Drug-Loaded Nanogel for Efficient Orchestration of Cell Death Pathways by Intramitochondrial Disulfide Polymerization.

Chemotherapy using a nanoscaled drug delivery system is an effective cancer therapy, but its high drug concentration often causes drug resistance in cancer cells and normal cell damage. Combination therapy involving two or more different cell signaling pathways can be a powerful tool to overcome the limitations of chemotherapy. Herein, this article presents nanogel (NG)-mediated co-delivery of a chemodrug camptothecin (CPT) and mitochondria-targeting monomer (MT monomer) for efficient activation of two modes of the programmed cell death pathway (apoptosis and necroptosis) and synergistic enhancement of cancer therapy. CPT and the monomer are incorporated together into the redox-degradable polymeric NGs for release in response to the intracellular glutathione. The MT monomer is shown to undergo reactive oxygen species (ROS)-triggered disulfide polymerization inside the cancerous mitochondria in cooperation with the chemotherapeutic CPT elevating the intracellular ROS level. The CPT/monomer interconnection in cell death mechanisms for mitochondrial dysfunction and enhanced cell death is evidenced by a series of cell analyses showing ROS generation, mitochondria damage, impacts on (non)cancerous or drug-resistant cells, and cell death modes. The presented work provides beneficial insights for utilizing combination therapy to facilitate a desired cell death mechanism and developing a novel nanosystem for more efficacious cancer treatment.

Protein-Precoated Surface of Metal-Organic Framework Nanoparticles for Targeted Delivery.

Metal-organic framework (MOF) nanoparticles have recently emerged as a promising vehicle for drug delivery with high porosity and feasibility. However, employing a MOF-based drug delivery system remains a challenge due to the difficulty in controlling interfaces of particles in a biological environment. In this paper, protein corona-blocked Zr6 -based MOF (PCN-224) nanoparticles are presented for targeted cancer therapy with high efficiency. The unmodified PCN-224 surface is precoated with glutathione transferase (GST)-fused targetable affibody (GST-Afb) proteins via simple mixing conjugations instead of chemical modifications that can induce the impairment of proteins. GST-Afb proteins are shown to stably protect the surface of PCN-224 particles in a specific orientation with GST adsorbed onto the porous surface and the GST-linked Afb posed outward, minimizing the unwanted interfacial interactions of particles with external biological proteins. The Afb-directed cell-specific targeting ability of particles and consequent induction of cell death is demonstrated both in vitro and in vivo by using two kinds of Afb, which targets the surface membrane receptor, human epidermal growth factor receptor 2 (HER2) or epidermal growth factor receptor (EGFR). This study provides insight into the way of regulating the protein-adhesive surface of MOF nanoparticles and designing a more effective MOF-hosted targeted delivery system.

Simultaneous Delivery of Electrostatically Complexed Multiple Gene-Targeting siRNAs and an Anticancer Drug for Synergistically Enhanced Treatment of Prostate Cancer.

Simultaneous silencing of multiple apoptosis-related genes is an attractive approach to treat cancer. In this article, we present a multiple gene-targeting siRNA/drug delivery system for prostate cancer treatment with a high efficiency. Bcl-2, survivin, and androgen receptor genes involved in the cell apoptosis pathways were chosen as silencing targets with three different siRNAs. The colloidal nanocomplex delivery system (<10 nm in size) was formulated electrostatically between anionic siRNAs and a cationic drug (BZT), followed by encapsulation with the Pluronic F-68 polymer. The formulated nanocomplex system exhibited sufficient stability against nuclease-induced degradation, leading to successful intracellular delivery for the desired therapeutic performance. Silencing of targeted genes and apoptosis induction were evaluated in vitro on human prostate LNCaP-LN3 cancer cells by using various biological analysis tools (e.g., real-time PCR, MTT cell viability test, and flow cytometry). It was demonstrated that when the total loaded siRNA amounts were kept the same in the nanocomplexes, the simultaneous silencing of triple genes with co-loaded siRNAs (i.e., Bcl-2, survivin, and AR-targeting siRNAs) enhanced BZT-induced apoptosis of cancer cells more efficiently than the silencing of each single gene alone, offering a novel way of improving the efficacy of gene therapeutics including anticancer drug.

How Can Doxorubicin Loading Orchestrate in Vitro Degradation Behaviors of Mesoporous Silica Nanoparticles under a Physiological Condition?

In the field of drug-delivery research, mesoporous silica nanoparticles (MSNs) have received a great deal of attention because of their capability to load and release drug molecules through the internal mesopores. To maximize the biomedical applicability of MSN-based drug carriers, it is important to ensure their degradability in a physiological environment as well as to obtain MSNs with desirable physicochemical properties. We present in vitro degradability of drug-loaded MSNs (DMSNs) that contain an anticancer drug (doxorubicin) in the pores and are suspended in physiological media (i.e., PBS at 37 °C). To obtain comprehensive understanding of the degradation process of DMSNs, cargo-free MSNs and nonporous solid silica nanoparticles (SSNs) were studied comparatively. Degradation of each particle was studied by using ICP, TEM, and gas sorption measurement and analyzed in terms of structural parameters, external particle surface dissolution, and acidity of the PBS. It is demonstrated for the first time that drug loading into the pores leads to better degradability of MSNs by combining each distinct advantage of bare MSNs and SSNs to make DMSNs simultaneously possess an initial degradation rate as fast as drug-unloaded MSNs and a total degradation quantity as high as SSNs. The presented data not only demonstrate a high biodegradability of MSN-based drug carriers but also provide new insights into their unique in vitro degradation pattern.

A multifunctional protein pre-coated metal-organic framework for targeted delivery with deep tissue penetration.

Targeted drug delivery using metal-organic frameworks (MOFs) has shown significant progress. However, the tumor microenvironment (TME) impedes efficient MOF particle transfer into tumor cells. To tackle this issue, we pre-coated nano-sized MOF-808 particles with multifunctional proteins: glutathione S-transferase (GST)-affibody (Afb) and collagenase, aiming to navigate the TME more effectively. The surface of MOF-808 particles is coated with GST-Afb-a fusion protein of GST and human epidermal growth factor receptor 2 (HER2) Afb or epidermal growth factor receptor (EGFR) Afb which has target affinity. We also added collagenase enzymes capable of breaking down collagen in the extracellular matrix (ECM) through supramolecular conjugation, all without chemical modification. By stabilizing these proteins on the surface, GST-Afb mitigate biomolecule absorption, facilitating specific tumor cell targeting. Simultaneously, collagenase degrades the ECM in the TME, enabling deep tissue penetration of MOF particles. Our resulting system, termed collagenase-GST-Afb-MOF-808 (Col-Afb-M808), minimizes undesired interactions between MOF particles and external biological proteins. It not only induces cell death through Afb-mediated cell-specific targeting, but also showcases advanced cellular internalization in 3D multicellular spheroid cancer models, with effective deep tissue penetration. The therapeutic efficacy of Col-Afb-M808 was further assessed via in vivo imaging and evaluation of tumor inhibition following injection of IR-780 loaded Col-Afb-M808 in 4T1tumor-bearing nude mice. This study offers key insights into the regulation of the multifunctional protein-adhesive surface of MOF particles, paving the way for the designing even more effective targeted drug delivery systems with nano-sized MOF particles.

Unveiling the Power of Cloaking Metal-Organic Framework Platforms via Supramolecular Antibody Conjugation.

Targeted drug delivery systems based on metal-organic frameworks (MOFs) have progressed tremendously since inception and are now widely applicable in diverse scientific fields. However, translating MOF agents directly to targeted drug delivery systems remains a challenge due to the biomolecular corona phenomenon. Here, we observed that supramolecular conjugation of antibodies to the surface of MOF particles (MOF-808) via electrostatic interactions and coordination bonding can reduce protein adhesion in biological environments and show stealth shields. Once antibodies are stably conjugated to particles, they were neither easily exchanged with nor covered by biomolecule proteins, which is indicative of the stealth effect. Moreover, upon conjugation of the MOF particle with specific targeted antibodies, namely, anti-CD44, human epidermal growth factor receptor 2 (HER2), and epidermal growth factor receptor (EGFR), the resulting hybrid exhibits an augmented targeting efficacy toward cancer cells overexpressing these receptors, such as HeLa, SK-BR-3, and 4T1, as evidenced by flow cytometry. The therapeutic effectiveness of the antibody-conjugated MOF (anti-M808) was further evaluated through in vivo imaging and the assessment of tumor inhibition effects using IR-780-loaded EGFR-M808 in a 4T1 tumor xenograft model employing nude mice. This study therefore provides insight into the use of supramolecular antibody conjugation as a promising method for developing MOF-based drug delivery systems.

Surface protein-retractive and redox-degradable mesoporous organosilica nanoparticles for enhanced cancer therapy.

Targeted delivery along with controlled drug release is considered crucial in development of a drug delivery system (DDS) for efficient cancer treatment. In this paper, we present a strategy to obtain such a DDS by utilizing disulfide-incorporated mesoporous organosilica nanoparticles (MONs), which were engineered to minimize the surface interactions with proteins for better targeting and therapeutic performance. That is, after MONs were loaded with a chemodrug doxorubicin (DOX) through the inner pores, their outer surface was treated for conjugation to the glutathione-S-transferase (GST)-fused cell-specific affibody (Afb) (GST-Afb). These particles exhibited prompt responsivity to the SS bond-dissociating glutathione (GSH), which resulted in considerable degradation of the initial particle morphology and DOX release. As the protein adsorption to the MON surface appeared largely reduced, their targeting ability with GSH-stimulated therapeutic activities was demonstrated in vitro by employing two kinds of the GST-Afb protein, which target human cancer cells with the surface membrane receptor, HER2 or EGFR. Compared with unmodified control particles, the presented results show that our system can significantly enhance cancer-therapeutic outcomes of the loaded drug, offering a promising way of designing a more efficacious DDS.

Metal-Organic Framework-Supported Catalase Delivery for Enhanced Photodynamic Therapy via Hypoxia Mitigation.

Tumor hypoxia poses a significant challenge in photodynamic therapy (PDT), which uses molecular oxygen to produce reactive oxygen species upon light excitation of a photosensitizer. For hypoxia mitigation, an enzyme catalase (CAT) can be beneficially used to convert intracellular hydrogen peroxide to molecular oxygen, but its utility is significantly limited due to the intrinsic membrane impermeability. Herein, we present direct integration of CAT into the outer surface of unmodified metal-organic framework (MOF) nanoparticles (NPs) via supramolecular interactions for effective cellular entry of CAT and consequent enhancement of PDT. The results demonstrated that CAT-loaded MOF NPs could successfully enter hypoxic cancer cells, after which the intracellularly delivered CAT molecules became dissociated from the MOF surface to efficiently initiate the oxygen generation and PDT process along with a co-delivered photosensitizer IR780. This achievement suggests that our protein-MOF integration strategy holds great potential in biomedical studies to overcome tumor hypoxia as well as to efficiently deliver biomolecular cargos.

Mesoporous silica nanoparticle-supported nanocarriers with enhanced drug loading, encapsulation stability, and targeting efficiency.

For efficient drug delivery, stable encapsulation of a large amount of anticancer drugs is crucial, not to mention cell-specific delivery. Among many possible nanocarriers, mesoporous silica nanoparticles are versatile frameworks that satisfy those requirements owing to their characteristic internal pores with a large surface area and a tunable surface composition. By using a noncovalent post-modification strategy, MSN-based drug delivery systems with enhanced therapeutic efficiency can be prepared in a simple one-pot process by loading small anticancer drugs in the unmodified mesopores and by subsequently blocking the drug-loaded pores with a stimuli-responsive polymer gatekeeper. For targeted delivery, drug-loaded MSNs can be functionalized with suitable targeting components such as targeting ligands or artificial protein corona. This mini-review highlights the recent research in which MSN-supported nanocarriers are designed, synthesized, and characterized to possess a high drug loading capacity and encapsulation stability along with targeting capability for more efficient cancer treatment.

Anisotropic Plasmonic Gold Nanorod-Indocyanine Green@Reduced Graphene Oxide-Doxorubicin Nanohybrids for Image-Guided Enhanced Tumor Theranostics.

The unique physicochemical and localized surface plasmon resonance assets of gold nanorods (GNRs) have offered combined cancer treatments with real-time diagnosis by integrating diverse theragnostic modalities into a single nanoplatform. In this work, a unique multifunctional nanohybrid material based on GNRs was designed for in vitro and in vivo tumor imaging along with synergistic and combinatorial therapy of tumor. The hybrid material with size less than 100 nm was achieved by embedding indocyanine green (ICG) on mesoporous silica-coated GNRs with further wrapping of reduced graphene oxide (rGO) and then attached with doxorubicin (DOX) and polyethylene glycol. The nanohybrid unveiled noteworthy stability and competently protected the embedded ICG from further aggregation, photobleaching, and nucleophilic attack by encapsulation of GNRs-ICG with rGO. Such combination of GNRs-ICG with rGO and DOX served as a real-time near-infrared (NIR) contrast imaging agent for cancer diagnosis. The hybrid material exhibits high NIR absorption property along with three destined capabilities, such as, nanozymatic activity, photothermal activity, and an excellent drug carrier for drug delivery. The integrated properties of the nanohybrid were then utilized for the triple mode of combined therapeutics of tumor cells, through synergistic catalytic therapy and chemotherapy with combinatorial photothermal therapy to achieve the maximum cancer killing efficiency. It is assumed that the assimilated multimodal imaging and therapeutic capability in single nanoparticle platform is advantageous for future practical applications in cancer diagnosis, therapy, and molecular imaging.

Hydrolytic surface erosion of mesoporous silica nanoparticles for efficient intracellular delivery of cytochrome c.

Delivery of apoptosis-associated proteins is an attractive approach to treat cancer, but their large molecular sizes and membrane-impermeability require the use of a suitable delivery carrier. As a versatile drug carrier, mesoporous silica nanoparticles (MSNs) have been utilized to transport a variety of therapeutic molecules. However, the use of MSNs for protein delivery has been limited because their conventionally obtainable pore size (ca. 2-3 nm in diameter) is too small to load large-sized biomolecular cargos. In this article, we present surface erosion of MSNs by hydrolytic degradation as a new strategy to obtain a mesoporous colloidal carrier for effective delivery of a bulky apoptosis-inducible protein, cytochrome c (CYT). A series of physicochemical properties of particles were analyzed before and after the hydrolytic surface erosion of pristine small-pored MSNs and the subsequent CYT loading. The results showed that hydrolytic degradation of MSNs imparts beneficial structural features for CYT loading and release, i.e., enlarged pores (up to ~10 nm in diameter) and roughened surface texture, leading to significantly enhanced intracellular delivery of CYT over conventional small-pored MSNs. The present results may offer a useful insight into silica degradability for tuning the internal/external surface characteristics of MSN-based colloidal particles to open a wide range of biomedical applications.

Mesostructured Silica for Optical Functionality, Nanomachines, and Drug Delivery.

Silica thin films and nanoparticles prepared using sol-gel chemistry are derivatized with active molecules to generate new functional materials. The mild conditions associated with sol-gel processing allow for the incorporation of a range of dopants including organic or inorganic dyes, biomolecules, surfactants, and molecular machines. Silica nanoparticles embedded with inorganic nanocrystals, and films containing living cells have also been synthesized. Silica templated with surfactants to create mesostructure contains physically and chemically different regions that can be selectively derivatized using defined techniques to create dynamic materials. Using two different techniques, donor-acceptor pairs can be doped into separated regions simultaneously and photo-induced electron transfer between the molecules can be measured. Mesoporous silica materials are also useful supports for molecular machines. Machines including snap-tops and nanoimpellers that are designed to control the release of guest molecules trapped within the pores are described. Mesoporous silica nanoparticles are promising materials for drug delivery and other biomedical applications because they are nontoxic and can be taken up by living cells. Through appropriate design and synthesis, multifunctional mesoporous silica nanoparticles for sophisticated bio-applications are created.

Surface pH buffering to promote degradation of mesoporous silica nanoparticles under a physiological condition.

Despite significant advancement of mesoporous silica nanoparticle (MSN)-based biomedical research, studies have not been done enough to understand biodegradability of functional MSNs for better clinical efficacy. Polyethyleneimine (PEI) is one of the mostly used surface functionalities of MSNs, owing to the amine-rich chemical composition and the well-known proton sponge effect. In this paper, we study degradation behaviors of PEI-coated MSNs (PEI-MSNs) under a neutral or acidic physiological condition in comparison to those of surface-uncoated or nonionic F-127-encapsulated MSNs. The results showed that the surface coating by PEI could promote particle degradation in both neutral and acidic phosphate buffered saline (PBS) solution (i.e., pH 7.4 and 5.0). Importantly, we demonstrated that the local pH buffering by the surface PEI could lead to a greater total degradation quantity of particles even in the acidic PBS solution. The PEI-induced pH buffering phenomenon was confirmed by using a fluorescent pH indicator dye, fluorescein, which was attached to the surface of PEI-MSNs (F-PEI-MSNs). The observed pH-insensitive fluorescing behavior of fluorescein attained by surface coating with PEI corroborates the buffering effect that minimizes the surface pH change regardless of the external pH. The presented results may offer a useful insight into the degradability of silica nanomaterials with PEI or related surface functionalities, especially in the acidic subcellular microenvironment.

Cumulative directional calcium gluing between phosphate and silicate: A facile, robust and biocompatible strategy for siRNA delivery by amine-free non-positive vector.

For siRNA therapeutics, the use of positively charged amine-rich delivery vectors has been indispensable, but the amine-associated toxicological responses remain a clinical conundrum. Herein, we report a new strategy of harnessing a biocompatible, biodegradable and well-tolerated nanomaterial as an amine-free non-positive carrier for siRNA delivery. By employing mesoporous silica nanoparticles (MSNs) as a biocompatible vector, siRNA is loaded nonconventionally through calcium ion (Ca2+)-mediated interconnection (calcium gluing) between phosphates of siRNA and surface silicates of MSNs in a sequential, cumulative and directional way. The "one-pot" gluing process utilizing endogenously abundant Ca2+ ions offers a simple but robust means of siRNA loading on the non-positive bare surface of MSNs without the aid of multi-amine functionalization, and thus minimizes the risk of amine-associated cytotoxicity and immunogenicity while keeping the intrinsic biocompatibility of MSNs. As demonstrated with loading of an anticancer siRNA, this strategy allows stable in vivo delivery of siRNA for targeted gene silencing, and capitalizes on the unique structural versatility of MSNs by simultaneously delivering a pore-loaded chemodrug to synergistically enhance the treatment efficacy. Therefore, the Ca2+-glued MSNs as a general siRNA carrier platform provide a less toxic, less laborious and more utilitarian delivery tool for more effective and safer siRNA therapeutics.

Nootropic nanocomplex with enhanced blood-brain barrier permeability for treatment of traumatic brain injury-associated neurodegeneration.

Traumatic brain injury (TBI) is an intracranial injury which can induce immediate neuroinflammation and long-term neurological deficits. Methylene blue (MB) as a nootropic has a great potential to treat neurodegeneration after TBI because of its anti-inflmmatory and neuroprotective functions. However, its limited accumulation to the brain across the blood-brain barrier (BBB) remains a major hurdle to be overcome. In this paper, we present a polymer surfactant-encapsulated nanocomplex of MB as a delivery system with high BBB permeability for efficacious treatment of TBI-induced neurodegeneration. MB was formulated via electrostatically/hydrophobically directed assembly with fatty acid and Pluronic surfactant (F-127 or F-68) to construct nanocomplexes of two different colloidal sizes (<10 nm and ~108 nm in hydrodynamic diameter for NanoMB-127 and NanoMB-68, respectively). Compared to uncomplexed free MB, formulation into the ultrasmall nanocomplex (NanoMB-127) significantly enhanced the uptake of MB by blood-brain vascular endothelial bEnd3 cells in vitro, and indeed improved its BBB penetration upon systemic administration to normal mice in vivo. However, large-size NanoMB-68 showed negligible BBB crossing despite the efficient bEnd3 cell internalization in vitro, probably due to the unfavorable pharmacokinetic profile associated with its large particle size. By virtue of the efficient BBB penetration and cellular uptake, ultrasmall NanoMB-127 was shown to distinctively reduce the expression level of an inflammatory cytokine with no notable toxicity in vitro and also considerably prevent the neurodegeneration after TBI in mice at much lower doses than free MB. Overall, the Pluronic-supported nanocomplexation method allows efficient brain delivery of MB, offering a novel way of enhancing the efficacy of neurotherapeutics to treat brain diseases.