Boosting H2O2 generation by shortening the charge migration distance in BiPO4 nanocrystals

The photocatalytic production of H2O2 has gained recognition as an economical and eco-friendly technology, but it suffers from limitations such as low production rates and difficulty in achieving high concentrations. This study was designed to overcome these limitations by preparing BiPO4 nanocrystals (BIP NCs) via high-temperature hydrolysis, and X-ray diffraction (XRD) and transmission electron microscopy (TEM) indicated that BIP NCs with particle sizes of 8.5 ± 3 nm were synthesized. In a photocatalytic performance test, only H2O and O2 were used to produce H2O2, resulting in an accumulation of H2O2 of up to 30.44 mM·g-1, as measured with the potassium titanium oxalate method; this value was 3.13 times greater than that of bulk BiPO4 (BIP-B). The resulting nanocrystals demonstrated superior electron-hole transport and separation efficiency compared to those of BIP-B, and H2O2 was formed in a one-step two-electron process. Furthermore, a film composed of a gas diffusion layer (GDL) and BIP NCs provided continuous accumulation of H2O2; a concentration of 7.23 mM was achieved after 96 h of reaction, and the stability of the film was confirmed by comparing scanning electron microscopy (SEM) images obtained before and after the reaction. Construction of a nanocrystalline structure to enhance the activities of photocatalysts and films and achieve continuous accumulation of H2O2 will provide insights into the photocatalytic production of highly concentrated H2O2.

Chemical Aspects of Halide Perovskite Nanocrystals

Halide perovskite nanocrystals (HPNCs) are currently among the most intensely investigated group of materials. Structurally related to the bulk halide perovskites (HPs), HPNCs are nanostructures with distinct chemical, optical, and electronic properties and significant practical potential. One of the keys to the effective exploitation of the HPNCs in advanced technologies is the development of controllable, reproducible, and scalable methods for preparation of materials with desired compositions, phases, and shapes and low defect content. Another important condition is a quantitative understanding of factors affecting the chemical stability and the optical and electronic properties of HPNCs. Here we review important recent developments in these areas. Following a brief historical prospective, we provide an overview of known chemical methods for preparation of HPNCs and approaches used to control their composition, phase, size, and shape. We then review studies of the relationship between the chemical composition and optical properties of HPNCs, degradation mechanisms, and effects of charge injection. Finally, we provide a short summary and an outlook. The aim of this review is not to provide a comprehensive summary of all relevant literature but rather a selection of highlights, which, in the subjective view of the authors, provide the most significant recent observations and relevant analyses.

Recent advances in nanocrystal-based technologies applied for ocular drug delivery

INTRODUCTION

The intricate physiological barriers of the eye and the limited volume of eye drops impede efficient delivery of poorly water-soluble drugs. In the last decade, nanocrystals have emerged as versatile drug delivery systems in various administration routes from bench to bedside. The unique superiorities of nanocrystals, mainly embodied in high drug-loading capacity, good mucosal adhesion and penetration, and greatly improved drug solubility, reveal a promising prospect for ocular delivery of poorly water-soluble drugs.

AREAS COVERED

This article focuses on the ophthalmic nanocrystal technologies and products that are in the literature, clinical trials, and even on the market. The recent research progress in the preparation, ocular application, and absorption of nanocrystals are highlighted, and the pros and cons of nanocrystals in overcoming the physiological barriers of the eye are also summarized.

EXPERT OPINION

Nanocrystals have demonstrated success as glucocorticoid eye drops in the treatment of anterior segment diseases. However, the thermodynamic stability of nanocrystals remains the major challenge in product development. New technologies for efficiently optimizing stabilizers and sterilization processes are still expected. Strategies to confer more diverse functions via surface modification are also worth exploration to improve the potential of nanocrystals in delivering poorly water-soluble drugs to posterior segment of the eye.

Formulation and optimization of ivermectin nanocrystals for enhanced topical delivery

The increasing resistance to antiparasitic drugs and limited availability of new agents highlight the need to improve the efficacy of existing treatments. Ivermectin (IVM) is commonly used for parasite treatment in humans and animals, however its efficacy is not optimal and the emergence of IVM-resistant parasites presents a challenge. In this context, the physico-chemical characteristics of IVM were modified by nanocrystallization to improve its equilibrium water-solubility and skin penetration, potentially improving its therapeutic effectiveness when applied topically. IVM-nanocrystals (IVM-NC) were prepared using microfluidization technique. The impact of several process/formulation variables on IVM-NC characteristics were studied using D-optimal statistical design. The optimized formulation was further lyophilized and evaluated using several in vitro and ex vivo tests. The optimal IVM-NC produced monodisperse particles with average diameter of 186 nm and polydispersity index of 0.4. In vitro results showed an impressive 730-fold increase in the equilibrium solubility and substantial 24-fold increase in dissolution rate. Ex vivo permeation study using pig's ear skin demonstrated 3-fold increase in dermal deposition of IVM-NC. Additionally, lyophilized IVM-NC was integrated into topical cream, and the resulting drug release profile was superior compared to that of the marketed product. Overall, IVM-NC presents a promising approach to improving the effectiveness of topically applied IVM in treating local parasitic infections.

Hyaluronic acid/inulin-based nanocrystals with an optimized ratio of indigo and indirubin for combined ulcerative colitis therapy via immune and intestinal flora regulation

Indigo (IND) and indirubin (INB) have demonstrated a synergistic effect in treating ulcerative colitis at a ratio of 7.5:1. However, the colon mucus layer, a critical physiological barrier against external threats, is also a biological barrier, limiting the potential for effective drug delivery to the lamina propria for regulating inflammatory cells. Inspired by the potential of Hyaluronic acid (HA), to enhance cellular uptake by inflammatory cells, and Pluronic® F127 (F127), known for overcoming the mucus barrier, this study innovatively developed INB/IND nanosuspensions by co-modifying with F127 and HA. Moreover, inulin serves a dual purpose as a spray protective agent and a regulator of intestinal flora. Therefore, it was incorporated into INB/IND nanosuspensions for subsequent spray drying, resulting in the preparation of INB/IND nanocrystals (INB/IND-NC). The mucus penetration of INB/IND-NC was 24.30 times that of the control group. Besides, INB/IND-NC exhibited enhanced cellular uptake properties proximately twice that of Raw INB/IND. Importantly, INB/IND-NC exhibited improved therapeutic efficacy in DSS-induced mice by regulating the expression of cytokines, regulating immune responses via downregulating the expression of macrophages, neutrophils, and dendritic cells and maintaining intestinal flora homeostasis. Our study provides a new perspective for applying natural products for treating inflammatory diseases.

Optimizing adjuvant inhaled chemotherapy: Synergistic enhancement in paclitaxel cytotoxicity by flubendazole nanocrystals in a cycle model approach

Lung cancer is the leading cause of cancer-related death. In addition to new innovative approaches, practical strategies that improve the efficacy of already available drugs are urgently needed. In this study, an inhalable dry powder formulation is used to repurpose flubendazole, a poorly soluble anthelmintic drug with potential against a variety of cancer lineages. Flubendazole nanocrystals were obtained through nanoprecipitation, and dry powder was produced by spray drying. Through fractional factorial design, the spray drying parameters were optimized and the impact of formulation on aerolization properties was clarified. The loading limitations were clarified through response surface methodology, and a 15% flubendazole loading was feasible through the addition of 20% L-leucine, leading to a flubendazole particle size of 388.6 nm, median mass aerodynamic diameter of 2.9 μm, 50.3% FPF, emitted dose of 83.2% and triple the initial solubility. Although the cytotoxicity of this formulation in A549 cells was limited, the formulation showed a synergistic effect when associated with paclitaxel, leading to a surprising 1000-fold reduction in the IC50. Compared to 3 cycles of paclitaxel alone, a 3-cycle model combined treatment increased the threshold of cytotoxicity by 25% for the same dose. Our study suggests, for the first time, that orally inhaled flubendazole nanocrystals show high potential as adjuvants to increase cytotoxic agents' potency and reduce adverse effects.

Prodrug approaches for the development of a long-acting drug delivery systems

Long-acting formulations are designed to reduce dosing frequency and simplify dosing schedules by providing an extended duration of action. One approach to obtain long-acting formulations is to combine long-acting prodrugs (LA-prodrug) with existing or emerging drug delivery technologies (DDS). The design criteria for long-acting prodrugs are distinct from conventional prodrug strategies that alter absorption, distribution, metabolism, and excretion (ADME) parameters. Our review focuses on long-acting prodrug delivery systems (LA-prodrug DDS), which is a subcategory of long-acting formulations where prodrug design enables DDS formulation to achieve an extended duration of action that is greater than the parent drug. Here, we define LA-prodrugs as the conjugation of an active pharmaceutical ingredient (API) to a promoiety group via a cleavable covalent linker, where both the promoiety and linker are selected to enable formulation and administration from a drug delivery system (DDS) to achieve an extended duration of action. These LA-prodrug DDS results in an extended interval where the API is within a therapeutic range without necessarily altering ADME as is typical of conventional prodrugs. The conversion of the LA-prodrug to the API is dependent on linker cleavage, which can occur before or after release from the DDS. The requirement for linker cleavage provides an additional tool to prolong release from these LA-prodrug DDS. In addition, the physicochemical properties of drugs can be tuned by promoiety selection for a particular DDS. Conjugation with promoieties that are carriers or amenable to assembly into carriers can also provide access to formulations designed for extending duration of action. LA-prodrugs have been applied to a wide variety of drug delivery strategies and are categorized in this review by promoiety size and complexity. Small molecule promoieties (typically MW < 1000 Da) have been used to improve encapsulation or partitioning as well as broaden APIs for use with traditional long-acting formulations such as solid drug dispersions. Macromolecular promoieties (typically MW > 1000 Da) have been applied to hydrogels, nanoparticles, micelles, dendrimers, and polymerized prodrug monomers. The resulting LA-prodrug DDS enable extended duration of action for active pharmaceuticals across a wide range of applications, with target release timescales spanning days to years.

Research progress on the preparation and application of flavonoid nanocrystals

Flavonoids have been reported to possess significant pharmacological activities,such as antioxidant, anti-inflammatory and anticancer effects. However, the low solubility and low bioavailability limits their clinical application. Nanocrystal technology can solve the delivery problems of flavonoids by reducing particle size, increasing the solubility of insoluble drugs and improving their bioavailability. This article summaries nanosuspension preparation methods and the stabilizers for flavonoid nanocrystals, and reviews the drug delivery routes including oral, Injection and transdermal of flavonoid nanocrystals, to provide information for further research on nanocrystal delivery system of flavonoids.

Polymeric Microarray Patches for Enhanced Transdermal Delivery of the Poorly Soluble Drug Olanzapine

Transdermal drug delivery is an alternative route of administration that offers avoidance of the associated drawbacks of orally and parenterally administered hydrophobics. However, owing to the extremely specific set of physicochemical characteristics required for passive transdermal drug permeation, the development of marketed transdermal products containing poorly soluble drugs has been severely limited. Microarray patches (MAPs) are a type of transdermal patch that differ from the traditional patch design due to the presence of tiny, micron-sized needles that permit enhanced drug permeation on their application surface. To date, MAPs have predominantly been used to deliver hydrophilic compounds. However, this work challenges this trend and focuses on the use of MAPs, in combination with commonly utilized solubility-enhancing techniques, to deliver the hydrophobic drug olanzapine (OLP) across the skin. Specifically, cyclodextrin (CD) complexation and particle size reduction were employed in tandem with hydrogel-forming and dissolving MAPs, respectively. In vivo experimentation using a female Sprague-Dawley rat model confirmed the successful delivery of OLP from hydrogel-forming MAPs (C_max = 611.13 ± 153.34 ng/mL, T_max = 2 h) and dissolving MAPs (C_max = 690.56 ± 161.33 ng/mL, T_max = 2 h) in a manner similar to that of oral therapy in terms of the rate and extent of drug absorption, as well as overall drug exposure and bioavailability. This work is the first reported use of polymeric MAPs in combination with the solubility-enhancing techniques of CD complexation and particle size reduction to successfully deliver the poorly soluble drug OLP via the transdermal route. Accordingly, this paper provides significant evidence to support an expansion of the library of molecules amenable to MAP-mediated drug delivery to include those that exhibit poor aqueous solubility.

Nanocrystals in cosmetics and cosmeceuticals by topical delivery

The main issues with local delivery of cosmetics are their high sensitivity and limited drug loading of active pharmaceutical ingredient. Nanocrystal technology offers consumers cutting-edge and effective products and exhibits enormous development potential in the beauty business as a new delivery method to address the issue of low solubility and low permeability of sensitive chemicals. In this review, we described the processes for making NCs, along with the impacts of loading and the uses of different carriers. Among them, nanocrystalline loaded gel and emulsion are widely used and may further improve the stability of the system. Then, we introduced the beauty efficacy of drug NCs from five aspects: anti-inflammation and acne, anti-bacterial, lightening and freckle removal, anti-aging as well as UV protection. Following that, we presented the current scenario about stability and safety. Finally, the challenges and vacancy were discussed along with the potential uses of NCs in the cosmetics industry. This review serves as a resource for the advancement of nanocrystal technology in the cosmetics sector.

High resveratrol-loaded microcapsules with trehalose and OSA starch as the wall materials: Fabrication, characterization, and evaluation

To improve the solubility and stability of resveratrol (Res), Res nanocrystals (Res-ncs) as the capsule core were prepared by wet milling using hydroxypropyl methyl cellulose (HPMC_E5), sodium dodecyl sulfate (SDS), and polyvinylpyrrolidone (PVP_K30) as stabilizers, along with trehalose and octenyl succinic anhydride (OSA) modified starch were used as the wall material to produce Res microcapsules (Res-mcs) via spray drying. The fresh-prepared Res-ncs and rehydrated Res-mcs had mean particle sizes of 190.30 ± 3.43 and 204.70 ± 3.60 nm, zeta potentials of -13.90 ± 0.28 and - 11.20 ± 0.34 mV, and the loading capacities (LC) were as high as 73.03 % and 28.83 %. Particle morphology showed that Res-mcs had more regular and smooth spherical structures. FTIR indicated that Res may have hydrogen bonding with the walls. XRD and DSC exhibited that Res in nanocrystals and microcapsules existed mostly as amorphous structures. The solubility of Res-mcs and Res-ncs was increased, with excellent redispersibility and rapid dissolution of Res in vitro. The antioxidant properties of Res-mcs were protected and improved. With the walls acting as a physical barrier, Res-mcs have better photothermal stability than raw Res. Res-mcs have a relative bioavailability of 171.25 %, which is higher than that of raw Res.

Injectable, Drug-Eluting Nanocrystals Prevent Fibrosis and Stricture Formation In Vivo

BACKGROUND & AIMS

Tissue fibrosis results from uncontrolled healing responses leading to excessive mesenchymal cell activation and collagen and other extracellular matrix deposition. In the gastrointestinal tract, fibrosis leads to narrowing of the lumen and stricture formation. A drug treatment to prevent fibrosis and strictures in the gastrointestinal tract would be transformational for patient care. We aimed to develop a stricture treatment with the following characteristics and components: a small molecule with strong antifibrotic effects that is delivered locally at the site of the stricture to ensure correct lesional targeting while protecting the systemic circulation, and that is formulated with sustained-release properties to act throughout the wound healing processes.

METHODS

A high-throughput drug screening was performed to identify small molecules with antifibrotic properties. Next, we formulated an antifibrotic small molecule for sustained release and tested its antifibrotic potential in 3 animal models of fibrosis.

RESULTS

Sulconazole, a US Food and Drug Administration-approved drug for fungal infections, was found to have strong antifibrotic properties. Sulconazole was formulated as sulconazole nanocrystals for sustained release. We found that sulconazole nanocrystals provided superior or equivalent fibrosis prevention with less frequent dosing in mouse models of skin and intestinal tissue fibrosis. In a patient-like swine model of bowel stricture, a single injection of sulconazole nanocrystals prevented stricture formation.

CONCLUSIONS

The current data lay the foundation for further studies to improve the management of a range of diseases and conditions characterized by tissue fibrosis.

Ligand Effects in Assembly of Cubic and Spherical Nanocrystals: Applications to Packing of Perovskite Nanocubes

We establish the formula representing cubic nanocrystals (NCs) as hard cubes taking into account the role of the ligands and describe how these results generalize to any other NC shapes. We derive the conditions under which the hard cube representation breaks down and provide explicit expressions for the effective size. We verify the results from the detailed potential of mean force calculations for two nanocubes in different orientations as well as with spherical nanocrystals. Our results explicitly demonstrate the relevance of certain ligand conformations, i.e., "vortices", and show that edges and corners provide natural sites for their emergence. We also provide both simulations and experimental results with single component cubic perovskite nanocrystals assembled into simple cubic superlattices, which further corroborate theoretical predictions. In this way, we extend the Orbifold Topological Model (OTM) accounting for the role of ligands beyond spherical nanocrystals and discuss its extension to arbitrary nanocrystal shapes. Our results provide detailed predictions for recent superlattices of perovskite nanocubes and spherical nanocrystals. Problems with existing united atom force fields are discussed.

Long Acting Ionically Paired Pamoate-based Suspension of Lurasidone: An exploration of Size Effects on in vitro Dissolution and in vivo Pharmacokinetic Behaviors

Latuda® is an oral tablet approved by the US Food and Drug Administration (FDA) for the treatment of schizophrenia. However, the clinical efficacy of Latuda® is compromised by patient noncompliance due to frequent daily administration, especially for patients experiencing severe schizophrenia, whose medication is often needed for several months to years. Hence, developing a long-acting injectable formulation of lurasidone is urgently needed. Herein, a poorly water-soluble lurasidone pamoate (LP) salt was synthesized via the facile ion pair-based salt formation technology. The solubility of LP was decreased by 233 folds compared with that of lurasidone hydrochloride (LH). Furthermore, suspensions of LH and LP with three different particle sizes, including 400 nm small-sized nanocrystals (SNCs), 4 μm medium-sized microcrystals (MMCs), and 15 μm large-sized microcrystals (LMCs) were prepared and characterized by powder X-ray diffraction (PXRD) and differential scanning calorimetry (DSC). The in vitro release results showed that particle sizes had great effects on the sustained release of LH, where large-sized particles exhibited superior sustained release than the smaller ones. Besides, LP suspensions exhibited better sustained release than LH suspensions at the same size scale. Moreover, the pharmacokinetics showed that LP LMCs produced an extended in vivo intramuscularly injectable profile for up to 45 days, which was 10 days longer than that of the LH LMCs. Our findings demonstrated that particle size had appreciable impacts on drug sustained release and provided valuable knowledge for the rational design of optimized micronized suspensions for long-acting injectables.

All-stage targeted therapy for the brain metastasis from triple-negative breast cancer

Brain metastasis is a common and serious complication of breast cancer, which is commonly associated with poor survival and prognosis. In particular, the treatment of brain metastasis from triple-negative breast cancer (BM-TNBC) has to face the distinct therapeutic challenges from tumor heterogeneity, circulating tumor cells (CTCs), blood-brain barrier (BBB) and blood-tumor barrier (BTB), which is in unmet clinical needs. Herein, combining with the advantages of synthetic and natural targeting moieties, we develop a "Y-shaped" peptide pVAP-decorated platelet-hybrid liposome drug delivery system to address the all-stage targeted drug delivery for the whole progression of BM-TNBC. Inherited from the activated platelet, the hybrid liposomes still retain the native affinity toward CTCs. Further, the peptide-mediated targeting to breast cancer cells and transport across BBB/BTB are demonstrated in vitro and in vivo. The resultant delivery platform significantly improves the drug accumulation both in orthotopic breast tumors and brain metastatic lesions, and eventually exhibits an outperformance in the inhibition of BM-TNBC compared with the free drug. Overall, this work provides a promising prospect for the comprehensive treatment of BM-TNBC, which could be generalized to other cell types or used in imaging platforms in the future.

Folded, undulating, and fibrous doxorubicin sulfate crystals in liposomes

High-resolution cryogenic transmission electron microscopy (cryo-TEM) evidenced that doxorubicin sulfate crystals in liposomes (prepared by remote loading with ammonium sulfate) form folded, undulating, and fibrous crystals with a diameter of approximately 2.4 nm. An undulating, fibrous crystal considered to be undergrowth, in addition to bundles of fibrous crystals, was also observed in doxorubicin-loaded liposomes. This explains the validity of the formation of doxorubicin sulfate crystals of various shapes, e.g., curved, U-shaped, or circular, in addition to cylinder and/or rod-like crystals reported in the literature. Liposomes that do not contain crystals have inner aqueous phases with high electron density, suggesting that the doxorubicin is remotely loaded and remains as a solute without precipitation.

Polydopamine-coated thalidomide nanocrystals promote DSS-induced murine colitis recovery through Macrophage M2 polarization together with the synergistic anti-inflammatory and anti-angiogenic effects

High levels of proinflammatory cytokines, macrophage polarization status and immune-mediated angiogenesis play pivotal roles in the pathogenesis of inflammatory bowel disease (IBD). Thalidomide, an anti-inflammatory, immunomodulatory and antiangiogenic agent, is used off-label for treatment of IBD. The therapeutic potential of thalidomide is limited by its poor solubility and side effects associated with its systemic exposure. To address these issues and promote its therapeutic effects on IBD, thalidomide nanocrystals (Thali NCs) were prepared and coated with polydopamine (PDA), a potential macrophage polarization modulator, to form PDA coated Thali NCs (Thali@PDA). Thali@PDA possessed a high drug loading and displayed average particle size of 764.7 ± 50.30 nm. It showed a better anti-colitis effect than bare thalidomide nanocrystals at the same dose of thalidomide. Synergistic effects of polydopamine on anti-inflammatory and anti-angiogenic activities of thalidomide were observed. Furthermore, PDA coating could direct polarization of macrophages towards M2 phenotype, which boosted therapeutic effects of Thali@PDA on IBD. Upon repeated dosing of Thali@PDA for one week, symptoms of IBD in mice were significantly relieved, and histomorphology of the colitis colons were normalized. Key proinflammatory cytokine levels in the inflamed intestines were significantly decreased. Toxicity study also revealed that Thali@PDA is a safe formulation.

Oral drug delivery strategies for development of poorly water soluble drugs in paediatric patient population

Selecting the appropriate formulation and solubility-enabling technology for poorly water soluble drugs is an essential element in the development of formulations for paediatric patients. Different methodologies and structured strategies are available to select a suitable approach and guide formulation scientists for development of adult formulations. However, there is paucity of available literature for selection of technology and overcoming the challenges in paediatric formulation development. The need for flexible dosing, and the limited knowledge of the safety of many formulation excipients in paediatric subjects, impose significant constraints and in some instances require adaptation of the approaches taken to formulating these drugs for the adult population. Selection of the best drug delivery system for paediatrics requires an efficient, systematic approach that considers a drug's physical and chemical properties and the targeted patient population's requirements. This review is a step towards development of a strategy for the design of solubility enhancing paediatric formulations of highly insoluble drugs. The aim of this review is to provide an overview of different approaches and strategies to consider in order to assist development of paediatric formulation for poorly water-soluble drugs with the provision of examples of some marketed products. In addition, it provides recommendations to overcome the range of challenges posed by these strategies and adaptations of the adult approach/product presentation required to enable paediatric drug development and administration.

Tacrolimus nanocrystals microneedle patch for plaque psoriasis

Plaque psoriasis is characterized by an abnormal thickening of the epidermis, which causes great difficulties for traditional topical drug delivery. Microneedles can pierce the thickened epidermis and deliver drugs to the skin for psoriasis treatment. Tacrolimus is a poorly water-soluble immunosuppressant used for the treatment of psoriasis. In this study, tacrolimus (TAC) nanocrystals (NCs) were produced using a bottom-up technique that dispersed TAC into a sodium hyaluronate-based microneedle patch (MNP), and its therapeutic efficacy was evaluated. The average particle size of the TAC NCs was 259.6 ± 2.3 nm. The mechanical strength of the microneedles was 0.41 ± 0.06 N/needle, which was sufficient to penetrate psoriatic skin. Microneedles were detached from the substrate 10 min after insertion into the psoriasis skin with an insertion depth of 258.8 ± 14.4 μm. The intradermal retention of the MNP (8.40 ± 0.33 μg/cm²) was six times that of the commercial ointment (1.40 ± 0.12 μg/cm²). In pharmacodynamic experiments, results indicated improvement in the phenotypic and histopathological features and reduction in the level of TNF-α, IL-17A, and IL-23 of psoriatic skin treated with TAC NCs MNP. Therefore, MNP loaded with TAC NCs may be a promising approach for psoriasis treatment.

Benchmarking supramolecular adhesive behavior of nanocelluloses, cellulose derivatives and proteins

One of the key steps towards a broader implementation of renewable materials is the development of biodegradable adhesives that can be attained at scale and utilized safely. Recently, cellulose nanocrystals (CNCs) were demonstrated to have remarkable adhesive properties. Herein, we study three classes of naturally synthesized biopolymers as adhesives, namely nanocelluloses (CNFs), cellulose derivatives, and proteins by themselves and when used as additives with CNCs. Among the samples evaluated, the adhesion strength was the highest for bovine serum albumin and hydroxypropyl cellulose (beyond 10 MPa). These were followed by carboxymethylcellulose and CNCs (ca. 5 MPa) and mechanically fibrillated CNFs (ca. 2 MPa), and finally by tempo-oxidized CNFs (0.2 MPa) and lysozyme (1.5 MPa). Remarkably, we find that the anisotropy of adhesion (in plane vs out of plane) falls within a narrow range across the bio-based adhesives studied. Collectively, this study benchmarks bio-based non-covalent adhesives aiming towards their improvement and implementation.

Use of Flory-Huggins Interaction Parameter and Contact Angle Values to Predict the Suitability of the Drug-Polymer System for the Production and Stability of Nanosuspensions

PURPOSE

Use of Flory-Huggins interaction parameter and contact angle values to predict the suitability of the drug-polymer system for the production and stability of nanosuspensions.

MATERIAL AND METHODS

Melting point depression of the drug was measured using differential scanning calorimetry. Interaction parameter, χ, was calculated using the melting point depression data to elucidate the drug-polymer interaction strength to predict the suitability of the drug-polymer system for the production and stability of nanosuspensions. Contact angle of the drug films were measured with purified water and 0.1%w/w polymer solutions to predict polymer's suitability for the production and stability of nanosuspension. Nanosuspensions were manufactured to validate the application of the melting point depression approach along with surface property information.

RESULTS

All three polymers, HPMC, Soluplus®, and poloxamer exhibited a negative interaction parameter with naproxen and budesonide. Higher negative interaction parameter values for the naproxen-polymer system indicated stronger drug-polymer interactions, while smaller negative interaction parameter values for the budesonide-polymer system indicated weaker drug-polymer interactions. Interaction parameter was not obtained for fenofibrate with HPMC and Soluplus®, and similarly, no interaction parameter was obtained for carvedilol with HPMC, most likely due to weaker drug-polymer interactions. All three polymers provided lower equilibrium contact angle values when compared to purified water, indicating an affinity for polymers.

CONCLUSIONS

Successful production and stability of several nanosuspensions were correlated with Flory-Huggins's interaction parameter and contact angle values. In the absence of melting point depression, contact angle values can also be used predict the agglomeration tendencies as we have shown for this study.

Recent advancement in isolation, processing, characterization and applications of emerging nanocellulose: A review

The emergence of nanocellulose from various natural resources as a promising nanomaterial has been gaining interest for a wide range application. Nanocellulose serves as an excellent candidate since it contributes numerous superior properties and functionalities. In this review, details of the three main nanocellulose categorised: cellulose nanocrystal (CNC), cellulose nanofibril (CNF), and bacterial nanocellulose (BNC) have been described. We focused on the preparation and isolation techniques to produce nanocellulose including alkaline pre-treatment, acid hydrolysis, TEMPO-mediated oxidation, and enzymatic hydrolysis. The surface modification of nanocellulose through esterification, silylation, amidation, phosphorylation, and carboxymethylation to improve the diverse applications has also been reviewed. Some invigorating perspectives on the applications, challenges, and future directions on the relevant issues regarding nanocellulose are also presented.

Integration of lornoxicam nanocrystals into hydroxypropyl methylcellulose-based sustained release matrix to form a novel biphasic release system

The study aims to (a) enhance the solubility of a poorly soluble drug by optimization of nanocrystal formulation using the top-down approach and (b) modify the release profile of this drug, which exhibits a short elimination half-life, by the integration of a fast-release phase containing the optimized nanocrystals and a sustained-release phase in a compression-coated tablet. Nanocrystals of the model drug (lornoxicam; LNX) was prepared by simultaneous application of jet-milling and ball-milling techniques. Investigation of the precipitation inhibition capacity, thermal property, and interaction of different polymers with the drug revealed polyvinyl pyrrolidone K30 (PVP) as the most effective stabilizer for nanocrystals. The immediate-release layer containing the optimized nanocrystals (size of 279.5 ± 11.25 nm and polydispersity index of 0.204 ± 0.01) was then compressed on a zero-order sustained-release matrix core using different derivatives of hydroxypropyl methylcellulose (HPMC). Application of the Design of Experiment approach (DoE) was applied to optimize the formulation of tablet. Analysis of drug concentration in dog plasma by liquid chromatography-tandem mass spectrometry demonstrated an improvement in the release behavior of LNX from the optimal compression-coated tablet integrating a HPMC-based sustained release matrix core and a PVP-stabilized lornoxicam nanocrystals coating layer compared to the reference product.

All-stage targeted therapy for glioblastoma based on lipid membrane coated cabazitaxel nanocrystals

Glioblastoma (GBM) is the most aggressive brain tumor with poor prognosis and frequent recurrence. The blood-brain barrier (BBB), blood-brain tumor barrier (BBTB) hinder the entry of therapeutics into the glioma region. Vasculogenic mimicry (VM) formed by invasive glioma cells is also related to recurrence of GBM. VAP is a D-peptide ligand of GRP78 protein overexpressed on BBTB, VM, and glioma cells but not on normal tissues. Besides, p-hydroxybenzoic acid (pHA) can effectively traverse the BBB. Herein we developed an all-stage glioma-targeted cabazitaxel (CBZ) nanocrystal loaded liposome modified with a "Y" shaped targeting ligand composed of pHA and VAP (pV-Lip/cNC). The pure drug nanocrystal core provided high drug loading, while lipid membrane promoted the stability and circulation time. pV-Lip/cNC exhibited excellent glioma homing, barriers crossing, and tumor spheroid penetrating capability in vitro. Treatment of pV-Lip/cNC displayed enhanced CBZ accumulation in glioma and anti-glioma effect with a median survival time (53 days) significantly longer than that of cNC loaded liposomes modified with either single ligand (42 days for VAP and 45 days for pHA) in the murine orthotopic GBM model. These results indicated pV-Lip/cNC could traverse the BBB and BBTB, destruct VM, and finally kill glioma cells to realize all-stage glioma therapy.

Ultrasound-based one-step fabrication of nobiletin particle: A facile stabilization strategy

As a typical representative of polymethoxylated flavones, nobiletin (NOB) is beneficial to health but hard to be processed, stored, and absorbed, due to its hydrophobicity and crystallinity. Herein, we developed a stabilization system based on an efficient manufacturing procedure of NOB nanocrystal by anti-solvent method combined with ultrasonic treatment. Metal-phenolic networks composed of tannic acid and metal ions were introduced to conformally coat on formed nanocrystal for further stabilization. From the results, the size and morphology of the prepared particles could be altered by the amount, ratio, and kind of the coating materials. The optimized samples could be redispersed after centrifugation, and keep stable at 4 ℃ for at least 120 days. Moreover, they possessed higher acid stability and more effective release than the control sample during the in vitro digestion experiment. Therefore, this work provided a promising idea for overcoming storage and delivery obstacle of hydrophobic crystalline bioactive components.

Electrochemiluminescent emission potential tunable Cu-Zn-In-S/ZnS nanocrystals for multiplex microRNAs potential-resolved detection

The development of a multi-target simultaneous detection electrochemiluminescence (ECL) strategy remains a great research interest, however, the limited choice of ECL luminophores is the main limitation holding the field back. In this study, a band gap tunable Cu-Zn-In-S/ZnS nanocrystals (CZIS/ZnS NCs) was synthesized and applied to a potential-resolved ECL detection strategy. By changing the Cu ratio in the precursor, the CZIS/ZnS NCs ECL emission spectrum and emission potential were tuned from 480 to 750 nm and -2.10 to -1.11 V, respectively. In addition, an ECL biosensor was fabricated with CZIS/ZnS NCs as signal reporters to detect three types of microRNAs, which could sensitively and selectively determine microRNA-21, microRNA-141, and microRNA-155 in a single cathodic ECL process. The results showed that the ECL intensity was directly linear to the logarithm of the concentration of microRNA-21, microRNA-141, and microRNA-155 from 0.00001 to 10 nM with detection limits of 2.2, 2.6, and 2.7 fM, respectively. This study demonstrates that the emission potential tunable CZIS/ZnS NCs can be employed as a promising alternative to the toxic II-V and II-V NCs to simultaneously detect multiple disease markers, and can guide the further rational design of both ECL luminophores and multi-analyte ECL sensors.

A novel lean alloy of biodegradable Mg-2Zn with nanograins

Lean alloy (low alloyed) is beneficial for long-term sustainable development of metal materials. Creating a nanocrystalline microstructure is a desirable approach to improve biodegradability and mechanical properties of lean biomedical Mg alloy, but it is nearly impossible to realize. In the present study, the bulk nanocrystalline Mg alloy (average grain size: ~70 nm) was successfully obtained by hot rolling process of a lean Mg-2wt.%Zn (Z2) alloy and both high strength ((223 MPa (YS) and 260 MPa (UTS)) and good corrosion resistance (corrosion rate in vivo: 0.2 mm/year) could be achieved. The microstructure evolution during the rolling process was analyzed and discussed. Several factors including large strain, fine grains, strong basal texture, high temperature and Zn segregation conjointly provided the possibility for the activation of pyramidal slip to produce nanocrystals. This finding could provide a new development direction and field of application for lean biomedical Mg alloys.

Combined chemotherapy for triple negative breast cancer treatment by paclitaxel and niclosamide nanocrystals loaded thermosensitive hydrogel

Triple negative breast cancer (TNBC) is the most dangerous subtype of breast cancer accompanying by unfavorable prognosis due to lack of specific therapeutic targets. Paclitaxel (PTX) is the first-line chemotherapeutic drug for TNBC and niclosamide (NLM) was identified as an inhibitor for TNBC and breast cancer stem cells (BCSCs). Intratumoral drug delivery system was a hopeful alternative for chemotherapeutic drug administration due to its targeting efficiency with lower systemic toxicity. Herein, an injectable PTX nanocrystals (PTX-NCs) and NLM nanocrystals (NLM-NCs) co-loaded PLGA-PEG-PLGA thermosensitive hydrogel (PNNCs-Ts Gel) was designed for TNBC intratumoral treatment. The final formulation realized high drug loading and appropriate particle size. PNNCs-Ts Gel displayed sustained drug release for up to 8 days in vitro. In vitro antitumor tests observed synergetic effects of combined therapy in terms of inhibiting cell proliferation and migration, inducing apoptosis. In vivo combined therapy presented a tumor growth inhibition rate about 68.8% and desired safety. Moreover, tumors after PNNCs-Ts Gel intratumoral injection possessed the lowest ratio of BCSCs, exhibiting this formulation had good ability in suppressing BCSCs and therefore could possibly prevent TNBC recurrence and metastasis. These results suggested that PNNCs-Ts Gel could be a promising strategy for TNBC treatment.

Grafting PEG on cellulose nanocrystals via polydopamine chemistry and the effects of PEG graft length on the mechanical performance of composite film

In this study, cellulose nanocrystals (CNCs) with PEG grafts of various lengths (1 k, 2 k, 5 k, and 10 kDa) were prepared via a polydopamine (PDA) mediated method in the aqueous solution. The prepared CNC-PEGs were further used to reinforce the polyvinyl alcohol (PVA) at the loading of 0, 1, 3, 5, and 7 wt% in order to demonstrate the effects of the PEG length on the properties of the PVA/CNC nanocomposites. PEG surface modification resulted in simultaneous improvements in stiffness and toughness. The graft lengths have noticeable impacts on the properties of composites. The shorter graft yields better enhancement in strength and stiffness, attributable to the high efficiency in the stress transfer and high interface adhesion. The longer PEG graft length yields high graft-matrix entanglement, forming a thicker rubbery coating layer that enhances the toughness of PVA/CNC composites.

Rod-shaped nintedanib nanocrystals improved oral bioavailability through multiple intestinal absorption pathways

Nintedanib (BIBF) is a biopharmaceutical classification system II (BCS II) drug that has a good therapeutic effect for the treatment of nonsmall cell lung cancer; however, it shows poor oral bioavailability due to low dissolution and intestinal absorption. This study aims to fabricate rod-shaped nanocrystals to enhance oral bioavailability by improving the dissolution and absorption of BIBF in the intestine. By prescription screening, BIBF nanocrystals (BIBF-NCs) with a particle size of 325.30 ± 1.03 nm and zeta potential of 32.70 ± 1.24 mV were fabricated by an antisolvent precipitation-ultrasound approach with a stabilizer of sodium carboxyl methyl cellulose (CMC-Na). BIBF-NCs exhibited a rod-shaped morphology by transmission electron microscopy (TEM). The results of powder X-ray diffraction (PXRD) and differential scanning calorimetry (DSC) showed that the crystal form of BIBF in BIBF-NCs was altered. The BIBF-NCs remarkably improved the saturation solubility and dissolution of BIBF compared with BIBF powder. According to the results of in situ single-pass intestinal perfusion (SPIP), BIBF-NCs showed improved absorption and membrane permeability, with K_a and P_app values in the jejunum of 0.21 ± 0.01 min^-1 and (4.34 ± 0.11) × 10^-4 cm/min, respectively. Further, the K_a and P_app values of BIBF-NCs were all reduced significantly after the addition of inhibitors colchicine, chlorpromazine and indomethacin, which demonstrated that BIBF-NCs could be absorbed by endocytosis mediated by caveolae and clathrin and micropinocytosis in the intestine. The cell evaluation results showed that BIBF-NCs could be taken up by macrophages and transported from Caco-2 monolayers. The in vivo pharmacokinetic results showed that the bioavailability of the BIBF-NCs was 2.51-fold higher than that of the BIBF solution (BIBF-Sol) after oral administration with a longer T_max (4.50 ± 1.00 h vs. 2.60 ± 1.92 h). In summary, rod-shaped BIBF-NCs could significantly improve oral bioavailability through multiple intestinal absorption pathways.

Development of Fully Redispersible Dried Nanocrystals by Using Sucrose Laurate as Stabilizer for Increasing Surface Area and Dissolution Rate of Poorly Water-Soluble Drugs

There is much interest in converting poorly water-soluble drugs into nanocrystals as they provide extremely high surface area that increases dissolution rate and oral bioavailability. However, nanocrystals are prepared as aqueous suspensions, and once the suspensions are dried for development of solid dosage forms, the nanocrystals agglomerate as large particles to reduce the excess surface energy. For successful development of drug products, it is essential that any agglomeration is reversible, and the dried nanocrystals regain original particle sizes after redispersion in aqueous media. We have established that sucrose laurate serves as a superb stabilizer to ensure complete redispersion of dried nanocrystals in aqueous media with mild agitation. Nanocrystals (150-300 nm) of three neutral drugs (fenofibrate, danazol and probucol) were produced with sucrose laurate by media milling, and suspensions were dried by tray drying under vacuum, spray drying, and lyophilization. Dried solids and their tablets redispersed into original particle sizes spontaneously. Preliminary studies showed that sucrose laurate can also redisperse acidic and basic drugs, indicating its versatile application. Fatty acid ester of another disaccharide, lactose laurate, also performed like sucrose laurate. Thus, we have developed a method of retaining high dissolution rate and, by implication, high bioavailability of nanocrystals from solid formulations.

Progress in the development of stabilization strategies for nanocrystal preparations

In recent years, nanocrystal technology has been extensively investigated. Due to the submicron particle size and unique physicochemical properties of nanocrystals, they overcome the problems of low drug solubility and poor bioavailability. Although the structures of nanocrystals are simple, the further development of these materials is hindered by their stability. Drug nanocrystals with particle sizes of 1∼1000 nm usually require the addition of stabilizers such as polymers or surfactants to enhance their stability. The stability of nanocrystal suspensions and the redispersibility of solid nanocrystal drugs are the key factors for the large-scale production of nanocrystal preparations. In this paper, the factors that affect the stability of drug nanocrystal preparations are discussed, and related methods for solving the stability problem are put forward.

Sub-50 nm ultra-small organic drug nanosuspension prepared by cavi-precipitation and its brain targeting potential

The purpose of this study was to show whether it is possible to prepare sub 100 nm or preferably sub-50 nm drug nanosuspension (NS) of suitable quality for intravenous administration. Furthermore, we have studied how the brain targeting potential of such small size organic NS differs from relatively bigger size NS. Two combination technologies (cavi-precipitation, H96) and a standard high-pressure homogenization (HPH) technology were used to prepare drug NS of different sizes. The cavi-precipitation process generated the smallest AmB NS, i.e., 27 nm compared to 79 nm by H96 technology and 252 nm by standard HPH technology. Dialysis of the nanosuspension in the original dispersion media was found to be the most efficient solvent removal method without negatively affecting particle size. The removal of organic solvent was found to drastically improve the stability of the formulations. The protein adsorption pattern shows that the small size NS particles obtained by the cavi-precipitation process have the potential to circulate longer in the bloodstream and have the potential to be taken up by the blood-brain barrier. The cavi-precipitation process generated ultrafine NS particles, which fulfilled the quality requirements for intravenous administration and offer a potential solution for brain targeting.

Enhanced mucosal penetration and efficient inhibition efficacy against cervical cancer of PEGylated docetaxel nanocrystals by TAT modification

To investigate the potential of cell penetrating peptide (CPP) modification on nanomedicine for improving mucosal penetration and effective therapy of cervical cancer, docetaxel nanocrystals modified with trans-activator of transcription (TAT) peptide were designed for treatment of cervical cancer via vaginal administration. Docetaxel nanocrystals were coated by polymerization of dopamine to form polydopamine (PDA) coating which facilitated TAT modification and PEGylation for less mucus entrapment to get PEGylated nanocrystals modified with TAT (NC@PDA-PEG-TAT). Enhanced cellular drug uptake and cytotoxicity of NC@PDA-PEG-TAT was observed in cervical cancer-related TC-1 cells than that of PEGylated nanocrystals (NC@PDA-PEG). Intravaginally administered NC@PDA-PEG-TAT dispersed in poloxamer 407-based thermosensitive gel exhibited prolonged in vivo intravaginal retention, deeper mucosal penetration and more potent inhibition on the growth of murine orthotopic cervical cancer than NC@PDA-PEG, PDA-coated nanocrystals or unmodified nanocrystals. All data suggested the significance of CPP-modification on nanocrystals in the local treatment of vaginal mucosa-related diseases by vaginal administration.

Use of 18β-glycyrrhetinic acid nanocrystals to enhance anti-inflammatory activity by improving topical delivery

18β-Glycyrrhetinic acid (GA) is often topically applied in clinical treatment of inflammatory skin diseases. However, GA has poor solubility in water, which results in poor skin permeability and low bioavailability. Nanocrystallization of drugs can enhance their permeability and improve bioavailability. We prepared GA nanocrystals (Nano GA) by high-pressure homogenization. These nanocrystals were characterized by photon correlation spectroscopy, scanning electron microscopy, thermogravimetric analysis, and X-ray diffractometry. The ability of Nano GA to improve dermal permeability was investigated ex vivo using Franz diffusion vertical cells and mouse skin. The topical anti-inflammatory activity of Nano GA was assessed in vivo by a 12-O-tetradecanoyl phorbol-13-acetate (TPA)-induced model in mouse ears. The average particle size of a GA nanocrystalline suspension was 288.6 ± 7.3 nm, with a narrow particle-size distribution (polydispersity index ∼0.13 ± 0.10), and the particle size of the lyophilized powder increased (552.0 ± 9.8 nm). After nanocrystallization, the thermal stability and crystallinity decreased but solubility increased significantly. Nano GA showed higher dermal permeability than Coarse GA. Macroscopic and staining-based observations of mouse ears and the levels of proinflammatory factors and myeloperoxidase revealed that the Nano GA hydrogel exhibited better anti-edema ability and more strongly inhibited inflammation development than the Coarse GA hydrogel and indomethacin hydrogel (positive drug). These results suggest that Nano GA could be an efficacious topical therapeutic agent for skin inflammation.

Intracellular uptake of nanocrystals: Probing with aggregation-induced emission of fluorescence and kinetic modeling

Nanocrystal formulations have been explored to deliver poorly water-soluble drug molecules. Despite various studies of nanocrystal formulation and delivery, much more understanding needs to be gained into absorption mechanisms and kinetics of drug nanocrystals at various levels, ranging from cells to tissues and to the whole body. In this study, nanocrystals of tetrakis (4-hydroxyphenyl) ethylene (THPE) with an aggregation-induced emission (AIE) property was used as a model to explore intracellular absorption mechanism and dissolution kinetics of nanocrystals. Cellular uptake studies were conducted with KB cells and characterized by confocal microscopy, flow cytometry, and quantitative analyses. The results suggested that THPE nanocrystals could be taken up by KB cells directly, as well as in the form of dissolved molecules. The cellular uptake was found to be concentration- and time-dependent. In addition, the intracellular THPE also could be exocytosed from cells in forms of dissolved molecules and nanocrystals. Kinetic modeling was conducted to further understand the cellular mechanism of THPE nanocrystals based on first-order ordinary differential equations (ODEs). By fitting the kinetic model against experimental measurements, it was found that the initial nanocrystal concentration had a great influence on the dynamic process of dissolution, cellular uptake, and exocytosis of THPE nanocrystals. As the nanocrystal concentration increased in the culture media, dissolution of endocytosed nanocrystals became enhanced, subsequently driving the efflux of THPE molecules from cells.

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Nanocrystals of Tetrakis(4-hydroxyphenyl) ethylene (THPE), an aggregation-induced emission (AIE) probe was used as a model.

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THPE nanocrystals could be taken up in forms of dissolved molecules and nanocrystals.

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The dynamic process of dissolution, cellular uptake, and exocytosis of THPE nanocrystals was concentration-dependent.

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Exocytosis of intracellular THPE-NCs bore different kinetics and/or mechanisms compared with endocytosis.

Theoretical analysis of the structural and electronic properties of the interaction of boron nitride diamantane nanocrystal with the drug hydroxyurea as an anticancer drug

The density functional theory calculations with hybrid B3LYP/6-31G(d,p) basis sets have been used to examine the structural and electronic properties of boron nitride (BN) diamantane interacted with the drug hydroxyurea (HU) as an anticancer drug. The findings have been shown that there is a decrease in the total energy after combining the drug with diamantane. The energy levels of HOMO and LUMO analyses indicate that the value of HOMO energy increased slightly, while the value of LUMO energy decreased significantly in these systems in the HU/BN diamantane. In addition, the decreasing of the energy gap between HOMO and LUMO confirms a strong bond between the drug hydroxyurea and BN diamantane. Finally, the drug's stability and reactivity with BN diamantane were investigated by measuring chemical reaction characteristics such as chemical potential, electron affinity, global hardness, and electrophilicity index. As a result, the nanocrystal of BN diamantane can be considered a vector for the delivery of anticancer drugs within biological systems.

Fluorescence In Situ Hybridization with Quantum Dot Labels in E. coli Cells

In this chapter we describe the use of fluorescent quantum dots (QDs) as labels for microbial mRNA transcripts using fluorescence in situ hybridization (FISH). Unlike organic dyes, which are the standard labels in modern FISH methods, QDs provide fluorescence signals that are much brighter and resistant to photobleaching, with an expanded spectral range for multiplexing. We describe the preparation of QDs with compact sizes necessary for accurate labeling, their application for analyzing lacZ transcripts in Escherichia coli cells using FISH, and an assessment of signal stability. We further discuss differences between methods for mammalian cells and bacteria, for which individual nucleic acids cannot be discretely counted due to the small cell size and the optical diffraction limit.

Ab Initio Determination of Peptide Structures by MicroED

Structural elucidation of small macromolecules such as peptides has recently been facilitated by a growing number of technological advances to existing crystallographic methods. The emergence of electron micro-diffraction (MicroED) of protein nanocrystals under cryogenic conditions has enabled the interrogation of crystalline peptide assemblies only hundreds of nanometers thick. Collection of atomic or near-atomic resolution data by these methods has permitted the ab initio determination of structures of various amyloid-forming peptides, including segments derived from prions and ice-nucleating proteins. This chapter focuses on the process of ab initio structural determination from nano-scale peptide assemblies and other similar molecules.

Protein and Small Molecule Structure Determination by the Cryo-EM Method MicroED

Microcrystal Electron Diffraction (MicroED) is the newest cryo-electron microscopy (cryo-EM) method, with over 70 protein, peptide, and several small organic molecule structures already determined. In MicroED, micro- or nanocrystalline samples in solution are deposited on electron microscopy grids and examined in a cryo-electron microscope, ideally under cryogenic conditions. Continuous rotation diffraction data are collected and then processed using conventional X-ray crystallography programs. The protocol outlined here details how to obtain and identify the nanocrystals, how to set up the microscope for screening and for MicroED data collection, and how to collect and process data to complete high-resolution structures. For well-behaving crystals with high-resolution diffraction in cryo-EM, the entire process can be achieved in less than an hour.

Conventional Nanosized Drug Delivery Systems for Cancer Applications

Clinical responses and tolerability of conventional nanocarriers (NCs) are sometimes different from those expected in anticancer therapy. Thus, new smart drug delivery systems (DDSs) with stimuli-responsive properties and novel materials have been developed. Several clinical trials demonstrated that these DDSs have better clinical therapeutic efficacy in the treatment of many cancers than free drugs. Composition of DDSs and their surface properties increase the specific targeting of therapeutics versus cancer cells, without affecting healthy tissues, and thus limiting their toxicity versus unspecific tissues. Herein, an extensive revision of literature on NCs used as DDSs for cancer applications has been performed using the available bibliographic databases.

Design, Fabrication and Characterization of Esomeprazole Nanocrystals for Enhancing the Dissolution Rate and Stability

BACKGROUND

Poor solubility and low dissolution rate limit the work at poorly water-soluble drugs like Esomeprazole. To overcome this problem, different technologies had to be used but could not resolve the problem, significantly. The main aim of this patent study was to prepare the nanocrystals using the evaporative precipitation ultrasonication method in order to improve the dissolution rate and stability of Esomeprazole (ESM).

METHODS

For obtaining the nanocrystals, different nanoformulations were prepared using the pluronic F-68 in different concentrations, and then the screened formulation was lyophilized in the presence of two distinct cryoprotectants; mannitol and sucrose. The obtained nanocrystals were characterized for their re-dispersibility, crystalline state, dissolution behavior, particle size, polydispersibility index and morphology. Dissolution study of ESM nanocrystals was performed in a buffer solution of pH-7.4, and compared to that of bulk ESM sample and ESM/pluronic F-68 physical mixture.

RESULTS

Cryoprotectant containing nanocrystals exhibit the re-dispersion in water after the manual shaking. 5% mannitol containing nanocrystals showed the least polydispersity index (0.42 ± 0.11) and narrowest particle size (186 ± 12.9 nm). The Powder X-ray Diffraction (PXRD) pattern and differential scanning calorimeter (DSC) thermograms revealed that the crystalline state of the drug was not changed after the different physical treatment. Freeze-dried nanocrystals showed a faster dissolution rate and almost 99.45% of the drug was released within 60 min. However, the bulk drug and a physical mixture of bulk drug/pluronic F-68 showed only 22.65% and 21.3% of drug release, respectively, after 60 min. This paper reviews the related patents on Esomeprazole Nanocrystals.

CONCLUSION

The different findings revealed that nanocrystals could be a potential alternate for solving the dissolution rate and stability issue of ESM like poorly soluble drugs.

Mucoadhesive nanocrystal-in-microspheres with high drug loading capacity for bioavailability enhancement of silybin

Nanocrystals, due to high drug loading efficiency, have drawn large attention as nanotechnology to enhance solubility and bioavailability of poorly soluble drugs. However, most nanocrystals still encountered low oral absorption percentage due to its insufficient retention time in the gastrointestinal tract (GI). In this work, silybin (SB) as model drug was fabricated to nanocrystals, and further loaded into a mucoadhesive microsphere to increase the GI retention. Such mucoadhesive microspheres were prepared with a wet media milling technique followed by coagulation and film coating. Nanocrystals and microspheres were thoroughly characterized by diverse complementary techniques. As results, such delivery system displayed an encapsulation efficiency of approximately 100 % and a drug loading capacity of up to 35.41 ± 0.31 %. In addition, mucoadhesiveness test ex vivo conducted with rat intestine showed that film-coated microspheres were retained for more than 1 h. Benefiting from nanocrystals technology, the drug cumulative release percentage of the microspheres was remarkable improved compared to unprocessed one in vitro. Finally, pharmacokinetics studies in rats showed a significant 3-fold increase of drug oral bioavailability compared to unprocessed SB. The current study demonstrates that the developed delivery vehicle can enhance the bioavailability of SB by increasing its dissolution percentage as well as through extending retention time in the GI tract, and achieve high drug loading capacity.

Freeze-Drying of Pharmaceutical and Nutraceutical Nanoparticles: The Effects of Formulation and Technique Parameters on Nanoparticles Characteristics

Nanoparticles (NPs) are of the most interesting novel vehicles for effective drug delivery to humans. Freeze drying is known as an engaging process to improve the long lasting stability of NPs formulations. This study aims to elucidate the importance of various parameters involving in freeze-drying of the most common pharmaceutical/nutraceutical NPs including nanosuspensions, nanocrystals (NCs), cocrystals/nanococrystals, nanoemulsions (NEs), nanocapsules (NCPs) and nanospheres (NSPs). Regarding this, the therapeutic goals of NPs and specifications of drug must be considered. According to our survey, the most influential factors for achieving optimum results include type and concentration of cryoprotectant/lyoprotectant, stabilizer structure and concentration, the NPs concentration in solution, freezing, annealing, and drying rate, the interaction between protectants and stabilizer, solvent type and antisolvent to solvent ratio. The study shows that for each class of NPs, specific variables are of highest significance and should be optimized. For instance, about NCs, freezing rate and antisolvent/solvent ratio should be particularly considered and for emulsified NPs, the best results have been obtained by 5-20% of saccharides as cryoprotectants. These findings suggest that to obtain a product with the lowest aggregation and particle size (PS), optimization of the effective factors in formulation and lyophilization process are essential.

Self-trapped exciton engineering for white-light emission in colloidal lead-free double perovskite nanocrystals

Intrinsic broadband photoluminescence (PL) of self-trapped excitons (STEs) are systematically studied in lead-free double perovskite nanocrystals (NCs). It is clarified that bandgap (direct/indirect) has important influence on the PL properties of STEs: indirect bandgap NCs exhibit strong exciton-phonon coupling which results in non-radiative STEs, while direct bandgap NCs exhibit moderate exciton-phonon coupling, inducing bright STE PL. Furthermore, by alloying K⁺ and Li⁺ ions in Cs₂AgInCl₆ NCs, the NCs exhibit broadband white-light emission. Charge-carrier dynamics study indicates that the efficient white-light emission originates from the further suppressed non-radiative processes of the STEs in the direct bandgap structure. This work may deepen the understanding of STEs and guide the design of high-performance lead-free perovskites.

Effect of A-Site Cation on Photoluminescence Spectra of Single Lead Bromide Perovskite Nanocrystals

Lead halide perovskite (APbX₃) nanocrystals exhibit photoluminescence (PL) with both wide wavelength tunability and high quantum efficiency. While the Pb-X₆ octahedra mainly determines the near-band-edge optical properties and the A-site cation affects the structural stability, the role of the A-site cation in determining the optical properties is still unclear. Here, we report the PL properties of three types of lead bromide perovskite APbBr₃ nanocrystals with different cations [A = HC(NH₂)₂⁺, CH₃NH₃⁺, and Cs⁺], as revealed by single-dot spectroscopy, and discuss the influence of the A-site cation on the PL spectrum. The nanocrystal size dependences of the PL energy and lifetime show no large variation with the species of the A-site cation. We find that the size of the A-site cation determines the coupling strength between electrons and longitudinal-optical phonons in the nanocrystal and thus affects the PL spectral shape, especially the low-energy tail.

Heterojunction Incorporating Perovskite and Microporous Metal-Organic Framework Nanocrystals for Efficient and Stable Solar Cells

In this paper, we present a facile approach to enhance the efficiency and stability of perovskite solar cells (PSCs) by incorporating perovskite with microporous indium-based metal-organic framework [In12O(OH)16(H2O)5(btc)6]n (In-BTC) nanocrystals and forming heterojunction light-harvesting layer. The interconnected micropores and terminal oxygen sites of In-BTC allow the preferential crystallization of perovskite inside the regular cavities, endowing the derived films with improved morphology/crystallinity and reduced grain boundaries/defects. Consequently, the In-BTC-modified PSC yields enhanced fill factor of 0.79 and power conversion efficiency (PCE) of 20.87%, surpassing the pristine device (0.76 and 19.52%, respectively). More importantly, over 80% of the original PCE is retained after 12 days of exposure to ambient environment (25 °C and relative humidity of ~ 65%) without encapsulation, while only about 35% is left to the pristine device.

Encapsulation of MnS Nanocrystals into N, S-Co-doped Carbon as Anode Material for Full Cell Sodium-Ion Capacitors

Sodium-ion capacitors (SICs) have received increasing interest for grid stationary energy storage application due to their affordability, high power, and energy densities. The major challenge for SICs is to overcome the kinetics imbalance between faradaic anode and non-faradaic cathode. To boost the Na+ reaction kinetics, the present work demonstrated a high-rate MnS-based anode by embedding the MnS nanocrystals into the N, S-co-doped carbon matrix (MnS@NSC). Benefiting from the fast pseudocapacitive Na+ storage behavior, the resulting composite exhibits extraordinary rate capability (205.6 mAh g-1 at 10 A g-1) and outstanding cycling stability without notable degradation after 2000 cycles. A prototype SIC was demonstrated using MnS@NSC anode and N-doped porous carbon (NC) cathode; the obtained hybrid SIC device can display a high energy density of 139.8 Wh kg-1 and high power density of 11,500 W kg-1, as well as excellent cyclability with 84.5% capacitance retention after 3000 cycles. The superior electrochemical performance is contributed to downsizing of MnS and encapsulation of conductive N, S-co-doped carbon matrix, which not only promote the Na+ and electrons transport, but also buffer the volume variations and maintain the structure integrity during Na+ insertion/extraction, enabling its comparable fast reaction kinetics and cyclability with NC cathode.

The elucidation of key factors for oral absorption enhancement of nanocrystal formulations: In vitro-in vivo correlation of nanocrystals

Nanocrystal formulation is a well-established approach for improving oral absorption of poorly water-soluble drugs. However, it is difficult to predict the in vivo performance of nanocrystal formulations from in vitro dissolution studies. The object of the present study was to investigate the in vitro-in vivo correlation of nanocrystal formulations of different particle sizes. A microsuspension and three nanosuspensions with different particle sizes for model drugs, fenofibrate and megestrol acetate, were prepared. In the comparison between the microsuspension and the nanosuspension having the smallest particle sizes, drug permeation rates from the nanosuspension were about 3-fold higher in the dissolution-permeation study. On the other hand, the solubility enhancement effect due to nanocrystal formation was only up by 1.4-fold, suggesting that nanocrystal formulations dramatically improved not the solubility but the apparent permeability. The oral absorption rate in rats increased with particle size reduction. There were positive and very strong correlations (R² > 0.95) between the in vitro permeation rate and in vivo maximum absorption rate. We concluded that the enhanced permeability rate due to nanocrystal formation is the main factor for improving oral absorption, and the in vitro dissolution-permeation study could be useful for predicting oral absorption enhancement of nanocrystal formulations.

Controlling the size and shape of liposomal ciprofloxacin nanocrystals by varying the lipid bilayer composition and drug to lipid ratio

Drug nanocrystals precipitated inside liposomes are of increasing interest in liposomal drug delivery. For liposomal nanocrystal formulations, the size and shape of the drug nanocrystals can influence the apparent drug release properties, providing opportunities for developing tailored liposomal drug release systems. Small angle X-ray scattering (SAXS) and quantitative transmission electron microscopy (TEM) can be used to analyse the size distributions of the nanoparticles. In this study, by changing the fluidity of the membrane through the use of different membrane phospholipids with varying cholesterol content, the impact of lipid phase, fluidity and permeability on the size distribution of ciprofloxacin nanocrystals were investigated using standard TEM and SAXS as orthogonal techniques. The results show that the phospholipid phase behaviour has a direct effect on the nanocrystal size distribution, where shorter and thinner nanocrystals were formed in liposomes made from hydrogenated soy phosphatidylcholine (HSPC) and 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC) phospholipids with higher phase transition temperatures than 1,2-dimyristoyl-sn-glycero-3-phosphocholine (DMPC) and 1,2-dioleoyl-sn-glycero-3-phosphocholine (DOPC) with lower transition temperatures. This is mainly due to the phase behaviour of the liposome during nanocrystal formation. The addition of cholesterol that reduces fluidity and permeability of the DOPC liposomes was also shown to restrict the growth of the ciprofloxacin nanocrystals. Moreover, increasing the drug loading of the liposomes made from HSPC and DPPC produced longer and wider nanocrystals. The findings open new opportunities to tailor nanocrystal size distributions, as well as the aspect ratio of the enclosing liposomes with potential to alter drug release and in vivo behaviour.