Enhanced effects of low molecular weight heparin intercalated with layered double hydroxide nanoparticles on rat vascular smooth muscle cells

NF-kB affects migration of vascular smooth muscle cells after treatment with heparin and ibrutinib

The migration of vascular smooth muscle cells (VSMCs) is one of the most important events in the remodeling of atherosclerosis plaque. The aim of study was to investigate the role of Heparin in the VSMC migration and its association with the NF-kB, collagen 1 and collagen 3 expression levels. Moreover, the incorporation of Heparin was studied in the VSMC cultures including Betulinic acid and Ibrutinib. Twelve cell groups were cultured and treated with the Heparin, Betulinic acid and Ibrutinib based on the viability and toxicity in 24-h and 48-h periods. The gene and protein expression levels were measured by RT-qPCR and western blotting techniques. The VSMC migration was determined by scratch test. In contrast with Ibrutinib (2 μM), Heparin (30 IU) increased significantly (P < 0.05) the NF-kB gene and protein expression levels and the VSMC migration during the exposure periods. Heparin (15 IU and 30 IU) also increased the collagen 1 gene expression level in the 48-h period while Heparin (5 IU and 15 IU) increased the collagen 3 gene expression levels in both periods. Incorporating Heparin into the cultures including Betulinic acid and Ibrutinib affected the collagen 1 and collagen 3 expression levels. The data suggested that the cell migration relates to NF-kB in the VSMCs treated with Heparin and Ibrutinib. Furthermore, the Heparin doses (5 IU and 15 IU) were safe for VSMCs based on the NF-kB, and collagen 3 expression levels.

Layered Double Hydroxides as the Unique Product of Target Ionic Construction for Energy, Chemical, Foods, Cosmetics, Medicine and Ecology Applications

Layered Double Hydroxide (LDH) is an α-modification of the M-host (M2+ ) hydroxide, in which some part of the M-host cations is replaced by M-guest cations (M3+ or M4+ ). The emerging excess positive charge is compensated by the intercalation of anions into the interlayer space, which also contains water molecules. LDHs exhibit anion exchange properties. Targeted ionic design of LDHs via combining three components (M-host, M-guest cations, intercalated anions) allows the creation of a very wide range of highly efficient electrochemical, electrocatalytic, electrochromic substances, catalysts, ion exchangers, sorbents, color pigments, pharmacological drugs, food, and cosmetic additives. In this review, the structure and areas of application of LDHs are considered from the perspective of the targeted ionic design of a substance for a specific application.

Experimental study of a heparin-coated venous stent fabricated by atomic layer deposition

OBJECTIVE

To evaluate the safety and efficacy of heparin-coated venous stents in animals.

METHODS

We used atomic layer deposition technology to obtain a heparin coating with good stability and then prepared a heparin-coated venous stent based on this technology. The experimental stents were prepared according to the diameter of the rabbit inferior vena cava and were divided into Ni-Ti alloy stent group, Ni-Ti-Al₂O₃ stent group and Ni-Ti-Al₂O₃-Heparin stent group. 3 days, 7 days and 14 days after stent implantation, the materials were collected, and the three groups of stents were observed by hard tissue section pathology, immunohistochemistry and scanning electron microscope to observe the differences in vascular wall inflammation, thrombosis, lumen stenosis and vascular intima regeneration.

RESULT AND CONCLUSION

The experiment confirmed the safety of the heparin-coated stent in vivo. Compared with the control group, the experimental group showed a high degree of vascular endothelialization and an intact neointimal structure 14 days after implantation. The long-term safety and biological effects of heparin-coated venous stents in animals require further study.

Surface modification of two-dimensional layered double hydroxide nanoparticles with biopolymers for biomedical applications

Layered double hydroxides (LDHs) are appealing nanomaterials for (bio)medical applications and their potential is threefold. One can gain advantage of the structure of LDH frame (i.e., layered morphology), anion exchanging property towards drugs with acidic character and tendency for facile surface modification with biopolymers. This review focuses on the third aspect, as it is necessary to evaluate the advantages of polymer adsorption on LDH surfaces. Beside the short discussion on fundamental and structural features of LDHs, LDH-biopolymer interactions will be classified in terms of the effect on the colloidal stability of the dispersions. Thereafter, an overview on the biocompatibility and biomedical applications of LDH-biopolymer composite materials will be given. Finally, the advances made in the field will be summarized and future research directions will be suggested.

Nanoparticles in the diagnosis and treatment of vascular aging and related diseases

Aging-induced alternations of vasculature structures, phenotypes, and functions are key in the occurrence and development of vascular aging-related diseases. Multiple molecular and cellular events, such as oxidative stress, mitochondrial dysfunction, vascular inflammation, cellular senescence, and epigenetic alterations are highly associated with vascular aging physiopathology. Advances in nanoparticles and nanotechnology, which can realize sensitive diagnostic modalities, efficient medical treatment, and better prognosis as well as less adverse effects on non-target tissues, provide an amazing window in the field of vascular aging and related diseases. Throughout this review, we presented current knowledge on classification of nanoparticles and the relationship between vascular aging and related diseases. Importantly, we comprehensively summarized the potential of nanoparticles-based diagnostic and therapeutic techniques in vascular aging and related diseases, including cardiovascular diseases, cerebrovascular diseases, as well as chronic kidney diseases, and discussed the advantages and limitations of their clinical applications.

Bioactive 2D nanomaterials for neural repair and regeneration

Biomaterials have provided promising strategies towards improving the functions of injured tissues of the nervous system. Recently, 2D nanomaterials, such as graphene, layered double hydroxides (LDHs), and black phosphorous, which are characterized by ultrathin film structures, have attracted much attention in the fields of neural repair and regeneration. 2D nanomaterials have extraordinary physicochemical properties and excellent biological activities, such as a large surface-area-to-thickness ratio, high levels of adhesion, and adjustable flexibility. In addition, they can be designed to have superior biocompatibility and electrical or nano-carrier properties. To date, many 2D nanomaterials have been used for synaptic modulation, neuroinflammatory reduction, stem cell fate regulation, and injured neural cell/tissue repair. In this review, we discuss the advances in 2D nanomaterial technology towards novel neurological applications and the mechanisms underlying their unique features. In addition, the future outlook of functional 2D nanomaterials towards addressing the difficult issues of neuropathy has been explored to introduce a promising strategy towards repairing and regenerating the injured nervous system.

Strategy for Cytoplasmic Delivery Using Inorganic Particles

Endosome escape is a key process for intracellular uptake of intact biomolecules and therapeutics, such as nucleic acids. Lysosome escape is a more common pathway during endocytosis, while some biomolecular, organic and inorganic materials are found to enhance the endosome escape, and several mechanisms have been proposed accordingly. Specifically, some inorganic nanomaterials show their unique mechanisms of action for enhanced endosome escape, including salt osmotic effect and gas blast effect. These inorganic nanomaterials are basically weakly alkaline and are naturally featured with the anti-acidification capacity, with limited solubility in neutral solutions. This review paper has briefly presented the strategies in the design of inorganic nanoparticle-based cellular delivery vehicles with endosome escapability and discussed a few typical inorganic nanomaterials that are currently widely examined for delivery purpose. A brief summary and prospect for this kind of inorganic nanomaterials are provided.

Emerging 2D Nanomaterials for Biomedical Applications

Two-dimensional (2D) nanomaterials are an emerging class of biomaterials with remarkable potential for biomedical applications. The planar topography of these nanomaterials confers unique physical, chemical, electronic and optical properties, making them attractive candidates for therapeutic delivery, biosensing, bioimaging, regenerative medicine, and additive manufacturing strategies. The high surface-to-volume ratio of 2D nanomaterials promotes enhanced interactions with biomolecules and cells. A range of 2D nanomaterials, including transition metal dichalcogenides (TMDs), layered double hydroxides (LDHs), layered silicates (nanoclays), 2D metal carbides and nitrides (MXenes), metal-organic framework (MOFs), covalent organic frameworks (COFs) and polymer nanosheets have been investigated for their potential in biomedical applications. Here, we will critically evaluate recent advances of 2D nanomaterial strategies in biomedical engineering and discuss emerging approaches and current limitations associated with these nanomaterials. Due to their unique physical, chemical, and biological properties, this new class of nanomaterials has the potential to become a platform technology in regenerative medicine and other biomedical applications.

Two-dimensional layered double hydroxide nanoadjuvant: recent progress and future direction

Layered double hydroxide (LDH) is a 'sandwich'-like two-dimensional clay material that has been systematically investigated for biomedical application in the past two decades. LDH is an alum-similar adjuvant, which has a well-defined layered crystal structure and exhibits high adjuvanticity. The unique structure of LDH includes positively charged layers composed of divalent and trivalent cations and anion-exchangeable interlayer galleries. Among the many variants of LDH, MgAl-LDH (the cationic ions are Mg2+ and Al3+) has the highest affinity to antigens, bioadjuvants and drug molecules, and exhibits superior biosafety. Past research studies indicate that MgAl-LDH can simultaneously load antigens, bioadjuvants and molecular drugs to amplify the strength of immune responses, and induce broad-spectrum immune responses. Moreover, the size and dispersity of MgAl-LDH in biological environments can be well controlled to actively deliver antigens to the immune system, realizing the rapid induction and maintenance of durable immune responses. Furthermore, the functionalization of MgAl-LDH nanoadjuvants enables it to capture antigens in situ and induce personalized immune responses, thereby more effectively overcoming complex diseases. In this review, we comprehensively summarize the development and application of MgAl-LDH nanoparticles as a vaccine adjuvant, demonstrating that MgAl-LDH is the most potential adjuvant for clinical application.

Controllable assembly/disassembly of polyphenol-DNA nanocomplex for cascade-responsive drug release in cancer cells

Developing nanocarrier systems with sufficient drug loading ability and efficient drug release behavior in cells is a powerful strategy to maximize therapeutic efficacies and minimize side effects of administered drugs. However, the two aspects are usually contradictory in a single nanocarrier. Herein, polyphenol-DNA nanocomplex with controllable assembly/disassembly behaviors is developed for responsive and sequential drug release in cancer cells. Programmable assembly of branched-DNA achieves multiple-gene loading, afterwards tannic acid (TA), plant-derived polyphenols as drugs mediate assembly of branched-DNA to form nanocomplex. Intracellularly, two-step disassembly process of nanocomplex enables efficient gene/drug release. Lysosomal acidic microenvironment induces the disassembly of nanocomplex to release TA and branched-DNA. Glutathione and DNase I in cytoplasm trigger the precise release of genes from branched-DNA. The efficacy of multiple-gene/chemo-therapy is demonstrated using in vitro and in vivo models. This work provides a controllable assembly/disassembly route to resolve the conflict between sufficient drug loading and efficient drug release in cells for therapeutics.

Layered double hydroxide nanostructures and nanocomposites for biomedical applications

Layered double hydroxide (LDH) nanostructures and related nanocomposites have attracted significant interest in biomedical applications including cancer therapy, bioimaging and antibacterial treatment. These materials hold great advantages including low cost and facile preparation, convenient drug loading, high drug incorporation capacity, good biocompatibility, efficient intracellular uptake and endosome/lysosome escape, and natural biodegradability in an acidic environment. In this review, we summarize the development of three types of LDH nanostructures including pristine LDH, surface modified LDH, and LDH nanocomposites for a range of biomedical applications. The advantages and disadvantages of LDH nanostructures and insights into the future development are also discussed.

Performance of Halloysite-Mg/Al LDH Materials for Aqueous As(V) and Cr(VI) Removal

This research focused on the investigation of layered double hydroxide (LDH)/halloysite materials’ adsorption efficiency and mechanisms in reactions with aqueous As(V) and Cr(VI) in a broad pH range. The materials consisting of Mg/Al LDH and halloysite were synthesized using both direct precipitation and physical mixing methods. The XRD, FTIR, DTA, SEM and XPS methods were used to evaluate the quality of the obtained materials and get insight into removal mechanisms. The XRD, FTIR and DTA confirmed LDH formation and showed the dominating presence of intercalated carbonates in the LDH structure. The SEM of the materials revealed characteristic agglomerates of layered LDH particles deposited on halloysite tubular forms. The raw LDH phases showed high removal efficiency of both As(V) and Cr (VI) for initial pH in the range of 3–7. In the studied concentration range the materials containing 25 wt % of LDH exhibited a removal efficiency very similar to the raw LDH. In particular, the halloysite presence in the materials’ mass had a positive effect in the reactions with As(V), which was removed by chemisorption. At a low pH the LDH component underwent partial dissolution, which lowered the adsorption efficiency. Apart from the anion exchange mechanism at a low pH the Cr(VI) was removed via formation of MgCrO₄ with Mg (II) being released from the LDH structure. The XPS spectra for As(V) did not show changes in oxidation state in the reactions. In turn, a partial reduction of Cr(VI) to Cr(III) was observed, especially at a high pH. The use of materials composed of two different minerals is promising due to reduction of costs as well as prevention of adsorbent swelling. This opens the possibility of its use in dynamic adsorption flow through systems.

Enhancing PD-1 Gene Silence in T Lymphocytes by Comparing the Delivery Performance of Two Inorganic Nanoparticle Platforms

Suitable carriers are crucial to RNAi applications for cancer genotherapy and T-cell immunotherapy. In this research, we selected two extensively-investigated biocompatible inorganic nanoparticle carriers, i.e., layered double hydroxide (LDH) and lipid-coated calcium phosphate (LCP) and then compared their efficacy for siRNA delivery in T cells, in order to understand which carrier is more efficient in delivering functional programmed cell death protein 1 siRNA (PD-1 siRNA) to suspended T lymphocytes. Both LDH and LCP nanoparticles quickly delivered gene segment to mouse T cell lines (EL4), while the LCP nanoparticles exhibited more cellular uptake and higher PD-1 gene silence efficiency. We further demonstrated that LCP nanoparticles successfully reduced the expression of PD-1 in human ex vivo tumor infiltrating lymphocytes (TILs). Thus, LCP nanoparticles can be used as a better nano-carrier for gene therapy in lymphocytes, especially in regards to TIL-related cancer immunotherapy.

Biodegradable 2D Fe-Al Hydroxide for Nanocatalytic Tumor-Dynamic Therapy with Tumor Specificity

Therapeutic nanocatalysis has emerged as an intriguing strategy for efficient cancer-specific therapy, but the traditional inorganic nanocatalysts suffer from low catalytic efficiency and difficulty in biodegradation, hindering their further clinical translation. Herein, a tumor microenvironment-triggered, biodegradable and biocompatible nanocatalyst employing 2D hydroxide nanosheet is presented, and is shown to have high catalytic capacity to efficiently produce abundant hydroxyl radicals under the tumor microenvironment and consequently kill tumor cells selectively. A polyethylene glycol (PEG)-conjugated Fe2+-containing hydroxide nanosheet is successfully constructed via a facile but efficient bottom-up approach that concurrently realizes nanosheet synthesis and PEGylation. Importantly, the nanosheets are featured with high catalytic activity to disproportionate H2O2 in tumors, and consequently generate abundant hydroxyl radicals at a high reaction rate under tumorous acidic condition; the highly toxic hydroxyl radicals, as a result, cause the death of tumor cells in vitro and suppress the tumor growth in vivo without the use of any supplementary toxic agent, only with the biocompatible nanocatalysts. Meanwhile, the desirable biodegradation and biocompatibility of the hydroxide nanosheet render a high degree of safety to the organism. Therefore, this work provides the first paradigm of biodegradable 2D nanocatalytic platform with concurrently high catalytic-therapeutic performance and biosafety for efficient tumor-specific treatment.

Macroporous nanofibrous vascular scaffold with improved biodegradability and smooth muscle cells infiltration prepared by dual phase separation technique

INTRODUCTION

The fast degradation of vascular graft and the infiltration of smooth muscle cells (SMCs) into the vascular graft are considered to be critical for the regeneration of functional neo-vessels. In our previous study, a novel dual phase separation technique was developed to one-pot prepare macroporous nanofibrous poly(L-lactic acid) (PLLA)/poly(ε-caprolactone) (PCL) vascular scaffold by phase separating the immiscible polymer blend. However, the slow degradation of PLLA/PCL limited cell infiltration. Herein, we hypothesized that poly(lactic-co-glycolic acid) (PLGA) would be miscible with PLLA but immiscible with PCL. Then, PLGA can be introduced into the PLLA/PCL blend to fabricate macroporous nanofibrous scaffold with improved biodegradability by using dual phase separation technique.

MATERIALS AND METHODS

The miscibility of PLGA with PLLA and PCL was evaluated. Then, the PLLA/PLGA/PCL scaffold was prepared by dual phase separation technique. The prepared scaffolds were characterized in terms of the morphology, in vitro degradation, mechanical properties, and cells' infiltration and viability for human vascular SMCs (HVSMCs). Finally, platelet-derived growth factor-BB (PDGF-BB) was immobilized on the scaffold and its effect on the bioactivity of HVSMCs was studied.

RESULTS

PLGA is miscible with PLLA but immiscible with PCL as hypothesized. The addition of PLGA enlarged the pore size and improved the biodegradability of composite scaffold. Notably, PLLA/PLGA/PCL scaffold with the blend ratio of 30:40:30 possessed improved pore interconnectivity for cells' infiltration and enough mechanical properties. Moreover, HVSMCs could grow and infiltrate into this scaffold, and surface modification with PDGF-BB on the nanofibrous scaffold enhanced HVSMCs migration and proliferation.

CONCLUSION

This study provides a strategy to expand dual phase separation technique into utilizing ternary even multinary polymer blend to fabricate macroporous nanofibrous scaffold with improved physicochemical properties. The prepared PLLA/PLGA/PCL scaffold would be promising for the regeneration of functional tunica media in vascular tissue engineering.

Tissue Engineering at the Blood-Contacting Surface: A Review of Challenges and Strategies in Vascular Graft Development

Tissue engineered vascular grafts (TEVGs) are beginning to achieve clinical success and hold promise as a source of grafting material when donor grafts are unsuitable or unavailable. Significant technological advances have generated small-diameter TEVGs that are mechanically stable and promote functional remodeling by regenerating host cells. However, developing a biocompatible blood-contacting surface remains a major challenge. The TEVG luminal surface must avoid negative inflammatory responses and thrombogenesis immediately upon implantation and promote endothelialization. The surface has therefore become a primary focus for research and development efforts. The current state of TEVGs is herein reviewed with an emphasis on the blood-contacting surface. General vascular physiology and developmental challenges and strategies are briefly described, followed by an overview of the materials currently employed in TEVGs. The use of biodegradable materials and stem cells requires careful control of graft composition, degradation behavior, and cell recruitment ability to ensure that a physiologically relevant vessel structure is ultimately achieved. The establishment of a stable monolayer of endothelial cells and the quiescence of smooth muscle cells are critical to the maintenance of patency. Several strategies to modify blood-contacting surfaces to resist thrombosis and control cellular recruitment are reviewed, including coatings of biomimetic peptides and heparin.

Enhanced colloidal stability and protein resistance of layered double hydroxide nanoparticles with phosphonic acid-terminated PEG coating for drug delivery

Conjugating nanoparticles with polyethylene glycol (PEG) is a useful strategy to improve the colloidal and biological stability of nanoparticles. However, studies on PEGylation of two-dimensional layered double hydroxide (LDH) nanoparticles are very limited. The present work reported two functionalization approaches to synthesize PEG-conjugated LDH nanoparticles by introducing phosphonic acid terminated PEG before and after LDH aging. The successful PEGylation was confirmed and suggested to be via electrostatic interaction and a ligand exchange process. Different functionalization approaches resulted in different binding types of PEG on/in LDH nanoparticles. The PEG coating maintained the dispersity of LDH nanoparticles in water and saline with the feeding mass ratio of 1:1. Further colloidal stability tests of PEGylated LDHs revealed that the PEGylated LDH dispersity was affected by the feeding mass ratio of PEG/LDH, the molar weight of PEG and anions intercalated in the LDHs. In a test to determine the extent of non-specific protein adsorption, the PEGylation was effective at resisting non-specific bovine serum albumin adsorption on LDH nanoparticles with both functionalization methods investigated. Moreover, PEGylated LDH nanoparticles had no effect on cell viability up to 500 µg/mL, and demonstrated enhanced cellular uptake in a SK-MEL-28 cell culture. The results in this work indicate that conjugating phosphonic acid-terminated PEG on LDH nanoparticles is a promising strategy to improve the colloidal and biological stability of LDHs for biomedical applications.

Development of low molecular weight heparin based nanoparticles for metastatic breast cancer therapy

Tumor metastasis is the primary obstacle in cancer treatment and is always the leading cause of human death. And heparin and its derivatives are potential anti-metastatic agents with good biocompatibility. In this work, low molecular weight heparin (LMWH) based LMWH-Cholesterol (LHC) conjugates were prepared for intravenous delivery of doxorubicin (DOX). The DOX/LHC nanoparticles (DOX/LHC NPs) exhibited a spherical shape with a mean diameter of 135.5±2.2nm and had a longer circulation time than that of DOX. The in vitro results confirmed that the DOX/LHC NPs was more effectively taken up by 4T1 cells and showed a stronger anti-metastatic effect by cell invasion and cell migration compared with DOX. Meanwhile, DOX/LHC NPs also exhibited superior anti-metastatic effects in the pulmonary metastasis model compared with other groups. The reason may be account for the synergistic effect between the cytotoxic drug of DOX and its drug carrier of LMWH based nanoparticles, which is capable of anti-metastatic and anti-angiogenic efficiency. Thus DOX/LHC nanoparticles could be a promising anti-metastatic drug delivery system for postoperative chemotherapy.

Catechol/polyethyleneimine conversion coating with enhanced corrosion protection of magnesium alloys: potential applications for vascular implants

A catechol/polyethyleneimine conversion coating on a MgZnMn alloy possessed good corrosion resistance. Heparin was further grafted on it and this showed the potential for surface modification of magnesium-based vascular implants.

A Novel Type of Aqueous Dispersible Ultrathin-Layered Double Hydroxide Nanosheets for in Vivo Bioimaging and Drug Delivery

Layered double hydroxide (LDH) nanoparticles have been widely used for various biomedical applications. However, because of the difficulty of surface functionalization of LDH nanoparticles, the systemic administration of these nanomaterials for in vivo therapy remains a bottleneck. In this work, we develop a novel type of aqueous dispersible two-dimensional ultrathin LDH nanosheets with a size of about 50 nm and a thickness of about 1.4 to 4 nm. We are able to covalently attach positively charged rhodamine B fluorescent molecules to the nanosheets, and the nanohybrid retains strong fluorescence in liquid and even dry powder form. Therefore, it is available for bioimaging. Beyond this, it is convenient to modify the nanosheets with neutral poly(ethylene glycol) (PEG), so the nanohybrid is suitable for drug delivery through systemic administration. Indeed, in the test of using these nanostructures for delivery of a negatively charged anticancer drug, methotrexate (MTX), in a mouse model, dramatically improved therapeutic efficacy is achieved, indicated by the effective inhibition of tumor growth. Furthermore, our systematic in vivo safety investigation including measuring body weight, determining biodistribution in major organs, hematology analysis, blood biochemical assay, and hematoxylin and eosin stain demonstrates that the new material is biocompatible. Overall, this work represents a major development in the path of modifying functional LDH nanomaterials for clinical applications.

MnAl Layered Double Hydroxide Nanoparticles as a Dual-Functional Platform for Magnetic Resonance Imaging and siRNA Delivery

Multifunctional nanoparticles for cancer theranosis have been widely explored for effective cancer detection and therapy. In this work, dually functionalised manganese-based layered double hydroxide nanoparticles (Mn-LDH) were examined as an effective anticancer drug/gene delivery system and for T₁ -weighted magnetic resonance imaging (MRI) in brain cancer theranostics. Such Mn-LDH have been shown to accommodate dsDNA/siRNAs and efficiently deliver them to Neuro-2a cells (N2a). Mn-LDH have also shown high biocompatibility with low cytotoxicity. Importantly, the cell-death siRNA (CD-siRNA) delivered with Mn-LDH more efficiently kills brain cancer cells than the free CD-siRNA. Moreover, Mn-LDH can act as excellent contrast agents for MRI, with an r₁ value of 4.47 mm^-1  s^-1 , which is even higher than that of commercial contrast agents based on Gd complexes (r₁ =3.4 mm^-1  s^-1 ). Altogether, the high delivery efficacy and MRI contrast capability make dual-functional Mn-LDH potential bimodal agents for simultaneous cancer diagnosis and therapy.

Manganese-Based Layered Double Hydroxide Nanoparticles as a T1 -MRI Contrast Agent with Ultrasensitive pH Response and High Relaxivity

Recently, Mn(II)-containing nanoparticles have been explored widely as an attractive alternative to Gd(III)-based T₁ -weighted magnetic resonance imaging (MRI) contrast agents (CAs) for cancer diagnosis. However, as far as it is known, no Mn-based MRI CAs have been reported to sensitively respond to a very weakly acidic environment (pH 6.5-7.0, i.e., the pH range in a tumor microenvironment) with satisfactory imaging performance. Here, recently devised pH-ultrasensitive Mn-based layered double hydroxide (Mn-LDH) nanoparticles with superb longitudinal relaxivity (9.48 mm^-1 s^-1 at pH 5.0 and 6.82 mm^-1 s^-1 at pH 7.0 vs 1.16 mm^-1 s^-1 at pH 7.4) are reported, which may result from the unique microstructure of Mn ions in Mn-LDH, as demonstrated by extended X-ray absorption fine structure. Further in vivo imaging reveals that Mn-LDH nanoparticles show clear MR imaging for tumor tissues in mice for 2 d post intravenous injection. Thus, this novel Mn-doped LDH nanomaterial, together with already demonstrated capacity for drug and gene delivery, is a very potential theranostic agent for cancer diagnosis and treatment.

A Facile Way of Modifying Layered Double Hydroxide Nanoparticles with Targeting Ligand-Conjugated Albumin for Enhanced Delivery to Brain Tumour Cells

Active targeting of nanoparticles (NPs) for cancer treatment has attracted increasing interest in the past decades. Various ligand modification strategies have been used to enhance the targeting of NPs to the tumor site. However, how to reproducibly fabricate diverse targeting NPs with narrowly changeable biophysiochemical properties remains as a major challenge. In this study, layered double hydroxide (LDH) NPs were modified as a target delivery system. Two brain tumor targeting ligands, i.e., angiopep-2 and rabies virus glycoprotein, were conjugated to the LDH NPs via an intermatrix protein moiety, bovine serum albumin (BSA), simultaneously endowing the LDHs with excellent colloidal stability and targeting capability. The ligands were first covalently linked with BSA through the heterobifunctional cross-linker sulfosuccinimidyl 4-(N-maleimidomethyl)cyclohexane-1-carboxylate. Then, the ligand-linked BSA and pristine BSA were together coated onto the surface of LDHs through electrostatic interaction, followed by cross-linking with the cross-linker glutaraldehyde to immobilize these BSAs on the LDH surface. In this way, we are able to readily prepare colloidally stabilized tumor-targeted LDH NPs. The targeting efficacy of the ligand-conjugated LDH delivery system has been evidenced in the uptake by two neutral cells (U87 and N2a) compared to unmodified LDHs. This new approach provides a promising strategy for rational design and preparation of target nanoparticles as a selective and effective therapeutic treatment for brain tumors.

Aggregation of layered double hydroxide nanoparticles in the presence of heparin: towards highly stable delivery systems

Heparin coating significantly enhanced the colloidal stability of layered double hydroxide nanoparticles.

Synthesis and characterization of layered double hydroxides and their potential as nonviral gene delivery vehicles

Layered double hydroxides (LDHs) exhibit characteristic anion-exchange chemistry making them ideal carriers of negatively charged molecules like deoxyribonucleic acid (DNA). In this study, hydrotalcite (Mg-Al) and hydrotalcite-like compounds (Mg-Fe, Zn-Al, and Zn-Fe), also known as LDHs, were evaluated for their potential application as a carrier of DNA. LDHs were prepared by coprecipitation at low supersaturation and characterized by Powder X-ray diffraction (XRD), infrared (IR), Raman, and inductively coupled plasma-optical emission spectroscopy, scanning electron microscopy (SEM), and transmission electron microscopy (TEM). XRD patterns showed strong and sharp diffraction peaks for the (003) and (006) planes indicating well-ordered crystalline materials. TEM images yielded irregular circular to hexagonal-shaped particles of 50-250 nm in size. Varying degrees of DNA binding was observed for all the compounds, and nuclease digestion studies revealed that the LDHs afford some degree of protection to the bound DNA. Minimal toxicity was observed in human embryonic kidney (HEK293), cervical cancer (HeLa) and hepatocellular carcinoma (HepG2) cell lines with most showing a cell viability in excess of 80 %. All LDH complexes promoted significant levels of luciferase gene expression, with the DNA:Mg-Al LDHs proving to be the most efficient in all cell lines.

Cooperative control of blood compatibility and re-endothelialization by immobilized heparin and substrate topography

A wide variety of environmental cues provided by the extracellular matrix, including biophysical and biochemical cues, are responsible for vascular cell behavior and function. In particular, substrate topography and surface chemistry have been shown to regulate blood and vascular compatibility individually. The combined impact of chemical and topographic cues on blood and vascular compatibility, and the interplay between these two types of cues, are subjects that are currently being explored. In the present study, a facile polydopamine-mediated approach is introduced for immobilization of heparin on topographically patterned substrates, and the combined effects of these cues on blood compatibility and re-endothelialization are systematically investigated. The results show that immobilized heparin and substrate topography cooperatively modulate anti-coagulation activity, endothelial cell (EC) attachment, proliferation, focal adhesion formation and endothelial marker expression. Meanwhile, the substrate topography is the primary determinant of cell alignment and elongation, driving in vivo-like endothelial organization. Importantly, combining immobilized heparin with substrate topography empowers substantially greater competitive ability of ECs over smooth muscle cells than each cue individually. Moreover, a model is proposed to elucidate the cooperative interplay between immobilized heparin and substrate topography in regulating cell behavior.

Layered double hydroxide nanoparticles to enhance organ-specific targeting and the anti-proliferative effect of cisplatin

The role of nanoparticle charge in biodistribution is evaluated by modifying the external surface of layered double hydroxides with various charges and a fluorescent dye (Cy5.5) is doped to assess the biodistribution.

Pre-coating layered double hydroxide nanoparticles with albumin to improve colloidal stability and cellular uptake

We introduced a new strategy of albumin pre-coating to effectively stabilise layered double hydroxide (LDH) nanoparticles for biomedical applications.

Controlled synthesis of monodisperse silver nanoparticles supported layered double hydroxide catalyst

Monodisperse silver nanoparticles supported layered double hydroxides (Ag NPs–LDH) were preferentially deposited on the outer surfaces of pillared LDH offered a high catalytic activity on alcohol oxidation.

Mussel-inspired one-step adherent coating rich in amine groups for covalent immobilization of heparin: hemocompatibility, growth behaviors of vascular cells, and tissue response

Heparin, an important polysaccharide, has been widely used for coatings of cardiovascular devices because of its multiple biological functions including anticoagulation and inhibition of intimal hyperplasia. In this study, surface heparinization of a commonly used 316L stainless steel (SS) was explored for preparation of a multifunctional vascular stent. Dip-coating of the stents in an aqueous solution of dopamine and hexamethylendiamine (HD) (PDAM/HD) was presented as a facile method to form an adhesive coating rich in primary amine groups, which was used for covalent heparin immobilization via active ester chemistry. A heparin grafting density of about 900 ng/cm(2) was achieved with this method. The retained bioactivity of the immobilized heparin was confirmed by a remarkable prolongation of the activated partial thromboplastin time (APTT) for about 15 s, suppression of platelet adhesion, and prevention of the denaturation of adsorbed fibrinogen. The Hep-PDAM/HD also presented a favorable microenvironment for selectively enhancing endothelial cell (EC) adhesion, proliferation, migration and release of nitric oxide (NO), and at the same time inhibiting smooth muscle cell (SMC) adhesion and proliferation. Upon subcutaneous implantation, the Hep-PDAM/HD exhibited mitigated tissue response, with thinner fibrous capsule and less granulation formation compared to the control 316L SS. This number of unique functions qualifies the heparinized coating as an attractive alternative for the design of a new generation of stents.

Influence of hydrothermal treatment on physicochemical properties and drug release of anti-inflammatory drugs of intercalated layered double hydroxide nanoparticles

The synthesis method of layered double hydroxides (LDHs) determines nanoparticles’ performance in biomedical applications. In this study, hydrothermal treatment as an important synthesis technique has been examined for its influence on the physicochemical properties and the drug release rate from drug-containing LDHs. We synthesised MgAl–LDHs intercalated with non-steroidal anti-inflammatory drugs (i.e., naproxen, diclofenac and ibuprofen) using a co-precipitation method with or without hydrothermal treatment (150 °C, 4 h). After being hydrothermally treated, LDH–drug crystallites increased in particle size and crystallinity, but did not change in the interlayer anion orientation, gallery height and chemical composition. The drug release patterns of all studied LDH–drug hybrids were biphasic and sustained. LDHs loaded with diclofenac had a quicker drug release rate compared with those with naproxen and ibuprofen, and the drug release from the hydrothermally-treated LDH–drug was slower than the freshly precipitated LDH–drug. These results suggest that the drug release of LDH–drugs is influenced by the crystallite size of LDHs, which can be controlled by hydrothermal treatment, as well as by the drug molecular physicochemical properties.

Release behavior and toxicity profiles towards A549 cell lines of ciprofloxacin from its layered zinc hydroxide intercalation compound

Background

Layered hydroxides salts (LHS), a layered inorganic compound is gaining attention in a wide range of applications, particularly due to its unique anion exchange properties. In this work, layered zinc hydroxide nitrate (LZH), a family member of LHS was intercalated with anionic ciprofloxacin (CFX), a broad spectrum antibiotic via ion exchange in a mixture solution of water:ethanol.

Results

Powder x-ray diffraction (XRD), Fourier transform infrared (FTIR) and thermogravimetric analysis (TGA) confirmed the drug anions were successfully intercalated in the interlayer space of LZH. Specific surface area of the obtained compound was increased compared to that of the host due to the different pore textures between the two materials. CFX anions were slowly released over 80 hours in phosphate-buffered saline (PBS) solution due to strong interactions that occurred between the intercalated anions and the host lattices. The intercalation compound demonstrated enhanced antiproliferative effects towards A549 cancer cells compared to the toxicity of CFX alone.

Conclusions

Strong host-guest interactions between the LZH lattice and the CFX anion give rise to a new intercalation compound that demonstrates sustained release mode and enhanced toxicity effects towards A549 cell lines. These findings should serve as foundations towards further developments of the brucite-like host material in drug delivery systems.

A calcium phosphate nanoparticle-based biocarrier for efficient cellular delivery of antisense oligodeoxynucleotides

Antisense oligodeoxynucleotides (ASODNs) can bind to some specific RNA of survivin can prevent the mRNA translation at the genetic level, which will inhibit survivin expression and make the cancer cells apoptosis. However, the ASODNs-based therapies are hampered by their instability to cellular nuclease and their weak intracellular penetration. Here we reported a calcium phosphate (CP)-based carrier to achieve efficient delivery of ASODNs into cells. In this study, we used a facile microemulsion approach to prepare spherical and porous ASODNs-CP nanoparticles (ASODNS-CPNPs) with the size of 50-70 nm in diameter, and their structure, morphology and composition were characterized by TEM, XRD, FTIR, ICP and DLS, UV-Vis spectroscopy and agarose gel electrophoresis. The results indicated that the nanoparticles have a high ASODNs loading capacity. Furthermore, cellular uptake and delivery efficiency of the ASODNS-CPNPs, as well as cellular apoptosis induced by the ASODNs doping into the calcium phosphate nanoparticles, were investigated by confocal laser scanning microscopy, biological TEM, flow cytometry, and MTT assay. Efficient intracellular delivery of the nanoparticles was observed. All these results suggested that the prepared calcium phosphate nanoparticles could be used as a promising biocarrier for delivery of ASODNs.

Layered double hydroxides as efficient drug delivery system of ciprofloxacin in the middle ear: an animal study in rabbits

Chronic otitis media is a common disease often accompanied by recurrent bacterial infections. These may lead to the destruction of the middle ear bones such that prostheses have to be implanted to restore sound transmission. Surface coatings with layered double hydroxides (LDHs) are evaluated here as a possibility for drug delivery systems with convenient advantages such as low cytotoxicity and easy synthesis. Male New Zealand White rabbits were implanted with Bioverit(®) II middle ear prostheses coated with the LDH Mg(4)Al(2)(OH)(12)(SO(4))(2)·6H(2)O impregnated with ciprofloxacin. 12 (group 1) were directly infected with Pseudomonas aeruginosa and another 12 (group 2) 1 week after the implantation. Clinical outcome, blood counts, histological analyses and microbiological examination showed an excellent antimicrobial activity for group 1, whereas this effect was attenuated in animals where infection was performed 1 week after implantation. This is the first study to demonstrate an efficient drug delivery system with an LDH coating on prostheses in the middle ear.

Reduction in the size of layered double hydroxide nanoparticles enhances the efficiency of siRNA delivery

Small interfering RNAs (siRNAs) are a potentially powerful new class of pharmaceutical drugs for many disease. However, the delivery of unprotected siRNAs is ineffective due to their susceptibility to degradation by ubiquitous nucleases under physiological conditions. Layered double hydroxide nanoparticles (LDHs) have been found to be efficient carriers of anionic drugs and nucleic acids. Our previous research has shown that LDHs (with the Z-average particle size of approximately 110 nm) can mediate siRNA delivery in mammalian cells, resulting in gene silencing. However, short double-stranded nucleic acids are mostly adsorbed onto the external surface and not well protected by LDHs. In order to enhance the intercalation of siRNA into the LDH interlayer and the efficiency of subsequent siRNA delivery, we prepared smaller LDHs (with the Z-average particle size of approximately 45 nm) with an engineered non-aqueous method. We demonstrate here that dsDNA/siRNA is more effectively intercalated into these small LDH nanoparticles, more dsDNA/siRNA is transfected into HEK 293T cells, and more efficient silencing of the target gene is achieved using smaller LDHs. Thus, smaller LDH particles have greater potential as a delivery system for the application of RNA interference.

Antibody-targeted drug delivery to injured arteries using layered double hydroxide nanoparticles

Targeted local delivery of a nanoparticle-based, antibody-targeted, and low molecular weight heparin (LMWH) delivery system successfully reduces restenosis and thrombus formation in an animal model. An antibody recognizing cross-linked fibrin (XLF) D-dimer is successfully conjugated to layered double hydroxide nanoparticles. Use of the anti-XLF-conjugated LMWH-carrying layered double hydroxide nanoparticles shows successful targeting of the nanoparticles (red) to the injured artery wall (green), resulting in decreased neointimal thickening and thrombus formation.

Efficiency of layered double hydroxide nanoparticle-mediated delivery of siRNA is determined by nucleotide sequence

In this paper, we report the novel finding that the cellular delivery efficiency of siRNAs or their mimic double-stranded (ds)DNA using layered double hydroxide (LDH) nanoparticles is dependent upon the nucleotide sequence. Efficacy of LDH-mediated delivery of four different siRNAs into cortical neurons and NIH 3T3 cells was found to vary widely (from 6 to 80%, and 2-11%, respectively). Our investigation into the formation of dsDNA-LDH complexes through monitoring the dsDNA:LDH mass ratio at the point of zero charge (PZC) indicated that the degree of intercalation of the individual dsDNA sequences into the LDH nanoparticles varied significantly. The dsDNA:LDH mass ratio at the PZC was found to be dependent on the nucleotide sequence. We further observed that PZC for each sequence was positively related to the extent of LDH-mediated internalization of the equivalent siRNA into neurons and fibroblasts. This novel finding therefore suggests that the mass ratio at the PZC is a useful predictive tool with which to assess the intercalation efficiency of selected siRNA sequences into the LDH interlayer and subsequent internalization into the cell cytoplasm. This finding will allow a more controlled approach to the design of suitable siRNA sequences for LDH-mediated siRNA delivery.