Pharmaceutical and toxicological properties of engineered nanomaterials for drug delivery

Nanoformulations in Pharmaceutical and Biomedical Applications: Green Perspectives

This study provides a brief discussion of the major nanopharmaceuticals formulations as well as the impact of nanotechnology on the future of pharmaceuticals. Effective and eco-friendly strategies of biofabrication are also highlighted. Modern approaches to designing pharmaceutical nanoformulations (e.g., 3D printing, Phyto-Nanotechnology, Biomimetics/Bioinspiration, etc.) are outlined. This paper discusses the need to use natural resources for the "green" design of new nanoformulations with therapeutic efficiency. Nanopharmaceuticals research is still in its early stages, and the preparation of nanomaterials must be carefully considered. Therefore, safety and long-term effects of pharmaceutical nanoformulations must not be overlooked. The testing of nanopharmaceuticals represents an essential point in their further applications. Vegetal scaffolds obtained by decellularizing plant leaves represent a valuable, bioinspired model for nanopharmaceutical testing that avoids using animals. Nanoformulations are critical in various fields, especially in pharmacy, medicine, agriculture, and material science, due to their unique properties and advantages over conventional formulations that allows improved solubility, bioavailability, targeted drug delivery, controlled release, and reduced toxicity. Nanopharmaceuticals have transitioned from experimental stages to being a vital component of clinical practice, significantly improving outcomes in medical fields for cancer treatment, infectious diseases, neurological disorders, personalized medicine, and advanced diagnostics. Here are the key points highlighting their importance. The significant challenges, opportunities, and future directions are mentioned in the final section.

High-precision targeting and destruction of cancer-associated PDGFR-β+ stromal fibroblasts through self-assembling, protein-only nanoparticles

The need for more effective and precision medicines for cancer has pushed the exploration of new materials appropriate for drug delivery and imaging, and alternative receptors for targeting. Among the most promising strategies, finding suitable cell surface receptors and targeting agents for cancer-associated platelet derived growth factor receptor β (PDGFR-β)+ stromal fibroblasts is highly appealing. As a neglected target, this cell type mechanically and biologically supports the growth, progression, and infiltration of solid tumors in non-small cell lung, breast, pancreatic, and colorectal cancers. We have developed a family of PDGFR-β-targeted nanoparticles based on biofabricated, self-assembling proteins, upon hierarchical and iterative selective processes starting from four initial candidates. The modular protein PDGFD-GFP-H6 is well produced in recombinant bacteria, resulting in structurally robust oligomeric particles that selectively penetrates into PDGFR-β+ stromal fibroblasts in a dose-dependent manner, by means of the PDGFR-β ligand PDGFD. Upon in vivo administration, these GFP-carrying protein nanoparticles precisely accumulate in tumor tissues and enlighten them for IVIS observation. When GFP is replaced by a microbial toxin, selective tumor tissue destruction is observed associated with a significant reduction in tumor volume growth. The presented data validate the PDGFR-β/PDGFD pair as a promising toolbox for targeted drug delivery in the tumor microenvironment and oligomeric protein nanoparticles as a powerful instrument to mediate highly selective biosafe targeting in cancer through non-cancer cells. STATEMENT OF SIGNIFICANCE: We have developed a transversal platform for nanoparticle-based drug delivery into cancer-associated fibroblasts. This is based on the engineered modular protein PDGFD-GFP-H6 that spontaneously self-assemble and selectively penetrates into PDGFR-β+ stromal fibroblasts in a dose-dependent manner, by means of the PDGFR-β ligand PDGFD. In vivo, these protein nanoparticles accumulate in tumor and when incorporating a microbial toxin, they destroy tumor tissues with a significant reduction in tumor volume, in absence of side toxicities. The data presented here validate the PDGFR-β/PDGFD pair as a fully versatile toolbox for targeted drug delivery in the tumor microenvironment intended as a synergistic treatment.

Research Progress of Nanomaterials in Chemotherapy of Osteosarcoma

Osteosarcoma (OS) is a common malignant bone tumor that occurs mostly in children and adolescents. At present, surgery after chemotherapy or postoperative adjuvant chemotherapy is the main treatment plan. However, the efficacy of chemotherapeutic drugs is limited by the occurrence of chemotherapeutic resistance, toxicity to normal cells, poor pharmacokinetic performance, and drug delivery failure. The delivery of chemotherapy drugs to the bone to treat OS may fail for a variety of reasons, such as a lack of selectivity for OS cells, initial sudden release, short-term release, and the presence of biological barriers (such as the blood-bone marrow barrier). Nanomaterials are new materials with at least one dimension on the nanometer scale (1-100 nm) in three-dimensional space. These materials have the ability to penetrate biological barriers and can accumulate preferentially in tumor cells. Studies have shown that the effective combination of nanomaterials and traditional chemotherapy can significantly improve the therapeutic effect. Therefore, this article reviews the latest research progress on the use of nanomaterials in OS chemotherapy.

Nanosponges- Versatile Platform as Drug Carrier

BACKGROUND

Recently, nano-drug delivery systems have become an integral part of the most novel drug delivery systems and have gained considerable importance owing to various advantages such as carriers for poorly soluble drugs, targeting molecules at the desired site, protection from degradation etc. Objective: One of the most studied areas of nanotechnology is nanosponges. The objective of this review was to extensively summarize the various strategies for the preparation, characterization and applications of nanosponges.

METHODS

In the current mini-review, we conducted a systemic search of the literature and patent inventions focusing on nanosponges. The summary of the search was inclusive of various aspects of nanosponges, such as drug characteristics to be considered while incorporating in nanosponges, other crucial additives during formulation of nanosponges, methods of preparation, characterization and applications of nanosponges in pharmaceuticals.

RESULTS

Nanosponges are nanocarriers for both lipophilic and hydrophilic drugs. These are prepared by different methods such as emulsion-solvent evaporation, solvent method, melting method, ultrasound assisted method etc., and all these methods were less time consuming, more economical and evaluated by sophisticated techniques available for routine analysis. These are among the most feasible alternative to address several formulation difficulties associated with the physicochemical properties of the drug. The porous nature and small particle size are vital properties of the nanosponges that contribute crucially to correcting the drawbacks of the drug. The properties of the nanosponges can be enhanced when combined with cyclodextrins. Extensive research work has been carried out in past to explore cyclodextrin based nanosponges. Besides, it is also used for smart targeting of tumors and for drug release in a sustainable pattern. Nanosponges can be prepared by simple methods. These can be tuned to release the drug by different routes so as to achieve the maximum benefits of the drug.

CONCLUSION

Huge amount of research has been carried out on nanosponges as drug carrier. The method of preparation and characterization of nanosponges are quite economical and routinely available. Owing to potential benefits and probable applications, these can be used as efficient carriers for certain drugs. The authors expect that the current review will guide the investigation of the nanosponges as nanodrug delivery systems.

Nanovaccines: Merits, and diverse roles in boosting antitumor immune responses

An attractive type of cancer immunotherapy is cancer therapeutic vaccines that induce antitumor immunity effectively. Although supportive results in the recent vaccine studies, there are still numerous drawbacks, such as poor stability, weak immunogenicity and strong toxicity, to be tackled for promoting the potency and durability of antitumor efficacy. NPs (Nanoparticles)-based vaccines offer unique opportunities to breakthrough the current bottleneck. As a rule, nanovaccines are new the generations of vaccines that use NPs as carriers and/or adjuvants. Several advantages of nanovaccines are constantly explored, including optimal nanometer size, high stability, plenty of antigen loading, enhanced immunogenicity, tunable antigen presentation, more retention in lymph nodes and promote patient compliance by a lower frequency of dosing. Here, we summarized the merits and highlight the diverse role nanovaccines play in improving antitumor responses.

Ion-dependent slow protein release from in vivo disintegrating micro-granules

Through the controlled addition of divalent cations, polyhistidine-tagged proteins can be clustered in form of chemically pure and mechanically stable micron-scale particles. Under physiological conditions, these materials act as self-disintegrating protein depots for the progressive release of the forming polypeptide, with potential applications in protein drug delivery, diagnosis, or theragnosis. Here we have explored the in vivo disintegration pattern of a set of such depots, upon subcutaneous administration in mice. These microparticles were fabricated with cationic forms of either Zn, Ca, Mg, or Mn, which abound in the mammalian body. By using a CXCR4-targeted fluorescent protein as a reporter building block we categorized those cations regarding their ability to persist in the administration site and to sustain a slow release of functional protein. Ca²⁺ and specially Zn²⁺ have been observed as particularly good promoters of time-prolonged protein leakage. The released polypeptides result is available for selective molecular interactions, such as specific fluorescent labeling of tumor tissues, in which the protein reaches nearly steady levels.

Nanovaccine-Based Strategies to Overcome Challenges in the Whole Vaccination Cascade for Tumor Immunotherapy

Nanovaccine-based immunotherapy (NBI) has received greater attention recently for its potential to prime tumor-specific immunity and establish a long-term immune memory that prevents tumor recurrence. Despite encouraging results in the recent studies, there are still numerous challenges to be tackled for eliciting potent antitumor immunity using NBI strategies. Based on the principles that govern immune response, here it is proposed that these challenges need to be addressed at the five critical cascading events: Loading tumor-specific antigens by nanoscale drug delivery systems (L); Draining tumor antigens to lymph nodes (D); Internalization by dendritic cells (DCs) (I); Maturation of DCs by costimulatory signaling (M); and Presenting tumor-peptide-major histocompatibility complexes to T cells (P) (LDIMP cascade in short). This review provides a detailed and objective overview of emerging NBI strategies to improve the efficacy of nanovaccines in each step of the LDIMP cascade. It is concluded that the balance between each step must be optimized by delicate designing and modification of nanovaccines and by combining with complementary approaches to provide a synergistic immunity in the fight against cancer.

Evaluating the Toxicity and Histological Effects of Al2O3 Nanoparticles on Bone Tissue in Animal Model: A Case-Control Study

The applications of nanostructures have been limited by their different toxicities. So, the investigation of these toxicities is necessary before nanostructure application. This study aimed to evaluate the effect of aluminum oxide (Al₂O₃) nanoparticles on bone density in Wistar rat. Al₂O₃ nanoparticle was prepared by the sol-gel method. Characterization was done by X-ray diffraction (XRD) and transmission electron microscopy (TEM). Sixty-four male adult Wistar rats were divided into eight groups including six groups intravenously treated with Al₂O₃ nanoparticle at concentrations of 25, 50, 100, 250, 500, and 1000 µg/ml: one group received food and water as the control group, and one group received food and water as well as intravenously distilled water as an injection control group. After 41 days, bone density was analyzed by dual-energy X-ray absorptiometry (DEXA). According to X-ray diffraction, the average particle size for Al₂O₃ nanoparticles was 20.85 nm. The data of densitometry showed that the bone density of right and left foot was reduced in concentrations of 250, 500, and 1000 µg/ml that were statistically significant in comparison with the control group. The reduction of bone density was increased with the enhancement of nanostructures concentration. The effect of Al₂O₃ nanoparticles on bone density was similar in the left and right legs. Histopatholological assessment also showed that Al₂O₃ nanoparticles (250, 500, and 1000 µg/ml) lead to significant reduction of trabeculae. Empty lacunae are observed in these three groups. Considering that high concentrations of Al₂O₃ nanoparticles had toxicity on bone tissue, it must be used by more caution, especially its use as a coating in different devices such as implants, surgical instruments, and bone prostheses.

Advanced nanomaterials for hypoxia tumor therapy: challenges and solutions

In recent years, nanomaterials and nanotechnology have emerged as vital factors in the medical field with a unique contribution to cancer medicine. Given the increasing number of cancer patients, it is necessarily required to develop innovative strategies and therapeutic modalities to tackle hypoxia, which forms a hallmark and great barrier in treating solid tumors. The present review details the challenges in nanotechnology-based hypoxia, targeting the strategies and solutions for better therapeutic performances. The interaction between hypoxia and tumor is firstly introduced. Then, we review the recently developed engineered nanomaterials towards multimodal hypoxia tumor therapies, including chemotherapy, radiotherapy, and sonodynamic treatment. In the next part, we summarize the nanotechnology-based strategies for overcoming hypoxia problems. Finally, current challenges and future directions are proposed for successfully overcoming the hypoxia tumor problems.

Current Status of Alginate in Drug Delivery

Alginate is one of the natural polymers that are often used in drug- and protein-delivery systems. The use of alginate can provide several advantages including ease of preparation, biocompatibility, biodegradability, and nontoxicity. It can be applied to various routes of drug administration including targeted or localized drug-delivery systems. The development of alginates as a selected polymer in various delivery systems can be adjusted depending on the challenges that must be overcome by drug or proteins or the system itself. The increased effectiveness and safety of sodium alginate in the drug- or protein-delivery system are evidenced by changing the physicochemical characteristics of the drug or proteins. In this review, various routes of alginate-based drug or protein delivery, the effectivity of alginate in the stem cells, and cell encapsulation have been discussed. The recent advances in the in vivo alginate-based drug-delivery systems as well as their toxicities have also been reviewed.

Acyclovir in the Treatment of Herpes Viruses – A Review

Background:

Herpes Simplex (HSV) viruses are widely spread, highly contagious human pathogens. The statistics indicate that 50-90% of adults worldwide are seropositive for these viruses, mainly HSV-1 and HSV-2. The primary infection results in the appearance of watery blisters (cold sores) on the skin, lips, tongue, buccal mucosa or genitals. The ocular infection is the major cause of corneal blindness in the Western World. Once the HSV virus enters human body, it cannot be completely eradicated because HSV viruses are able to change into their latent form which can survive the treatment. The viron resides in trigeminal ganglia of the host, who becomes vulnerable to the reoccurrence of the disease during the whole lifespan. The neurotropic and neuro-invasive properties of HSV are responsible for neurodegenerative illnesses, such as Alzheimer's disease. Acyclovir and its analogues, being the inhibitors of the viral DNA replication, are the only approved medicines for HSV infection therapies.

Objective:

The current paper presents the up-to-date overview of the important pharmacological features of acyclovir, its analogues and their delivery systems including the mechanism of action, routes of administration, absorption and metabolism, as well as side effects of the therapy.

Conclusion:

Acyclovir remains the gold standard in the treatment of herpes virus infections, mainly due to the emerging of the new delivery systems improving considerably its bioavailability. The analogues of acyclovir, especially their esters, characterized by significantly higher bioavailability and safety, may gradually replace acyclovir in selected applications.

Considerations and Caveats in Combating ESKAPE Pathogens against Nosocomial Infections

ESKAPE pathogens (Enterococcus faecium, Staphylococcus aureus, Klebsiella pneumoniae, Acinetobacter baumannii, Pseudomonas aeruginosa, and Enterobacter species) are among the most common opportunistic pathogens in nosocomial infections. ESKAPE pathogens distinguish themselves from normal ones by developing a high level of antibiotic resistance that involves multiple mechanisms. Contemporary therapeutic strategies which are potential options in combating ESKAPE bacteria need further investigation. Herein, a broad overview of the antimicrobial research on ESKAPE pathogens over the past five years is provided with prospective clinical applications.

Lipid core nanoparticles resembling low-density lipoprotein and regression of atherosclerotic lesions: effects of particle size

Particles are usually polydispersed and size is an important feature for lipid-based drug delivery systems in order to optimize cell-particle interactions as to pharmacologic action and toxicity. Lipid nanoparticles (LDE) with composition similar to that of low-density lipoprotein carrying paclitaxel were shown to markedly reduce atherosclerosis lesions induced in rabbits by cholesterol feeding. The aim of this study was to test whether two LDE fractions, one with small (20-60 nm) and the other with large (60-100 nm) particles, had different actions on the atherosclerotic lesions. The two LDE-paclitaxel fractions, prepared by microfluidization, were separated by density gradient ultracentrifugation and injected (4 mg/body weight, intravenously once a week) into two groups of rabbits previously fed cholesterol for 4 weeks. A group of cholesterol-fed animals injected with saline solution was used as control to assess lesion reduction with treatment. After the treatment period, the animals were euthanized for analysis. After treatment, both the small and large nanoparticle preparations of LDE-paclitaxel had equally strong anti-atherosclerosis action. Both reduced lesion extension in the aorta by roughly 50%, decreased the intima width by 75% and the macrophage presence in the intima by 50%. The two preparations also showed similar toxicity profile. In conclusion, within the 20-100 nm range, size is apparently not an important feature regarding the LDE nanoparticle system and perhaps other solid lipid-based systems.

The potential of multi-compound nanoparticles to bypass drug resistance in cancer

PURPOSE

The therapeutic efficacy of conventional chemotherapy against several solid tumors is generally limited and this is often due to the development of resistance or poor delivery of the drugs to the tumor. Mechanisms of resistance may vary between cancer types. However, with current development of genetic analyses, imaging, and novel delivery systems, we may be able to characterize and bypass resistance, e.g., by inhibition of the right target at the tumor site. Therefore, combined drug treatments, where one drug will revert or obstruct the development of resistance and the other will concurrently kill the cancer cell, are rational solutions. However, drug exposure of one drug will defer greatly from the other due to their physicochemical properties. In this sense, multi-compound nanoparticles are an excellent modality to equalize drug exposure, i.e., one common physicochemical profile. In this review, we will discuss novel approaches that employ nanoparticle technology that addresses specific mechanisms of resistance in cancer.

METHODS

The PubMed literature was consulted and reviewed.

RESULTS

Nanoparticle technology is emerging as a dexterous solution that may address several forms of resistance in cancer. For instance, we discuss advances that address mechanisms of resistance with multi-compound nanoparticles which co-deliver chemotherapeutics with an anti-resistance agent. Promising anti-resistance agents are (1) targeted in vivo gene silencing methods aimed to disrupt key resistance gene expression or (2) protein kinase inhibitors to disrupt key resistance pathways or (3) efflux pumps inhibitors to limit drug cellular efflux.

Heterogeneous Vascular Bed Responses to Pulmonary Titanium Dioxide Nanoparticle Exposure

A growing body of research links engineered nanomaterial (ENM) exposure to adverse cardiovascular endpoints. The purpose of this study was to evaluate the impact of ENM exposure on vascular reactivity in discrete segments so that we may determine the most sensitive levels of the vasculature where these negative cardiovascular effects are manifest. We hypothesized that acute nano-TiO₂ exposure differentially affects reactivity with a more robust impairment in the microcirculation. Sprague-Dawley rats (8–10 weeks) were exposed to nano-TiO₂via intratracheal instillation (20, 100, or 200 µg suspended per 250 µL of vehicle) 24 h prior to vascular assessments. A serial assessment across distinct compartments of the vascular tree was then conducted. Wire myography was used to evaluate macrovascular active tension generation specifically in the thoracic aorta, the femoral artery, and third-order mesenteric arterioles. Pressure myography was used to determine vascular reactivity in fourth- and fifth-order mesenteric arterioles. Vessels were treated with phenylephrine, acetylcholine (ACh), and sodium nitroprusside. Nano-TiO₂ exposure decreased endothelium-dependent relaxation in the thoracic aorta and femoral arteries assessed via ACh by 53.96 ± 11.6 and 25.08 ± 6.36%, respectively. Relaxation of third-order mesenteric arterioles was impaired by 100 and 20 µg nano-TiO₂ exposures with mean reductions of 50.12 ± 8.7 and 68.28 ± 8.7%. Cholinergic reactivity of fourth- and fifth-order mesenteric arterioles was negatively affected by nano-TiO₂ with diminished dilations of 82.86 ± 12.6% after exposure to 200 µg nano-TiO₂, 42.6 ± 12.6% after 100 µg nano-TiO₂, and 49.4 ± 12.6% after 20 µg nano-TiO₂. Endothelium-independent relaxation was impaired in the thoracic aorta by 34.05 ± 25% induced by exposure to 200 µg nano-TiO₂ and a reduction in response of 49.31 ± 25% caused by 100 µg nano-TiO₂. Femoral artery response was reduced by 18 ± 5%, while third-order mesenteric arterioles were negatively affected by 20 µg nano-TiO₂ with a mean decrease in response of 38.37 ± 10%. This is the first study to directly compare the differential effect of ENM exposure on discrete anatomical segments of the vascular tree. Pulmonary ENM exposure produced macrovascular and microvascular dysfunction resulting in impaired responses to endothelium-dependent, endothelium-independent, and adrenergic agonists with a more robust dysfunction at the microvascular level. These results provide additional evidence of an endothelium-dependent and endothelium-independent impairment in vascular reactivity.

Nanomaterials for In Vivo Imaging

In vivo imaging, which enables us to peer deeply within living subjects, is producing tremendous opportunities both for clinical diagnostics and as a research tool. Contrast material is often required to clearly visualize the functional architecture of physiological structures. Recent advances in nanomaterials are becoming pivotal to generate the high-resolution, high-contrast images needed for accurate, precision diagnostics. Nanomaterials are playing major roles in imaging by delivering large imaging payloads, yielding improved sensitivity, multiplexing capacity, and modularity of design. Indeed, for several imaging modalities, nanomaterials are now not simply ancillary contrast entities, but are instead the original and sole source of image signal that make possible the modality's existence. We address the physicochemical makeup/design of nanomaterials through the lens of the physical properties that produce contrast signal for the cognate imaging modality-we stratify nanomaterials on the basis of their (i) magnetic, (ii) optical, (iii) acoustic, and/or (iv) nuclear properties. We evaluate them for their ability to provide relevant information under preclinical and clinical circumstances, their in vivo safety profiles (which are being incorporated into their chemical design), their modularity in being fused to create multimodal nanomaterials (spanning multiple different physical imaging modalities and therapeutic/theranostic capabilities), their key properties, and critically their likelihood to be clinically translated.

Tailoring Nanostructure Morphology for Enhanced Targeting of Dendritic Cells in Atherosclerosis

Atherosclerosis, a leading cause of heart disease, results from chronic vascular inflammation that is driven by diverse immune cell populations. Nanomaterials may function as powerful platforms for diagnostic imaging and controlled delivery of therapeutics to inflammatory cells in atherosclerosis, but efficacy is limited by nonspecific uptake by cells of the mononuclear phagocytes system (MPS). MPS cells located in the liver, spleen, blood, lymph nodes, and kidney remove from circulation the vast majority of intravenously administered nanomaterials regardless of surface functionalization or conjugation of targeting ligands. Here, we report that nanostructure morphology alone can be engineered for selective uptake by dendritic cells (DCs), which are critical mediators of atherosclerotic inflammation. Employing near-infrared fluorescence imaging and flow cytometry as a multimodal approach, we compared organ and cellular level biodistributions of micelles, vesicles (i.e., polymersomes), and filomicelles, all assembled from poly(ethylene glycol)-bl-poly(propylene sulfide) (PEG-bl-PPS) block copolymers with identical surface chemistries. While micelles and filomicelles were respectively found to associate with liver macrophages and blood-resident phagocytes, polymersomes were exceptionally efficient at targeting splenic DCs (up to 85% of plasmacytoid DCs) and demonstrated significantly lower uptake by other cells of the MPS. In a mouse model of atherosclerosis, polymersomes demonstrated superior specificity for DCs (p < 0.005) in atherosclerotic lesions. Furthermore, significant differences in polymersome cellular biodistributions were observed in atherosclerotic compared to naïve mice, including impaired targeting of phagocytes in lymph nodes. These results present avenues for immunotherapies in cardiovascular disease and demonstrate that nanostructure morphology can be tailored to enhance targeting specificity.

Metal Nanomaterial Toxicity Variations Within the Vascular System

Engineered nanomaterials (ENM) are anthropogenic materials with at least one dimension less than 100 nm. Their ubiquitous employment in biomedical and industrial applications in the absence of full toxicological assessments raises significant concerns over their safety on human health. This is a significant concern, especially for metal and metal oxide ENM as they may possess the greatest potential to impair human health. A large body of literature has developed that reflects adverse systemic effects associated with exposure to these materials, but an integrated mechanistic framework for how ENM exposure influences morbidity remains elusive. This may be due in large part to the tremendous diversity of existing ENM and the rate at which novel ENM are produced. In this review, the influence of specific ENM physicochemical characteristics and hemodynamic factors on cardiovascular toxicity is discussed. Additionally, the toxicity of metallic and metal oxide ENM is presented in the context of the cardiovascular system and its discrete anatomical and functional components. Finally, future directions and understudied topics are presented. While it is clear that the nanotechnology boom has increased our interest in ENM toxicity, it is also evident that the field of cardiovascular nanotoxicology remains in its infancy and continued, expansive research is necessary in order to determine the mechanisms via which ENM exposure contributes to cardiovascular morbidity.

Target therapy of multiple myeloma by PTX-NPs and ABCG2 antibody in a mouse xenograft model

Multiple myeloma (MM) remains to be an incurable disease. The purpose of this study was to evaluate the effect of ABCG2 monoclonal antibody (McAb) combined with paclitaxel (PTX) conjugated with Fe₃O₄ nanoparticles (NPs) on MM progressed from cancer stem cells (CSCs)in non-obese-diabetic/severe-combined-immunodeficiency (NOD/SCID) mouse model. Mice were injected with MM CSCs as marked by CD138⁻CD34⁻ phenotypes through tail veins. The developed MM mice were examined by micro-computer tomography scanning, ultrasonography and enzyme-linked immunosorbent analysis. These mice were then intravenously treated with different combinations of NPs, PTX, McAb, PTX-NPs and melphalan/prednisone once a week for four weeks. The injected mice developed characteristic MM-associated syndromes, including lytic bone lesions, renal damages and proteinuria. All the treated mice showed decrease in bone lesions, renal damages and anemia but increase in apoptosis compared with the mice treated with NPs only. In particular, the treatment with ABCG2 McAb plus PTX-NPs induced the strongest therapeutic response and had an efficacy even better than that of melphalan/prednisone, a conventional regimen for MM patients. These data suggest that PTX-NPs with ABCG2 McAb can be developed into potential treatment regimens for patients with relapsed/refractory MM.

Smart micro/nanoparticles in stimulus-responsive drug/gene delivery systems

New achievements in the realm of nanoscience and innovative techniques of nanomedicine have moved micro/nanoparticles (MNPs) to the point of becoming actually useful for practical applications in the near future. Various differences between the extracellular and intracellular environments of cancerous and normal cells and the particular characteristics of tumors such as physicochemical properties, neovasculature, elasticity, surface electrical charge, and pH have motivated the design and fabrication of inventive "smart" MNPs for stimulus-responsive controlled drug release. These novel MNPs can be tailored to be responsive to pH variations, redox potential, enzymatic activation, thermal gradients, magnetic fields, light, and ultrasound (US), or can even be responsive to dual or multi-combinations of different stimuli. This unparalleled capability has increased their importance as site-specific controlled drug delivery systems (DDSs) and has encouraged their rapid development in recent years. An in-depth understanding of the underlying mechanisms of these DDS approaches is expected to further contribute to this groundbreaking field of nanomedicine. Smart nanocarriers in the form of MNPs that can be triggered by internal or external stimulus are summarized and discussed in the present review, including pH-sensitive peptides and polymers, redox-responsive micelles and nanogels, thermo- or magnetic-responsive nanoparticles (NPs), mechanical- or electrical-responsive MNPs, light or ultrasound-sensitive particles, and multi-responsive MNPs including dual stimuli-sensitive nanosheets of graphene. This review highlights the recent advances of smart MNPs categorized according to their activation stimulus (physical, chemical, or biological) and looks forward to future pharmaceutical applications.

Localized delivery of low-density lipoprotein docosahexaenoic acid nanoparticles to the rat brain using focused ultrasound

Focused ultrasound exposures in the presence of microbubbles can achieve transient, non-invasive, and localized blood-brain barrier (BBB) opening, offering a method for targeted delivery of therapeutic agents into the brain. Low-density lipoprotein (LDL) nanoparticles reconstituted with docosahexaenoic acid (DHA) could have significant therapeutic value in the brain, since DHA is known to be neuroprotective. BBB opening was achieved using pulsed ultrasound exposures in a localized brain region in normal rats, after which LDL nanoparticles containing the fluorescent probe DiR (1,1'-Dioctadecyl-3,3,3',3'-Tetramethylindotricarbocyanine Iodide) or DHA were administered intravenously. Fluorescent imaging of brain tissue from rats administered LDL-DiR demonstrated strong localization of fluorescence signal in the exposed hemisphere. LDL-DHA administration produced 2 × more DHA in the exposed region of the brain, with a corresponding increase in Resolvin D1 levels, indicating DHA was incorporated into cells and metabolized. Histological evaluation did not indicate any evidence of increased tissue damage in exposed brain regions compared to normal brain. This work demonstrates that localized delivery of DHA to the brain is possible using systemically-administered LDL nanoparticles combined with pulsed focused ultrasound exposures in the brain. This technology could be used in regions of acute brain injury or as a means to target infiltrating tumor cells in the brain.

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

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

Application of mass spectrometry to characterize localization and efficacy of nanoceria in vivo

In vivo study of nanomaterials is complicated by the physical and chemical changes induced in the nanomaterial by exposure to biological compartments. A diverse array of proteins can bind to the nanomaterial, forming a protein corona which may alter the dispersion, surface charge, distribution, and biological activity of the material. Evidence suggests that unique synthesis and stabilization strategies can greatly affect the composition of the corona, and thus, the in vivo properties of the nanomaterial. Protein and elemental analyses techniques are critical to characterizing the nature of the protein corona in order to best predict the in vivo behavior of the nanomaterial. Further, as described here, inductively coupled mass spectroscopy (ICP-MS) can also be used to quantify nanomaterial deposition in tissues harvested from exposed animals. Elemental analysis of ceria content demonstrated deposition of cerium oxide nanoparticles (CeNPs) in various tissues of healthy mice and in the brains of mice with a model of multiple sclerosis. Thus, ICP-MS analysis of nanomaterial tissue distribution can complement data illustrating the biological, and in this case, therapeutic efficacy of nanoparticles delivered in vivo.