Laponite nanoclays for the sustained delivery of therapeutic proteins

Protein therapeutics hold immense promise for treating a wide array of diseases. However, their efficacy is often compromised by rapid degradation and clearance. The synthetic smectite clay Laponite emerges as a promising candidate for their sustained delivery. Despite its unique properties allow to load and release proteins mitigating burst release and extending their effects, precise control over Laponite-protein interactions remains challenging since it depends on a complex interplay of factors whose implication is not fully understood yet. The aim of this review article is to shed light on this issue, providing a comprehensive discussion of the factors influencing protein loading and release, including the physicochemical properties of the nanoclay and proteins, pH, dispersion buffer, clay/protein concentration and Laponite degradation. Furthermore, we thoroughly revise the array of bioactive proteins that have been delivered from formulations containing the nanoclay, highlighting Laponite-polymer nanocomposite hydrogels, a promising avenue currently under extensive investigation.

Optimizing Nanofluidic Energy Harvesting in Synthetic Clay-based Membranes by Annealing Treatment

Nanofluidic energy harvesting from salinity gradients is studied in 2D nanomaterials-based membranes with promising performance as high ion selectivity and fast ion transport. In addition, moving forward to scalable, feasible systems requires environmentally friendly materials to make the application sustainable. Clay-based membranes are attractive for being environmentally friendly, non-hazardous, and easy to manipulate materials. However, achieving underwater stability for clay-based membranes remains challenging. In this work, the synthetic clay Laponite is used to prepare clay-based membranes with high stability and excellent performance for osmotic energy harvesting. The Laponite membranes (Lap-membranes) are stabilized by low-temperature annealing treatment to effectively reduce the interlayer space, achieving a continuous operation under salinity gradients. Furthermore, the Lap-membranes conserve integrity while soaking in water for more than one month. The output power density improves from ≈4.97 W m-2 on the pristine membrane to ≈9.89 W m-2 in the membrane treated 12 h at 300 °C from a 30-fold concentration gradient. Especially, It is found that the presence of interlayer water to be favorable for ion transport. Different mechanisms are proposed in the Lap-membranes involved for efficient ion selectivity and the states found with varying annealing temperatures. This work demonstrates the potential application of Laponite based nanomaterials for nanofluidic energy harvesting.

Laponite®-From Dispersion to Gel-Structure, Properties, and Applications

Laponite® (LAP) is an intensively studied synthetic clay due to the versatility given by its layered structure, which makes it usable in various applications. This review describes the multifaceted properties and applications of LAP in aqueous dispersions and gel systems. The first sections of the review discuss the LAP structure and the interactions between clay discs in an aqueous medium under different conditions (such as ionic strength, pH, temperature, and the addition of polymers) in order to understand the function of clay in tailoring the properties of the designed material. Additionally, the review explores the aging phenomenon characteristic of LAP aqueous dispersions as well as the development of shake-gels by incorporating LAP. The second part shows the most recent studies on materials containing LAP with possible applicability in the drilling industry, cosmetics or care products industry, and biomedical fields. By elucidating the remarkable versatility and ease of integration of LAP into various matrices, this review underscores its significance as a key ingredient for the creation of next-generation materials with tailored functionalities.

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.

Bistratal Au@Bi2S3 nanobones for excellent NIR-triggered/multimodal imaging-guided synergistic therapy for liver cancer

To fabricate a highly biocompatible nanoplatform enabling synergistic therapy and real-time imaging, novel Au@Bi2S3 core shell nanobones (NBs) (Au@Bi2S3 NBs) with Au nanorods as cores were synthesized. The combination of Au nanorods with Bi2S3 film made the Au@Bi2S3 NBs exhibit ultrahigh photothermal (PT) conversion efficiency, remarkable photoacoustic (PA) imaging and high computed tomography (CT) performance; these Au@Bi2S3 NBs thus are a promising nanotheranostic agent for PT/PA/CT imaging. Subsequently, poly(N-vinylpyrrolidone)-modified Au@Bi2S3 NBs (Au@Bi2S3-PVP NBs) were successfully loaded with the anticancer drug doxorubicin (DOX), and a satisfactory pH sensitive release profile was achieved, thus revealing the great potential of Au@Bi2S3-PVP NBs in chemotherapy as a drug carrier to deliver DOX into cancer cells. Both in vitro and in vivo investigations demonstrated that the Au@Bi2S3-PVP NBs possessed multiple desired features for cancer therapy, including extremely low toxicity, good biocompatibility, high drug loading ability, precise tumor targeting and effective accumulation. Highly efficient ablation of the human liver cancer cell HepG2 was achieved through Au@Bi2S3-PVP NB-mediated photothermal therapy (PTT). As both a contrast enhancement probe and therapeutic agent, Au@Bi2S3-PVP NBs provided outstanding NIR-triggered multi-modal PT/PA/CT imaging-guided PTT and effectively inhibited the growth of HepG2 liver cancer cells via synergistic chemo/PT therapy.

Brimonidine-LAPONITE® intravitreal formulation has an ocular hypotensive and neuroprotective effect throughout 6 months of follow-up in a glaucoma animal model

Intravitreal administration is widely used in ophthalmological practice to maintain therapeutic drug levels near the neuroretina and because drug delivery systems are necessary to avoid reinjections and sight-threatening side effects. However, currently there is no intravitreal treatment for glaucoma. The brimonidine-LAPONITE® formulation was created with the aim of treating glaucoma for extended periods with a single intravitreal injection. Glaucoma was induced by producing ocular hypertension in two rat cohorts: [BRI-LAP] and [non-bri], with and without treatment, respectively. Eyes treated with brimonidine-LAPONITE® showed lower ocular pressure levels up to week 8 (p < 0.001), functional neuroprotection explored by scotopic and photopic negative response electroretinography (p = 0.042), and structural protection of the retina, retinal nerve fibre layer and ganglion cell layer (p = 0.038), especially on the superior-inferior axis explored by optical coherence tomography, which was corroborated by a higher retinal ganglion cell count (p = 0.040) using immunohistochemistry (Brn3a antibody) up to the end of the study (week 24). Furthermore, delayed neuroprotection was detected in the contralateral eye. Brimonidine was detected in treated rat eyes for up to 6 months. Brimonidine-LAPONITE® seems to be a potential sustained-delivery intravitreal drug for glaucoma treatment.

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.

Hybridization of graphene oxide into nanogels to acquire higher photothermal effects for therapeutic delivery

Although the special architecture of two-dimensional (2D) nanomaterials endows them with unique properties, their poor colloidal stability remains a main bottleneck to fully exploit their applications in the biomedical field. Herein, this study aims to develop a simple and effective approach to in situ incorporate 2D graphene oxide (GO) nanoplatelets into a thermosensitive matrix to acquire hybrid nanogels with good stability and photothermal effect. In order to improve its stability, GO firstly underwent silanization to its surface with double bonds, followed by intercalation with N-isopropylacrylamide (NIPAM) in the presence of a disulfide-containing crosslinker via an emulsion method. Radical polymerization was then initiated to accelerate direct GO exfoliation in PNIPAM nanogels by forming covalent bonds between them. The well-dispersed GO nanopletlets in the nanogels not only displayed an enhanced photothermal effect, but also improved the encapsulation efficiency of an anticancer drug. The hybrid nanogels accelerate drug release under conditions mimicking the acidic/reducible solid tumor and intracellular microenvironments, most importantly, it can be further enhanced via remote photothermal treatment. The multifunctional nanogels potentiate their synergistic anticancer bioactivity as an ideal nanoplatform for cancer treatment.

Formation of enzymatic/redox-switching nanogates on mesoporous silica nanoparticles for anticancer drug delivery

In this study, we demonstrate a simple approach to developing mesoporous nanohybrids via a process of pre-loading of an anticancer drug (doxorubicin, DOX) into mesoporous silica nanoparticles (MSN), followed by assembly with a kind of naturally-derived polymer (gelatin, cleavable by matrix metalloproteinase 2 overexpressed by tumor). The gelatin shell is then in situ crosslinked by degradable N,N'-bis(acryloyl)cystamine (BAC) to form enzymatic and redox switchable nanogates on the mesoporous nanoparticles. The nanohybrids displayed pH/redox/enzymatic sensitivity in DOX release under conditions mimicking tumor microenvironments. The nanocarriers can be effectively taken up by A549 cells (a carcinomic human alveolar basal epithelial cell line), resulting in a high DOX intracellular accumulation and an improved anticancer cytotoxicity when compared with free DOX, suggesting their potential as a nanoplatform for therapeutic delivery.

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.

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.

Charge-Reversal APTES-Modified Mesoporous Silica Nanoparticles with High Drug Loading and Release Controllability

In this study, we demonstrate a facile strategy (DL-SF) for developing MSN-based nanosystems through drug loading (DL, using doxorubicin as a model drug) followed by surface functionalization (SF) of mesoporous silica nanoparticles (MSNs) via aqueous (3-aminopropyl)triethoxysilane (APTES) silylation. For comparison, a reverse functionalization process (i.e., SF-DL) was also studied. The pre-DL process allows for an efficient encapsulation (encapsulation efficiency of ∼75%) of an anticancer drug [doxorubicin (DOX)] inside MSNs, and post-SF allows in situ formation of an APTES outer layer to restrict DOX leakage under physiological conditions. This method makes it possible to tune the DOX release rate by increasing the APTES decoration density through variation of the APTES concentration. However, the SF-DL approach results in a rapid decrease in drug loading capacity with an increase in APTES concentration because of the formation of the APTES outer layer hampers the inner permeability of the DOX drug, resulting in a burst release similar to that of undecorated MSNs. The resulting DOX-loaded DL-SF MSNs present a slightly negatively charged surface under physiological conditions and become positively charged in and extracellular microenvironment of solid tumor due to the protonation effect under acidic conditions. These merits aid their maintenance of long-term stability in blood circulation, high cellular uptake by a kind of skin carcinoma cells, and an enhanced intracellular drug release behavior, showing their potential in the delivery of many drugs beyond anticancer chemotherapeutics.