Soft Nanohydrogels Based on Laponite Nanodiscs: A Versatile Drug Delivery Platform for Theranostics and Drug Cocktails

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 for biomedical applications: An ophthalmological perspective

Clay minerals have been applied in biomedicine for thousands of years. Laponite is a nanostructured synthetic clay with the capacity to retain and progressively release drugs. In recent years there has been a resurgence of interest in Laponite application in various biomedical areas. This is the first paper to review the potential biomedical applications of Laponite in ophthalmology. The introduction briefly covers the physical, chemical, rheological, and biocompatibility features of different routes of administration. After that, emphasis is placed on 1) drug delivery for antibiotics, anti-inflammatories, growth factors, other proteins, and cancer treatment; 2) bleeding prevention or treatment; and 3) tissue engineering through regenerative medicine using scaffolds in intraocular and extraocular tissue. Although most scientific research is not performed on the eye, both the findings and the new treatments resulting from that research are potentially applicable in ophthalmology since many of the drugs used are the same, the tissue evaluated in vitro or in vivo is also present in the eye, and the pathologies treated also occur in the eye. Finally, future prospects for this emerging field are discussed.

Biomedical Applications of Deformable Hydrogel Microrobots

Hydrogel, a material with outstanding biocompatibility and shape deformation ability, has recently become a hot topic for researchers studying innovative functional materials due to the growth of new biomedicine. Due to their stimulus responsiveness to external environments, hydrogels have progressively evolved into "smart" responsive (such as to pH, light, electricity, magnetism, temperature, and humidity) materials in recent years. The physical and chemical properties of hydrogels have been used to construct hydrogel micro-nano robots which have demonstrated significant promise for biomedical applications. The different responsive deformation mechanisms in hydrogels are initially discussed in this study; after which, a number of preparation techniques and a variety of structural designs are introduced. This study also highlights the most recent developments in hydrogel micro-nano robots' biological applications, such as drug delivery, stem cell treatment, and cargo manipulation. On the basis of the hydrogel micro-nano robots' current state of development, current difficulties and potential future growth paths are identified.

Bioderived Mesoporous Carbon@Tungsten Oxide Nanocomposite as a Drug Carrier Vehicle of Doxorubicin for Potent Cancer Therapy

Scientists have investigated the possibility of employing nanomaterials as drug carriers. These nanomaterials can preserve their content and transport it to the target region in the body. In this investigation, we proposed a simple method for developing distinctive, bioderived nanostructures with mesoporous carbon nanoparticles impregnated with tungsten oxide (WO3). Prior to characterizing and encapsulating WO3 with bioderived mesoporous carbon, the anticancer drug doxorubicin (DOX) was added to the nanoparticles and examined loading and release study. The approaches for both nanoparticle production and characterization are discussed in detail. Colloidal qualities of the nanomaterial can be effectively preserved while also allowing transdermal transportation of nanoparticles into the body by forming them into green, reusable, and porous nanostructures. Although the theories of nanoparticles and bioderived carbon each have been studied separately, the combination presents a new route to applications connected to nanomedicine. Furthermore, this sample was used to study exotic biomedical applications, such as antioxidant, antimicrobial, and anticancer activities. The W-3 sample had lower antioxidant activity (44.01%) than the C@W sample (56.34%), which was the most potent. A high DOX entrapment effectiveness of 97% was eventually achieved by the C@W sample, compared to a pure WO3 entrapment efficiency of 91%. It was observed that the Carbon/WO3 composite (C@W) sample showed more efficacy because the mesoporous carbon composition with WO3 increases the average surface area and surface-active locations.

Gelatin methacryloyl and Laponite bioink for 3D bioprinted organotypic tumor modeling

Three-dimensional (3D)in vitrotumor models that can capture the pathophysiology of human tumors are essential for cancer biology and drug development. However, simulating the tumor microenvironment is still challenging because it consists of a heterogeneous mixture of various cellular components and biological factors. In this regard, current extracellular matrix (ECM)-mimicking hydrogels used in tumor tissue engineering lack physical interactions that can keep biological factors released by encapsulated cells within the hydrogel and improve paracrine interactions. Here, we developed a nanoengineered ion-covalent cross-linkable bioink to construct 3D bioprinted organotypic tumor models. The bioink was designed to implement the tumor ECM by creating an interpenetrating network composed of gelatin methacryloyl (GelMA), a light cross-linkable polymer, and synthetic nanosilicate (Laponite) that exhibits a unique ionic charge to improve retention of biological factors released by the encapsulated cells and assist in paracrine signals. The physical properties related to printability were evaluated to analyze the effect of Laponite hydrogel on bioink. Low GelMA (5%) with high Laponite (2.5%-3.5%) composite hydrogels and high GelMA (10%) with low Laponite (1.0%-2.0%) composite hydrogels showed acceptable mechanical properties for 3D printing. However, a low GelMA composite hydrogel with a high Laponite content could not provide acceptable cell viability. Fluorescent cell labeling studies showed that as the proportion of Laponite increased, the cells became more aggregated to form larger 3D tumor structures. Reverse transcription-polymerase chain reaction (RT-qPCR) and western blot experiments showed that an increase in the Laponite ratio induces upregulation of growth factor and tissue remodeling-related genes and proteins in tumor cells. In contrast, cell cycle and proliferation-related genes were downregulated. On the other hand, concerning fibroblasts, the increase in the Laponite ratio indicated an overall upregulation of the mesenchymal phenotype-related genes and proteins. Our study may provide a rationale for using Laponite-based hydrogels in 3D cancer modeling.

Laponite-Based Nanocomposite Hydrogels for Drug Delivery Applications

Hydrogels are widely used for therapeutic delivery applications due to their biocompatibility, biodegradability, and ability to control release kinetics by tuning swelling and mechanical properties. However, their clinical utility is hampered by unfavorable pharmacokinetic properties, including high initial burst release and difficulty in achieving prolonged release, especially for small molecules (<500 Da). The incorporation of nanomaterials within hydrogels has emerged as viable option as a method to trap therapeutics within the hydrogel and sustain release kinetics. Specifically, two-dimensional nanosilicate particles offer a plethora of beneficial characteristics, including dually charged surfaces, degradability, and enhanced mechanical properties within hydrogels. The nanosilicate-hydrogel composite system offers benefits not obtainable by just one component, highlighting the need for detail characterization of these nanocomposite hydrogels. This review focuses on Laponite, a disc-shaped nanosilicate with diameter of 30 nm and thickness of 1 nm. The benefits of using Laponite within hydrogels are explored, as well as examples of Laponite-hydrogel composites currently being investigated for their ability to prolong the release of small molecules and macromolecules such as proteins. Future work will further characterize the interplay between nanosilicates, hydrogel polymer, and encapsulated therapeutics, and how each of these components affect release kinetics and mechanical properties.

Laponite Composites: In Situ Films Forming as a Possible Healing Agent

A healing material must have desirable characteristics such as maintaining a physiological environment, protective barrier-forming abilities, exudate absorption, easy handling, and non-toxicity. Laponite is a synthetic clay with properties such as swelling, physical crosslinking, rheological stability, and drug entrapment, making it an interesting alternative for developing new dressings. This study evaluated its performance in lecithin/gelatin composites (LGL) as well as with the addition of maltodextrin/sodium ascorbate mixture (LGL MAS). These materials were applied as nanoparticles, dispersed, and prepared by using the gelatin desolvation method-eventually being turned into films via the solvent-casting method. Both types of composites were also studied as dispersions and films. Dynamic Light Scattering (DLS) and rheological techniques were used to characterize the dispersions, while the films' mechanical properties and drug release were determined. Laponite in an amount of 8.8 mg developed the optimal composites, reducing the particulate size and avoiding the agglomeration by its physical crosslinker and amphoteric properties. On the films, it enhanced the swelling and provided stability below 50 °C. Moreover, the study of drug release in maltodextrin and sodium ascorbate from LGL MAS was fitted to first-order and Korsmeyer-Peppas models, respectively. The aforementioned systems represent an interesting, innovative, and promising alternative in the field of healing materials.

Cellulose/pectin-based materials incorporating Laponite-indole derivative hybrid for oral administration and controlled delivery of the neuroprotective drug

Bionanocomposite materials based on clays have been designed for oral administration and controlled release of a neuroprotective drug derivative of 5-methylindole, which had featured an innovative pharmacological mechanism for the treatment of neurodegenerative diseases such as Alzheimer's. This drug was adsorbed in the commercially available Laponite® XLG (Lap). X-ray diffractograms confirmed its intercalation in the interlayer region of the clay. The loaded drug was 62.3 meq/100 g Lap, close to the cation exchange capacity of Lap. Per se toxicity studies and neuroprotective experiments versus the neurotoxin okadaic acid, a potent and selective inhibitor of protein phosphatase 2A (PP2A), confirmed that the clay-intercalated drug did not exert toxicity in cell cultures and provided neuroprotection. Release tests of the hybrid material performed in media mimicking the gastrointestinal tract indicated a drug release in acid medium close to 25 %. The hybrid was encapsulated in a micro/nanocellulose matrix and processed as microbeads, with pectin coating for additional protection, to minimize release under acidic conditions. Alternatively, low density materials based on a microcellulose/pectin matrix were evaluated as orodispersible foams showing fast disintegration times, sufficient mechanical resistance for handling, and release profiles in simulated media that confirmed a controlled release of the encapsulated neuroprotective drug.

Gum arabic/guar gum stabilized Hydnocarpus wightiana oil nanohydrogel: Characterization, antimicrobial, anti-inflammatory, and anti-biofilm activities

Hydnocarpus wightiana oil has proven to inhibit the growth of pathogenic microorganisms; however, the raw form is highly susceptible to oxidation, and thus it becomes toxic when uptake is in high amounts. Therefore, to minimize the deterioration, we formulated Hydnocarpus wightiana oil-based nanohydrogel and studied its characteristics as well biological activity. The low energy-assisted hydrogel was formulated by including gelling agent, connective linker, and cross-linker and it resulted in internal micellar polymerization of the milky white emulsion. The oil showed the presence of octanoic acid, n-tetradecane, methyl 11-(2-cyclopenten-1-yl) undecanoate (methyl hydnocarpate), 13-(2-cyclopenten-1-yl) tridecanoic acid (methyl chaulmoograte), and 10,13-eicosadienoic acid. The amount of caffeic acid was 0.0636 mg/g, which was higher than the amount of gallic acid (0.0076 mg/g) in the samples. The formulated nanohydrogel showed an average droplet size of 103.6 nm with a surface charge of -17.6 mV. The minimal inhibitory bactericidal, and fungicidal concentrations of nanohydrogel against pathogenic bacteria and fungi were ranging from 0.78 to 1.56 μl/mL with 70.29-83.62 % antibiofilm activity. Also, nanohydrogel showed a significantly (p < 0.05) higher killing rate for Escherichia coli (7.89 log CFU/mL) than Staphylococcus aureus (7.81 log CFU/mL) with comparable anti-inflammatory activity than commercial standard (49.28-84.56 %). Therefore, it can be concluded that being hydrophobic, and having the capability of target-specific drug absorption as well as biocompatibility nanohydrogels can be utilized to cure various pathogenic microbial infections.

Advances of Mussel-Inspired Nanocomposite Hydrogels in Biomedical Applications

Hydrogels, with 3D hydrophilic polymer networks and excellent biocompatibilities, have emerged as promising biomaterial candidates to mimic the structure and properties of biological tissues. The incorporation of nanomaterials into a hydrogel matrix can tailor the functions of the nanocomposite hydrogels to meet the requirements for different biomedical applications. However, most nanomaterials show poor dispersion in water, which limits their integration into the hydrophilic hydrogel network. Mussel-inspired chemistry provides a mild and biocompatible approach in material surface engineering due to the high reactivity and universal adhesive property of catechol groups. In order to attract more attention to mussel-inspired nanocomposite hydrogels, and to promote the research work on mussel-inspired nanocomposite hydrogels, we have reviewed the recent advances in the preparation of mussel-inspired nanocomposite hydrogels using a variety of nanomaterials with different forms (nanoparticles, nanorods, nanofibers, nanosheets). We give an overview of each nanomaterial modified or hybridized by catechol or polyphenol groups based on mussel-inspired chemistry, and the performances of the nanocomposite hydrogel after the nanomaterial's incorporation. We also highlight the use of each nanocomposite hydrogel for various biomedical applications, including drug delivery, bioelectronics, wearable/implantable biosensors, tumor therapy, and tissue repair. Finally, the challenges and future research direction in designing mussel-inspired nanocomposite hydrogels are discussed.

Well-Defined Bifunctional Dendrimer Bearing 54 Nitric Oxide-Releasing Moieties and 54 Ursodeoxycholic Acid Groups Presenting High Anti-Inflammatory Activity

Nitric oxide (NO) and ursodeoxycholic acid (UDCA) are endogenous molecules involved in physiological processes associated with inflammation. Since inflammatory processes are present in the mechanisms of many diseases, these molecules are important for the development of new drugs. Herein, we describe the synthesis of a well-defined bifunctional dendrimer with 108 termini bearing 54 NO-releasing groups and 54 UDCA units (Dendri-(NO/UDCA)₅₄). For comparison, a lower-generation dendrimer bearing 18 NO-releasing groups and 18 UDCA units (Dendri-(NO/UDCA)₁₈) was also synthesized. The anti-inflammatory activity of these dendrimers was evaluated, showing that the bifunctional dendrimers have an inverse correlation between concentration and anti-inflammatory activity, with an effect dramatically pronounced for Dendri-(NO/UDCA)₅₄ 20, which at just 0.25 nM inhibited 76.1% of IL-8 secretion. Data suggest that nanomolar concentrations of these dendrimers aid in releasing NO in a safe and controlled way. This bifunctional dendrimer has great potential as a drug against multifactorial diseases associated with inflammatory processes.

A Shear-Thinning Biomaterial-Mediated Immune Checkpoint Blockade

Systemic administration of immune checkpoint blockade agents can activate the anticancer activity of immune cells; however, the response varies from patient to patient and presents potential off-target toxicities. Local administration of immune checkpoint inhibitors (ICIs) can maximize therapeutic efficacies while reducing side effects. This study demonstrates a minimally invasive strategy to locally deliver anti-programmed cell death protein 1 (anti-PD-1) with shear-thinning biomaterials (STBs). ICI can be injected into tumors when loaded in STBs (STB-ICI) composed of gelatin and silicate nanoplatelets (Laponite). The release of ICI from STB was mainly affected by the Laponite percentage in STBs and pH of the local microenvironment. Low Laponite content and acidic pH can induce ICI release. In a murine melanoma model, the injection of STB-ICI significantly reduced tumor growth and increased CD8⁺ T cell level in peripheral blood. STB-ICI also induced increased levels of tumor-infiltrating CD4⁺ helper T cells, CD8⁺ cytotoxic T cells, and tumor death. The STB-based minimally invasive strategy provides a simple and efficient approach to deliver ICIs locally.

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.

Adsorption and Sustained Delivery of Small Molecules from Nanosilicate Hydrogel Composites

Two-dimensional nanosilicate particles (NS) have shown promise for the prolonged release of small-molecule therapeutics while minimizing burst release. When incorporated in a hydrogel, the high surface area and charge of NS enable electrostatic adsorption and/or intercalation of therapeutics, providing a lever to localize and control release. However, little is known about the physio-chemical interplay between the hydrogel, NS, and encapsulated small molecules. Here, we fabricated polyethylene glycol (PEG)-NS hydrogels for the release of model small molecules such as acridine orange (AO). We then elucidated the effect of NS concentration, NS/AO incubation time, and the ability of NS to freely associate with AO on hydrogel properties and AO release profiles. Overall, NS incorporation increased the hydrogel stiffness and decreased swelling and mesh size. When individual NS particles were embedded within the hydrogel, a 70-fold decrease in AO release was observed compared to PEG-only hydrogels, due to adsorption of AO onto NS surfaces. When NS was pre-incubated and complexed with AO prior to hydrogel encapsulation, a >9000-fold decrease in AO release was observed due to intercalation of AO between NS layers. Similar results were observed for other small molecules. Our results show the potential for use of these nanocomposite hydrogels for the tunable, long-term release of small molecules.

Controlled and Local Delivery of Antibiotics by 3D Core/Shell Printed Hydrogel Scaffolds to Treat Soft Tissue Infections

Soft tissue infections in open fractures or burns are major cause for high morbidity in trauma patients. Sustained, long-term and localized delivery of antimicrobial agents is needed for early eradication of these infections. Traditional (topical or systemic) antibiotic delivery methods are associated with a variety of problems, including their long-term unavailability and possible low local concentration. Novel approaches for antibiotic delivery via wound coverage/healing scaffolds are constantly being developed. Many of these approaches are associated with burst release and thus seldom maintain long-term inhibitory concentrations. Using 3D core/shell extrusion printing, scaffolds consisting of antibiotic depot (in the core composed of low concentrated biomaterial ink 3% alginate) surrounded by a denser biomaterial ink (shell) were fabricated. Denser biomaterial ink (composed of alginate and methylcellulose or alginate, methylcellulose and Laponite) retained scaffold shape and modulated antibiotic release kinetics. Release of antibiotics was observed over seven days, indicating sustained release characteristics and maintenance of potency. Inclusion of Laponite in shell, significantly reduced burst release of antibiotics. Additionally, the effect of shell thickness on release kinetics was demonstrated. Amalgamation of such a modular delivery system with other biofabrication methods could potentially open new strategies to simultaneously treat soft tissue infections and aid wound regeneration.

Self-Assembly of a Triazolylferrocenyl Dendrimer in Water Yields Nontraditional Intrinsic Green Fluorescent Vesosomes for Nanotheranostic Applications

The promising field of nanomedicine stimulates a continuous search for multifunctional nanotheranostic systems for imaging and drug delivery. Herein, we demonstrate that application of supramolecular chemistry's concepts in dendritic assemblies can enable the formation of advanced dendrimer-based nanotheranostic devices. A dendrimer bearing 81 triazolylferrocenyl terminal groups adopts a more compact shell-like structure in polar solvents with the ferrocenyl peripheral groups backfolding toward the hydrophobic dendrimer interior, while exposing the more polar triazole moieties as the dendritic shell. Akin to lipids, the compact dendritic structure self-assembles into uniform nanovesicles that in turn self-assemble into larger vesosomes in water. The vesosomes emit green nontraditional intrinsic fluorescence (NTIL), which is an emerging property as there are no classical fluorophores in the dendritic macromolecular structure. This work confirms the hypothesis that the NTIL emission is greatly enhanced by rigidification of the supramolecular assemblies containing heteroatomic subluminophores (HASLs) and by the presence of electron rich functional groups on the periphery of dendrimers. This work is the first one detecting NTIL in ferrocenyl-terminated dendrimers. Moreover, the vesosomes are stable in biological medium, are uptaken by cells, and show cytotoxic activity against cancer cells. Accordingly, the self-organization of these dendrimers into tertiary structures promotes the emergence of new properties enabling the same component, in this case, ferrocenyl group, to function as both antitumoral drug and fluorophore.

Development of Nanosilicate-Hydrogel Composites for Sustained Delivery of Charged Biopharmaceutics

Nanocomposite hydrogels containing two-dimensional nanosilicates (NS) have emerged as a new technology for the prolonged delivery of biopharmaceuticals. However, little is known about the physical-chemical properties governing the interaction between NS and proteins and the release profiles of NS-protein complexes in comparison to traditional poly(ethylene glycol) (PEG) hydrogel technologies. To fill this gap in knowledge, we fabricated a nanocomposite hydrogel composed of PEG and laponite and identified simple but effective experimental conditions to obtain sustained protein release, up to 23 times slower as compared to traditional PEG hydrogels, as determined by bulk release experiments and fluorescence correlation spectroscopy. Slowed protein release was attributed to the formation of NS-protein complexes, as NS-protein complex size was inversely correlated with protein diffusivity and release rates. While protein electrostatics, protein concentration, and incubation time were important variables to control protein-NS complex formation, we found that one of the most significant and less appreciated variable to obtain a sustained release of bioactive proteins was the buffer chosen for preparing the initial suspension of NS particles. The buffer was found to control the size of nanoparticles, the absorption potential, morphology, and stiffness of hydrogels. From these studies, we conclude that the PEG-laponite composite fabricated is a promising new platform for sustained delivery of positively charged protein therapeutics.

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.

Enhancing the Anticancer Activity and Selectivity of Goniothalamin Using pH-Sensitive Acetalated Dextran (Ac-Dex) Nanoparticles: A Promising Platform for Delivery of Natural Compounds

Goniothalamin (GTN), a natural compound isolated from Goniothalamus species, has previously demonstrated cytotoxic activity against several cancer cell lines. However, similarly to many natural and synthetic anticancer compounds, GTN presents toxicity toward some healthy cells and low aqueous solubility, decreasing its bioavailability and precluding its application as an antineoplastic drug. In our efforts to improve the pharmacokinetic behavior and selectivity of GTN against cancer cells, we developed a polymeric nanosystem, in which rac-GTN was encapsulated in pH-responsive acetalated dextran (Ac-Dex) nanoparticles (NPs) with high loadings of the bioactive compound. Dynamic light scattering (DLS) analysis showed that the nanoparticles obtained presented a narrow size distribution of around 100 nm in diameter, whereas electron microscopy (EM) images showed nanoparticles with a regular spherical morphology in agreement with the size range obtained by DLS. Stability and release studies indicated that the GTN@Ac-Dex NPs presented high stability under physiological conditions (pH 7.4) and disassembled under slightly acidic conditions (pH 5.5), releasing the rac-GTN in a sustained manner. In vitro assays showed that GTN@Ac-Dex NPs significantly increased cytotoxicity and selectivity against cancer cells when compared with the empty Ac-Dex NPs and the free rac-GNT. Cellular uptake and morphology studies using MCF-7 cells demonstrated that GTN@Ac-Dex NPs are rapidly internalized into the cancer cells, causing cell death. In vivo investigation confirmed the efficient release of rac-GTN from GTN@Ac-Dex NPs, resulting in the delay of prostate cancer progression in transgenic adenocarcinoma of the mouse prostate (TRAMP) model. Furthermore, liver histopathology evaluation after treatment with GTN@Ac-Dex NPs showed no evidence of toxicity. Therefore, the in vitro and in vivo findings suggest that the Ac-Dex NPs are a promising nanosystem for the sustained delivery of rac-GTN into tumors.

3D-bioprinted functional and biomimetic hydrogel scaffolds incorporated with nanosilicates to promote bone healing in rat calvarial defect model

Three-dimensional (3D) bioprinting is an extremely convenient biofabrication technique for creating biomimetic tissue-engineered bone constructs and has promising applications in regenerative medicine. However, existing bioinks have shown low mechanical strength, poor osteoinductive ability, and lacking a suitable microenvironment for laden cells. Nanosilicate (nSi) has shown to be a promising biomaterial, due to its unique properties such as excellent biocompatibility, degrade into nontoxic products, and with osteoinductive properties, which has been used in bone bioprinting. However, the long term bone healing effects and associating risks, if any, of using nSi in tissue engineering bone scaffolds in vivo are unclear and require a more thorough assessment prior to practical use. Hence, a functional and biomimetic nanocomposite bioink composed of rat bone marrow mesenchymal stem cells (rBMSCs), nSi, gelatin and alginate for the 3D bioprinting of tissue-engineered bone constructs is firstly demonstrated, mimicking the structure of extracellular matrix, to create a conducive microenvironment for encapsulated cells. It is shown that the addition of nSi significantly increases the printability and mechanical strength of fabricated human-scale tissue or organ structures (up to 15 mm height) and induces osteogenic differentiation of the encapsulated rBMSCs in the absence of in vitro osteoinductive factors. A systematic in vivo research of the biomimetic nanocomposite bioink scaffolds is further demonstrated in a rat critical-size (8 mm) bone defect-repair model. The in vivo results demonstrate that the 3D bioprinted nanocomposite scaffolds can significantly promote the bone healing of the rat calvarial defects compared to other scaffolds without nSi or cells, and show rarely side effects on the recipients. Given the above advantageous properties, the 3D bioprinted nanocomposite scaffolds can greatly accelerate the bone healing in critical bone defects, thus providing a clinical potential candidate for orthopedic applications.

Applications of Two-Dimensional Nanomaterials in Breast Cancer Theranostics

Breast cancer is the leading cause of cancer-related mortality among women. Early stage diagnosis and treatment of this cancer are crucial to patients' survival. In addition, it is important to avoid severe side effects during the process of conventional treatments (surgery, chemotherapy, hormonal therapy, and targeted therapy) and increase the patients' quality of life. Over the past decade, nanomaterials of all kinds have shown excellent prospects in different aspects of oncology. Among them, two-dimensional (2D) nanomaterials are unique due to their physical and chemical properties. The functional variability of 2D nanomaterials stems from their large specific surface area as well as the diversity of composition, electronic configurations, interlayer forces, surface functionalities, and charges. In this review, the current status of 2D nanomaterials in breast cancer diagnosis and therapy is reviewed. In this respect, sensing of the tumor biomarkers, imaging, therapy, and theranostics are discussed. The ever-growing 2D nanomaterials are building blocks for the development of a myriad of nanotheranostics. Accordingly, there is the possibility to explore yet novel properties, biological effects, and oncological applications.

Soft and Condensed Nanoparticles and Nanoformulations for Cancer Drug Delivery and Repurpose

Drug repurpose or reposition is recently recognized as a high-performance strategy for developing therapeutic agents for cancer treatment. This approach can significantly reduce the risk of failure, shorten R&D time, and minimize cost and regulatory obstacles. On the other hand, nanotechnology-based delivery systems are extensively investigated in cancer therapy due to their remarkable ability to overcome drug delivery challenges, enhance tumor specific targeting, and reduce toxic side effects. With increasing knowledge accumulated over the past decades, nanoparticle formulation and delivery have opened up a new avenue for repurposing drugs and demonstrated promising results in advanced cancer therapy. In this review, recent developments in nano-delivery and formulation systems based on soft (i.e., DNA nanocages, nanogels, and dendrimers) and condensed (i.e., noble metal nanoparticles and metal-organic frameworks) nanomaterials, as well as their theranostic applications in drug repurpose against cancer are summarized.

Cell-loaded injectable gelatin/alginate/LAPONITE® nanocomposite hydrogel promotes bone healing in a critical-size rat calvarial defect model

An injectable cell-laden nanocomposite hydrogel simulate natural ECM, promote cell proliferation, and accelerate bone healing of critical-size rat calvarial defects.

Biodegradable and pH-Responsive Acetalated Dextran (Ac-Dex) Nanoparticles for NIR Imaging and Controlled Delivery of a Platinum-Based Prodrug into Cancer Cells

Nanoparticles (NPs) based on the biodegradable acetalated dextran polymer (Ac-Dex) were used for near-infrared (NIR) imaging and controlled delivery of a Pt^IV prodrug into cancer cells. The Ac-Dex NPs loaded with the hydrophobic Pt^IV prodrug 3 (Pt^IV/Ac-Dex NPs) and with the novel hydrophobic NIR-fluorescent dye 9 (NIR-dye 9/Ac-Dex NPs), as well as Ac-Dex NPs coloaded with both compounds (coloaded Ac-Dex NPs), were assembled using a single oil-in-water nanoemulsion method. Dynamic light scattering measurements and scanning electron microscopy images showed that the resulting Ac-Dex NPs are spherical with an average diameter of 100 nm, which is suitable for accumulation in tumors via the enhanced permeation and retention effect. The new nanosystems exhibited high drug-loading capability, high encapsulation efficiency, high stability in physiological conditions, and pH responsiveness. Drug-release studies clearly showed that the Pt^IV prodrug 3 release from Ac-Dex NPs was negligible at pH 7.4, whereas at pH 5.5, this compound was completely released with a controlled rate. Confocal laser scanning microscopy unambiguously showed that the NIR-dye 9/Ac-Dex NPs were efficiently taken up by MCF-7 cells, and cytotoxicity assays against several cell lines showed no significant toxicity of blank Ac-Dex NPs up to 1 mg mL^-1. The IC₅₀ values obtained for the Pt^IV prodrug encapsulated in Ac-Dex NPs were much lower when compared with the IC₅₀ values obtained for the free Pt^IV complex and cisplatin in all cell lines tested. Overall, our results demonstrate, for the first time, that Ac-Dex NPs constitute a promising drug delivery platform for cancer therapy.