A General Protocol for Synthesizing Thiolated Folate Derivatives

Folic acid (FA) has shown great potential in the fields of targeted drug delivery and disease diagnosis due to its highly tumor-targeting nature, biocompatibility, and low cost. However, FA is generally introduced in targeted drug delivery systems through macromolecular linkage via complex synthetic processes, resulting in lower yields and high costs. In this work, we report a general protocol for synthesizing thiolated folate derivatives. The small molecule thiolated folate (TFa) was first synthesized with a purity higher than 98.20%. First, S-S-containing diol was synthesized with a purity higher than 99.44 through a newly developed green oxidation protocol, which was carried out in water with no catalyst. Then, folic acid was modified using the diol through esterification, and TFa was finally synthesized by breaking the disulfide bond. Further, the synthesized TFa was utilized to modify silver nanoparticles. The results showed that TFa could be easily bonded to metal particles. The protocol could be extended to the synthesis of a series of thiolated derivatives of folate, such as mercaptohexyl folate, mercaptoundecyl folate, etc., which would greatly benefit the biological applications of FA.

Laponite-Based Nanomaterials for Drug Delivery

Laponite is a clay-based material composed of synthetic disk-shaped crystalline nanoparticles with highly ionic, large surface area. These characteristics enable the intercalation and dissolution of biomolecules in Laponite-based drug delivery systems. Furthermore, Laponite's innate physicochemical properties and architecture enable the development of tunable pH-responsive drug delivery systems. Laponite's coagulation capacity and cation exchangeability determine its exchange capabilities, drug encapsulation efficiency, and release profile. These parameters are exploited to design highly controlled and efficacious drug delivery platforms for sustained drug release. In this review, they provide an overview of how to design efficient delivery of therapeutics by leveraging the properties and specific interactions of various Laponite-polymer composites and drug moieties.

Self-assembled caseinate-laponite® nanocomposites for curcumin delivery

In this study, novel self-assembled protein-clay nanocomposites were developed for curcumin delivery. Experimentally, curcumin was dissolved and deprotonated in sodium caseinate-laponite® (NaCas-LAP) dispersion at pH 12.0 for 30 min followed by neutralization to pH = 7. Due to the pH-mediated dissociation and re-association process, curcumin was successfully encapsulated into NaCas-LAP nanocomposites. The colloidal properties and encapsulation capabilities of NaCas-LAP nanocomposites were investigated, including particle size, zeta potential, encapsulation efficiency, release profile in simulated gastrointestinal tract, as well as nanoscale morphology. The results indicated that upon neutralization, NaCas-LAP nanocomposites were re-associated into smaller particles due to strong hydrophobic interactions among NaCas, LAP and curcumin. Specifically, 0.10% curcumin loaded nanocomposites prepared with 2% NaCas and 0.5% LAP showed improved encapsulation performance (73.4%) with smaller particle size (100 nm). The as-prepared protein-clay nanocomposites hold promising potential to deliver lipophilic bioactive compounds, such as curcumin.

NIR-responsive reversible phase transition of supramolecular hydrogels for tumor treatment

Locally administrable drugs with controllable release on external cues hold great promise for antitumor therapy. Here, we report an injectable, supramolecular hydrogel (SHG), where the drug release can be controllably driven by near infrared (NIR) irradiation. The SHGs are formed by electrostatic interactions with LAPONITE® (XLG), in which upconverting nanoparticles (UCNPs) modified with α-cyclodextrin (α-CD) are used as the core, and azobenzene quaternary ammonium salts (E-azo) are further assembled through host-guest interactions. The hydrogel demonstrates reversible phase transition between gel and sol states and photothermal conversion capability. In detailed in vitro and vivo trials, drug-loaded SHGs successfully suppressed invasion by cancer cells. Phase transitions that are regulated by NIR light and promote drug release using photothermal effects, highlighting the considerable potential of supramolecular hydrogels in anticancer therapies, especially for treatments requiring long-term, on-demand drug supply in clinics.

Recent advances in the design of inorganic and nano-clay particles for the treatment of brain disorders

Inorganic materials, in particular nanoclays and silica nanoparticles, have attracted enormous attention due to their versatile and tuneable properties, making them ideal candidates for a wide range of biomedical applications, such as drug delivery. This review aims at overviewing recent developments of inorganic nanoparticles (like porous or mesoporous silica particles) and different nano-clay materials (like montmorillonite, laponites or halloysite nanotubes) employed for overcoming the blood brain barrier (BBB) in the treatment and therapy of major brain diseases such as Alzheimer's, Parkinson's, glioma or amyotrophic lateral sclerosis. Recent strategies of crossing the BBB through invasive and not invasive administration routes by using different types of nanoparticles compared to nano-clays and inorganic particles are overviewed.

Polydopamine-Coated Laponite Nanoplatforms for Photoacoustic Imaging-Guided Chemo-Phototherapy of Breast Cancer

Theranostic nanoplatforms combining photosensitizers and anticancer drugs have aroused wide interest due to the real-time photoacoustic (PA) imaging capability and improved therapeutic efficacy by the synergistic effect of chemotherapy and phototherapy. In this study, polydopamine (PDA) coated laponite (LAP) nanoplatforms were synthesized to efficiently load indocyanine green (ICG) and doxorubicin (DOX), and modified with polyethylene glycol-arginine-glycine-aspartic acid (PEG-RGD) for PA imaging-guided chemo-phototherapy of cancer cells overexpressing α_vβ₃ integrin. The formed ICG/LAP-PDA-PEG-RGD/DOX nanoplatforms showed significantly higher photothermal conversion efficiency than ICG solution and excellent PA imaging capability, and could release DOX in a pH-sensitive and NIR laser-triggered way, which is highly desirable feature in precision chemotherapy. In addition, the ICG/LAP-PDA-PEG-RGD/DOX nanoplatforms could be uptake by cancer cells overexpressing α_vβ₃ integrin with high specificity, and thus serve as a targeted contrast agent for in vivo PA imaging of cancer. In vivo experiments with 4T1 tumor-bearing mouse model demonstrated that ICG/LAP-PDA-PEG-RGD/DOX nanoplatforms exhibited much stronger therapeutic effect and higher survival rate than monotherapy due to the synergetic chemo-phototherapy under NIR laser irradiation. Therefore, the reported ICG/LAP-PDA-PEG-RGD/DOX represents a promising theranostic nanoplatform for high effectiveness PA imaging-guided chemo-phototherapy of cancer cells overexpressing α_vβ₃ integrin.

Functional LAPONITE Nanodisks Enable Targeted Anticancer Chemotherapy in Vivo

Development of nanoplatforms for targeted anticancer drug delivery for effective tumor therapy still remains challenging in the development of nanomedicine. Here, we present a facile method to formulate a LAPONITE (LAP) nanodisk-based nanosystem for anticancer drug doxorubicin (DOX) delivery to folic acid (FA) receptor-overexpressing tumors. In the current work, aminated LAP nanodisks were first prepared through silanization, then functionalized with polyethylene glycol-linked FA (PEG-FA) via 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide hydrochloride (EDC) chemistry, and finally employed to physically encapsulate DOX. The formed functional LAP nanodisks (for short, LM-PEG-FA) possess a high DOX loading efficiency (88.6 ± 1.2%) and present a pH-dependent release feature with a quicker DOX release under acidic pH conditions (pH 5.0) than under physiological pH conditions (pH 7.4). In vitro flow cytometry, confocal microscopic observation, and cell viability assay show that the LM-PEG-FA/DOX complexes can be specifically taken up by FAR-overexpressing human ovarian cancer cells (SK-OV-3 cells) and present a specific cancer cell therapeutic effect. Further tumor treatment results reveal that the LM-PEG-FA/DOX complexes can exert a specific therapeutic efficacy to a xenografted SK-OV-3 tumor model in vivo when compared with nontargeted LM-mPEG/DOX complexes. Therefore, the developed LM-PEG-FA nanodisks could be employed as a potential platform for targeted cancer chemotherapy.

Laponite-based Nanomaterials for Biomedical Applications: A Review

Laponite based nanomaterials (LBNMs) are highly diverse regarding their mechanical, chemical, and structural properties, coupled with shape, size, mass, biodegradability and biocompatibility. These ubiquitous properties of LBNMs make them appropriate materials for extensive applications. These have enormous potential for effective and targeted drug delivery comprised of numerous biodegradable materials which results in enhanced bioavailability. Moreover, the clay material has been explored in tissue engineering and bioimaging for the diagnosis and treatment of various diseases. The material has been profoundly explored for minimized toxicity of nanomedicines. The present review compiled relevant and informative data to focus on the interactions of laponite nanoparticles and application in drug delivery, tissue engineering, imaging, cell adhesion and proliferation, and in biosensors. Eventually, concise conclusions are drawn concerning biomedical applications and identification of new promising research directions.

Recent developments in the use of organic-inorganic nanohybrids for drug delivery

Organic-inorganic nanohybrid (OINH) structures providing a versatile platform for drug delivery with improved characteristics are an area which has gained recent attention. Much effort has been taken to develop these structures to provide a viable treatment options for much alarming diseases such as cancer, bone destruction, neurological disorders, and so on. This review focuses on current work carried out in producing different types of hybrid drug carriers identifying their properties, fabrication techniques, and areas where they have been applied. A brief introduction on understating the requirement for blending organic-inorganic components into a nanohybrid drug carrier is followed with an elaboration given about the different types of OINHs developed currently highlighting their properties and applications. Then, different fabrication techniques are discussed given attention to surface functionalization, one-pot synthesis, wrapping, and electrospinning methods. Finally, it is concluded by briefing the challenges that are remaining to be addressed to obtain multipurpose nanohybrid drug carriers with wider applicability. This article is categorized under: Therapeutic Approaches and Drug Discovery > Emerging Technologies.

Synthesis, Formulation, and Characterization of Doxorubicin-Loaded Laponite/Oligomeric Hyaluronic Acid-Aminophenylboronic Acid Nanohybrids and Cytological Evaluation against MCF-7 Breast Cancer Cells

As a synthetic clay material, laponite RDS (LR) was investigated as an effective drug carrier as a result of the special nanodisk structure together with the negative-charged surface to achieve enhanced cellular uptake and targeted delivery. In this research work, the synthesized oligomeric hyaluronic acid-aminophenylboronic acid (oHA-APBA) was entangled onto LR nanodisks to fabricate a valid targeted platform for breast cancer therapy. Briefly, through the formation of amide bonds, 3-APBA was connected to the chain of oHA with a substituted ratio of 4.0 ± 0.2% to synthesize oHA-APBA copolymer. Thereafter, doxorubicin (DOX) was inserted into the interlayer space of LR by the way of the ion exchange process, followed by an assembly with oHA-APBA as a targeted protection layer. The satisfactory drug encapsulation efficiency (> 80%) and narrow size distribution were achieved. The in vitro drug release study demonstrated the release of DOX from DOX@LR/oHA-APBA was sustained and acid dependent. In addition, after fitting the drug cumulative release of DOX@LR/oHA-APBA under different pH conditions with several kinetic models, it was identified that drug release from DOX@LR/oHA-APBA nanohybrids at pH 5.0 was mainly dependent on both diffusion and ion exchange effects. However, under the condition of pH 7.4, the drug was most efficiently released by diffusion effect. Importantly, DOX@LR/oHA-APBA showed remarkable cellular uptake and intracellular drug distribution in MCF-7 cells, which were consistent with inhibitory ability against MCF-7 cells. Hence, the high DOX loading capacity and enhanced cellular tracking can enlighten LR/oHA-APBA as an effective drug delivery carrier for breast cancer therapy.

2D Nanoclay for Biomedical Applications: Regenerative Medicine, Therapeutic Delivery, and Additive Manufacturing

Clay nanomaterials are an emerging class of 2D biomaterials of interest due to their atomically thin layered structure, charged characteristics, and well-defined composition. Synthetic nanoclays are plate-like polyions composed of simple or complex salts of silicic acids with a heterogeneous charge distribution and patchy interactions. Due to their biocompatible characteristics, unique shape, high surface-to-volume ratio, and charge, nanoclays are investigated for various biomedical applications. Here, a critical overview of the physical, chemical, and physiological interactions of nanoclay with biological moieties, including cells, proteins, and polymers, is provided. The state-of-the-art biomedical applications of 2D nanoclay in regenerative medicine, therapeutic delivery, and additive manufacturing are reviewed. In addition, recent developments that are shaping this emerging field are discussed and promising new research directions for 2D nanoclay-based biomaterials are identified.

The structure-property relationship in LAPONITE® materials: from Wigner glasses to strong self-healing hydrogels formed by non-covalent interactions

Rheology, small-angle X-ray scattering (SAXS), and dynamic light scattering (DLS) analysis, zeta potential measurement, scanning electron microscopy (SEM), and micro-FTIR and absorbance spectroscopy were used to enlighten the controversial literature about LAPONITE® materials. Our data suggest that pristine LAPONITE® in water does not form hydrogels induced by the so-called "house of cards" assembly, but rather forms Wigner glasses governed by repulsive forces. Ionic interactions between anisotropic LAPONITE® nanodiscs, sodium polyacrylate and inorganic salts afforded hydrogels that were transparent, self-standing, moldable, strong, and biocompatible with shear-thinning and self-healing behavior. An extensive study on the role of salts in the gelification process dictates a trend that relates the valence of cations with the viscoelastic properties of the bulk material (G' values follow the trend, monovalent < divalent < trivalent). These hydrogels present G' values up to 5.1 × 104 Pa, which are considered high values for non-covalent hydrogels. Hydrogels crosslinked with sodium phosphate salts are biocompatible, and might be valid candidates for injectable drug delivery systems due to their shear-thinning behavior with rapid self-healing after injection.

Hyaluronic Acid-Decorated Laponite® Nanocomposites for Targeted Anticancer Drug Delivery

In this study, hyaluronic acid (HA), a natural polysaccharide that can specifically bind to CD44 receptors, was conjugated onto laponite® (LAP) nanodisks for the encapsulation and specific delivery of the anti-cancer drug doxorubicin (DOX) to CD44-overexpressed cancer cells. The prepared LM-HA could encapsulate DOX efficiently and release drug in a continuous manner with pH-responsiveness. In vitro cell viability assay proved that LM-HA had good biocompatibility, and drug-loaded LM-HA/DOX exhibited targeted anti-tumor effects against HeLa cells with CD44 receptors overexpressed. In addition, the flow cytometric detection and confocal laser scanning microscope results confirmed that LM-HA/DOX could be specifically internalized by HeLa cells via CD44-mediated endocytosis. Therefore, the HA-modified LAP nanodisks with high drug loading efficiency, pH-sensitive drug release properties and CD44 targetability might be an efficient nanoplatform for cancer chemotherapy.

Laponite®: A key nanoplatform for biomedical applications?

Laponite® is a synthetic smectite clay that already has many important technological applications, which go beyond the conventional uses of clays in pharmaceutics and cosmetics. In biomedical applications, particularly in nanomedicine, this material holds great potential. Laponite® is a 2-dimensional (2D) nanomaterial composed of disk-shaped nanoscale crystals that have a high aspect ratio. These disks can strongly interact with many types of chemical entities (from small molecules or ions, to natural or synthetic polymers, to different inorganic nanoparticles) and are also easily functionalized and readily degraded in the physiological environment giving rise to non-toxic and even bioactive products. This review will highlight the potential of Laponite® as a nanomaterial in the fields of drug delivery, bioimaging, tissue engineering and regenerative medicine. New concepts, as well as novel innovative materials that stand out from the usual ones due to the unique properties of Laponite®, will also be presented and discussed.

Multivalent Interactions between 2D Nanomaterials and Biointerfaces

2D nanomaterials, particularly graphene, offer many fascinating physicochemical properties that have generated exciting visions of future biological applications. In order to capitalize on the potential of 2D nanomaterials in this field, a full understanding of their interactions with biointerfaces is crucial. The uptake pathways, toxicity, long-term fate of 2D nanomaterials in biological systems, and their interactions with the living systems are fundamental questions that must be understood. Here, the latest progress is summarized, with a focus on pathogen, mammalian cell, and tissue interactions. The cellular uptake pathways of graphene derivatives will be discussed, along with health risks, and interactions with membranes-including bacteria and viruses-and the role of chemical structure and modifications. Other novel 2D nanomaterials with potential biomedical applications, such as transition-metal dichalcogenides, transition-metal oxide, and black phosphorus will be discussed at the end of this review.

Loading of Indocyanine Green within Polydopamine-Coated Laponite Nanodisks for Targeted Cancer Photothermal and Photodynamic Therapy

The combination of photothermal therapy (PTT) and photodynamic therapy (PDT) in cancer treatment has attracted much attention in recent years. However, developing highly efficient and targeted therapeutic nanoagents for amplifying PTT and PDT treatments remains challenging. In this work, we developed a novel photothermal and photodynamic therapeutic nanoplatform for treatment of cancer cells overexpressing integrin αvβ₃ through the coating of polydopamine (PDA) on indocyanine green (ICG)-loaded laponite (LAP) and then further conjugating polyethylene glycol-arginine-glycine-aspartic acid (PEG-RGD) as targeted agents on the surface. The ICG/LAP⁻PDA⁻PEG⁻RGD (ILPR) nanoparticles (NPs) formed could load ICG with a high encapsulation efficiency of 94.1%, improve the photostability of loaded ICG dramatically via the protection of PDA and LAP, and display excellent colloidal stability and biocompatibility due to the PEGylation. Under near-infrared (NIR) laser irradiation, the ILPR NPs could exert enhanced photothermal conversion reproducibly and generate reactive oxygen species (ROS) efficiently. More importantly, in vitro experiments proved that ILPR NPs could specifically target cancer cells overexpressing integrin αvβ₃, enhance cellular uptake due to RGD-mediated targeting, and exert improved photothermal and photodynamic killing efficiency against targeted cells under NIR laser irradiation. Therefore, ILPR may be used as effective therapeutic nanoagents with enhanced photothermal conversion performance and ROS generating ability for targeted PTT and PDT treatment of cancer cells with integrin αvβ₃ overexpressed.

Distributions: The Importance of the Chemist's Molecular View for Biological Materials

Characterization of materials with biological applications and assessment of physiological effects of therapeutic interventions are critical for translating research to the clinic and preventing adverse reactions. Analytical techniques typically used to characterize targeted nanomaterials and tissues rely on bulk measurement. Therefore, the resulting data represent an average structure of the sample, masking stochastic (randomly generated) distributions that are commonly present. In this Perspective, we examine almost 20 years of work our group has done in different fields to characterize and control distributions. We discuss the analytical techniques and statistical methods we use and illustrate how we leverage them in tandem with other bulk techniques. We also discuss the challenges and time investment associated with taking such a detailed view of distributions as well as the risks of not fully appreciating the extent of heterogeneity present in many systems. Through three case studies showcasing our research on conjugated polymers for drug delivery, collagen in bone, and endogenous protein nanoparticles, we discuss how identification and characterization of distributions, i.e., a molecular view of the system, was critical for understanding the observed biological effects. In all three cases, data would have been misinterpreted and insights missed if we had only relied upon spatially averaged data. Finally, we discuss how new techniques are starting to bridge the gap between bulk and molecular level analysis, bringing more opportunity and capacity to the research community to address the challenges of distributions and their roles in biology, chemistry, and the translation of science and engineering to societal challenges.

Mesoporous inorganic nanoscale particles for drug adsorption and controlled release

The review provides an overview of the mesoporous inorganic particles employed as drug delivery systems for controlled and sustained release of drugs. We have classified promising nanomaterials for drug delivery on the basis of their natural or synthetic origin. Nanoclays are available in different morphologies (nanotubes, nanoplates and nanofibers) and they are typically available at low cost from natural resources. The surface chemistry of nanoclays is versatile for targeted modifications to control loading and release properties. Synthetic nanomaterials (imogolite, laponite and mesoporous silica) present the advantages of well-established purity and availability with size features that are finely controlled. Both nanoclays and inorganic synthetic nanoparticles can be functionalized forming organic/inorganic architectures with stimuli-responsive features.

Laponite-Based Surfaces with Holistic Self-Cleaning Functionality by Combining Antistatics and Omniphobicity

In the present work, perfluoroalkylated laponite nanoparticles with a high degree of functionalization (60 wt %) have been prepared and a methodology to prepare transparent, antistatic, and omniphobic laponite-based films with holistic self-cleaning properties against liquids, solids and liquid-solid mixtures has been developed. The intrinsic electrical and ionic conductivities observed in unmodified laponite coatings are combined with perfluoroalkyl-modified laponite clays. As a result, films with improved self-cleaning functionality based on dust-repellency and omniphobic liquid-repellence (sheet resistance in the range of 10⁷ Ω/□ and contact angles of 106° (H₂O) and 93° (oil)) were obtained. These unique films, being capable to repel dust and liquids, were applied to a variety of substrates (i.e., glass and plastics) and tested against solids and liquids of different nature with excellent performance. Bending tests of these holistic self-cleaning films deposited over flexible substrates showed better mechanical performance than unmodified laponite films.

An RGD-modified hollow silica@Au core/shell nanoplatform for tumor combination therapy

The combination of chemotherapy and photothermal therapy (PTT) in multifunctional nanoplatforms to improve cancer therapeutic efficacy is of great significance while it still remains to be a challenging task. Herein, we report Au nanostar (NS)-coated hollow mesoporous silica nanocapsules (HMSs) with surface modified by arginine-glycine-aspartic acid (RGD) peptide as a drug delivery system to encapsulate doxorubicin (DOX) for targeted chemotherapy and PTT of tumors. Au NSs-coated HMSs core/shell nanocapsules (HMSs@Au NSs) synthesized previously were conjugated with RGD peptide via a spacer of polyethylene glycol (PEG). We show that the prepared HMSs@Au-PEG-RGD NSs are non-cytotxic in the given concentration range, and have a DOX encapsulation efficiency of 98.6±0.7%. The designed HMSs@Au-PEG-RGD NSs/DOX system can release DOX in a pH/NIR laser dual-responsive manner. Importantly, the formed HMSs@Au-PEG-RGD NSs/DOX nanoplatform can specifically target cancer cells overexpressing α_vβ₃ intergrin and exert combination chemotherapy and PTT efficacy to the cells in vitro and a xenografted tumor model in vivo. Our results suggest that the designed HMSs@Au-PEG-RGD NSs/DOX nanoplatform may be used for combination chemotherapy and PTT of tumors.

STATEMENT OF SIGNIFICANCE

We demonstrate a convenient approach to preparing a novel RGD-targeted drug delivery system of HMSs@Au-PEG-RGD NSs/DOX that possesses pH/NIR laser dual-responsive drug delivery performance for combinational chemotherapy and PTT of tumors. The developed Au NS-coated HMS capsules have both merits of HMS capsules that can be used for high payload drug loading and Au NSs that have NIR laser-induced photothermal conversion efficiency (70.8%) and can be used for PTT of tumors.

Patterning of Nanoclays on Positively Charged Self-Assembled Monolayers via Micromolding in Capillaries

Nanoclays are nanomaterials with versatile adsorptive properties. This contribution describes the generation of micropatterns of a nanoclay ("laponite") on ammonium-terminated, self-assembled monolayers (SAMs) on glass and silicon. Microstructured immobilization of the laponite was performed using micromolding in capillaries (MIMIC). The immobilization was verified using contact angle goniometry, X-ray photoelectron spectroscopy (XPS), atomic force microscopy (AFM), scanning electron microscopy (SEM), time-of-flight secondary ion mass spectrometry (ToF-SIMS), and fluorescence microscopy. Furthermore, laponite was modified with Nile red to generate a fluorescence enhancement-based surface sensor for the vitamin choline.

Conjugation Dependent Interaction of Folic Acid with Folate Binding Protein

Serum proteins play a critical role in the transport, uptake, and efficacy of targeted drug therapies, and here we investigate the interactions between folic acid-polymer conjugates and serum folate binding protein (FBP), the soluble form of the cellular membrane-bound folate receptor. We demonstrate that both choice of polymer and method of ligand conjugation affect the interactions between folic acid-polymer conjugates and serum FBP, resulting in changes in the folic acid-induced protein aggregation process. We have previously demonstrated that individual FBP molecules self-aggregate into nanoparticles at physiological concentrations. When poly(amidoamine) dendrimer-folic acid conjugates bound to FBP, the distribution of nanoparticles was preserved. However, the dendritic conjugates produced larger nanoparticles than those formed in the presence of physiologically normal human levels of folic acid, and the conjugation method affected particle size distribution. In contrast, poly(ethylene glycol)-folic acid conjugates demonstrated substantially reduced binding to FBP, did not cause folic acid-induced aggregation, and fully disrupted FBP self-aggregation. On the basis of these results, we discuss the potential implications for biodistribution, trafficking, and therapeutic efficacy of targeted nanoscale therapeutics, especially considering the widespread clinical use of poly(ethylene glycol) conjugates. We highlight the importance of considering specific serum protein interactions in the rational design of similar nanocarrier systems. Our results suggest that prebinding therapeutic nanocarriers to serum FBP may allow folate-specific metabolic pathways to be exploited for delivery while also affording benefits of utilizing an endogenous protein as a vector.

A smart pH-responsive nano-carrier as a drug delivery system for the targeted delivery of ursolic acid: suppresses cancer growth and metastasis by modulating P53/MMP-9/PTEN/CD44 mediated multiple signaling pathways

Ursolic acid (UA) has been recently used as a promising anti-tumor and cancer metastatic chemo-preventive agent due to its low toxicity and liver-protecting property. However, the low bioavailability and nonspecific tumor targeting restrict its further clinical application. To address the problem, a silica-based mesoporous nanosphere (MSN) controlled-release drug delivery system (denoted UA@M-CS-FA) was designed and successfully synthesized, and was functionalized with folic acid (FA) and pH-sensitive chitosan (CS) for the targeted delivery of UA to folate receptor (FR) positive tumor cells. UA@M-CS-FA were spherical with mean diameter below 150 nm, and showed about -20 mV potential. Meanwhile, UA@M-CS-FA exhibited a pH-sensitive release manner and high cellular uptake in FR over-expressing HeLa cancer cells. Also, in vitro cellular assays suggested that UA@M-CS-FA inhibited cancer cell growth, invasion and migration. Mechanistically, UA@M-CS-FA induced cancer cell apoptosis and inhibited migration via cell cycle arrest in the G0/G1 stage, regulating the PARP/Bcl-2/MMP-9/CD44/PTEN/P53. Importantly, in vivo experiments further confirmed that UA@M-CS-FA significantly suppressed the tumor progression and lung metastasis in tumor-bearing nude mice. Immunohistochemical analysis revealed that UA@M-CS-FA treatment regulated CD44, a biomarker of cancer metastasis. Overall, our data demonstrated that a CS and FA modified MSN controlled-release drug delivery system could help broaden the usage of UA and reflect the great application potential of the UA as an anticancer or cancer metastatic chemopreventive agent.

Monitoring of nanoclay-protein adsorption isotherms via fluorescence techniques

The investigation of nanoparticles and their interaction with bio-macromolecules have become an important issue; the widely discussed protein corona around nanoparticles and their biological fate in general have drawn particular attention. Here, we focus on nanoclay dispersions and the use of solvatochromic fluorescent dyes (Dansyl and Coumarin 153) for monitoring the interaction with two model proteins, bovine serum albumin and β-lactoglobulin. On one hand, these dyes are poorly emissive in water, but experience a boost in their fluorescence when adsorbed into the hydrophobic domains of proteins. On the other hand, (nano)clays and clay minerals have previously been investigated in terms of their individual protein adsorption isotherms and their usefulness for the solubilization of water-insoluble dyes into an aqueous environment. In the following, we have combined all three individual parts (nanoclay, fluorophore and protein) in dispersions in a wide range of concentration ratios to systematically study the various adsorption processes via fluorescence techniques. In order to clarify the extent of dye diffusion and adsorption-desorption equilibria in the investigations, nanoclay hybrids with an adsorbed dye (Coumarin 153) and a covalently conjugated dye (Dansyl) were compared. The results suggest that the fluorescence progression of protein titration curves correlate with the amount of protein adsorbed, matching their reported adsorption isotherms on hectorite clays. Furthermore, experimental data on the protein monolayer formation around the nanoclays could be extracted due to only minor alterations of the dispersions' optical quality and transparency. In this manner, a fluorescence-based monitor for the formation of the globular protein layer around the nanoclay was realized.

LAPONITE®-stabilized iron oxide nanoparticles for in vivo MR imaging of tumors

We report the synthesis, characterization and utilization of LAPONITE®-stabilized magnetic iron oxide nanoparticles (LAP-Fe3O4 NPs) as a high performance contrast agent for in vivo magnetic resonance (MR) detection of tumors. In this study, Fe3O4 NPs were synthesized by a facile controlled coprecipitation route in LAP solution, and the formed LAP-Fe3O4 NPs have great colloidal stability and about 2-fold increase of T2 relaxivity than Fe3O4 NPs (from 247.6 mM(-1) s(-1) to 475.9 mM(-1) s(-1)). Moreover, cytotoxicity assay and cell morphology observation demonstrate that LAP-Fe3O4 NPs display good biocompatibility in the given Fe concentration range, and in vivo biodistribution results prove that NPs can be metabolized and cleared out of the body. Most importantly, LAP-Fe3O4 NPs can not only be used as a contrast agent for MR imaging of cancer cells in vitro due to the effective uptake by tumor cells, but also significantly enhance the contrast of a xenografted tumor model. Therefore, the developed LAP-based Fe3O4 NPs with good colloidal stability and exceptionally high transverse relaxivity may have tremendous potential in MR imaging applications.

LAPONITE-Polyethylenimine Based Theranostic Nanoplatform for Tumor-Targeting CT Imaging and Chemotherapy

In this study, laponite (LAP) nanodisks and polyethylenimine (PEI) were used to build a hybrid theranostic nanoplatform for targeted computed tomography (CT) imaging and chemotherapy of cancer cells overexpressing CD44 receptors. First, amphiphilic copolymer poly(lactic acid)-poly(ethylene glycol) (PLA-PEG-COOH) were assembled on the surface of LAP nanodisks via hydrophobic interaction, and then PEI were conjugated by the formation of amide groups via1-ethyl-3-(3-(dimethylamino)propyl) carbodiimide (EDC) coupling chemistry. The developed LAP-PLA-PEG-PEI nanoparticles were used as templates for the embedding of gold nanoparticles (Au NPs), followed by modification with hyaluronic acid (HA) as a targeting ligand for cancer cells overexpressing CD44 receptors. Finally, anticancer drug doxorubicin (DOX) was loaded. The formed LAP-PLA-PEG-PEI-(Au⁰)₅₀-HA/DOX nanocomplexes display good stability, a high drug loading efficiency as 91.0 ± 1.8%, and sustained drug release profile with a pH-sensitive manner. In vitro cell viability assay, flow cytometric analysis, and laser scanning confocal microscopy observation demonstrate that the formed nanocomplexes can specifically deliver and inhibit cancer cells overexpressing CD44 receptors. In vivo experiments illustrate that LAP-PLA-PEG-PEI-(Au⁰)₅₀-HA/DOX nanocomplexes can not only significantly inhibit the growth of tumors and decrease the side-effect of DOX, but also be used as a targeted contrast agent for CT imaging of tumors. Therefore, the developed LAP-PLA-PEG-PEI-(Au⁰)₅₀-HA/DOX nanocomplexes can be used as a promising theranostic platform for targeted imaging and chemotherapy of CD44-overexpressed tumors.

A shear-thinning hydrogel that extends in vivo bioactivity of FGF2

We designed and tested a versatile hydrogel for tissue regeneration by preserving the bioactivity of growth factors. The shear-thinning gel self-assembles within 1 min from heparin and Laponite-a silicate nanoparticle, thus the name HELP gel. By not covalently modifying heparin, it should retain its natural affinity towards many proteins anchored in the extracellular matrix. In principle, HELP gel can bind any heparin-binding growth factor; we use fibroblast growth factor-2 (FGF2) in this study to demonstrate its utility. Heparin in the gel protects FGF2 from proteolytic degradation and allows it to be released over time with preserved bioactivity. FGF2 released from subcutaneously injected gel induces strong angiogenesis in a mouse model. The hydrogel degrades completely in vivo in 8 weeks with or without growth factors, eliciting mild inflammatory response but having little impacts on the surrounding tissue. The ease of preparation and scale-up makes this protein delivery platform attractive for clinical translation.

Laponite as carrier for controlled in vitro delivery of dexamethasone in vitreous humor models

Laponite clay is able to retain dexamethasone by simple physisorption, presumably accomplished by hydrogen bonding formation and/or complexation with sodium counterions, as shown by solid state NMR. The physisorption can be somehow modulated by changing the solvent in the adsorption process. This simple system is able to deliver dexamethasone in a controlled manner to solutions used as models for vitreous humor. The proven biocompatibility of laponite as well as its transparency in the gel state, together with the simplicity of the preparation method, makes this system suitable for future in vivo tests of ophthalmic treatment.

Immobilization of iron oxide nanoparticles within alginate nanogels for enhanced MR imaging applications

We report the design of iron oxide (Fe3O4) nanoparticle (NP)-immobilized alginate (AG) nanogels (NGs) as a novel contrast agent for enhanced magnetic resonance (MR) imaging applications. In this study, an aqueous solution of AG activated by 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide hydrochloride was double emulsified to form NGs, followed by in situ cross-linking with polyethyleneimine (PEI)-coated Fe3O4 NPs (PEI-Fe3O4 NPs). The resultant Fe3O4 NP-immobilized AG NGs (AG/PEI-Fe3O4 NGs) were characterized via different techniques. Our results reveal that the hybrid NGs with a size of 186.1 ± 33.1 nm are water dispersible, colloidally stable, and cytocompatible in the given concentration range. Importantly, these NGs have a high r2 relaxivity (170.87 mM(-1) s(-1)) due to the high loading of Fe3O4 NPs within the NGs, and can be more significantly uptaken by cancer cells when compared with carboxylated Fe3O4 NPs. The formed AG/PEI-Fe3O4 NGs are able to be used as an effective contrast agent for the MR imaging of cancer cells in vitro and the xenografted tumor model in vivo after intravenous injection. The developed AG/PEI-Fe3O4 NGs may hold great promise for use as a novel contrast agent for the enhanced MR imaging of different biological systems.

Biomedical Uses for 2D Materials Beyond Graphene: Current Advances and Challenges Ahead

Currently, a broad interdisciplinary research effort is pursued on biomedical applications of 2D materials (2DMs) beyond graphene, due to their unique physicochemical and electronic properties. The discovery of new 2DMs is driven by the diverse chemical compositions and tuneable characteristics offered. Researchers are increasingly attracted to exploit those as drug delivery systems, highly efficient photothermal modalities, multimodal therapeutics with non-invasive diagnostic capabilities, biosensing, and tissue engineering. A crucial limitation of some of the 2DMs is their moderate colloidal stability in aqueous media. In addition, the lack of suitable functionalisation strategies should encourage the exploration of novel chemical methodologies with that purpose. Moreover, the clinical translation of these emerging materials will require undertaking of fundamental research on biocompatibility, toxicology and biopersistence in the living body as well as in the environment. Here, a thorough account of the biomedical applications using 2DMs explored today is given.

Highly Fluorescent dye-nanoclay Hybrid Materials Made from Different Dye Classes

Nanoclays like laponites, which are commercially avaible in large quantities for a very moderate price, provide a facile solubilization strategy for hydrophobic dyes without the need for chemical functionalization and can act as a carrier for a high number of dye molecules. This does not require reactive dyes, amplifies fluorescence signals from individual emitters due to the high number of dyes molecules per laponite disk, and renders hydrophobic emitters applicable in aqueous environments. Aiming at the rational design of bright dye-loaded nanoclays as a new class of fluorescent reporters for bioanalysis and material sciences and the identification of dye structure-property relationships, we screened a series of commercial fluorescent dyes, differing in dye class, charge, and character of the optical transitions involved, and studied the changes of their optical properties caused by clay adsorption at different dye loading concentrations. Upon the basis of our dye loading density-dependent absorption and fluorescence measurements with S2105 and Lumogen F Yellow 083, we could identify two promising dye-nanoclay hybrid materials that reveal high fluorescence quantum yields of the nanoclay-adsorbed dyes of at least 0.20 and low dye self-quenching even at high dye-loading densities of up to 50 dye molecules per laponite platelet.

Fine tuning of the pH-sensitivity of laponite-doxorubicin nanohybrids by polyelectrolyte multilayer coating

Despite the wide research done in the field, the development of advanced drug delivery systems with improved drug delivery properties and effective anticancer capability still remains a great challenge. Based on previous work that showed the potentialities of the nanoclay Laponite as a pH-sensitive doxorubicin (Dox) delivery vehicle, herein we report a simple method to modulate its extent of drug release at different pH values. This was achieved by alternate deposition of cationic poly(allylamine) hydrochloride and anionic poly(sodium styrene sulfonate) (PAH/PSS) polyelectrolytes over the surface of Dox-loaded Laponite nanoparticles using the electrostatic layer-by-layer (LbL) self-assembly approach. The successful formation of polyelectrolyte multilayer-coated Dox/Laponite systems was confirmed by Dynamic Light Scattering and zeta potential measurements. Systematic studies were performed to evaluate their drug release profiles and anticancer efficiency. Our results showed that the presence of the polyelectrolyte multilayers improved the sustained release properties of Laponite and allowed a fine tuning of the extension of drug release at neutral and acidic pH values. The cytotoxicity presented by polyelectrolyte multilayer-coated Dox/Laponite systems towards MCF-7 cells was in accordance with the drug delivery profiles. Furthermore, cellular uptake studies revealed that polyelectrolyte multilayer-coated Dox/Laponite nanoparticles can be effectively internalized by cells conducting to Dox accumulation in cell nucleus.

Branched polyethyleneimine modified with hyaluronic acid via a PEG spacer for targeted anticancer drug delivery

Branched polyethyleneimine can be modified with hyaluronic acid via a PEG spacer for targeted anticancer drug delivery to cancer cells.

Dendrimer-functionalized LAPONITE® nanodisks loaded with gadolinium for T1-weighted MR imaging applications

Dendrimer-functionalized LAPONITE® nanodisks loaded with gadolinium can be used as an efficient contrast agent for different MR imaging applications.

Synthesis of diatrizoic acid-modified LAPONITE® nanodisks for CT imaging applications

Nanoscale diatrizoic acid-modified LAPONITE® nanodisks can be synthesized for CT imaging of animal organs and tumors in vivo.

Two-Dimensional Nanomaterials for Biomedical Applications: Emerging Trends and Future Prospects

Two-dimensional (2D) nanomaterials are ultrathin nanomaterials with a high degree of anisotropy and chemical functionality. Research on 2D nanomaterials is still in its infancy, with the majority of research focusing on elucidating unique material characteristics and few reports focusing on biomedical applications of 2D nanomaterials. Nevertheless, recent rapid advances in 2D nanomaterials have raised important and exciting questions about their interactions with biological moieties. 2D nanoparticles such as carbon-based 2D materials, silicate clays, transition metal dichalcogenides (TMDs), and transition metal oxides (TMOs) provide enhanced physical, chemical, and biological functionality owing to their uniform shapes, high surface-to-volume ratios, and surface charge. Here, we focus on state-of-the-art biomedical applications of 2D nanomaterials as well as recent developments that are shaping this emerging field. Specifically, we describe the unique characteristics that make 2D nanoparticles so valuable, as well as the biocompatibility framework that has been investigated so far. Finally, to both capture the growing trend of 2D nanomaterials for biomedical applications and to identify promising new research directions, we provide a critical evaluation of potential applications of recently developed 2D nanomaterials.

In-vitro cytotoxicity assessment of carbon-nanodot-conjugated Fe-aminoclay (CD-FeAC) and its bio-imaging applications

We have investigated the cytotoxic assay of Fe-aminoclay (FeAC) nanoparticles (NPs) and simultaneous imaging in HeLa cells by photoluminescent carbon nanodots (CD) conjugation. Non-cytotoxic, photostable, and CD NPs are conjugated with cationic FeAC NPs where CD NPs play a role in bio-imaging and FeAC NPs act as a substrate for CD conjugation and help to uptake of NPs into cancer cells due to positively charged surface of FeAC NPs in physiological media. As increase of CD-FeAC NPs loading in HeLa cell in vitro, it showed slight cytotoxicity at 1000 μg/mL but no cytotoxicity for normal cells up to concentration of 1000 μg/mL confirmed by two 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) and neutral red (NR) assays, with further observations by 4',6-diamidino-2-phenylindole (DAPI) stained confocal microscopy images, possessing that CD-FeAC NPs can be used as potential drug delivery platforms in cancer cells with simultaneous imaging. Graphical abstract CD conjugation with organo-building blocks of delaminated FeAC NPs.

Multifunctional Bioconjugate for Cancer Cell-Targeted Theranostics

Cancer cell-targeted imaging and drug delivery remain a challenge for precise cancer theranostics. MUC1 is a large transmembrane glycoprotein that may potentially serve as a target for cancer theranostics. Herein, using a MUC1-targeting aptamer (APT) as the "warhead", we rationally designed and constructed a hybrid nanoparticle 1-NPs-QDs-hAPT (Vehicle) that could be applied for MUC1-targeted cell uptake and imaging. By intercalating different Vehicle amounts with the anticancer drug doxorubicin (DOX), we obtained the multifunctional bioconjugate Vehicle-DOX with a maximized drug payload and DOX fluorescence quenching capability. Confocal microscopy cell imaging indicated that Vehicle-DOX could be used to track MUC1-targeted drug release. A cytotoxicity study indicated that Vehicle-DOX could be applied for MUC1-targeted cytotoxicity. We anticipate that our multifunctional bioconjugate Vehicle-DOX could be applied for in vivo tumor-targeted theranostics.

Dendrimer-Functionalized Laponite Nanodisks as a Platform for Anticancer Drug Delivery

In this study, we synthesized dendrimer-functionalized laponite (LAP) nanodisks for loading and delivery of anticancer drug doxorubicin (DOX). Firstly, LAP was modified with silane coupling agents and succinic anhydride to render abundant carboxyl groups on the surface of LAP. Then, poly(amidoamine) (PAMAM) dendrimer of generation 2 (G2) were conjugated to form LM-G2 nanodisks. Anticancer drug DOX was then loaded on the LM-G2 with an impressively high drug loading efficiency of 98.4% and could be released in a pH-sensitive and sustained manner. Moreover, cell viability assay results indicate that LM-G2/DOX complexes could more effectively inhibit the proliferation of KB cells (a human epithelial carcinoma cell line) than free DOX at the same drug concentration. Flow cytometry analysis and confocal laser scanning microscope demonstrated that LM-G2/DOX could be uptaken by KB cells more effectively than free DOX. Considering the exceptional high drug loading efficiency and the abundant dendrimer amine groups on the surface that can be further modified, the developed LM-G2 nanodisks may hold a great promise to be used as a novel platform for anticancer drug delivery.

Selective Inactivation of Resistant Gram-Positive Pathogens with a Light-Driven Hybrid Nanomaterial

Herein, we present a straightforward strategy to disperse highly insoluble photosensitizers in aqueous environments, without major synthetic efforts and keeping their photosensitizing abilities unaffected. A layered nanoclay was employed to adsorb and to solubilize a highly efficient yet hydrophobic Si(IV) phthalocyaninate in water. The aggregation of the photoactive dye was correlated with its photophysical properties, particularly with the ability to produce highly cytotoxic singlet oxygen. Moreover, the resulting hybrid nanomaterial is able to selectively photoinactivate Gram-positive pathogens, due to local interactions between the bacterial membranes and the negatively charged nanodiscs. Nanotoxicity assays confirmed its innocuousness toward eukaryotic cells, showing that it constitutes a new class of "phototriggered magic bullet" for the inactivation of pathogens in phototherapy, as well as in the development of coatings for self-disinfecting surfaces.