Controlling self-assembling and tumor cell-targeting of protein-only nanoparticles through modular protein engineering

Modular protein engineering is suited to recruit complex and multiple functionalities in single-chain polypeptides. Although still unexplored in a systematic way, it is anticipated that the positioning of functional domains would impact and refine these activities, including the ability to organize as supramolecular entities and to generate multifunctional protein materials. To explore this concept, we have repositioned functional segments in the modular protein T22-GFP-H6 and characterized the resulting alternative fusions. In T22-GFP-H6, the combination of T22 and H6 promotes selfassembling as regular nanoparticles and selective binding and internalization of this material in CXCR4-overexpressing tumor cells, making them appealing as vehicles for selective drug delivery. The results show that the pleiotropic activities are dramatically affected in module-swapped constructs, proving the need of a carboxy terminal positioning of H6 for protein self-assembling, and the accommodation of T22 at the amino terminus as a requisite for CXCR4^+ cell binding and internalization. Furthermore, the failure of self-assembling as regular oligomers reduces cellular penetrability of the fusions while keeping the specificity of the T22-CXCR4 interaction.All these data instruct how multifunctional nanoscale protein carriers can be designed for smart, protein-driven drug delivery, not only for the treatment of CXCR4^+ human neoplasias, but also for the development of anti-HIV drugs and other pathologies in which CXCR4 is a relevant homing marker.     

Selective CXCR4+ Cancer Cell Targeting and Potent Antineoplastic Effect by a Nanostructured Version of Recombinant Ricin

Under the unmet need of efficient tumor‐targeting drugs for oncology, a recombinant version of the plant toxin ricin (the modular protein T22‐mRTA‐H6) is engineered to self‐assemble as protein‐only, CXCR4‐targeted nanoparticles. The soluble version of the construct self‐organizes as regular 11 nm planar entities that are highly cytotoxic in cultured CXCR4⁺ cancer cells upon short time exposure, with a determined IC50 in the nanomolar order of magnitude. The chemical inhibition of CXCR4 binding sites in exposed cells results in a dramatic reduction of the cytotoxic potency, proving the receptor‐dependent mechanism of cytotoxicity. The insoluble version of T22‐mRTA‐H6 is, contrarily, moderately active, indicating that free, nanostructured protein is the optimal drug form. In animal models of acute myeloid leukemia, T22‐mRTA‐H6 nanoparticles show an impressive and highly selective therapeutic effect, dramatically reducing the leukemia cells affectation of clinically relevant organs. Functionalized T22‐mRTA‐H6 nanoparticles are then promising prototypes of chemically homogeneous, highly potent antitumor nanostructured toxins for precise oncotherapies based on self‐mediated intracellular drug delivery.     

Targeted Drug Delivery to Stroke via Chemotactic Recruitment of Nanoparticles Coated with Membrane of Engineered Neural Stem Cells

Cell membrane coating has recently emerged as a promising biomimetic approach to engineering nanoparticles (NPs) for targeted drug delivery. However, simple cell membrane coating may not meet the need for efficient drug delivery to the brain. Here, a novel molecular engineering strategy to modify the surface of NPs with a cell membrane coating for enhanced brain penetration is reported. By using poly(lactic‐co‐glycolic) acid NPs as a model, it is shown that delivery of NPs to the ischemic brain is enhanced through surface coating with the membrane of neural stem cells (NSCs), and the delivery efficiency can be further increased using membrane isolated from NSCs engineered for overexpression of CXCR4. It is found that this enhancement is mediated by the chemotactic interaction of CXCR4 with SDF‐1, which is enriched in the ischemic microenvironment. It is demonstrated that the resulting CXCR4‐overexpressing membrane‐coated NPs, termed CMNPs, significantly augment the efficacy of glyburide, an anti‐edema agent, for stroke treatment. The study suggests a new approach to improving drug delivery to the ischemic brain and establishes a novel formulation of glyburide that can be potentially translated into clinical applications to improve management of human patients with stroke.     

Biodegradable Microalgae‐Based Carriers for Targeted Delivery and Imaging‐Guided Therapy toward Lung Metastasis of Breast Cancer

High delivery efficiency, prolonged drug release, and low systemic toxicity are effective weapons for drug delivery systems to win the battle against metastatic breast cancer. Herein, it is shown that Spirulina platensis (S. platensis) can be used as natural carriers to construct a drug‐loaded system for targeted delivery and fluorescence imaging‐guided chemotherapy on lung metastasis of breast cancer. The chemotherapeutic doxorubicin (DOX) is loaded into S. platensis (SP) via only one facile step to fabricate the DOX‐loaded SP (SP@DOX), which exhibits ultrahigh drug loading efficiency and PH‐responsive drug sustained release. The rich chlorophyll endows SP@DOX excellent fluorescence imaging capability for noninvasive tracking and real‐time monitoring in vivo. Moreover, the micrometer‐sized and spiral‐shaped SP carriers enable the as‐prepared SP@DOX to passively target the lungs and result in a significantly enhanced therapeutic efficacy on lung metastasis of 4T1 breast cancer. Finally, the undelivered carriers can be biodegraded through renal clearance without notable toxicity. The SP@DOX described here presents a novel biohybrid strategy for targeted drug delivery and effective treatment on cancer metastasis.     

Drug delivery devices based on macroporous silica spheres

A new kind of silica materials was proposed as carriers for drug delivery. The materials are characterized by the presence of hierarchical macro/mesopores, penetrable macropores and large pore volumes. The unique structure renders them ideal carriers for efficient and sufficient loading of drugs to establish controlled delivery systems. A series of such materials were synthesized and derivatized with octyl or octadecyl to investigate their drug delivery behavior. Nimodipine, as a model drug, was entrapped into the carriers by repeated soaking, filtration and evaporation. It is found that the drug-loading amount increased with increasing mesopore sizes of the carriers. The loading amount can reach as high as 350 wt% (drug/carrier). The in vitro release studies demonstrate that both enhanced release and sustained release can be achieved on the proposed materials. Moreover, the release speed can be controlled by the macropore sizes and surface characteristics of the materials.     

On the design of human immunodeficiency virus treatment based on a non‐linear time‐delay model

Mathematical modelling and methods from control theory can be employed to find appropriate drug regimens in human immunodeficiency virus (HIV) treatment. In this study, using a non‐linear time‐delay model, the authors design some suboptimal highly active antiretroviral therapy (HAART) [http://www.en.wikipedia.org/wiki/Protease_inhibitor_%28pharmacology%29] regimens for patients with HIV. The non‐linear delayed model is used to describe the dynamical interactions between HIV and human immune system in the presence of HAART. Based on the model, a set point tracking problem is defined in order to set the number of susceptible CD4⁺ T cells to a desired value. To solve this set point tracking problem in a suboptimal way, the authors introduce a new method which is able to consider constraints on the amount of drug dosage. It is proved that the proposed method is able to set the number of susceptible CD4⁺ T cells to the desired value. Simulation results confirm that the method is efficient even in the presence of parametric uncertainties.Inspec keywords: control theory, delays, diseases, patient treatmentOther keywords: human immunodeficiency virus treatment design, nonlinear time delay model, control theory, HIV treatment, suboptimal highly active antiretroviral therapy, suboptimal HAART, human immune system, set point tracking problem, CD4+T cells, drug dosage     

Zn2+‐Triggered Drug Release from Biocompatible Zirconium MOFs Equipped with Supramolecular Gates

A new theranostic nanoplatform, comprising of monodisperse zirconium metal‐organic frameworks (MOFs) as drug carriers and carboxylatopillar[5]arene‐based supramolecular switches as gating entities, is constructed, and controlled drug release triggered by bio‐friendly Zn²⁺ ions (abundant in synaptic vesicles) and auxiliary thermal stimulus is realized. This on‐command drug delivery system exhibits large pore sizes for drug encapsulation, excellent biodegradability and biocompatibility, extremely low cytotoxicity and premature drug release, and superior dual‐stimuli responsiveness, opening a new avenue in targeted drug delivery and controlled release of therapeutic agents, especially in the treatment of central nervous system diseases.     

Immune Cell‐Mediated Biodegradable Theranostic Nanoparticles for Melanoma Targeting and Drug Delivery

Although tremendous efforts have been made on targeted drug delivery systems, current therapy outcomes still suffer from low circulating time and limited targeting efficiency. The integration of cell‐mediated drug delivery and theranostic nanomedicine can potentially improve cancer management in both therapeutic and diagnostic applications. By taking advantage of innate immune cell's ability to target tumor cells, the authors develop a novel drug delivery system by using macrophages as both nanoparticle (NP) carriers and navigators to achieve cancer‐specific drug delivery. Theranostic NPs are fabricated from a unique polymer, biodegradable photoluminescent poly (lactic acid) (BPLP‐PLA), which possesses strong fluorescence, biodegradability, and cytocompatibility. In order to minimize the toxicity of cancer drugs to immune cells and other healthy cells, an anti‐BRAF V600E mutant melanoma specific drug (PLX4032) is loaded into BPLP‐PLA nanoparticles. Muramyl tripeptide is also conjugated onto the nanoparticles to improve the nanoparticle loading efficiency. The resulting nanoparticles are internalized within macrophages, which are tracked via the intrinsic fluorescence of BPLP‐PLA. Macrophages carrying nanoparticles deliver drugs to melanoma cells via cell–cell binding. Pharmacological studies also indicate that the PLX4032 loaded nanoparticles effectively kill melanoma cells. The “self‐powered” immune cell‐mediated drug delivery system demonstrates a potentially significant advancement in targeted theranostic cancer nanotechnologies.     

Cytocompatible chitosan-graft-mPEG-based 5-fluorouracil-loaded polymeric nanoparticles for tumor-targeted drug delivery

Biodegradable materials like chitosan (CH) and methoxy polyethylene glycol (mPEG) are widely being used as drug delivery carriers for various therapeutic applications. In this study, copolymer (CH-g-mPEG) of CH and carboxylic acid terminated mPEG was synthesized by carbodiimide-mediated acid amine reaction. The resultant hydrophilic copolymer was characterized by Fourier transform infrared spectroscopy and ¹H NMR studies, revealing its relevant functional bands and proton peaks, respectively. Blank polymeric nanoparticles (B-PNPs) and 5-fluorouracil loaded polymeric nanoparticles (5-FU-PNPs) were formulated by ionic gelation method. Furthermore, folic acid functionalized FA-PNPs and FA-5-FU-PNPs were prepared for folate receptor-targeted drug delivery. FA-5-FU-PNPs were characterized by particle size, zeta potential, and in vitro drug release studies, resulting in 197.7?nm,?+29.9?mv, and sustained drug release of 88% in 24?h, respectively. Cytotoxicity studies were performed for FA-PNPs and FA-5-FU-PNPs in MCF-7 cell line, which exhibited a cell viability of 80 and 41%, respectively. In vitro internalization studies were carried out for 5-FU-PNPs and FA-5-FU-PNPs which demonstrated increased cellular uptake of FA-5-FU-PNPs by receptor-mediated transport. Significant (p?相似文献   

Tetracycline-encapsulated P(3HB) microsphere-coated 45S5 Bioglass®-based scaffolds for bone tissue engineering

Bioglass^®-based scaffolds for bone tissue engineering have been developed, which can also serve as carriers for drug delivery. For this, P(3HB) microspheres (PMSs) loaded with tetracycline were fabricated and immobilised on the scaffold surfaces by a modified slurry dipping technique. The sustained drug delivery ability in simulated body fluid was confirmed by using UV–Vis absorption spectroscopy measurements. The MTT assay using mouse fibroblast cells provided evidence that the tetracycline loaded microspheres produced in this study show limited cytotoxicity. The scaffolds developed in this work provide mechanical support, adequate 3D surface roughness, bioactivity and controlled drug delivery function, and are thus interesting candidates for bone tissue engineering applications.     

DNA Nanostructures as Pt(IV) Prodrug Delivery Systems to Combat Chemoresistance

Cisplatin is a first‐line drug in clinical cancer treatment but its efficacy is often hindered by chemoresistance in cancer cells. Reduced intracellular drug accumulation is revealed to be a major mechanism of cisplatin resistance. Nanoscale drug delivery systems could help to overcome this problem because of their more active cellular uptake and more accurate tumor localization. DNA nanostructures have emerged as promising drug delivery systems because of their intrinsic biocompatibility and structural programmability. Herein, three diverse DNA nanostructures are constructed and their potential for cisplatin prodrug delivery is investigated. Results found that these DNA nanostructures could remarkably enhance the cellular internalization of platinum drugs and thus increase the anticancer activity, not only to regular lung cancer cells (A549), but more importantly to cisplatin‐resistant cancer cells (A549cisR). Further, in vivo studies also demonstrate that cisplatin prodrug loaded DNA nanostructures could effectively suppress tumor growth in both regular and cisplatin‐resistant tumor models. This study suggests that DNA nanostructures are effective carriers for platinum prodrug delivery to combat chemoresistance.     

Enhancing oral bioavailability of poorly soluble drugs with mesoporous silica based systems: opportunities and challenges

Porous silica-based drug delivery systems have shown considerable promise for improving the oral delivery of poorly water-soluble drugs. More specifically, micro- and meso-porous silica carriers have high surface areas with associated ability to physically adsorb high-drug loads in a molecular or amorphous form; this allows molecular state drug release in aqueous gastrointestinal environments, potential for supersaturation, and hence facilitates enhanced absorption and increased bioavailability. This review focuses primarily on the ability of porous silica materials to modulate in vitro drug release and enhance in vivo biopharmaceutical performance. The key considerations identified and addressed are the physicochemical properties of the porous silica materials (e.g. the particle and pore size, shape, and surface chemistry), drug specific properties (e.g. pKa, solubility, and nature of interactions with the silica carrier), potential for both immediate and controlled release, drug release mechanisms, potential for surface functionalization and inclusion of precipitation inhibitors, and importance of utilizing relevant and effective in vitro dissolution methods with discriminating dissolution media that provides guidance for in vivo outcomes (i.e. IVIVC).     

新型药物载体岩藻聚糖硫酸酯的研究进展

结合近年来岩藻聚糖硫酸酯作为新型药物转运载体的研究现状,重点介绍了岩藻聚糖硫酸酯在缓释包衣、微球栓塞、纳米给药、基因治疗、外科修复和透皮给药等新型药物转运体系方面的应用研究,总结了目前岩藻聚糖硫酸酯作为药物载体仍存在的一些问题,并展望了其应用前景。     

In vitro evaluation of compression-coated glycyl-l-histidyl-l-lysine–Cu(II) (GHK–Cu2+)-loaded microparticles for colonic drug delivery

Glycyl-l-histidyl-l-lysine–Cu(II) (GHK–Cu²⁺)-loaded Zn-pectinate microparticles in the form of hydroxypropyl cellulose (HPC) compression-coated tablets were prepared and their in vitro behavior tested. GHK–Cu²⁺ delivery to colon can be useful for the inhibition of matrix metalloproteinase, with the increasing secretion of tissue inhibitors of metalloproteinases (TIMPS),which are the major factors contributing in mucosal ulceration and inflammation in inflammatory bowel disease. The concentration of peptide was determined spectrophotometrically. The results obtained implied that surfactant ratio had a significant effect on percent production yield (1.25 to 1.75 w/w; 72.22% to 80.84%), but cross-linking agent concentration had not. The entrapment efficiency (EE) was found to be in the range of 58.25–78.37%. The drug-loading factor significantly increased the EE; however, enhancement of cross-linking agent concentration decreased it. The release of GHK–Cu²⁺ from Zn-pectinate microparticles (F1–F8) in simulated intestinal fluid was strongly affected by cross-linking agent concentration and drug amount (50?mg for F1–F6; 250?mg for F7–F8), but not particularly affected by surfactant amount. Release profiles represented that the microparticles released 50–80% their drug load within 4?h. Therefore, the optimum microparticle formulation (F8) coated with a relatively hydrophobic polymer HPC to get a suitable colonic delivery system. The optimum colonic delivery tablets prepared with 700?mg HPC-SL provided the expected delayed release with a lag time of 6?h. The effects of polymer viscosity and coat weight on GHK–Cu²⁺ release were found to be crucial for the optimum delay of lag time. The invention was found to be promising for colonic delivery.     

Protein‐Based Nanomedicine Platforms for Drug Delivery

Protein‐based nanomedicine platforms for drug delivery comprise naturally self‐assembled protein subunits of the same protein or a combination of proteins making up a complete system. They are ideal for drug‐delivery platforms due to their biocompatibility and biodegradability coupled with low toxicity. A variety of proteins have been used and characterized for drug‐delivery systems, including the ferritin/apoferritin protein cage, plant‐derived viral capsids, the small Heat shock protein (sHsp) cage, albumin, soy and whey protein, collagen, and gelatin. There are many different types and shapes that have been prepared to deliver drug molecules using protein‐based platforms, including various protein cages, microspheres, nanoparticles, hydrogels, films, minirods, and minipellets. The protein cage is the most newly developed biomaterial for drug delivery and therapeutic applications. The uniform size, multifunctionality, and biodegradability push it to the frontier of drug delivery. In this Review, the recent strategic development of drug delivery is discussed with emphasis on polymer‐based, especially protein‐based, nanomedicine platforms for drug delivery. The advantages and disadvantages are also discussed for each type of protein‐based drug‐delivery system.

     

Calcium phosphate/block copolymer hybrid porous nanospheres: Preparation and application in drug delivery

Calcium phosphate (CaP)/block copolymer hybrid porous nanospheres were synthesized by a simple solution method using CaCl₂ and (NH₄)₂HPO₄ in the presence of a block copolymer at room temperature. X-ray diffraction showed that the sample consisted of amorphous calcium phosphate (ACP). The BET specific surface area and the pore size distribution of the CaP/PLLA-mPEG hybrid porous nanospheres were also characterized. The as-prepared CaP/PLLA-mPEG hybrid porous nanospheres were explored as drug carriers, and showed a high ibuprofen loading capacity and in vitro prolonged drug release behavior in a simulated body fluid. These CaP/block copolymer hybrid porous nanospheres exhibit a great potential for application in drug delivery.     

Novel strategies for the buccal delivery of macromolecules

For years now, the delivery of small molecules through the buccal mucosal route has been described in the literature, but it has only been over the past decade that investigations into macromolecule delivery via the buccal route have sharply increased. The administration of macromolecules such as proteins and peptides, antibodies, or nucleic acids by buccal administration would be greatly enhanced due to the avoidance of the gastrointestinal conditions, rapid uptake into systemic circulation, as well as the potential for controlled drug delivery. Since macromolecules are faced with a number of specific challenges related to permeation through the epithelium, several strategies have been employed historically to improve their buccal absorption and subsequent bioavailability. Several conventional strategies to improve macromolecule penetration include the use of chemical permeation enhancers, enzyme inhibitors and the use of mucoadhesive materials acting as carriers. More recent approaches include the incorporation of the macromolecule as part of nanostructured delivery systems to further enhance targeting and delivery. This review focuses on the different permeation enhancing strategies as well as formulation design that are tailored to meet the challenges of active macromolecule delivery using the buccal mucosal route of administration.     

Multifunctional Upconversion Mesoporous Silica Nanostructures for Dual Modal Imaging and In Vivo Drug Delivery

Incorporating the agents for magnetic resonance imaging (MRI), optical imaging, and therapy in one nanostructured matrix to construct multifunctional nanomedical platform has attracted great attention for simultaneous diagnostic and therapeutic applications. In this work, a facile methodology is developed to construct a multifunctional anticancer drug nanocarrier by combining the special advantages of upconversion nanoparticles and mesoporous silica. β‐NaYF₄:Yb³⁺, Er³⁺@β‐NaGdF₄:Yb³⁺ is chosen as it can provide the dual modality of upconversion luminescence and MRI. Then mesoporous silica is directly coated onto the upconversion nanoparticles to form discrete, monodisperse, highly uniform, and core–shell structured nanospheres (labeled as UCNPs@mSiO₂), which are subsequently functionalized with hydrophilic polymer poly(ethylene glycol) (PEG) to improve the colloidal stability and biocompatibility. The obtained multifunctional nanocomposites can be used as an anticancer drug delivery carrier and applied for imaging. The anticancer drug doxorubicin (DOX) is absorbed into UCNPs@mSiO₂‐PEG nanospheres and released in a pH‐sensitive pattern. In vitro cell cytotoxicity tests on cancer cells verify that the DOX‐loaded UCNPs@mSiO₂‐PEG has comparable cytotoxicity with free DOX at the same concentration of DOX. In addition, the T₁‐weighted MRI that measures in aqueous solutions reveals that the contrast brightening increases with the concentration of Gd³⁺ component. Upconversion luminescence images of UCNPs@mSiO₂‐PEG uptaken by cells show green emission under 980 nm infrared laser excitation. Finally, the nanocomposites show low systematic toxicity and high in vivo antitumor therapy efficacy. These findings highlight the fascinating features of upconversion‐mesoporous nanocomposites as multimodality imaging contrast agents and nanocarrier for drug molecules.     

Immediate release of ibuprofen from Fujicalin®-based fast-dissolving self-emulsifying tablets

Background: Drug release from a solid form of self-emulsifying drug delivery system (SEDDS) has greatly been limited due to strong adsorption and physical interaction with carriers. To facilitate drug release process in the stomach, an acid-soluble powderizing carrier, Fujicalin^® was evaluated together with different disintegrants and hydrophilic lubricants. Method: Immediate-release self-emulsifying tablets (IR-SETs) of ibuprofen (IBU) was prepared with solidified SEDDS of IBU, various disintegrants, and lubricants, and drug release was evaluated to develop IR-SET that can release IBU with a similar IBU release rate to that obtained with liquid SEDDS. Results: The liquid SEDDS consisted of Capryol 90, Cremophor EL, Labrasol, and IBU at a ratio of 3:4:3:3, and was solidified with various adsorbents. The powderized SEDDS was tabletted by a direct compression. Fujicalin^®-based SEDDS tablets demonstrated remarkably higher dissolution rate of IBU compared with Neusilin^® and Neosyl^®-based SEDDS tablets. The IR-SET formula of IBU prepared with Fujicalin^® as an adsorbent, Polyplasdone^® as a disintegrant, and sodium bicarbonate as a co-disintegrant showed over 90% of initially loaded dose of IBU released within 5?min in a stimulated gastric juice (pH 1.2), exhibiting almost equivalent rate of IBU release to that shown by liquid SEDDS. The particle size analysis revealed no significant differences in droplet sizes of the microemulsions formed from liquid (116?nm) and IR-SET (110?nm). Conclusion: The novel IR-SET can be promising as a fast-releasing SEDDS tablet of IBU for fast onset of action.