Analysis of plasma protein adsorption on polymeric nanoparticles with different surface characteristics

ApoE-functionalization of nanoparticles for targeted brain delivery-a feasible method for polyplexes?

The blood-brain barrier (BBB) poses a major obstacle in the treatment of all types of central nervous system (CNS) diseases. Small interfering RNA (siRNA) offers in principle a promising therapeutic approach by downregulating disease-related genes via RNA interference. However, the BBB is a formidable barrier for macromolecules such as nucleic acids. In an effort to develop a brain-targeted strategy for siRNA delivery systems formed by electrostatic interactions with cationic polymers (polyplexes (PXs)), we investigated the suitability of the well-known surfactant-based approach for Apolipoprotein E (ApoE)-functionalization of nanoparticles (NPs). The aim of this present work was to investigate if ApoE coating of siRNA PXs formed with cationic branched 25-kDa poly(ethyleneimine) (b-PEI) and nylon-3 polymers without or after precoating with polysorbate 80 (PS 80) would promote successful delivery across the BBB. We utilized highly hydrophobic NM0.2/CP0.8 nylon-3 polymers to evaluate the effects of hydrophobic cyclopentyl (CP) subunits on ApoE binding efficacy and observed successful ApoE binding with and without PS 80 precoating to the nylon-3 but not the PEI polyplexes. Accordingly, ApoE-coated nylon-3 polyplexes showed significantly increased uptake and gene silencing in U87 glioma cells but no benefit in vivo. In conclusion, further optimization of ApoE-functionalized polyplexes and more sophisticated in vitro models are required to achieve more successful in vitro-in vivo translation in future approaches.

Surface Bio-engineered Polymeric Nanoparticles

Surface bio-engineering of polymeric nanoparticles (PNPs) has emerged as a cornerstone in contemporary biomedical research, presenting a transformative avenue that can revolutionize diagnostics, therapies, and drug delivery systems. The approach involves integrating bioactive elements on the surfaces of PNPs, aiming to provide them with functionalities to enable precise, targeted, and favorable interactions with biological components within cellular environments. However, the full potential of surface bio-engineered PNPs in biomedicine is hampered by obstacles, including precise control over surface modifications, stability in biological environments, and lasting targeted interactions with cells or tissues. Concerns like scalability, reproducibility, and long-term safety also impede translation to clinical practice. In this review, these challenges in the context of recent breakthroughs in developing surface-biofunctionalized PNPs for various applications, from biosensing and bioimaging to targeted delivery of therapeutics are discussed. Particular attention is given to bonding mechanisms that underlie the attachment of bioactive moieties to PNP surfaces. The stability and efficacy of surface-bioengineered PNPs are critically reviewed in disease detection, diagnostics, and treatment, both in vitro and in vivo settings. Insights into existing challenges and limitations impeding progress are provided, and a forward-looking discussion on the field's future is presented. The paper concludes with recommendations to accelerate the clinical translation of surface bio-engineered PNPs.

Protein corona investigations of polyplexes with varying hydrophobicity - From method development to in vitro studies

In the field of non-viral drug delivery, polyplexes (PXs) represent an advanced investigated and highly promising tool for the delivery of nucleic acids. Upon encountering physiological fluids, they adsorb biological molecules to form a protein corona (PC), that influence PXs biodistribution, transfection efficiencies and targeting abilities. In an effort to understand protein - PX interactions and the effect of PX material on corona composition, we utilized cationic branched 10 kDa polyethyleneimine (b-PEI) and a hydrophobically modified nylon-3 polymer (NM0.2/CP0.8) within this study to develop appropriate methods for PC investigations. A centrifugation procedure for isolating hard corona - PX complexes (PCPXs) from soft corona proteins after incubating the PXs in fetal bovine serum (FBS) for PC formation was successfully optimized and the identification of proteins by a liquid chromatography-tandem mass spectrometry (LC-MS-MS) method clearly demonstrated that the PC composition is affected by the underlying PXs material. With regard to especially interesting functional proteins, which might be able to induce active targeting effects, several candidates could be detected on b-PEI and NM0.2/CP0.8 PXs. These results are of high interest to better understand how the design of PXs impacts the PC composition and subsequently PCPXs-cell interactions to enable precise adjustment of PXs for targeted drug delivery.

Revealing Population Heterogeneity in Vesicle-Based Nanomedicines Using Automated, Single Particle Raman Analysis

The intrinsic heterogeneity of many nanoformulations is currently challenging to characterize on both the single particle and population level. Therefore, there is great opportunity to develop advanced techniques to describe and understand nanomedicine heterogeneity, which will aid translation to the clinic by informing manufacturing quality control, characterization for regulatory bodies, and connecting nanoformulation properties to clinical outcomes to enable rational design. Here, we present an analytical technique to provide such information, while measuring the nanocarrier and cargo simultaneously with label-free, nondestructive single particle automated Raman trapping analysis (SPARTA). We first synthesized a library of model compounds covering a range of hydrophilicities and providing distinct Raman signals. These compounds were then loaded into model nanovesicles (polymersomes) that can load both hydrophobic and hydrophilic cargo into the membrane or core regions, respectively. Using our analytical framework, we characterized the heterogeneity of the population by correlating the signal per particle from the membrane and cargo. We found that core and membrane loading can be distinguished, and we detected subpopulations of highly loaded particles in certain cases. We then confirmed the suitability of our technique in liposomes, another nanovesicle class, including the commercial formulation Doxil. Our label-free analytical technique precisely determines cargo location alongside loading and release heterogeneity in nanomedicines, which could be instrumental for future quality control, regulatory body protocols, and development of structure-function relationships to bring more nanomedicines to the clinic.

In vitro-in vivo correlation in nanocarriers: From protein corona to therapeutic implications

Understanding and establishing a link between the physicochemical characteristics of nanoparticles (NPs) and their biological interactions poses to be a great challenge in the field of nanotherapeutics. Recent analytical advancements concerning bio-nanointerfaces have accelerated the quest to comprehend the fate of nanocarrier systems in vivo. Scientists have discovered that protein corona, an adsorbed layer of biomolecules on the surface of NPs takes a leading part in interacting with cells and in the cellular uptake process, thereby determining the in vivo behaviour of NPs. Another useful method to assess the in vivo fate of NPs is by performing dissolution testing. This forms the basis for in vitro in vivo correlation (IVIVC), relating in vitro dissolution of NPs and their in vivo properties. Scientists are continuously directing their efforts towards establishing IVIVC for different nanocarrier systems while concurrently gaining insights into protein corona. This review primarily summarizes the importance of protein corona and its interaction with nanoparticles. It also gives an insight into the factors affecting the interaction and various in vitro dissolution media used for varied nanocarrier systems. The article concludes with a discussion of the limitations of IVIVC modelling and its position from a regulatory perspective.

The advances in nanomedicine for bone and cartilage repair

With the gradual demographic shift toward an aging and obese society, an increasing number of patients are suffering from bone and cartilage injuries. However, conventional therapies are hindered by the defects of materials, failing to adequately stimulate the necessary cellular response to promote sufficient cartilage regeneration, bone remodeling and osseointegration. In recent years, the rapid development of nanomedicine has initiated a revolution in orthopedics, especially in tissue engineering and regenerative medicine, due to their capacity to effectively stimulate cellular responses on a nanoscale with enhanced drug loading efficiency, targeted capability, increased mechanical properties and improved uptake rate, resulting in an improved therapeutic effect. Therefore, a comprehensive review of advancements in nanomedicine for bone and cartilage diseases is timely and beneficial. This review firstly summarized the wide range of existing nanotechnology applications in the medical field. The progressive development of nano delivery systems in nanomedicine, including nanoparticles and biomimetic techniques, which are lacking in the current literature, is further described. More importantly, we also highlighted the research advancements of nanomedicine in bone and cartilage repair using the latest preclinical and clinical examples, and further discussed the research directions of nano-therapies in future clinical practice.

Optimal centrifugal isolating of liposome-protein complexes from human plasma

In the past few years, characterization of the protein corona (PC) that forms around liposomal systems has gained increasing interest for the development of novel therapeutic and diagnostic technologies. At the crossroads of fast-moving research fields, the interdisciplinarity of protein corona investigations poses challenges for experimental design and reporting. Isolation of liposome-protein complexes from biological fluids has been identified as a fundamental step of the entire workflow of PC characterization but exact specifications for conditions to optimize pelleting remain elusive. In the present work, key factors affecting precipitation of liposome-protein complexes by centrifugation, including time of centrifugation, total sample volume, lipid : protein ratio and contamination from biological NPs were comprehensively evaluated. Here we show that the total amount of isolated liposome-protein complexes and the extent of contamination from biological NPs may vary with influence factors. Our results provide protein corona researchers with precise indications to separate liposome-protein complexes from protein-rich fluids and include proper controls, thus they are anticipated to catalyze improved consistency of data mining and computational modelling of protein corona composition.

Adsorption-Reaction Processes Between Gelatin and PDMS-E Emulsion Droplets

In this work, the effects of droplet size and reaction time on the adsorption-reaction processes between gelatin and α-[3-(2,3-epoxypropoxy) propyl]-ω-butyl-polydimethylsiloxane (PDMS-E) emulsion droplets were studied. Gelatin molecules were only physically adsorbed on the surface of the PDMS-E droplet in the 0-75 min range, which was unrelated to the droplet size (100-1000 nm). For the small-size droplets (<410 nm), the physical adsorption proceeded over 75 min followed by agglomeration. For middle-size droplets (410-680 nm), the physical adsorption finished at 125 min; subsequently, the nucleophilic reaction between the primary amino group and the epoxy group began to happen, and globular-like or core-shell colloidal particles were formed. For large-size droplets (>680 nm), the nucleophilic reaction occurred at 75 min and produced core-shell or multi-layered colloidal particles. In a word, the physical absorption or nucleophilic reaction between gelatin and PDMS-E emulsion droplets could be controlled by controlling the droplet size and reaction time. Furthermore, the soft tissue paper coated with large-size droplets exhibited excellent resistance to water permeability and flame-resistant performance, which were carried out by water resistance and flammability tests.

Innate Immune Invisible Ultrasmall Gold Nanoparticles-Framework for Synthesis and Evaluation

Nanomedicine is seen as a potential central player in the delivery of personalized medicine. Biocompatibility issues of nanoparticles have largely been resolved over the past decade. Despite their tremendous progress, less than 1% of applied nanosystems can hit their intended target location, such as a solid tumor, and this remains an obstacle to their full ability and potential with a high translational value. Therefore, achieving immune-tolerable, blood-compatible, and biofriendly nanoparticles remains an unmet need. The translational success of nanoformulations from bench to bedside involves a thorough assessment of their design, compatibility beyond cytotoxicity such as immune toxicity, blood compatibility, and immune-mediated destruction/rejection/clearance profile. Here, we report a one-pot process-engineered synthesis of ultrasmall gold nanoparticles (uGNPs) suitable for better body and renal clearance delivery of their payloads. We have obtained uGNP sizes of as low as 3 nm and have engineered the synthesis to allow them to be accurately sized (almost nanometer by nanometer). The synthesized uGNPs are biocompatible and can easily be functionalized to carry drugs, peptides, antibodies, and other therapeutic molecules. We have performed in vitro cell viability assays, immunotoxicity assays, inflammatory cytokine analysis, a complement activation study, and blood coagulation studies with the uGNPs to confirm their safety. These can help to set up a long-term safety-benefit framework of experimentation to reveal whether any designed nanoparticles are immune-tolerable and can be used as payload carriers for next-generation vaccines, chemotherapeutic drugs, and theranostic agents with better body clearance ability and deep tissue penetration.

Enhanced siRNA Delivery and Selective Apoptosis Induction in H1299 Cancer Cells by Layer-by-Layer-Assembled Se Nanocomplexes: Toward More Efficient Cancer Therapy

Nanotechnology has made an important contribution to oncology in recent years, especially for drug delivery. While many different nano-delivery systems have been suggested for cancer therapy, selenium nanoparticles (SeNPs) are particularly promising anticancer drug carriers as their core material offers interesting synergistic effects to cancer cells. Se compounds can exert cytotoxic effects by acting as pro-oxidants that alter cellular redox homeostasis, eventually leading to apoptosis induction in many kinds of cancer cells. Herein, we report on the design and synthesis of novel layer-by-layer Se-based nanocomplexes (LBL-Se-NCs) as carriers of small interfering RNA (siRNA) for combined gene silencing and apoptosis induction in cancer cells. The LBL-Se-NCs were prepared using a straightforward electrostatic assembly of siRNA and chitosan (CS) on the solid core of the SeNP. In this study, we started by investigating the colloidal stability and protection of the complexed siRNA. The results show that CS not only functioned as an anchoring layer for siRNA, but also provided colloidal stability for at least 20 days in different media when CS was applied as a third layer. The release study revealed that siRNA remained better associated with LBL-Se-NCs, with only a release of 35% after 7 days, as compared to CS-NCs with a siRNA release of 100% after 48 h, making the LBL nanocarrier an excellent candidate as an off-the-shelf formulation. When applied to H1299 cells, it was found that they can selectively induce around 32% apoptosis, while significantly less apoptosis (5.6%) was induced in NIH/3T3 normal cells. At the same time, they were capable of efficiently inducing siRNA downregulation (35%) without loss of activity 7 days post-synthesis. We conclude that LBL-Se-NCs are promising siRNA carriers with enhanced stability and with a dual mode of action against cancer cells.

From adsorption to covalent bonding: Apolipoprotein E functionalization of polymeric nanoparticles for drug delivery across the blood-brain barrier

The blood-brain barrier (BBB) is composed of brain endothelial cells, pericytes, and astrocytes, which build a tight cellular barrier. Therapeutic (macro)molecules are not able to transit through the BBB in their free form. This limitation is bypassed by apolipoprotein E (ApoE)-functionalized polymeric nanoparticles (NPs) that are able to transport drugs (e.g. dalargin, loperamide, doxorubicin, nerve growth factor) across the BBB via low density lipoprotein (LDL) receptor mediated transcytosis. Coating with polysorbate 80 or poloxamer 188 facilitates ApoE adsorption onto polymeric NPs enabling recognition by LDL receptors of brain endothelial cells. This effect is even enhanced when NPs are directly coated with ApoE without surfactant anchor. Similarly, covalent coupling of ApoE to NPs that bear reactive groups on their surface leads to significantly improved brain uptake while avoiding the use of surfactants. Several in vitro BBB models using brain endothelial cells or co-cultures with astrocytes/pericytes/glioma cells are described which provide first insights regarding the ability of a drug delivery system to cross this barrier. In vivo models are employed to simulate central nervous system-relevant diseases such as Alzheimer's or Parkinson's disease and cerebral cancer.

Three Decades of Research about the Corona Around Nanoparticles: Lessons Learned and Where to Go Now

The research about how a nanoparticle (NP) interacts with a complex biological solution has been conducted, according to the literature, for almost three decades. A significant amount of data has been generated, especially in the last one and a half decade. First, it became its own research field which was later divided into many subresearch fields. This outlook does not aim to be a comprehensive review of the field or any of its subresearch fields. There is too much data published to attempt that. Instead, here it has been tried to highlight what, in the opinion, is the main step taken during these three decades. Thereafter, the weaknesses and end are pointed out with what needs to be the main focus for the future to understand the protein corona formation in the bloodstream, which is a prerequisite for the developing of true target specific drug-delivering nanoparticles.

Protein Nanoparticle Charge and Hydrophobicity Govern Protein Corona and Macrophage Uptake

Protein nanoparticles are biomaterials composed entirely of proteins, with the protein sequence and structure determining the nanoparticle physicochemical properties. Upon exposure to physiological or environmental fluids, it is likely that protein nanoparticles, like synthetic nanoparticles, will adsorb proteins and this protein corona will be dependent on the surface properties of the protein nanoparticles. As there is little understanding of this phenomenon for engineered protein nanoparticles, the purpose of this work was to create protein nanoparticles with variable surface hydrophobicity and surface charge and establish the effect of these properties on the mass and composition of the adsorbed corona, using the fetal bovine serum as a model physiological solution. Albumin, cationic albumin, and ovalbumin cross-linked nanoparticles were developed for this investigation and their adsorbed protein coronas were isolated and characterized by gel electrophoresis and nanoliquid chromatography mass spectrometry. Distinct trends in corona mass and composition were identified for protein nanoparticles based on surface charge and surface hydrophobicity. Proteomic analyses revealed unique protein corona patterns and identified distinct proteins that are known to affect nanoparticle clearance in vivo. Further, the protein corona influenced nanoparticle internalization in vitro in a macrophage cell line. Altogether, these results demonstrate the strong effect protein identity and properties have on the corona formed on nanoparticles made from that protein. This work builds the foundation for future study of protein coronas on the wide array of protein nanoparticles used in nanomedicine and environmental applications.

Micro- and nanoplastics - current state of knowledge with the focus on oral uptake and toxicity

The production and use of plastics has constantly increased over the last 30 years. Over one third of the plastics is used in disposables, which are discarded within three years of their production. Despite efforts towards recycling, a substantial volume of debris has accumulated in the environment and is slowly degraded to micro- and nanoplastics by weathering and aging. It has recently been discovered that these small particles can enter the food chain, as for example demonstrated by the detection of microplastic particles in honey, beer, salt, sea food and recently in mineral water. Human exposure has further been documented by the detection of plastic microparticles in human feces. Potential toxic consequences of oral exposure to small plastic particles are discussed. Due to lacking data concerning exposure, biodistribution and related effects, the risk assessment of micro- and nanoplastics is still not possible. This review focuses on the oral uptake of plastic and polymer micro- and nanoparticles. Oral exposure, particle fate, changes of particle properties during ingestion and gastrointestinal digestion, and uptake and transport at the intestinal epithelium are reviewed in detail. Moreover, the interaction with intestinal and liver cells and possibly resulting toxicity are highlighted.

Modeling the interaction of amphiphilic polymer nanoparticles with biomembranes to Guide rational design of drug delivery systems

Nanoparticle assisted drug delivery to the cytoplasm is limited by sequestration of nanoparticles in endosomes. Endosomal escape through polymer-induced membrane destabilization is one of a few well characterized mechanisms to overcome it. Aiming to utilize this method in vivo, it is necessary to understand how modulating the structural and chemical features of the polymer and the presence of proteins in biological fluids can affect this activity. Here, as a model for the endosomal membrane, we use the membrane of red blood cells to evaluate the membrane destabilization ability of a model amphiphilic polymer in the presence of blood plasma using a hemolysis assay. This allows determination of red blood cells membrane permeabilization through the quantification of hemoglobin leakage. Our results showed a strong inhibitory effect of plasma, and that hemolytic activity can be improved by chemical modification of the polymeric micelle, reducing its interaction with plasma proteins. Finally, a second mechanism of pH-induced direct diffusion is proposed and tested using an oil/water partitioning model. These results offer a body of knowledge to improve delivery of drugs across biological membranes using carefully designed polymeric nanocarriers.

Surface-modified polymeric nanoparticles for drug delivery to cancer cells

INTRODUCTION

The utilization of polymeric nanoparticles, as drug payloads, has been extensively prevailed in cancer therapy. However, the precise distribution of these nanocarriers is restrained by various physiological and cellular obstacles. Nanoparticles must avoid nonspecific interactions with healthy cells and in vivo compartments to circumvent these barriers. Since in vivo interactions of nanoparticles are mainly dependent on surface properties of nanoparticles, efficient control on surface constituents is necessary for the determination of nanoparticles' fate in the body.

AREAS COVERED

In this review, the surface-modified polymeric nanoparticles and their utilization in cancer treatment were elaborated. First, the interaction of nanoparticles with numerous in vivo barriers was highlighted. Second, different strategies to overcome these obstacles were described. Third, some inspiring examples of surface-modified nanoparticles were presented. Later, fabrication and characterization methods of surface-modified nanoparticles were discussed. Finally, the applications of these nanoparticles in different routes of treatments were explored.

EXPERT OPINION

Surface modification of anticancer drug-loaded polymeric nanoparticles can enhance the efficacy, selective targeting, and biodistribution of the anticancer drug at the tumor site.

Formulation aspects of intravenous nanosuspensions

Intravenous (IV) route is preferred for rapid onset of action, avoiding first pass metabolism and achieving site specific delivery. Development of IV formulations for poorly water soluble drugs poses significant challenges. Formulation approaches like salt formation, co-solvents, surfactants and inclusion complexation using cyclodextrins are used for solubilisation. However, these approaches are not applicable universally and have limitations in extent of solubilisation, hypersensitivity, toxicity and application to only specific type of molecules. IV nanosuspension have been attracting attention as a viable strategy for development of IV formulations of poorly water-soluble drugs. Nanosuspension consists of nanocrystals of poorly water soluble drug suspended in aqueous media and stabilized using minimal concentration of stabilizers. Recent years have witnessed their potential in formulations for toxicological studies and clinical trials. However various challenges are associated with the translational development of IV nanosuspensions. Therefore, the objective of the current review is to provide a holistic view of formulation development and desired properties of IV nanosuspensions. It will also focus on advancements in characterization tools, manufacturing techniques and post-production processing. Challenges associated with translational development and regulatory aspects of IV nanosuspension will be addressed. Additionally, their role in preclinical evaluation and special applications like targeting will also be discussed with the help of case studies. The applications of IV nanosuspensions shall expand as their applications move from preclinical phase to commercialization.

A flexible, robust microbead-based assay for quantification and normalization of target protein concentrations

Although there are many methods for quantifying the concentration of specific proteins in samples, current techniques are technically challenging or do not easily lend themselves to normalization. Here, we describe a microbead-based assay for quantifying specific protein concentration(s) that is high-throughput, inexpensive, simple-to-use, and intrinsically incorporates normalization against the sample total protein content. This assay, termed the FRANC assay, exploits high affinity biotin-streptavidin binding to couple sample proteins to streptavidin-labelled magnetic microbeads. Proteins are then antibody-probed, followed by labeling of proteins on the microbead with fluorescent dye, and flow cytometry-based analysis. The FRANC assay demonstrates detection limits for target proteins in the femtogram range, with a linear range up to as much as 10 ng. Normalization of target protein concentrations resulted in an 80% reduction in variability as compared to non-normalized measurements. We conclude that the FRANC assay offers attractive advantages over current methods for quantifying specific protein(s) in samples.

Amphiphilic nanogels: influence of surface hydrophobicity on protein corona, biocompatibility and cellular uptake

BACKGROUND AND PURPOSE

Nanogels (NGs) are promising drug delivery tools but are typically limited to hydrophilic drugs. Many potential new drugs are hydrophobic. Our study systematically investigates amphiphilic NGs with varying hydrophobicity, but similar colloidal features to ensure comparability. The amphiphilic NGs used in this experiment consist of a hydrophilic polymer network with randomly distributed hydrophobic groups. For the synthesis we used a new synthetic platform approach. Their amphiphilic character allows the encapsulation of hydrophobic drugs. Importantly, the hydrophilic/hydrophobic balance determines drug loading and biological interactions. In particular, protein adsorption to NG surfaces is dependent on hydrophobicity and critically determines circulation time. Our study investigates how network hydrophobicity influences protein binding, biocompatibility and cellular uptake.

METHODS

Biocompatibility of the NGs was examined by WST-1 assay in monocytic-like THP-1 cells. Serum protein corona formation was investigated using dynamic light scattering and two-dimensional gel electrophoresis. Proteins were identified by liquid chromatography-tandem mass spectrometry. In addition, cellular uptake was analyzed via flow cytometry.

RESULTS

All NGs were highly biocompatible. The protein binding patterns for the two most hydrophobic NGs were very similar to each other but clearly different from the hydrophilic ones. Overall, protein binding was increased with increasing hydrophobicity, resulting in increased cellular uptake.

CONCLUSION

Our study supports the establishment of structure-property relationships and contributes to the accurate balance between maximum loading capacity with low protein binding, optimal biological half-life and good biocompatibility. This is an important step to derive design principles of amphiphilic NGs to be applied as drug delivery vehicles.

Bioformulative concepts on intracellular organ specific bioavailability

Bioavailability is an ancient but effective terminology by which the entire therapeutic efficacy of a drug directly or indirectly relays. Despite considering general plasma bioavailability, specific organ/tissue bioavailability will pave the path to broad spectrum dose calculation. Clear knowledge and calculative vision on bioavailability can improve the research and organ-targeting phenomenon. This article comprises a detailed introduction on bioavailability along with regulatory aspects, kinetic data and novel bioformulative approaches to achieve improved organ specific bioavailability, which may not be readily related to blood plasma bioavailability.

Repeated gestational exposure to diesel engine exhaust affects the fetal olfactory system and alters olfactory-based behavior in rabbit offspring

BACKGROUND

Airborne pollution, especially from diesel exhaust (DE), is known to have a negative effect on the central nervous system in exposed human populations. However, the consequences of gestational exposure to DE on the fetal brain remain poorly explored, with various effects depending on the conditions of exposure, as well as little information on early developmental stages. We investigated the short-term effects of indirect DE exposure throughout gestation on the developing brain using a rabbit model. We analyzed fetal olfactory tissues at the end of gestation and tested behaviors relevant to pups' survival at birth. Pregnant dams were exposed by nose-only inhalation to either clean air or DE with a content of particles (DEP) adjusted to 1 mg/m3 by diluting engine exhaust, for 2 h/day, 5 days/week, from gestational day 3 (GD3) to day 27 (GD27). At GD28, fetal olfactory mucosa, olfactory bulbs and whole brains were collected for anatomical and neurochemical measurements. At postnatal day 2 (PND2), pups born from another group of exposed or control female were examined for their odor-guided behavior in response to the presentation of the rabbit mammary pheromone 2-methyl-3-butyn-2-ol (2MB2).

RESULTS

At GD28, nano-sized particles were observed in cilia and cytoplasm of the olfactory sensory neurons in the olfactory mucosa and in the cytoplasm of periglomerular cells in the olfactory bulbs of exposed fetuses. Moreover, cellular and axonal hypertrophies were observed throughout olfactory tissues. Concomitantly, fetal serotoninergic and dopaminergic systems were affected in the olfactory bulbs. Moreover, the neuromodulatory homeostasis was disturbed in a sex-dependent manner in olfactory tissues. At birth, the olfactory sensitivity to 2MB2 was reduced in exposed PND2 pups.

CONCLUSION

Gestational exposure to DE alters olfactory tissues and affects monoaminergic neurotransmission in fetuses' olfactory bulbs, resulting in an alteration of olfactory-based behaviors at birth. Considering the anatomical and functional continuum between the olfactory system and other brain structures, and due to the importance of monoamine neurotransmission in the plasticity of neural circuits, such alterations could participate to disturbances in higher integrative structures, with possible long-term neurobehavioral consequences.

Particle Targeting in Complex Biological Media

Over the past few decades, nanoengineered particles have gained increasing interest for applications in the biomedical realm, including diagnosis, imaging, and therapy. When functionalized with targeting ligands, these particles have the potential to interact with specific cells and tissues, and accumulate at desired target sites, reducing side effects and improve overall efficacy in applications such as vaccination and drug delivery. However, when targeted particles enter a complex biological environment, the adsorption of biomolecules and the formation of a surface coating (e.g., a protein corona) changes the properties of the carriers and can render their behavior unpredictable. For this reason, it is of importance to consider the potential challenges imposed by the biological environment at the early stages of particle design. This review describes parameters that affect the targeting ability of particulate drug carriers, with an emphasis on the effect of the protein corona. We highlight strategies for exploiting the protein corona to improve the targeting ability of particles. Finally, we provide suggestions for complementing current in vitro assays used for the evaluation of targeting and carrier efficacy with new and emerging techniques (e.g., 3D models and flow-based technologies) to advance fundamental understanding in bio-nano science and to accelerate the development of targeted particles for biomedical applications.

Combating malaria with nanotechnology-based targeted and combinatorial drug delivery strategies

Despite the advancement of science, infectious diseases such as malaria remain an ongoing challenge globally. The main reason this disease still remains a menace in many countries around the world is the development of resistance to many of the currently available anti-malarial drugs. While developing new drugs is rather expensive and the prospect of a potent vaccine is still evading our dream of a malaria-free world, one of the feasible options is to package the older drugs in newer ways. For this, nano-sized drug delivery vehicles have been used and are proving to be promising prospects in the way malaria will be treated in the future. Since, monotherapy has given way to combination therapy in malaria treatment, nanotechnology-based delivery carriers enable to encapsulate various drug moieties in the same package, thus avoiding the complications involved in conjugation chemistry to produce hybrid drug molecules. Further, we envisage that using targeted delivery approaches, we may be able to achieve a much better radical cure and curb the side effects associated with the existing drug molecules. Thus, this review will focus on some of the nanotechnology-based combination and targeted therapies and will discuss the possibilities of better therapies that may be developed in the future.

Bio-inspired engineering of cell- and virus-like nanoparticles for drug delivery

The engineering of future generations of nanodelivery systems aims at the creation of multifunctional vectors endowed with improved circulation, enhanced targeting and responsiveness to the biological environment. Moving past purely bio-inert systems, researchers have begun to create nanoparticles capable of proactively interacting with the biology of the body. Nature offers a wide-range of sources of inspiration for the synthesis of more effective drug delivery platforms. Because the nano-bio-interface is the key driver of nanoparticle behavior and function, the modification of nanoparticles' surfaces allows the transfer of biological properties to synthetic carriers by imparting them with a biological identity. Modulation of these surface characteristics governs nanoparticle interactions with the biological barriers they encounter. Building off these observations, we provide here an overview of virus- and cell-derived biomimetic delivery systems that combine the intrinsic hallmarks of biological membranes with the delivery capabilities of synthetic carriers. We describe the features and properties of biomimetic delivery systems, recapitulating the distinctive traits and functions of viruses, exosomes, platelets, red and white blood cells. By mimicking these biological entities, we will learn how to more efficiently interact with the human body and refine our ability to negotiate with the biological barriers that impair the therapeutic efficacy of nanoparticles.

Recent advances in use of silver nanoparticles as antimalarial agents

Malaria is one of the most common infectious diseases, which has become a great public health problem all over the world. Ineffectiveness of available antimalarial treatment is the main reason behind its menace. The failure of current treatment strategies is due to emergence of drug resistance in Plasmodium falciparum and drug toxicity in human beings. Therefore, the development of novel and effective antimalarial drugs is the need of the hour. Considering the huge biomedical applications of nanotechnology, it can be potentially used for the malarial treatment. Silver nanoparticles (AgNPs) have demonstrated significant activity against malarial parasite (P. falciparum) and vector (female Anopheles mosquito). It is believed that AgNPs will be a solution for the control of malaria. This review emphasizes the pros- and cons of existing antimalarial treatments and in depth discussion on application of AgNPs for treatment of malaria. The role of nanoparticles for site specific drug delivery and toxicological issues have also been discussed.

Interactions of organic nanoparticles with proteins in physiological conditions

The efficacy of nanoparticles in biomedical applications is strongly influenced by their ability to bind proteins onto their surface. The analysis of organic nanoparticles interacting with proteins in physiological conditions may help in the successful design of next generation nanoparticles with improved biodistributions and therapeutic performances.

Effect of Polyethylene Oxide Blocks or Grafts on the Physicochemical Properties of Poly(2-N-(Dimethylaminoethyl) Methacrylate) DNA Complexes

The synthesis and the physicochemical evaluation of a series of polyethylene oxide (PEO) containing polyamines are described as potential vectors in gene therapy. Two different types of vectors were synthesized: PEO block copolymers and copolymers containing PEO grafts. The building unit of the polyamine is 2-N-(dimethylaminoethyl) methacrylate. All polymers are able to condense DNA according to dynamic light scattering measurements and ethidium bromide exclusion tests. Complexes of PEO block copolymers and DNA show a stability comparable to that of the homopolymer poly(2-N-(dimethylaminoethyl) methacrylate) (PDMAEMA). Polymers with a PEO graft show a lower stability compared to the unmodified polymer. Incorporation of a PEO graft resulted in a decrease in the zeta potential of the complexes at all charge ratios. The interaction of a serum albumin with complexes of DNA and PEO containing polymers was studied at different protein concentrations. Polymers with a PEO graft show a lower interaction with serum albumin compared to the homopolymer based on turbidity measurements.

Controlling the Stealth Effect of Nanocarriers through Understanding the Protein Corona

The past decade has seen a significant increase in interest in the use of polymeric nanocarriers in medical applications. In particular, when used as drug vectors in targeted delivery, nanocarriers could overcome many obstacles for drug therapy. Nevertheless, their application is still impeded by the complex composition of the blood proteins covering the particle surface, termed the protein corona. The protein corona complicates any prediction of cell interactions, biodistribution, and toxicity. In particular, the unspecific uptake of nanocarriers is a major obstacle in clinical studies. This Minireview provides an overview of what we currently know about the characteristics of the protein corona of nanocarriers, with a focus on surface functionalization that reduces unspecific uptake (the stealth effect). The ongoing improvement of nanocarriers to allow them to meet all the requirements necessary for successful application, including targeted delivery and stealth, are further discussed.

The impact of nanoparticle protein corona on cytotoxicity, immunotoxicity and target drug delivery

In a perfect sequence of events, nanoparticles (NPs) are injected into the bloodstream where they circulate until they reach the target tissue. The ligand on the NP surface recognizes its specific receptor expressed on the target tissue and the drug is released in a controlled manner. However, once injected in a physiological environment, NPs interact with biological components and are surrounded by a protein corona (PC). This can trigger an immune response and affect NP toxicity and targeting capabilities. In this review, we provide a survey of recent findings on the NP-PC interactions and discuss how the PC can be used to modulate both cytotoxicity and the immune response as well as to improve the efficacy of targeted delivery of nanocarriers.

PEG/heparin-decorated lipid–polymer hybrid nanoparticles for long-circulating drug delivery

Surface modification of lipid–polymer hybrid nanoparticles with the combined PEG and heparin was developed to achieve a significant prolongation in blood circulation.

Comparison of the uptake of methacrylate-based nanoparticles in static and dynamic in vitro systems as well as in vivo

Polymer-based nanoparticles are promising drug delivery systems allowing the development of new drug and treatment strategies with reduced side effects. However, it remains a challenge to screen for new and effective nanoparticle-based systems in vitro. Important factors influencing the behavior of nanoparticles in vivo cannot be simulated in screening assays in vitro, which still represent the main tools in academic research and pharmaceutical industry. These systems have serious drawbacks in the development of nanoparticle-based drug delivery systems, since they do not consider the highly complex processes influencing nanoparticle clearance, distribution, and uptake in vivo. In particular, the transfer of in vitro nanoparticle performance to in vivo models often fails, demonstrating the urgent need for novel in vitro tools that can imitate aspects of the in vivo situation more accurate. Dynamic cell culture, where cells are cultured and incubated in the presence of shear stress has the potential to bridge this gap by mimicking key-features of organs and vessels. Our approach implements and compares a chip-based dynamic cell culture model to the common static cell culture and mouse model to assess its capability to predict the in vivo success more accurately, by using a well-defined poly((methyl methacrylate)-co-(methacrylic acid)) and poly((methyl methacrylate)-co-(2-dimethylamino ethylmethacrylate)) based nanoparticle library. After characterization in static and dynamic in vitro cell culture we were able to show that physiological conditions such as cell-cell communication of co-cultured endothelial cells and macrophages as well as mechanotransductive signaling through shear stress significantly alter cellular nanoparticle uptake. In addition, it could be demonstrated by using dynamic cell cultures that the in vivo situation is simulated more accurately and thereby can be applied as a novel system to investigate the performance of nanoparticle systems in vivo more reliable.

Synthesis and antioxidant properties of chitosan and carboxymethyl chitosan-stabilized selenium nanoparticles

Monodispersible selenium nanoparticles (SeNPs) were synthesized by using chitosan (CS) and carboxymethyl chitosan (CCS) as the stabilizer and capping agent using a facile synthetic approach. The structure, size, morphology and antioxidant activity of the nanocomposites were characterized by transmission electron microscopy (TEM), Ultraviolet-visible spectroscopy (UV-vis), Dynamic Light Scattering (DLS), Fourier transform infrared (FTIR), Thermogravimetric analysis (TGA). The results revealed that the monodispersible SeNPs (mean particle size of about 50 nm) were ligated with CS and CCS to form nanocomposites in aqueous solution for at least 30 days, and for 120 days the nanoparticles increased to 180 nm or so in size. The DPPH scavenging ability of CS-SeNPs was higher than that of CCS-SeNPs, and could reach 93.5% at a concentration of 0.6 mmol/L. Moreover, SeNPs, CS-SeNPs and CCS-SeNPs exhibited a higher ABTS scavenging ability in comparison to Na2SeO3.

Surface chemistry and serum type both determine the nanoparticle-protein corona

The protein corona that forms around nanoparticles in vivo is a critical factor that affects their physiological response. The potential to manipulate nanoparticle characteristics such that either proteins advantageous for delivery are recruited and/or detrimental proteins are avoided offers exciting possibilities for improving drug delivery. In this work, we used nanoliquid chromatography tandem mass spectrometry to characterize the corona of five lipid formulations after incubation in mouse and human plasma with the hope of providing data that may contribute to a better understanding of the role played by both the nanoparticle properties and the physiological environment in recruiting specific proteins to the corona. Notably, we showed that minor changes in the lipid composition might critically affect the protein corona composition demonstrating that the surface chemistry and arrangement of lipid functional groups are key players that regulate the liposome-protein interactions. Notably, we provided evidence that the protein corona that forms around liposomes is strongly affected by the physiological environment, i.e., the serum type. These results are likely to suggest that the translation of novel pharmaceutical formulations from animal models to the clinic must be evaluated on a case-by-case basis.

BIOLOGICAL SIGNIFICANCE

In the present work nanoliquid chromatography tandem mass spectrometry was used to characterize the protein corona of five different liposome formulations after exposure to mouse and human plasma. The modern proteomic methods employed have clarified that the arrangement of lipid functional groups is a key player that regulates the liposome-protein interactions. We also clarified that the protein corona enrichment and complexity depend on the serum type. Our results suggest that the translational of novel pharmaceutical formulations from animal models to the clinic must be evaluated on a case-by-case basis.

Design attributes of long-circulating polymeric drug delivery vehicles

Following systemic administration polymeric drug delivery vehicles allow for a controlled and targeted release of the encapsulated medication at the desired site of action. For an elevated and organ specific accumulation of their cargo, nanocarriers need to avoid opsonization, activation of the complement system and uptake by macrophages of the mononuclear phagocyte system. In this respect, camouflaged vehicles revealed a delayed elimination from systemic circulation and an improved target organ deposition. For instance, a steric shielding of the carrier surface by poly(ethylene glycol) substantially decreased interactions with the biological environment. However, recent studies disclosed possible deficits of this approach, where most notably, poly(ethylene glycol)-modified drug delivery vehicles caused significant immune responses. At present, identification of novel potential carrier coating strategies facilitating negligible immune reactions is an emerging field of interest in drug delivery research. Moreover, physical carrier properties including geometry and elasticity seem to be very promising design attributes to surpass numerous biological barriers, in order to improve the efficacy of the delivered medication.

Physical chemistry of nanomedicine: understanding the complex behaviors of nanoparticles in vivo

Nanomedicine is an interdisciplinary field of research at the interface of science, engineering, and medicine, with broad clinical applications ranging from molecular imaging to medical diagnostics, targeted therapy, and image-guided surgery. Despite major advances during the past 20 years, there are still major fundamental and technical barriers that need to be understood and overcome. In particular, the complex behaviors of nanoparticles under physiological conditions are poorly understood, and detailed kinetic and thermodynamic principles are still not available to guide the rational design and development of nanoparticle agents. Here we discuss the interactions of nanoparticles with proteins, cells, tissues, and organs from a quantitative physical chemistry point of view. We also discuss insights and strategies on how to minimize nonspecific protein binding, how to design multistage and activatable nanostructures for improved drug delivery, and how to use the enhanced permeability and retention effect to deliver imaging agents for image-guided cancer surgery.

Protein corona - from molecular adsorption to physiological complexity

In biological environments, nanoparticles are enshrouded by a layer of biomolecules, predominantly proteins, mediating its subsequent interactions with cells. Detecting this protein corona, understanding its formation with regards to nanoparticle (NP) and protein properties, and elucidating its biological implications were central aims of bio-related nano-research throughout the past years. Here, we discuss the mechanistic parameters that are involved in the protein corona formation and the consequences of this corona formation for both, the particle, and the protein. We review consequences of corona formation for colloidal stability and discuss the role of functional groups and NP surface functionalities in shaping NP-protein interactions. We also elaborate the recent advances demonstrating the strong involvement of Coulomb-type interactions between NPs and charged patches on the protein surface. Moreover, we discuss novel aspects related to the complexity of the protein corona forming under physiological conditions in full serum. Specifically, we address the relation between particle size and corona composition and the latest findings that help to shed light on temporal evolution of the full serum corona for the first time. Finally, we discuss the most recent advances regarding the molecular-scale mechanistic role of the protein corona in cellular uptake of NPs.

Closing the gap: accelerating the translational process in nanomedicine by proposing standardized characterization techniques

On the cusp of widespread permeation of nanomedicine, academia, industry, and government have invested substantial financial resources in developing new ways to better treat diseases. Materials have unique physical and chemical properties at the nanoscale compared with their bulk or small-molecule analogs. These unique properties have been greatly advantageous in providing innovative solutions for medical treatments at the bench level. However, nanomedicine research has not yet fully permeated the clinical setting because of several limitations. Among these limitations are the lack of universal standards for characterizing nanomaterials and the limited knowledge that we possess regarding the interactions between nanomaterials and biological entities such as proteins. In this review, we report on recent developments in the characterization of nanomaterials as well as the newest information about the interactions between nanomaterials and proteins in the human body. We propose a standard set of techniques for universal characterization of nanomaterials. We also address relevant regulatory issues involved in the translational process for the development of drug molecules and drug delivery systems. Adherence and refinement of a universal standard in nanomaterial characterization as well as the acquisition of a deeper understanding of nanomaterials and proteins will likely accelerate the use of nanomedicine in common practice to a great extent.