Engineered protein nanoparticles for in vivo tumor detection

Two different protein nanoparticles that are totally different in shape and surface structure, i.e. Escherichia coli DNA-binding protein (eDPS) (spherical, 10 nm) and Thermoplasma acidophilum proteasome (tPTS) (cylindrical, 12 × 15 nm) were engineered for in vivo optical tumor detection: arginine–glycine–aspartic acid (RGD) peptide (CDCRGDCFC) was genetically inserted to the surface of each protein nanoparticle, and also near-infrared fluorescence dye was chemically linked to the surface lysine residues. The specific affinity of RGD for integrin (α_vβ₃) facilitated the uptake of RGD-presenting protein nanoparticles by integrin-expressing tumor cells, and also the protein nanoparticles neither adversely affected cell viability nor induced cell damage. After intravenously injected to tumor-bearing mice, all the protein nanoparticles successfully reached tumor with negligible renal clearance, and then the surface RGD peptides caused more prolonged retention of protein nanoparticles in tumor and accordingly higher fluorescence intensity of tumor image. In particular, the fluorescence of tumor image was more intensive with tPTS than eDPS, which is due presumably to longer in vivo half-life and circulation of tPTS that originates from thermophilic and acidophilic bacterium. Although eDPS and tPTS were used as proof-of-concept in this study, it seems that other protein nanoparticles with different size, shape, and surface structure can be applied to effective in vivo tumor detection.     

PEGylated carboxymethyl chitosan/calcium phosphate hybrid anionic nanoparticles mediated hTERT siRNA delivery for anticancer therapy

Lack of safe and effective delivery vehicle is the main obstacle for siRNA mediated cancer therapy. In this study, we synthesized a pH-sensitive polymer of PEG grafted carboxymethyl chitosan (PEG-CMCS) and developed anionic-charged hybrid nanoparticles of PEG-CMCS and calcium phosphate (CaP) for siRNA delivery through a single-step self-assembly method in aqueous condition. The formed nanoparticles with charge of around −8.25 mv and average diameter of 102.1 nm exhibited efficient siRNA encapsulation and enhanced colloidal and serum stability. The test in vitro indicated that the nanoparticles entered into HepG2 cells by endocytosis, and achieved endosomal escape of siRNA effectively due to the pH-responsive disassembly of nanoparticles and dissolution of CaP in the endosome. Reporter gene silencing assay showed that luciferase siRNA delivered by the anionic nanoparticles could achieve gene silencing efficacy comparable to that of conventional Lipofectamine 2000. Additionally, dramatic hTERT knockdown mediated by the anionic nanoparticles transfection induced significant apoptosis of HepG2 cells in vitro. After intravenous injection in tumor-bearing BALB/c nude mice, the nanoparticles specifically accumulated into tumor regions by EPR effect, leading to efficient and specific gene silencing sequentially. Most importantly, the nanoparticles carrying hTERT siRNA inhibited tumor growth significantly via silencing hTERT expression and inducing cells apoptosis in HepG2 tumor xenograft. Moreover, comprehensive safety studies of the nanoparticles confirmed their superior safety both in vitro and in vivo. We concluded that the PEG-CMCS/CaP hybrid anionic nanoparticles possessed potential as a safe and effective siRNA delivery system for anticancer therapy.     

Sensitive in vivo cell detection using size-optimized superparamagnetic nanoparticles

Magnetic nanoparticle (MNP) enabled cell visualization with magnetic resonance imaging (MRI) is currently an intensively studied area of research. In the present study, we have synthesized polyethylene glycolated (PEG) MNPs and validated their suitability as MR cell labeling agents in in vitro and in vivo experiments. The labeling of therapeutic potent mesenchymal stem cells (MSCs) with small core and large core MNPs was evaluated. Both MNPs were, in combination with a transfection agent, stably internalized into the MSCs and didn't show an effect on cell metabolism. The labeled cells showed high contrast in MRI phantom studies. For quantification purposes, the MRI contrast generating properties of cells labeled with small core MNPs were compared with large core MNPs and with the commercial contrast agent Endorem. MSCs labeled with the large core MNPs showed the highest contrast generating properties in in vitro phantom studies and in in vivo intracranial stereotactic injection experiments, confirming the size–relaxivity relationship in biological systems. Finally, the distribution of MSCs pre-labeled with large core PEGylated MNPs was visualized non-invasively with MRI in a glioma model.     

Naturally enveloped AAV vectors for shielding neutralizing antibodies and robust gene delivery in vivo

Recently adeno-associated virus (AAV) became the first clinically approved gene therapy product in the western world. To develop AAV for future clinical application in a widespread patient base, particularly in therapies which require intravenous (i.v.) administration of vector, the virus must be able to evade pre-existing antibodies to the wild type virus. Here we demonstrate that in mice, AAV vectors associated with extracellular vesicles (EVs) can evade human anti-AAV neutralizing antibodies. We observed different antibody evasion and gene transfer abilities with populations of EVs isolated by different centrifugal forces. EV-associated AAV vector (ev-AAV) was up to 136-fold more resistant over a range of neutralizing antibody concentrations relative to standard AAV vector in vitro. Importantly in mice, at a concentration of passively transferred human antibodies which decreased i.v. administered standard AAV transduction of brain by 80%, transduction of ev-AAV transduction was not reduced and was 4000-fold higher. Finally, we show that expressing a brain targeting peptide on the EV surface allowed significant enhancement of transduction compared to untargeted ev-AAV. Using ev-AAV represents an effective, clinically relevant approach to evade human neutralizing anti-AAV antibodies after systemic administration of vector.     

Cysteine modified rare-earth up-converting nanoparticles for in vitro and in vivo bioimaging

Cysteine, as a small organic molecule and amino acid, is a basic building block for proteins and has special physiological functions in vivo. Cysteine has strong affinity for cells, which can be taken advantage for various applications. A new and facile surface modification method has been developed for rare-earth doped upconversion nanoparticles (UCNs) using cysteine. Compared with unmodified samples, the water-solubility and biocompatibility of the cysteine modified NaYF₄:Yb,Er and NaYF₄:Yb,Tm UCNs (termed as UCN-Er-Cys and UCN-Tm-Cys, respectively) have been significantly improved, while their particle size and emission properties did not change substantially. Due to the low cytotoxicity as revealed by methyl thiazolyl tetrazolium assay, the cysteine modified UCNs were successfully applied to imaging of Hela cells in vitro and nude mouse in vivo. Most significant is that the method offers the advantages of ease of synthesis and handling as well as potentially low cost for biomedical emerging applications.     

Therapeutic nanomedicine based on dual-intelligent functionalized gold nanoparticles for cancer imaging and therapy in vivo

A novel strategy to construct a therapeutic system based on functionalized AuNPs which can specifically respond to tumor microenvironment was reported. In the therapeutic system, doxorubicin was conjugated to AuNPs via thiol–Au bond by using a peptide substrate, CPLGLAGG, which can be specifically cleaved by the protease. In vivo study shows that after injection of the functionalized AuNPs to the tumor-bearing mice, the over-expressed protease of MMP-2 in tumor tissue and intracellular GSH can lead to the rapid release of the anti-tumor drug (doxorubicin) from the functionalized AuNPs to inhibit tumor growth and realize fluorescently imaging simultaneously. The functionalized AuNPs with tumor-triggered drug release property can further improve the efficacy and reduce side effects significantly.     

Visible-light-excited and europium-emissive nanoparticles for highly-luminescent bioimaging in vivo

Europium(III)-based material showing special milliseconds photoluminescence lifetime has been considered as an ideal time-gated luminescence probe for bioimaging, but is still limited in application in luminescent small-animal bioimaging in vivo. Here, a water-soluble, stable, highly-luminescent nanosystem, Ir–Eu–MSN (MSN = mesoporous silica nanoparticles, Ir–Eu = [Ir(dfppy)₂(pic–OH)]₃Eu·2H₂O, dfppy = 2-(2,4-difluorophenyl)pyridine, pic–OH = 3-hydroxy-2-carboxypyridine), was developed by an in situ coordination reaction to form an insoluble dinuclear iridium(III) complex-sensitized-europium(III) emissive complex within mesoporous silica nanoparticles (MSNs) which had high loading efficiency. Compared with the usual approach of physical adsorption, this in-situ reaction strategy provided 20-fold the loading efficiency (43.2%) of the insoluble Ir–Eu complex in MSNs. These nanoparticles in solid state showed bright red luminescence with high quantum yield of 55.2%, and the excitation window extended up to 470 nm. These Ir–Eu–MSN nanoparticles were used for luminescence imaging in living cells under excitation at 458 nm with confocal microscopy, which was confirmed by flow cytometry. Furthermore, the Ir–Eu–MSN nanoparticles were successfully applied into high-contrast luminescent lymphatic imaging in vivo under low power density excitation of 5 mW cm⁻². This synthetic method provides a universal strategy of combining hydrophobic complexes with hydrophilic MSNs for in vivo bioimaging.     

Tumor targeting RGD conjugated bio-reducible polymer for VEGF siRNA expressing plasmid delivery

Targeted delivery of therapeutic genes to the tumor site is critical for successful and safe cancer gene therapy. The arginine grafted bio-reducible poly (cystamine bisacrylamide-diaminohexane, CBA-DAH) polymer (ABP) conjugated poly (amido amine) (PAMAM), PAM-ABP (PA) was designed previously as an efficient gene delivery carrier. To achieve high efficacy in cancer selective delivery, we developed the tumor targeting bio-reducible polymer, PA-PEG_1k-RGD, by conjugating cyclic RGDfC (RGD) peptides, which bind α_vβ_3/5 integrins, to the PAM-ABP using polyethylene glycol (PEG, 1 kDa) as a spacer. Physical characterization showed nanocomplex formation with bio-reducible properties between PA-PEG_1k-RGD and plasmid DNA (pDNA). In transfection assays, PA-PEG_1k-RGD showed significantly higher transfection efficiency in comparison with PAM-ABP or PA-PEG_1k-RAD in α_vβ_3/5 positive MCF7 breast cancer and PANC-1 pancreatic cancer cells. The targeting ability of PA-PEG_1k-RGD was further established using a competition assay. To confirm the therapeutic effect, the VEGF siRNA expressing plasmid was constructed and then delivered into cancer cells using PA-PEG_1k-RGD. PA-PEG_1k-RGD showed 20–59% higher cellular uptake rate into MCF7 and PANC-1 than that of non-targeted polymers. In addition, MCF7 and PANC-1 cancer cells transfected with PA-PEG_1k-RGD/pshVEGF complexes had significantly decreased VEGF gene expression (51–71%) and cancer cell viability (35–43%) compared with control. These results demonstrate that a tumor targeting bio-reducible polymer with an anti-angiogenic therapeutic gene could be used for efficient and safe cancer gene therapy.     

Oral delivery of shRNA and siRNA via multifunctional polymeric nanoparticles for synergistic cancer therapy

Galactose modified trimethyl chitosan-cysteine (GTC) conjugates with various galactose grafting densities were developed for oral delivery of Survivin shRNA-expression pDNA (iSur-pDNA) and vascular endothelial growth factor (VEGF) siRNA (siVEGF) in the synergistic and targeted treatment of hepatoma. iSur-pDNA and siVEGF loaded GTC nanoparticles (NPs) were prepared via electrostatic complexation and showed desirable stability in physiological fluids and improved intestinal permeation compared to naked genes. Galactose grafting density of GTC NPs significantly affected their in vitro and in vivo antitumor activities. GTC NPs with moderate galactose grafting density, termed GTC2 NPs, were superior in facilitating cellular uptake, promoting nuclear distribution, and silencing target genes, leading to notable inhibition of cell growth. In tumor-bearing mice, orally delivered GTC2 NPs could effectively accumulate in the tumor tissues and silence the expression of Survivin and VEGF, evoking increased apoptosis, inhibited angiogenesis, and thus the most efficient tumor regression. Moreover, compared with single gene delivery, co-delivery of iSur-pDNA and siVEGF showed synergistic effects on inhibiting in vitro cell proliferation and in vivo tumor growth. This study could serve as an effective approach for synergistic cancer therapy via oral gene delivery, and highlighted the importance of ligand grafting density in the rational design of targeted nanocarriers.     

Enhanced antitumor efficacies of multifunctional nanocomplexes through knocking down the barriers for siRNA delivery

Multifunctional nanocomplexes (NCs) consisting of urocanic acid-modified galactosylated trimethyl chitosan (UA-GT) conjugates as polymeric vectors, poly(allylamine hydrochloride)-citraconic anhydride (PAH-Cit) as charge-reversible crosslinkers, and vascular endothelial growth factor (VEGF) siRNA as therapeutic genes, were rationally designed to simultaneously overcome the extracellular, cellular, and intracellular barriers for siRNA delivery. The strong physical stability of UA-GT/PAH-Cit/siRNA NCs (UA-GT NCs) at pH 7.4 and 6.5 endowed protection from massive dilution, competitive ions, and ubiquitous nucleases in the blood and tumorous microenvironment. Their internalization into hepato-carcinoma cells was facilitated through the recognition of galactose receptors, followed by effective escape from endosomes/lysosomes owing to the strong buffering capacity of imidazole residues. At the meantime, the endosomal/lysosomal acidity triggered the charge reversal of PAH-Cit in UA-GT NCs, thus evoking their structural disassembly and subsequently accelerated release of siRNA in the cytosol. As a result, robust in vivo performance in terms of both gene silencing and tumor inhibition was achieved by UA-GT NCs at a low siRNA dose. Moreover, neither histological nor hematological toxicity was detected following repeated intravenous administration. Therefore, UA-GT NCs potentially served as an efficient and safe candidate in the treatment of hepatocellular carcinoma through knocking down the overall barriers for siRNA delivery.     

Rose-bengal-conjugated gold nanorods for in vivo photodynamic and photothermal oral cancer therapies

Gold nanorods (GNRs) conjugated with rose bengal (RB) molecules exhibit efficient singlet oxygen generation when illuminated by 532 nm green light and high photothermal efficiency under 810 nm near-infrared (NIR) irradiation. In vitro experiments show that reactive oxygen species generated by green light and hyperthermia produced by NIR light constitute two different mechanisms for cancer cell death. The RB-GNRs also exhibit improved photodynamic efficacy by enhancing the uptake of RB by cancer cells. In vivo experiments are conducted on hamster cheek pouches to resemble the human oral cancer conditions more accurately to assess the therapeutic effectiveness. Compared to the single photodynamic therapy (PDT) or photothermal therapy (PTT), the RB-GNRs with combined PDT-PTT capabilities provide better therapeutic effects against oral cancer and have large potential in cancer treatment.     

Polycation-detachable nanoparticles self-assembled from mPEG-PCL-g-SS-PDMAEMA for in vitro and in vivo siRNA delivery

Long circulation, cell internalization, endosomal escape and small interfering RNA (siRNA) release to the cytoplasm are the prerequisite considerations for siRNA delivery vectors. Herein, a kind of sheddable nanoparticles (NPs) with micelle architecture for siRNA delivery were fabricated by using an intracellular-activated polycation-detachable copolymer (PECssD), which was prepared by introducing highly reducing environment-responsive disulfide linkages between PEGylated polycaprolactone (PCL) and the grafted polycation, poly(2-dimethylaminoethyl methacrylate) (PDMAEMA). The architecture of PECssD self-assembled NPs includes a biodegradable hydrophobic PCL core, a PEG shield and a detachable comb-like polycation surface. The stable nanosized complexes of PECssD NPs with siRNA, termed PECssD/siRNA micelleplexes, were formed, which could prolong circulation, improve accumulation and retention in tumor tissue, and be favorable for internalization. In particular, the cleavage of the disulfide linkages in the intracellular microenvironment and the subsequent dissociation of the PDMAEMA/siRNA polyplexes from the PEGylated PCL cores of PECssD/siRNA micelleplexes were also confirmed, which facilitated the endosomal escape and the efficient release of siRNA. As a result, the distribution of siRNA in cytoplasm was enhanced and subsequently promoted the efficiency of siRNA in gene silencing. Furthermore, systemic administration of the NPs carrying siPlk1 (polo-like kinase 1 specific siRNA) induced a tumor-suppressing effect in the HeLa-Luc xenograft murine model. Therefore, the devised strategy of the polycation-detachable copolymer PECssD NPs could address the requirements of the multistep systemic delivery process of siRNA. The hydrophobic core of the PECssD/siRNA micelleplexes is expected to entrap antitumor drugs or other therapeutic agents for combined therapies.     

Pluronic-encapsulated natural chlorophyll nanocomposites for in vivo cancer imaging and photothermal/photodynamic therapies

A great challenge in developing nanotechnologies for cancer diagnosis and therapy has been the combined functionalities required for complicated clinical procedures. Among all requirements, toxicity has been the major hurdle that has prevented most of the nano-carriers from clinical use. Here, we extracted chlorophyll (Chl) from vegetable and encapsulated it into polymer (pluronic F68, Plu) micelles for cancer imaging and therapy. The results showed that the Chl-containing nanocomposites were capable of mouse tumor targeting, and the nanocomposite fluorescence within the tumor sites remained at high intensity more than two days after tail-vein injection. It is interesting that oral administration with the nanocomposites was also successful for tumor target imaging. Furthermore, the dietary Chl was found to be able to efficiently convert near-infrared laser irradiation to heat. The growths of melanoma cells and mouse tumors were effectively inhibited after being treated with the nanocomposites and irradiation. The suppression of the tumors was achieved by laser-triggered photothermal and photodynamic synergistic effects of Chl. As a natural substance from vegetable, Chl is non-toxic, making it an ideal nano-carrier for cancer diagnosis and treatment. Based on the results of this research, the Plu–Chl nanocomposites have shown promise for future clinical applications.     

Matrix metalloproteinase 2-responsive micelle for siRNA delivery

Systemic delivery of small interfering RNA (siRNA) into cancer cells remains the major obstacle to siRNA drug development. An ideal siRNA delivery vehicle for systemic administration should have long circulation time in blood, accumulate at tumor site, and sufficiently internalize into cancer cells for high-efficiency of gene silence. Herein, we report a core–shell Micelleplex delivery system that made from block copolymer bearing poly(ethylene glycol) (PEG), matrix metalloproteinase 2 (MMP-2)-degradable peptide PLG*LAG, cationic cell penetrating peptide polyarginine r₉ and poly(ε-caprolactone) (PCL) for siRNA delivery. We show clear evidences in vitro and in vivo to prove that the micelle carrying siRNA can circulate enough time in blood, enrich accumulation at tumor sites, shed the PEG layer when triggered by tumor overexpressing MMP-2, and then the exposing cell penetrating peptide r₉ enhanced cellular uptake of siRNA. Accordingly, this design strategy enhances the inhibition of breast tumor growth following systemic injection of this system carrying siRNA against Polo-like kinase 1, which demonstrating this Micelleplex can be a potential delivery system for systemic siRNA delivery in cancer therapy.     

Dual delivery of PDGF and simvastatin to accelerate periodontal regeneration in vivo

The emphasis on periodontal regeneration has been shifted towards the harmonization of bioactive molecules and physiological phases during regeneration. This study investigated whether the combination and sequential-release of platelet-derived growth factor (PDGF, mitogen) and simvastatin (differentiation factor) facilitated periodontal regeneration. PDGF and simvastatin were encapsulated in double-walled poly-( d,l-lactide) and poly-(d,l-lactide-co-glycolide) (PDLLA-PLGA) microspheres using the co-axial electrohydrodynamic atomization technique. Critical-sized periodontal defects on rat maxillae were filled with microspheres encapsulating BSA-in-core-shell (BB), PDGF-in-shell (XP), simvastatin-in-core and BSA-in-shell (SB), simvastatin-in-core and PDGF-in-shell, or unfilled with microspheres (XX), and examined at 14 and 28 days post-operatively. The resultant microspheres were around 15 μm diameter with distinct core–shell structure, and the fast-release of PDGF followed by slow-release of simvastatin was noted in the SP group. The SP group demonstrated significantly greater bone volume fraction and decreased trabecular separation compared to the XX group at day 14, and milder inflammatory cells infiltration and elevated tartrate-resistant acid phosphatase level were noted at day 28. Fibers were also well-aligned and obliquely inserted onto the root surface similar to native periodontal ligament with signs of cementogenesis in the SP group. In conclusion, the combination and sequential-release of PDGF-simvastatin accelerates the regeneration of the periodontal apparatus.     

Actively-targeted polyion complex micelles stabilized by cholesterol and disulfide cross-linking for systemic delivery of siRNA to solid tumors

For small interfering RNA (siRNA)-based cancer therapies, we report an actively-targeted and stabilized polyion complex micelle designed to improve tumor accumulation and cancer cell uptake of siRNA following systemic administration. Improvement in micelle stability was achieved using two stabilization mechanisms; covalent disulfide cross-linking and non-covalent hydrophobic interactions. The polymer component was designed to provide disulfide cross-linking and cancer cell-targeting cyclic RGD peptide ligands, while cholesterol-modified siRNA (Chol-siRNA) provided additional hydrophobic stabilization to the micelle structure. Dynamic light scattering confirmed formation of nano-sized disulfide cross-linked micelles (<50 nm in diameter) with a narrow size distribution. Improved stability of Chol-siRNA-loaded micelles (Chol-siRNA micelles) was demonstrated by resistance to both the dilution in serum-containing medium and counter polyion exchange with dextran sulfate, compared to control micelles prepared with Chol-free siRNA (Chol-free micelles). Improved stability resulted in prolonged blood circulation time of Chol-siRNA micelles compared to Chol-free micelles. Furthermore, introduction of cRGD ligands onto Chol-siRNA micelles significantly facilitated accumulation of siRNA in a subcutaneous cervical cancer model following systemic administration. Ultimately, systemically administered cRGD/Chol-siRNA micelles exhibited significant gene silencing activity in the tumor, presumably due to their active targeting ability combined with the enhanced stability through both hydrophobic interactions of cholesterol and disulfide cross-linking.     

Polyethyleneimine-mediated synthesis of folic acid-targeted iron oxide nanoparticles for in vivo tumor MR imaging

We report a facile polyethyleneimine (PEI)-mediated approach to synthesizing folic acid (FA)-targeted magnetic iron oxide nanoparticles (Fe₃O₄ NPs) for in vivo magnetic resonance (MR) imaging of tumors. In this study, stable PEI-coated Fe₃O₄ NPs were prepared by a one-pot hydrothermal route. The aminated Fe₃O₄ NPs with PEI coating enabled covalent conjugation of fluorescein isothiocyanate (FI) and folate-conjugated polyethylene glycol (PEG) with one end of carboxyl groups (FA-PEG-COOH). Followed by final acetylation, FA-targeted PEGylated Fe₃O₄ NPs (Fe₃O₄-PEI-Ac-FI-PEG-FA NPs) were formed. The formed multifunctional Fe₃O₄ NPs were characterized via different techniques. We show that the PEI-mediated approach along with the PEGylation conjugation enables the generation of water-dispersible and stable multifunctional Fe₃O₄ NPs, and the particles are quite cytocompatible and hemocompatible in the given concentration range as confirmed by in vitro cytotoxicity assay, cell morphology observation, and hemolysis assay. In addition, flow cytometry and confocal microscopy data show that the multifunctional Fe₃O₄ NPs are able to target a model cancer cell line (KB cells) overexpressing FA receptors in vitro. Importantly, the FA-targeted Fe₃O₄ NPs are able to be used as an efficient nanoprobe for MR imaging of cancer cells in vitro and a xenografted tumor model in vivo via an active FA targeting pathway. With the facile PEI-mediated formation strategy and PEGylation conjugation chemistry, the Fe₃O₄ NPs may be multifunctionalized with other biological ligands for MR imaging of different biological systems.     

F127/Calcium phosphate hybrid nanoparticles: a promising vector for improving siRNA delivery and gene silencing

Calcium phosphate-based transfection method had been used to transfer DNA into living cells. However, it had so far not been studied in detail to what extend siRNA delivery system. In this study, Pluronic F127/calcium phosphate hybrid nanoparticles (F127/CaP) were prepared by a facile room temperature method and employed as carriers to deliver siRNA to silence tumor cell. The morphology of the F127/CaP hybrid nanoparticles was investigated with TEM. In order to determine the ratio of F127 to CaP in the hybrid nanoparticles, TGA (the thermogravimetric analysis) was applied. MTT assays confirmed that the F127/CaP hybrid nanoparticles were quite safe. The hybrid F127/CaP nanoparticles obtained were 120–210?nm in diameter, and they were applied as siRNA carriers for siRNA loading and in vitro transfection. The siRNA encapsulating efficiency was 91.5 wt.% with a loading content of 6.5 wt.%. Compared to traditional CaP transfection method, the siRNA-loaded F127/CaP exhibited higher gene inhibition efficiency, and this was supported by fluorescence microscopy. Quantitative analysis of GFP silencing efficiency of various siRNA formulations was measured by using FACS flow cytometry analysis. Additionally, both custom CaP and F127/CaP are biocompatible and biodegradable, thus the as-prepared F127/CaP hybrid nanoparticles are promising for siRNA delivery.     

Genetically modified Tomato aspermy virus 2b protein as a tumor-targeting siRNA delivery carrier

In nature, there exist a wide range of dsRNA-binding proteins that have different binding modes for small interfering RNA (siRNA) as well as structural differences, and some of these proteins have potential as effective siRNA delivery carriers. In order to deliver siRNA into cancer cells, a dsRNA-binding 2b protein derived from Tomato aspermy virus was genetically modified by fusing the integrin-targeting RGD peptide to its C-terminus, and biosynthesized. The resulting 2b-RGD protein possesses distinct characteristics favorable for biomedical applications of siRNA: (i) high affinity for siRNA, (ii) siRNA protection against RNases in serum, (iii) low cytotoxicity compared to the polycationic polymers often employed in conventional siRNA carriers, (iv) specific binding to integrins on cancer cells, and the ability to pass through the cell membrane via endocytosis, and (v) the ability to facilitate cytosolic release of siRNA. Here, we demonstrate that the 2b-RGD/siRNA complexes have great potential as a tumor-targeting siRNA delivery carrier and suggest their possible therapeutic applications for cancer treatment.