vectors, development of new non-viral, biomaterial vectors is occurring at a rapid rate. This review discusses the challenges of delivering various forms of genetic material to the CNS, the use and limitations of current viral vector delivery systems, and the use of non-viral, biomaterial vectors for CNS applications.

RNA-silencing nanoprobes for effective activation and dynamic imaging of neural stem cell differentiation

To achieve the clinical potential of neural stem cells (NSCs), it is crucial to activate NSC differentiation into neurons and simultaneously monitor the process of NSC differentiation. However, there are many challenges associated with regulating and tracking NSC differentiation.

Methods: We developed a redox-responsive multifunctional nanocomplex with a disulfide bond—cvNC—for the delivery of siRNAs to induce NSC differentiation through sequence-specific RNA interference (RNAi) and real-time imaging of sequential mRNA expression during differentiation. The stability and specificity of cvNCs were studied in vitro. Controlled release of siRNA, gene silencing efficiency, as well as real-time imaging of cvNCs on Tubb3 and Fox3 mRNAs during NSC differentiation were evaluated.

Results: The introduction of a redox-sensitive disulfide bond not only ensures the remarkable performance of cvNC, such as high stability, controlled siRNA release, and enhanced gene silencing efficiency, but also effectively stimulates NSC differentiation into neurons. More importantly, the cvNC can track NSC differentiation in real-time by monitoring the sequential expression of mRNAs.

Conclusion: Our study indicates that cvNC can serve as a robust system for exploring NSCs differentiation process as well as other biological events in living cells.

Restoration of p53 Function in Ovarian Cancer Mediated by Gold Nanoparticle-Based EGFR Targeted Gene Delivery System

Targeted gene delivery of wild type tumor suppressor gene p53 is a promising approach to inhibit the progression of ovarian cancer. Although several gene delivery vehicles have been reported earlier, there is paucity for targeted delivery of wild type p53 to ovarian cancer using gold nanoparticles. As it is well-known that EGFR (epidermal growth factor receptor) is overexpressed in ovarian cancer, in this study we hypothesized that the FDA approved monoclonal antibody C225 (cetuximab) that targets EGFR could be used for targeted delivery of wild type p53 gene. With this impetus, we devised an approach wherein cationic gold nanoparticles (AuNPs) were employed to generate gold nanoparticle-based drug delivery system (DDS, Au-C225-p53DNA where p53DNA is pCMVp53 plasmid) that was formulated and characterized by biochemical and biophysical methods. The nanoconjugate complexed with DNA (Au-C225-p53DNA) is serum-stable and protects the bound DNA from digestion by DNase-I. Additionally, in vitro reporter gene expression assays demonstrated efficient and specific gene transfection in EGFR overexpressing SK-OV-3 cells. Further, the intraperitoneal administration of Au-C225-p53DNA in SK-OV-3 xenograft mouse model displayed significant tumor targeting and tumor regression. Altogether, these studies indicated a promising nanoparticle-based approach for targeting ovarian cancers caused by mutated p53.

In vivo targeting of DNA vaccines to dendritic cells using functionalized gold nanoparticles

The clinical success of dendritic cell (DC)-based genetic immunization remains critically dependent on the availability of effective and safe nano-carriers for targeting antigen-encoded DNA vaccines to DCs, the most potent antigen-presenting cells in the human body in vivo. Recent studies revealed the efficacies of mannose receptor-mediated in vivo DC-targeted genetic immunization by liposomal DNA vaccine carriers containing both mannose-mimicking shikimoyl and transfection enhancing guanidinyl functionalities. However, to date, the efficacies of this approach have not been examined for metal-based nanoparticle DNA vaccine carriers. Herein, we report for the first time, the design, synthesis, physico-chemical characterization and bioactivities of gold nanoparticles covalently functionalized with a thiol ligand containing both shikimoyl and guanidinyl functionalities (Au-SGSH). We show that Au-SGSH nanoparticles can deliver DNA vaccines to mouse DCs under in vivo conditions. Subcutaneous administration of near infrared (NIR) dye-labeled Au-SGSH showed significant accumulation of the NIR dye in the DCs of the nearby lymph nodes compared to that for the non-targeting NIR-labeled Au-GSH nanoconjugate containing only a covalently tethered guanidinyl group, not the shikimoyl-functionality. Under prophylactic settings, in vivo immunization (s.c.) with the Au-SGSH-pCMV-MART1 nanoplex induced a long-lasting (180 days) immune response against murine melanoma. Notably, mannose receptor-mediated in vivo DC-targeted immunization (s.c.) with the Au-SGSH-MART1 nanoplex significantly inhibited established melanoma growth and increased the overall survivability of melanoma-bearing mice under therapeutic settings. The Au-SGSH nanoparticles reported herein have potential use for in vivo DC-targeted genetic immunization against cancer and infectious diseases.

Dually functional polyethylenimine-coated gold nanoparticles: a versatile material for electrode modification and highly sensitive simultaneous determination of four tumor markers

A novel sandwich-type electrochemical multiplex immunoassay is described for simultaneous detection of the tumor biomarkers alpha fetoprotein (AFP), carcinoembryonic antigen (CEA), prostate-specific antigen (PSA) and interleukin-8 (IL-8). Polyethylenimine-coated gold nanoparticles (PEI-AuNPs) were used for both modification of a screen-printed carbon electrode (SPCE) and as labeling tags. The coated AuNPs can be easily adsorbed on the electrodes which also are loaded with the electroactive metal ions cadmium(II), lead(II) copper(II) and silver(I) and related secondary antibodies (Ab₂). These give distinct voltammetric signals at -0.80, -0.55, -0.20 and + 0.05 V, respectively (vs Ag/AgCl). Four corresponding capture antibodies (Ab₁) were then conjugated to one of the electrodes. After a sandwich-type structure was formed by binding of the analytes and the labeling AuNPs, the electrochemical signal responses were recorded. Under the optimized testing conditions, there is a linear relationship in range from 0.25-10 ng mL^-1 for AFP, CEA and PSA, and from 0.50-100 pg mL^-1 for IL-8. The corresponding detection limits are 1.7, 1.6, 0.9 and 1.0 fg mL^-1, respectively. Cross reactivity, interferences and stability of the modified electrodes and of the signal nanotags are satisfying in that they can be stored for >4 weeks without significant signal reduction. The method was successfully applied to the determination of the biomarkers in spiked human serum. Graphical abstract Poly(ethylenimine)-coated gold nanoparticles were used in a sandwich-type multiplex electrochemical immunosensor. The coated gold nanoparticles were used for both electrode modification and as electrochemical nanotags. The resultingvmmunosensor exhibits excellent sensitivity for the four analytes studied, and also displays selectivity and long-term stability.

Shikimoyl-ligand decorated gold nanoparticles for use in ex vivo engineered dendritic cell based DNA vaccination

Since mannose receptors (MRs) are expressed on the surfaces of dendritic cells (DCs), the most professional antigen presenting cells in our body, DNA vaccine carriers containing either covalently grafted mannosyl- or mannose-mimicking shikimoyl-ligands are being increasingly used in ex vivo DC-transfection based DNA vaccination. To this end, we have recently demonstrated that ex vivo immunization of mice with liposomes of shikimoylated cationic amphiphiles containing a 6-amino hexanoic acid spacer group in the head-group region in complexation with melanoma antigen (MART1) encoded DNA vaccine (pCMV-MART1) induces long lasting anti-melanoma immune responses (C. Voshavar, et al., J. Med. Chem., 2017, 60, 1605-1610). This finding prompted us to examine, in the present investigation, the efficacies of gold nanoparticles conjugated to the mannose-mimicking shikimoyl ligand (SL) via a 6-amino hexane thiol spacer (AuNPs-SL) for use in ex vivo DC-transfection based genetic immunization. Herein, we report on the design, synthesis, physico-chemical characterization and bioactivities of AuNPs-SL. Dynamic light scattering and transmission electron microscopy studies revealed the hydrodynamic diameters of theAuNPs-SL nanoconjugates to be within the range of 23-44 nm and their surface potentials within the range of 9-28 mV. MTT-assay showed the non-cytotoxic nature of AuNPs-SL and the findings in the electrophoretic gel retardation assays revealed strong DNA binding properties of the AuNPs-SL. Importantly, subcutaneous immunization of C57BL/6J mice with DCs ex vivo transfected with an electrostatic complex of AuNPs-SL & melanoma antigen (MART1) encoded DNA vaccine (p-CMV-MART1) induced a long lasting (100 days) anti-tumor immune response in immunized mice upon subsequent challenge with a lethal dose of melanoma. Notably, mice immunized with either autologous mbmDCs ex vivo pre-transfected with nanoplexes of shikimoylated AuNPs-SL & an irrelevant pCMV-SPORT-β-gal plasmid (without having encoded melanoma antigen) or untransfected DCs showed no lasting protection against subsequent tumor challenge. The presently described shikimoyl-decorated gold nanoparticles (AuNPs-SL) are expected to find future use in ex vivo DC-transfection based genetic immunization against cancer and other infectious diseases.

Delivery technologies for cancer immunotherapy

Immunotherapy has become a powerful clinical strategy for treating cancer. The number of immunotherapy drug approvals has been increasing, with numerous treatments in clinical and preclinical development. However, a key challenge in the broad implementation of immunotherapies for cancer remains the controlled modulation of the immune system, as these therapeutics have serious adverse effects including autoimmunity and nonspecific inflammation. Understanding how to increase the response rates to various classes of immunotherapy is key to improving efficacy and controlling these adverse effects. Advanced biomaterials and drug delivery systems, such as nanoparticles and the use of T cells to deliver therapies, could effectively harness immunotherapies and improve their potency while reducing toxic side effects. Here, we discuss these research advances, as well as the opportunities and challenges for integrating delivery technologies into cancer immunotherapy, and we critically analyse the outlook for these emerging areas.

Polyethyleneimine-assisted one-pot synthesis of quasi-fractal plasmonic gold nanocomposites as a photothermal theranostic agent

Gold nanoparticles have been thoroughly used in designing thermal ablative therapies and in photoacoustic imaging in cancer treatment owing to their unique and tunable plasmonic properties. While the plasmonic properties highly depend on the size and structure, controllable aggregation of gold nanoparticles can trigger a plasmonic coupling of adjacent electronic clouds, henceforth leading to an increase of light absorption within the near-infrared (NIR) window. Polymer-engraftment of gold nanoparticles has been investigated to achieve the plasmonic coupling phenomenon, but complex chemical steps are often needed to accomplish a biomedically relevant product. An appealing and controllable manner of achieving polymer-based plasmon coupling is a template-assisted Au+3 reduction that ensures in situ gold reduction and coalescence. Among the polymers exploited as reducing agents are polyethyleneimines (PEI). In this study, we addressed the PEI-assisted synthesis of gold nanoparticles and their further aggregation to obtain fractal NIR-absorbent plasmonic nanoaggregates for photothermal therapy and photoacoustic imaging of colorectal cancer. PEI-assisted Au+3 reduction was followed up by UV-visible light absorption, small-angle X-ray scattering (SAXS), and photo-thermal conversion. The reaction kinetics, stability, and the photothermal plasmonic properties of the as-synthesized nanocomposites tightly depended on the PEI : Au ratio. We defined a PEI-Au ratio range (2.5-5) for the one-pot synthesis of gold nanoparticles that self-arrange into fractal nanoaggregates with demonstrated photo-thermal therapeutic and imaging efficiency both in vitro and in vivo in a colorectal carcinoma (CRC) animal model.

Parallel multi-parameter study of PEI-functionalized gold nanoparticle synthesis for bio-medical applications: part 1-a critical assessment of methodology, properties, and stability

Cationic polyethyleneimine (PEI)-conjugated gold nanoparticles (AuNPs) that are chemically and physically stable under physiological conditions are an ideal candidate for certain bio-medical applications, in particular DNA transfection. However, the issue remains in reproducibly generating uniform stable species, which can cause the inadequate characterization of the resulting product under relevant conditions and timepoints. The principal objective of the present study was to develop an optimized and reproducible synthetic route for preparing stable PEI-conjugated AuNPs (Au-PEIs). To achieve this objective, a parallel multi-parametric approach involving a total of 96 reaction studies evaluated the importance of 6 key factors: PEI molar mass, PEI structure, molar ratio of PEI/Au, concentration of reaction mixtures, reaction temperature, and reaction time. Application of optimized conditions exhibited narrow size distributions with characteristic surface plasmon resonance absorption and positive surface charge. The optimized Au-PEI product generated by this study exhibits exceptional stability under a physiological isotonic medium (phosphate-buffered saline) over 48 h and shelf-life in ambient condition without any significant change or sedimentation for at least 6 months. Furthermore, the optimized Au-PEI product was highly reproducible. Contributions from individual factors were elucidated using a broad and orthogonal characterization suite examining size and size distribution, optical absorbance, morphological transformation (agglomeration/aggregation), surface functionalities, and stability. Overall, this comprehensive multi-parametric investigation, supported by thorough characterization and rigorous testing, provides a robust foundation for the nanomedicine research community to better synthesize nanomaterials for biomedical use.

Collagen-based materials combined with microRNA for repairing cornea wounds and inhibiting scar formation

AuNP/miR-133b can be released from cornea regeneration materials and entered into stromal cells to inhibit cornea scar formation.

Corneal chemical burn treatment through a delivery system consisting of TGF-β1 siRNA: in vitro and in vivo

Chemical burns are major causes of corneal blindness. Transforming growth factor beta-1 (TGFβ₁) plays an important role in induction of corneal inflammation-related-fibrosis leading to the blindness. Here, a topical delivery system consisting anti-fibrotic TGF-β₁ siRNA, an inflammatory suppressing gene, was designed for treatment of corneal injuries. TGF-β₁ siRNA loaded in nanoparticles (NPs) made up of polyethyleneimine polymer demonstrated high fibroblast transfection efficiency. Moreover, TGF-β₁ and PDGF genes and ECM deposition were suppressed in isolated human corneal fibroblasts. NPs inhibited proliferation and transformation of fibroblasts to myofibroblasts by S-phase arrest and α-SMA suppression in vitro, respectively. The mentioned finding was also confirmed in vivo, addressing high wound-healing potential of prepared gene delivery system which was superior to conventional betamethasone treatment. Besides, CD4⁺ and α-SMA antibody staining showed inhibited angiogenesis and myofibroblast accumulation in treated corneas. This study opens a new way for treating corneal fibrosis through topical siRNA delivery.

Polymer-augmented liposomes enhancing antibiotic delivery against intracellular infections

Pulmonary intracellular infections, such as tuberculosis, anthrax, and tularemia, have remained a significant challenge to conventional antibiotic therapy. Ineffective antibiotic treatment of these infections can lead not only to undesired side effects, but also to the emergence of antibiotic resistance. Aminoglycosides (e.g., streptomycin) have long been part of the therapeutic regiment for many pulmonary intracellular infections. Their bioavailability for intracellular bacterial pools, however, is limited by poor membrane permeability and rapid elimination. To address this challenge, polymer-augmented liposomes (PALs) were developed to provide improved cytosolic delivery of streptomycin to alveolar macrophages, an important host cell for intracellular pathogens. A multifunctional diblock copolymer was engineered to functionalize PALs with carbohydrate-mediated targeting, pH-responsive drug release, and endosomal release activity with a single functional polymer that replaces the pegylated lipid component to simplify the liposome formulation. The pH-sensing functionality enabled PALs to provide enhanced release of streptomycin under endosomal pH conditions (70% release in 6 hours) with limited release at physiological pH 7.4 (16%). The membrane-destabilizing activity connected to endosomal release was characterized in a hemolysis assay and PALs displayed a sharp pH profile across the endosomal pH development target range. The direct connection of this membrane-destabilizing pH profile to model drug release was demonstrated in an established pyranine/p-xylene bispyridinium dibromide (DPX) fluorescence dequenching assay. PALs displayed similar sharp pH-responsive release, whereas PEGylated control liposomes did not, and similar profiles were then shown for streptomycin release. The mannose-targeting capability of the PALs was also demonstrated with 2.5 times higher internalization compared to non-targeted PEGylated liposomes. Finally, the streptomycin-loaded PALs were shown to have a significantly improved intracellular antibacterial activity in a Francisella-macrophage co-culture model, compared with free streptomycin or streptomycin delivered by control PEGylated liposomes (13× and 16×, respectively). This study suggests the potential of PALs as a useful platform to deliver antibiotics for the treatment of intracellular macrophage infections.

A facile approach to enhance antigen response for personalized cancer vaccination

Existing strategies to enhance peptide immunogenicity for cancer vaccination generally require direct peptide alteration, which, beyond practical issues, may impact peptide presentation and result in vaccine variability. Here, we report a simple adsorption approach using polyethyleneimine (PEI) in a mesoporous silica microrod (MSR) vaccine to enhance antigen immunogenicity. The MSR-PEI vaccine significantly enhanced host dendritic cell activation and T-cell response over the existing MSR vaccine and bolus vaccine formulations. Impressively, a single injection of the MSR-PEI vaccine using an E7 peptide completely eradicated large, established TC-1 tumours in about 80% of mice and generated immunological memory. When immunized with a pool of B16F10 or CT26 neoantigens, the MSR-PEI vaccine eradicated established lung metastases, controlled tumour growth and synergized with anti-CTLA4 therapy. Our findings from three independent tumour models suggest that the MSR-PEI vaccine approach may serve as a facile and powerful multi-antigen platform to enable robust personalized cancer vaccination.

Probing the nanoparticle-AGO2 interaction for enhanced gene knockdown

RNAi is emerging as a promising technology for treatment of various diseases due to its ability to silence specific target genes. To date, a number of nanoparticle based formulations have been reported for the delivery of small interfering RNA (siRNA), with continuous modifications in the nanoparticle design for enhancing their efficiency. While majority of the design aspects are focused on avoiding or overcoming endosomal entrapment, limited studies are available that address the role of interaction of nanoparticles with the RNA induced silencing complex (RISC) machinery, which is a crucial aspect deciding the outcome. Here, we systematically probed the effect of steric hindrance of nanoparticles on RISC interaction, by modulating two parameters, nanoparticle size and hardness. An assay was developed for quantifying the extent of RISC interaction of different nanoparticles in vitro, which was then correlated with their gene knockdown efficiency. The results suggest that the soft and small nanoparticles were most efficacious in knocking down polo-like-kinase 1 (PLK1) siRNA, a gene overexpressed in a variety of cancer types.

Engineering functional inorganic-organic hybrid systems: advances in siRNA therapeutics

Cancer treatment still faces a lot of obstacles such as tumor heterogeneity, drug resistance and systemic toxicities. Beyond the traditional treatment modalities, exploitation of RNA interference (RNAi) as an emerging approach has immense potential for the treatment of various gene-caused diseases including cancer. The last decade has witnessed enormous research and achievements focused on RNAi biotechnology. However, delivery of small interference RNA (siRNA) remains a key challenge in the development of clinical RNAi therapeutics. Indeed, functional nanomaterials play an important role in siRNA delivery, which could overcome a wide range of sequential physiological and biological obstacles. Nanomaterial-formulated siRNA systems have potential applications in protection of siRNA from degradation, improving the accumulation in the target tissues, enhancing the siRNA therapy and reducing the side effects. In this review, we explore and summarize the role of functional inorganic-organic hybrid systems involved in the siRNA therapeutic advancements. Additionally, we gather the surface engineering strategies of hybrid systems to optimize for siRNA delivery. Major progress in the field of inorganic-organic hybrid platforms including metallic/non-metallic cores modified with organic shells or further fabrication as the vectors for siRNA delivery is discussed to give credit to the interdisciplinary cooperation between chemistry, pharmacy, biology and medicine.

Neuroprotective effect of gold nanoparticles composites in Parkinson's disease model

Parkinson's disease (PD) is second most common neurodegenerative disorder worldwide. Although drugs and surgery can relieve the symptoms of PD, these therapies are incapable of fundamentally treating the disease. For PD patients, over-expression of α-synuclein (SNCA) leads to the death of dopaminergic neurons. This process can be prevented by suppressing SNCA over-expression through RNA interference. Here, we successfully synthesized gold nanoparticles (GNP) composites (CTS@GNP-pDNA-NGF) via the combination of electrostatic adsorption and photochemical immobilization, which could load plasmid DNA (pDNA) and target specific cell types. GNP was transfected into cells via endocytosis to inhibiting the apoptosis of PC12 cells and dopaminergic neurons. Simultaneously, GNP composites are also used in PD models in vivo, and it can successfully cross the blood-brain barrier by contents of GNP in the mice brain. In general, all the works demonstrated that GNP composites have good therapeutic effects for PD models in vitro and in vivo.

A Highly Sensitive and Selective Colorimetric Hg2+ Ion Probe Using Gold Nanoparticles Functionalized with Polyethyleneimine

A highly sensitive and selective colorimetric assay for the detection of Hg²⁺ ions was developed using gold nanoparticles (AuNPs) conjugated with polyethyleneimine (PEI). The Hg²⁺ ion coordinates with PEI, decreasing the interparticle distance and inducing aggregation. Time-of-flight secondary ion mass spectrometry showed that the Hg²⁺ ion was bound to the nitrogen atoms of the PEI in a bidentate manner (N-Hg²⁺-N), which resulted in a significant color change from light red to violet due to aggregation. Using this PEI-AuNP probe, determination of Hg²⁺ ion can be achieved by the naked eye and spectrophotometric methods. Pronounced color change of the PEI-AuNPs in the presence of Hg²⁺ was optimized at pH 7.0, 50°C, and 300 mM·NaCl concentration. The absorption intensity ratio (A₇₀₀/A₅₁₄) was correlated with the Hg²⁺ concentration in the linear range of 0.003-5.0 μM. The limits of detection were measured to be 1.72, 1.80, 2.00, and 1.95 nM for tap water, pond water, tuna fish, and bovine serum, respectively. Owing to its facile and sensitive nature, this assay method for Hg²⁺ ions can be applied to the analysis of water and biological samples.

The influence of amine structures on the stability and catalytic activity of gold nanoparticles stabilized by amine-modified hyperbranched polymers

Amine-modified amphiphilic hyperbranched polymers (MePEG-H104-Nx) were prepared from hyperbranched 2,2-bis(methylol)propionic acid polyester (H104) by decoration with polyethylene glycol monomethyl ether (MePEG) and different classes of oligo(ethylenimine)s. By using the MePEG-H104-Nx polymers as stabilizers, gold nanoparticles (AuNPs) were prepared in an aqueous medium by the reduction of HAuCl₄ with NaBH₄. The AuNPs were sphere-like with diameters of 2-4 nm, which were dependent on the structure of the amines. Further, the catalytic activity of these AuNPs was evaluated by monitoring the reduction reaction of 4-nitrophenol by sodium borohydride. The results demonstrate that the longer chain length and the branched structure of the amine moieties are beneficial for the stability and catalytic activity of the AuNPs. The AuNPs stabilized by MePEG-H104-N4 and MePEG-H104-Nb3 showed high catalytic activity for the reduction of 4-nitrophenol to 4-aminophenol.

Atom Transfer Radical Polymerization of Multishelled Cationic Corona for the Systemic Delivery of siRNA

We propose an effective siRNA delivery system by preparing poly(DAMA-HEMA)-multilayered gold nanoparticles using multiple surface-initiated atom transfer radical polymerization processes. The polymeric multilayer structure is characterized by transmission electron microscopy, matrix-associated laser desorption/ionization time-of-flight mass spectrometry, UV-vis spectroscopy, Fourier transform infrared spectroscopy, dynamic light scattering, and ζ-potential. The amount of siRNA electrostatically incorporated into the nanoparticle can be tuned by the number of polymeric shells, which in turn influences the cellular uptake and gene silencing effect. In a bioreductive environment, the interlayer disulfide bond breaks to release the siRNA from the degraded polymeric shells. Intravenously injected c-Myc siRNA-incorporated particles accumulate in the tumor site of a murine lung carcinoma model and significantly suppress the tumor growth. Therefore, the combination of a size-tunable AuNP core and an ATRP-functionalized shell offers control and versatility in the effective delivery of siRNA.

Construction of iron oxide nanoparticle-based hybrid platforms for tumor imaging and therapy

This review highlights the most recent progress in the construction of iron oxide nanoparticle-based hybrid platforms for tumor imaging and therapy.

pH and molecular weight dependence of auric acid reduction by polyethylenimine and the gene transfection efficiency of cationic gold nanoparticles thereof

Small, cationic gold nanoparticles (GNPs) are produced by the direct reduction of auric acid in a non-reducing solvent, water, with branched polyethylenimine (bPEI) in a broad pH range (3.0–9.0).

Co-Delivery of Drugs and Genes Using Polymeric Nanoparticles for Synergistic Cancer Therapeutic Effects

Drug and gene delivery systems based on nanoparticles, microparticles and hydrogels have been widely studied for cancer treatment in the past decade. To achieve an efficient and safe delivery, selection of drug and gene delivery carrier is critical. Biocompatible polymeric nanoparticles are considerably promising carrier candidates in delivery of drugs and genes because of their unique chemical and physical properties. However, delivery of a drug or gene sometimes cannot achieve a satisfactory treatment effect. Therefore, co-delivery of dual drugs or co-delivery of a drug and a gene in a polymeric nanoparticle has attracted attention. Such co-delivery systems can overcome multi-drug resistance of chemical drugs and achieve a synergistic therapeutic effect. In this progress report, we summarize recent progress in the preparation and application of polymeric drug and gene co-delivery nanosystems. The remaining challenges and future trends in this field are also included.

Intramolecular Self-Enhanced Nanochains Functionalized by an Electrochemiluminescence Reagent and Its Immunosensing Application for the Detection of Urinary β2-Microglobulin

In this study, polyethylenimine (PEI) is discovered to possess a noticeable amplification effect for the electrochemiluminescence (ECL) of N-(aminobutyl)-N-(ethylisoluminol) (ABEI); thus, a novel self-enhanced ECL reagent (ABEI-PEI) is prepared by covalent cross-linking. Because of the shortened electron-transfer path and reduced energy loss, the intramolecular ECL reaction between ABEI and PEI exhibited enhanced luminous efficiency compared with the traditional intermolecular ECL reaction. Owing to the amine-rich property of PEI, abundant ABEI could be immobilized on the molecular chains of PEI to strengthen the luminous intensity of ABEI-PEI. On account of the reducibility of remaining amino groups, ABEI-PEI, as the self-enhanced ECL reagent, has also been chosen as a reductant and stabilizer for in situ preparation of Au@Ag nanochains (Au@AgNCs) which has the catalytic activity for the ECL reaction. Moreover, using ABEI-PEI as a template to directly prepare Au@AgNCs realizes the immobilization of the ECL reagent with large amounts. Meanwhile, in virtue of the electropositivity of ABEI-PEI-capped Au@AgNCs (ABEI-PEI-Au@AgNCs), polyacrylic acid (PAA) with electronegativity is pervaded on the surface of nanochains and further chelates with Co²⁺ to form an ABEI-PEI-Au@AgNCs-PAA/Co²⁺ complex, which could introduce Co²⁺ as a catalyst to promote H₂O₂ decomposition and thus oxidize ABEI to produce an enhanced ECL signal. Here, the obtained self-enhanced ABEI-PEI-Au@AgNCs-PAA/Co²⁺ complex is utilized to capture the detection antibody (Ab₂). According to sandwiched immunoreactions, a sensitive ECL immunosensor is constructed for the detection of β2-microglobulin with a wide linearity from 0.01 pg mL^-1 to 200 ng mL^-1 and a detection limit of 3.3 fg mL^-1.

Strategies in the design of gold nanoparticles for intracellular targeting: opportunities and challenges

With unique physicochemical properties, gold nanoparticles (Au NPs) have demonstrated their potential as drug carriers or therapeutic agents. Effective guidance of Au NPs into specific intracellular destinations becomes increasingly important as we strive to further improve the efficiency of drug delivery and modulate controllable cellular responses. In this review, we summarized recent advances in designing Au NPs with the capabilities of cellular penetration and internalization, endosomal escape, intracellular trafficking and subcellular localization via various approaches including physical injection, tuning the physiochemical parameters of Au NPs, and surface modification with targeting ligands. Strategies for delivering Au NPs to specific subcellular destinations including the nucleus, mitochondria, endoplasmic reticulum, lysosomes are also discussed. Moreover, current challenges associated with intracellular targeting of Au NPs are discussed with future perspectives proposed.

Fluorescence guided photothermal/photodynamic ablation of tumours using pH-responsive chlorin e6-conjugated gold nanorods

Photothermal/photodynamic therapies (PTT/PDT) have been widely accepted as non-invasive therapeutic modalities to erase tumours. However, both therapies face the problem of precisely locating tumours and reducing their side effects. Herein, chlorin e6 conjugated gold nanorod, (Ce6-PEG-AuNR), a type of gold nanorod-photosensitizer conjugate, is designed as a kind of nano-therapeutic agent to simultaneously realize combined PTT/PDT. Compared to free Ce6, the fluorescence of Ce6 adhered to the conjugate is effectively quenched by the longitudinal surface plasmon resonance (LSPR) of in the Ce6-PEG-AuNR. However, the specific fluorescence of Ce6 can be recovered in tumour tissue when Ce6 is separated from the conjugate owing to the cleavage of hydrazone bond between Ce6 and PEG caused by intracellular acidic conditions in tumour tissue. Based on this effect, we can precisely locate tumours and further kill cancer cells by combined PTT/PDT. In addition, the combined therapy (PTT/PDT) function is more efficient in cancer treatment than that of PTT or PDT alone. Therefore, Ce6-PEG-AuNR can serve as a promising dual-modal phototherapeutic agent as well as a tumour-sensitive fluorescent probe to diagnose and treat cancer.

Core-shell hybrid nanostructured delivery platforms for advanced RNAi therapeutics

AIM

Study was aimed at combining the advantages of nonclassical RNAi-triggering oligonucleotides with nanoparticle-based advanced delivery platforms for developing efficient therapeutic systems.

MATERIALS & METHODS

We utilized a core-shell hybrid nanostructured platform for effectively delivering nonclassical RNAi triggers, namely long double stranded interfering RNA and tripodal interfering RNA. Core-shell structure was prepared by stably anchoring thiol-modified cationic polymer on the surface of growing crystal gold (Au) seeds, and the resulting particles were further complexed with nonclassical RNAi candidates via electrostatic interactions.

RESULTS

Our studies clearly demonstrated that the unique combination of nonclassical RNAi structures with an advanced core-shell hybrid nanostructured platform is an effective module for advanced RNAi-based therapeutic development.

Efficacious cellular codelivery of doxorubicin and EGFP siRNA mediated by the composition of PLGA and PEI protected gold nanoparticles

This study reports the simultaneous delivery of EGFP siRNA and the chemotherapeutic drug, doxorubicin by means of the composition that results from the electrostatic interaction between positively charged siRNA-complexes of gold nanoparticles (AuNPs) capped with PEI, 25kDa (P25-AuNPs) and negatively charged carboxymethyl cellulose formulated PLGA nanoparticles loaded with doxorubicin. The nanoparticles and their facile interaction were studied by means of dynamic light scattering (DLS), zeta potential, transmission electron microscopic (TEM) measurements. The flow cytometric and confocal microscopic analysis evidenced the simultaneous internalization of both labelled siRNA and doxorubin into around 55% of the HeLa cancer cell population. Fluorescence microscopic studies enabled the visual analysis of EGFP expressing HeLa cells which suggested that the composition mediated codelivery resulted in a substantial downregulation of EGFP expression and intracellular accumulation of doxorubicin. Interestingly, codelivery treatment resulted in an increased cellular delivery of doxorubicin when compared to PLGA-DOX alone treatment. On the other hand, the activity of siRNA complexes of PEI-AuNPs was completely retained even when they were part of composition. The results suggest that this formulation can serve as promising tool for delivery applications in combinatorial anticancer therapy.

Gold nanoparticles capped with benzalkonium chloride and poly (ethylene imine) for enhanced loading and skin permeability of 5-fluorouracil

OBJECTIVE

To enhance 5-fluorouracil (5-FU) permeability through the skin by loading onto gold nanoparticles (GNPs) capped with two cationic ligands, benzalkonium chloride (BC) or poly (ethylene imine) (PEI). Whereas 5-FU has excellent efficacy against many cancers, its poor permeability through biological membranes and several adverse effects limit its clinical benefits. BC and PEI were selected to stabilize GNPs and to load 5-FU through ionic interactions.

METHODS

5-FU/BC-GNPs and 5-FU/PEI-GNPs were prepared at different 5-FU/ligand molar ratios and different pH values and were evaluated using different techniques. GNPs stability was tested as a function of salt concentration and storage time. 5-FU release from BC- and PEI-GNPs was evaluated as a function of solution pH. Ex vivo permeability studies of different 5-FU preparations were carried out using mice skin.

RESULTS

5-FU-loaded GNPs size and surface charge were dependent on the 5-FU/ligand molar ratios. 5-FU entrapment efficiency and loading capacity were dependent on the used ligand, 5-FU/ligand molar ratio and solution pH. Maximum drug entrapment efficiency of 59.0 ± 1.7% and 46.0 ± 1.1% were obtained for 5-FU/BC-GNPs and 5-FU/PEI-GNPs, respectively. 5-FU-loaded GNPs had good stability against salinity and after storage for 4 months at room temperature and at 4 °C. In vitro 5-FU release was pH- and ligand-dependent where slower release was observed at higher pH and for 5-FU/BC-GNPs. 5-FU permeability through mice skin was significantly higher for drug-loaded GNPs compared with drug-ligand complex or drug aqueous solution.

CONCLUSION

Based on these results, BC- and PEI-GNPs might find applications as effective topical delivery systems of 5-FU.

A promising dual mode SPECT/CT imaging platform based on 99mTc-labeled multifunctional dendrimer-entrapped gold nanoparticles

Multifunctional ^99mTc-labeled dendrimer-entrapped gold nanoparticles (^99mTc-Au DENPs) were designed and synthesized. Our results show that the type of surface groups (acetyl or hydroxyl) significantly impact the biodistribution profile of the ^99mTc-Au DENPs, thereby allowing for preferential SPECT/CT imaging of different organs.

Advances in siRNA delivery in cancer therapy

RNA interference (RNAi)-based therapeutic approaches are under vibrant scrutinisation to seek cancer cure. siRNA suppress expression of the carcinogenic genes by targeting the mRNA expression. However, in vivo systemic siRNA therapy is hampered by the barriers such as poor cellular uptake, instability under physiological conditions, off-target effects and possible immunogenicity. To overcome these challenges, systemic siRNA therapy warrants the development of clinically suitable, safe, and effective drug delivery systems. Herein, we review the barriers, potential siRNA drug delivery systems, and application of siRNA in clinical trials for cancer therapy. Further research is required to harness the full potential of siRNA as a cancer therapeutic.

Facial Layer-by-Layer Engineering of Upconversion Nanoparticles for Gene Delivery: Near-Infrared-Initiated Fluorescence Resonance Energy Transfer Tracking and Overcoming Drug Resistance in Ovarian Cancer

Development of multidrug resistance (MDR) contributes to the majority of treatment failures in clinical chemotherapy. We report facial layer-by-layer engineered upconversion nanoparticles (UCNPs) for near-infrared (NIR)-initiated tracking and delivery of small interfering RNA (siRNA) to enhance chemotherapy efficacy by silencing the MDR1 gene and resensitizing resistant ovarian cancer cells to drug. Layer-by-layer engineered UCNPs were loaded with MDR1 gene-silencing siRNA (MDR1-siRNA) by electrostatic interaction. The delivery vehicle enhances MDR1-siRNA cellular uptake, protects MDR1-siRNA from nuclease degradation, and promotes endosomal escape for silencing the MDR gene. The intrinsic photon upconversion of UCNPs provides an unprecedented opportunity for monitoring intracellular attachment and release of MDR1-siRNA by NIR-initiated fluorescence resonance energy transfer occurs between donor UCNPs and acceptor fluorescence dye-labeled MDR1-siRNA. Enhanced chemotherapeutic efficacy in vitro was demonstrated by cell viability assay. The developed delivery vehicle holds great potential in delivery and imaging-guided tracking of therapeutic gene targets for effective treatment of drug-resistant cancers.

Engineering the RNA-Nanobio Interface

RNA nanotechnology is attracting a great deal of attention recently. As the multiple roles that RNA plays in molecular biology and physiological regulation become clearer, there are many opportunities for engineering RNA-Nanoparticle Complexes (RNA-NPCs). The high “engineerability” of RNA-NPCs comes from the ability to modify the RNA and NP chemistry. For example, the NP can be derived from materials with anticancer activity and the RNA delivered by it, designed to target cell signaling pathways that contribute to the molecular basis of these diseases. Despite this rapid advancement and the availability of new quantification and characterization techniques, a key challenge is to develop a better understanding of the RNA-nanobio interface; that is, the interactions of RNA with NP (RNA-nanobio interface) and how that impacts the structure, function, delivery, and activity of the RNA. Here, we attempt to summarize the state-of-the-art in this new and exciting field, and to lay out potential directions for bioengineering research on RNA-NPCs.

Functionalized gold nanoparticles manifested as potent carriers for nucleolar targeting

It is generally known that gold nanoparticles are localised in the cytoplasm and, if synthesised in small sizes or functionalized with specific proteins, they enter the cell nucleus. However, there is no report emphasising the importance of surface functionalization in their accumulation in the nucleolus. Here, for the first time in the literature, it is proposed that functionalization of gold nanoparticles with a thin layer of polyethyleneimine (PEI) spearheads them to the nucleolus of hard-to-transfect post-mitotic dorsal root ganglion neurones in a size-independent manner. As a potential for theranostic applications, it was found that functionalization with a thin layer of PEI affected the emission signal intensity of gold nanoparticles so that the cellular biodistribution of nanoparticles was visualised clearly under both confocal and two-photon microscopes.