Liposome-encapsulated actin–hemoglobin (LEAcHb) artificial blood substitutes

Protein and peptide-based renal targeted drug delivery systems

Renal diseases have become an increasingly concerned public health problem in the world. Kidney-targeted drug delivery has profound transformative potential on increasing renal efficacy and reducing extra-renal toxicity. Protein and peptide-based kidney targeted drug delivery systems have garnered more and more attention due to its controllable synthesis, high biocompatibility and low immunogenicity. At the same time, the targeting methods based on protein/peptide are also abundant, including passive renal targeting based on macromolecular protein and active targeting mediated by renal targeting peptide. Here, we review the application and the drug loading strategy of different proteins or peptides in targeted drug delivery, including the ferritin family, albumin, low molecular weight protein (LMWP), different peptide sequence and antibodies. In addition, we summarized the factors influencing passive and active targeting in drug delivery system, the main receptors related to active targeting in different kidney diseases, and a variety of nano forms of proteins based on the controllable synthesis of proteins.

Tracking Research on Hemoglobin-Based Oxygen Carriers: A Scientometric Analysis and In-Depth Review

Numerous studies on the formulation and clinical applications of novel hemoglobin-based oxygen carriers (HBOCs) are reported in the scientific literature. However, there are fewer scientometric analysis related to HBOCs. Here, we illustrate recent studies on HBOCs using both a scientometric analysis approach and a scope review method. We used the former to investigate research on HBOCs from 1991 to 2022, exploring the current hotspots and research trends, and then we comprehensively analyzed the relationship between concepts based on the keyword analysis. The evolution of research fields, knowledge structures, and research topics in which HBOCs located are revealed by scientometric analysis. The elucidation of type, acting mechanism, potential clinical practice, and adverse effects of HBOCs helps to clarify the prospects of this biological agent. Scientometrics analyzed 1034 publications in this research field, and these findings provide a promising roadmap for further study.

Field-Flow Fractionation in Molecular Biology and Biotechnology

Field-flow fractionation (FFF) is a family of single-phase separative techniques exploited to gently separate and characterize nano- and microsystems in suspension. These techniques cover an extremely wide dynamic range and are able to separate analytes in an interval between a few nm to 100 µm size-wise (over 15 orders of magnitude mass-wise). They are flexible in terms of mobile phase and can separate the analytes in native conditions, preserving their original structures/properties as much as possible. Molecular biology is the branch of biology that studies the molecular basis of biological activity, while biotechnology deals with the technological applications of biology. The areas where biotechnologies are required include industrial, agri-food, environmental, and pharmaceutical. Many species of biological interest belong to the operational range of FFF techniques, and their application to the analysis of such samples has steadily grown in the last 30 years. This work aims to summarize the main features, milestones, and results provided by the application of FFF in the field of molecular biology and biotechnology, with a focus on the years from 2000 to 2022. After a theoretical background overview of FFF and its methodologies, the results are reported based on the nature of the samples analyzed.

Research of storable and ready-to-use artificial red blood cells (hemoglobin vesicles) for emergency medicine and other clinical applications

Hemoglobin (Hb) is the most abundant protein in blood, with concentration of about 12-15 g/dl. The highly concentrated Hb solution (35 g/dl) is compartmentalized in red blood cells (RBCs). Once Hb is released from RBCs by hemolysis during blood circulation, it induces renal and cardiovascular toxicities. To date, hemoglobin-based oxygen carriers of various types have been developed as blood substitutes to mitigate the Hb toxicities. One method is Hb encapsulation in phospholipid vesicles (liposomes). Although the Hb toxicity can be shielded, it is equally important to ensure the biocompatibility of the liposomal membrane. We have developed Hb-vesicles (HbV). A new encapsulation method using a rotation-revolution mixer which enabled efficient production of HbV with a high yield has considerably facilitated R&D of HbV. Along with our academic consortium, we have studied the preclinical safety and efficacy of HbV extensively as a transfusion alternative, and finally conducted a phase I clinical trial. Moreover, carbonyl-HbV and met-HbV are developed respectively for an anti-inflammatory and anti-oxidative agent and an antidote for poisons. This review paper specifically presents past trials of liposome encapsulated Hb, biocompatible lipid bilayer membranes, and efficient HbV preparation methods, in addition to potential clinical applications of HbV based on results of our in vivo studies.

Effect of micro- and nanoparticle shape on biological processes

In the drug delivery field, there is beyond doubt that the shape of micro- and nanoparticles (M&NPs) critically affects their biological fate. Herein, following an introduction describing recent technological advances for designing nonspherical M&NPs, we highlight the role of particle shape in cell capture, subcellular distribution, intracellular drug delivery, and cytotoxicity. Then, we discuss theoretical approaches for understanding the effect of particle shape on internalization by the cell membrane. Subsequently, recent advances on shape-dependent behaviors of M&NPs in the systemic circulation are detailed. In particular, the interaction of M&NPs with blood proteins, biodistribution, and circulation under flow conditions are analyzed. Finally, the hurdles and future directions for developing nonspherical M&NPs are underscored.

Biomaterials for human space exploration: A review of their untapped potential

As biomaterial advances make headway into lightweight radiation protection, wound healing dressings, and microbe resistant surfaces, a relevance to human space exploration manifests itself. To address the needs of the human in space, a knowledge of the space environment becomes necessary. Both an understanding of the environment itself and an understanding of the physiological adaptations to that environment must inform design parameters. The space environment permits the fabrication of novel biomaterials that cannot be produced on Earth, but benefit Earth. Similarly, designing a biomaterial to address a space-based challenge may lead to novel biomaterials that will ultimately benefit Earth. This review describes several persistent challenges to human space exploration, a variety of biomaterials that might mitigate those challenges, and considers a special category of space biomaterial. STATEMENT OF SIGNIFICANCE: This work is a review of the major human and environmental challenges facing human spaceflight, and where biomaterials may mitigate some of those challenges. The work is significant because a broad range of biomaterials are applicable to the human space program, but the overlap is not widely known amongst biomaterials researchers who are unfamiliar with the challenges to human spaceflight. Additionaly, there are adaptations to microgravity that mimic the pathology of certain disease states ("terrestrial analogs") where treatments that help the overwhelmingly healthy astronauts can be applied to help those with the desease. Advances in space technology have furthered the technology in that field on Earth. By outlining ways that biomaterials can promote human space exploration, space-driven advances in biomaterials will further biomaterials technology.

Modelling of damage of a liquid-core microcapsule in simple shear flow until rupture

Capsules, composed of a liquid core protected by a thin deformable membrane, offer high-potential applications in many fields of industry such as bioengineering. One of their limitations comes from the absence of models of capsule damage and/or rupture when they are subjected to an external flow. To assess when rupture is initiated, we develop a fluid-structure interaction (FSI) numerical model of a capsule in Stokes flow that accounts for potential damage of the capsule membrane. We consider the framework of Continuum Damage Mechanics and model the membrane with an isotropic brittle damage model, in which the membrane damage state depends on the history of loading. The FSI problem is solved by coupling the finite element method, to solve for the membrane deformation, with the boundary integral method, to solve for the inner and outer fluid flows. The model is applied to an initially spherical capsule subjected to a simple shear flow. Damage initiates at a critical value of the capillary number, ratio of the fluid viscous forces to the membrane elastic forces, and rupture at a higher capillary number, when it reaches a threshold value. The material parameters introduced in the damage model do not influence the mode of damage but only the values of the critical and threshold capillary numbers. When the capillary number is larger than the critical value, damage develops in the two symmetric central regions containing the vorticity axis. It is indeed in these regions that the internal tensions are the highest on the membrane.

Improving kidney targeting: The influence of nanoparticle physicochemical properties on kidney interactions

Kidney-targeted nanoparticles have become of recent interest due to their potential to deliver drugs directly to diseased tissue, decrease off-target adverse effects, and increase overall tolerability to patients with chronic kidney disease that require lifelong drug exposure. Given the physicochemical properties of nanoparticles can drastically affect their ability to extravasate past cellular and biological barriers and access the kidneys, we surveyed the literature from the past decade and analyzed how nanoparticle size, charge, shape, and material density affects passage and interaction with the kidneys. Specifically, we found that nanoparticle size impacted the mechanism of nanoparticle entry into the kidneys such as glomerular filtration or tubular secretion. In addition, we found charge, aspect ratio, and material density influences nanoparticle renal retention and provide insights for designing nanoparticles for passive kidney targeting. Finally, we conclude by highlighting active targeting strategies that bolster kidney retention and discuss the clinical status of nanomedicine for kidney diseases.

An overview of liposomal nano-encapsulation techniques and its applications in food and nutraceutical

Encapsulation in packaging of food ingredients is of great interest at micro and nano levels. It is a distinct process leading to the entrapping of one substance within another material. Lipid oriented encapsulation methods are currently considered as a superior choice for encapsulation of sensitive ingredients, focusing on foods and dietary supplements of hydrophobic and hydrophilic molecules along with bioactive compounds, food ingredients supplementary systems for therapeutic purpose. Liposome and nanoliposome techniques have been widely used in food industry in nutrient enrichment and supplements. It enhances the sensory attributes and shelf life of the food product and serves as an alternative to micro encapsulation. These lipid and water oriented systems have distinguished advantages and provide higher surface area in food processing, which increases product solubility, bioavailability and permits accurate targeting of the encapsulated material to a greater extent in food and nutraceutical production. This review article focuses on nanoliposome, its preparation techniques, advantages and application of nanoliposome in food and nutraceutical process.

Hemoglobin-based Oxygen Carriers: Current State-of-the-art and Novel Molecules

In blood, the primary role of red blood cells (RBCs) is to transport oxygen via highly regulated mechanisms involving hemoglobin (Hb). Hb is a tetrameric porphyrin protein comprising of two α- and two β-polypeptide chains, each containing an iron-containing heme group capable of binding one oxygen molecule. In military as well as civilian traumatic exsanguinating hemorrhage, rapid loss of RBCs can lead to suboptimal tissue oxygenation and subsequent morbidity and mortality. In such cases, transfusion of whole blood or RBCs can significantly improve survival. However, blood products including RBCs present issues of limited availability and portability, need for type matching, pathogenic contamination risks, and short shelf-life, causing substantial logistical barriers to their prehospital use in austere battlefield and remote civilian conditions. While robust research is being directed to resolve these issues, parallel research efforts have emerged toward bioengineering of semisynthetic and synthetic surrogates of RBCs, using various cross-linked, polymeric, and encapsulated forms of Hb. These Hb-based oxygen carriers (HBOCs) can potentially provide therapeutic oxygenation when blood or RBCs are not available. Several of these HBOCs have undergone rigorous preclinical and clinical evaluation, but have not yet received clinical approval in the USA for human use. While these designs are being optimized for clinical translations, several new HBOC designs and molecules have been reported in recent years, with unique properties. The current article will provide a comprehensive review of such HBOC designs, including current state-of-the-art and novel molecules in development, along with a critical discussion of successes and challenges in this field.

Nanotechnology-based Drug Delivery, Metabolism and Toxicity

BACKGROUND

Nanoparticles (NPs) are being used extensively owing to their increased surface area, targeted delivery and enhanced retention. NPs have the potential to be used in many disease conditions. Despite widespread use, their toxicity and clinical safety still remain a major concern.

OBJECTIVE

The purpose of this study was to explore the metabolism and toxicological effects of nanotherapeutics.

METHODS

Comprehensive, time-bound literature search was done covering the period from 2010 till date. The primary focus was on the metabolism of NP including their adsorption, degradation, clearance, and bio-persistence. This review also focuses on updated investigations on NPs with respect to their toxic effects on various in vitro and in vivo experimental models.

RESULTS

Nanotechnology is a thriving field of biomedical research and an efficient drug delivery system. Further their applications are under investigation for diagnosis of disease and as medical devices.

CONCLUSION

The toxicity of NPs is a major concern in the application of NPs as therapeutics. Studies addressing metabolism, side-effects and safety of NPs are desirable to gain maximum benefits of nanotherapeutics.

From omics technologies to personalized transfusion medicine

INTRODUCTION

Blood transfusion is the single most frequent in-hospital medical procedure, a life-saving intervention for millions of recipients worldwide every year. Storage in the blood bank is an enabling strategy for this critical procedure, as it logistically solves the issue of making ~110 million units available for transfusion every year. Unfortunately, storage in the blood bank promotes a series of biochemical and morphological changes to the red blood cell that compromise the integrity and functionality of the erythrocyte in vitro and in animal models, and could negatively impact transfusion outcomes in the recipient. Areas covered: While commenting on the clinical relevance of the storage lesion is beyond the scope of this manuscript, here we will review recent advancements in our understanding of the storage lesion as gleaned through omics technologies. We will focus on how the omics-scale appreciation of the biological variability at the donor and recipient level is impacting our understanding of red blood cell storage biology. Expert commentary: Omics technologies are paving the way for personalized transfusion medicine, a discipline that promises to revolutionize a critical field in medical practice. The era of recipient-tailored additives, processing, and storage strategies may not be too far distant in the future.

How Synthetic Biology and Metabolic Engineering Can Boost the Generation of Artificial Blood Using Microbial Production Hosts

Hemoglobin is an essential protein to the human body as it transports oxygen to organs and tissues through the bloodstream (Looker et al., 1992). In recent years, there has been an increasing concern regarding the global supply of this vital protein, as blood availability cannot currently meet the high demands in many developing countries. There are, in addition, several risks associated with conventional blood transfusions such as the presence of blood-borne viruses like HIV and Hepatitis. These risks along with some limitations are presented in Figure 1 (Kim and Greenburg, 2013; Martínez et al., 2015). As an alternative, producing hemoglobin recombinantly will eliminate the obstacles, since hemoglobin-based oxygen carriers are pathogen-free, have a longer shelf-life, are universally compatible and the supply can be adjusted to meet the demands (Chakane, 2017). A stable, safe, and most importantly affordable production, will lead to high availability of blood to the world population, and hence reduce global inequality, which is a focus point of the World Health Organization for the millennium (WHO, 2018). Synthetic biology and metabolic engineering have created a unique opportunity to construct promising candidates for hemoglobin production (Liu et al., 2014; Martínez et al., 2016). This review sets out to describe the recent advances in recombinant hemoglobin production, the societal and the economic impact along with the challenges that researchers will face in the coming years, such as low productivity, degradation, and difficulties in scale-up. The challenges are diverse and complex but with the powerful tools provided by synthetic biology and metabolic engineering, they are no longer insurmountable. An efficient production of cell-free recombinant hemoglobin poses tremendous challenges while having even greater potential, therefore some possible future directions are suggested in this review.

The Chemistry of Lyophilized Blood Products

With the development of new biologics and bioconjugates, storage and preservation have become more critical than ever before. Lyophilization is a method of cell and protein preservation by removing a solvent such as water from a substance followed by freezing. This technique has been used in the past and still holds promise for overcoming logistic challenges in safety net hospitals with limited blood banking resources, austere environments such as combat, and mass casualty situations where existing resources may be outstripped. This method allows for long-term storage and transport but requires the bioconjugation of preservatives to prevent cell destabilization. Trehalose is utilized as a bioconjugate in platelet and red blood cell preservation to maintain protein thermodynamics and stabilizing protein formulations in liquid and freeze-dried states. Biomimetic approaches have been explored as alternatives to cryo- and lyopreservation of blood components. Intravascular hemostats such as PLGA nanoparticles functionalized with PEG motifs, topical hemostats utilizing fibrinogen or chitosan, and liposomal encapsulated hemoglobin with surface modifications are effectively stored long-term through bioconjugation. In thinking about the best methods for storage and transport, we are focusing this topical review on blood products that have the longest track record of preservation and looking at how these methods can be applied to synthetic systems.

Bio-inspired nanomedicine strategies for artificial blood components

Blood is a fluid connective tissue where living cells are suspended in noncellular liquid matrix. The cellular components of blood render gas exchange (RBCs), immune surveillance (WBCs) and hemostatic responses (platelets), and the noncellular components (salts, proteins, etc.) provide nutrition to various tissues in the body. Dysfunction and deficiencies in these blood components can lead to significant tissue morbidity and mortality. Consequently, transfusion of whole blood or its components is a clinical mainstay in the management of trauma, surgery, myelosuppression, and congenital blood disorders. However, donor-derived blood products suffer from issues of shortage in supply, need for type matching, high risks of pathogenic contamination, limited portability and shelf-life, and a variety of side-effects. While robust research is being directed to resolve these issues, a parallel clinical interest has developed toward bioengineering of synthetic blood substitutes that can provide blood's functions while circumventing the above problems. Nanotechnology has provided exciting approaches to achieve this, using materials engineering strategies to create synthetic and semi-synthetic RBC substitutes for enabling oxygen transport, platelet substitutes for enabling hemostasis, and WBC substitutes for enabling cell-specific immune response. Some of these approaches have further extended the application of blood cell-inspired synthetic and semi-synthetic constructs for targeted drug delivery and nanomedicine. The current study provides a comprehensive review of the various nanotechnology approaches to design synthetic blood cells, along with a critical discussion of successes and challenges of the current state-of-art in this field. WIREs Nanomed Nanobiotechnol 2017, 9:e1464. doi: 10.1002/wnan.1464 For further resources related to this article, please visit the WIREs website.

Polyanhydride micelles with diverse morphologies for shape-regulated cellular internalization and blood circulation

Biodegradable amphiphilic poly (ethylene glycol) (PEG) based ether-anhydride terpolymer, consisting of PEG, 1, 3-bis (p-carboxyphenoxy) propane (CPP) and sebacic acid (SA), namely PEG-CPP-SA terpolymer, was employed to self-assemble into micelles by adding water into a solution of the terpolymer in tetrahydrofuran (THF). The shape of polyanhydride micelles can be regulated by simply adjusting the water addition rate, where spherical, rod-like and comb-like micelles can obtained under water addition rate of 20, 3 and 1 ml/h, respectively. The effect of micellar morphologies on the cellular internalization and intracellular distribution were characterized qualitatively with cervical cancer cells (HeLa cells) and hepatoma cells (HepG2 cells) by fluorescence microscopy, confocal laser scanning microscopy (CLSM), flow cytometry (FCM) and transmission electron microscopy (TEM). The results reveal that the cellular uptake of micelles are micelle-shape-dependent (rod-like micelles may possess the highest cellular internalization rate) and cell-type-specific. Each endocytic pathway can make a contribution to this process in different degree. Moreover, blood circulation experiments of these micelles were carried out, demonstrating that comb-like micelles have a relatively longer blood circulating feature, which may due to its irregular shape help to increase the sensitivity to fluid forces and allows them to tumble and align with the blood flow.

A portable and reconfigurable multi-organ platform for drug development with onboard microfluidic flow control

The drug development pipeline is severely limited by a lack of reliable tools for prediction of human clinical safety and efficacy profiles for compounds at the pre-clinical stage. Here we present the design and implementation of a platform technology comprising multiple human cell-based tissue models in a portable and reconfigurable format that supports individual organ function and crosstalk for periods of up to several weeks. Organ perfusion and crosstalk are enabled by a precision flow control technology based on electromagnetic actuators embedded in an arrayed format on a microfluidic platform. We demonstrate two parallel circuits of connected airway and liver modules on a platform containing 62 electromagnetic microactuators, with precise and controlled flow rates as well as functional biological metrics over a two week time course. Technical advancements enabled by this platform include the use of non-sorptive construction materials, enhanced scalability, portability, flow control, and usability relative to conventional flow control modes (such as capillary action, pressure heads, or pneumatic air lines), and a reconfigurable and modular organ model format with common fluidic port architecture. We demonstrate stable biological function for multiple pairs of airway-liver models for periods of 2 weeks in the platform, with precise control over fluid levels, temperature, flow rate and oxygenation in order to support relevant use cases involving drug toxicity, efficacy testing, and organ-organ interaction.

Artificial Blood Substitutes: First Steps on the Long Route to Clinical Utility

The 21st century is challenging for human beings. Increased population growth, population aging, generation of new infectious agents, and natural disasters are some threatening factors for the current state of blood transfusion. However, it seems that science and technology not only could overcome these challenges but also would turn many human dreams to reality in this regard. Scientists believe that one of the future evolutionary innovations could be artificial blood substitutes that might pave the way to a new era in transfusion medicine. In this review, recent status and progresses in artificial blood substitutes, focusing on red blood cells substitutes, are summarized. In addition, steps taken toward the development of artificial blood technology and some of their promises and hurdles will be highlighted. However, it must be noted that artificial blood is still at the preliminary stages of development, and to fulfill this dream, ie, to routinely transfuse artificial blood into human vessels, we still have to strengthen our knowledge and be patient.

Design Advances in Particulate Systems for Biomedical Applications

The search for more efficient therapeutic strategies and diagnosis tools is a continuous challenge. Advances in understanding the biological mechanisms behind diseases and tissues regeneration have widened the field of applications of particulate systems. Particles are no more just protective systems for the encapsulated drugs, but they play an active role in the success of the therapy. Moreover, particles have been explored for innovative purposes as templates for cells growth and as diagnostic tools. Until few years ago the most relevant parameters in particles formulation were the chemistry and the size. Currently, it is known that other physical characteristics can remarkably affect the performance of particulate systems. Particles with non-conventional shapes exhibit advantages due to the increasing circulation time in blood stream, less clearance by the immune system and more efficient cell internalization and trafficking. Creation of compartments has been found useful to control drug release, to tune the transport of substances across biological barriers, to supply the target with more than one bioactive agent or even to act as theranostic systems. It is expected that such complex shaped and compartmentalized systems improve the therapeutic outcomes and also the patient's compliance, acting as advanced devices that serve for simultaneous diagnosis and treatment of the disease, combining agents of very different features, at the same time. In this review, we overview and analyse the most recent advances in particle shape and compartmentalization and applications of newly designed particulate systems in the biomedical field.

Progressive Saturation Improves the Encapsulation of Functional Proteins in Nanoscale Polymer Vesicles

PURPOSE

To develop a technique that maximizes the encapsulation of functional proteins within neutrally charged, fully PEGylated and nanoscale polymer vesicles (i.e., polymersomes).

METHODS

Three conventional vesicle formation methods were utilized for encapsulation of myoglobin (Mb) in polymersomes of varying size, PEG length, and membrane thickness. Mb concentrations were monitored by UV-Vis spectroscopy, inductively coupled plasma optical emission spectroscopy (ICP-OES) and by the bicinchoninic acid (BCA) assay. Suspensions were subject to protease treatment to differentiate the amounts of surface-associated vs. encapsulated Mb. Polymersome sizes and morphologies were monitored by dynamic light scattering (DLS) and by cryogenic transmission electron microscopy (cryo-TEM), respectively. Binding and release of oxygen were measured using a Hemeox analyzer.

RESULTS

Using the established "thin-film rehydration" and "direct hydration" methods, Mb was found to be largely surface-associated with negligible aqueous encapsulation within polymersome suspensions. Through iterative optimization, a novel "progressive saturation" technique was developed that greatly increased the final concentrations of Mb (from < 0.5 to > 2.0 mg/mL in solution), the final weight ratio of Mb-to-polymer that could be reproducibly obtained (from < 1 to > 4 w/w% Mb/polymer), as well as the overall efficiency of Mb encapsulation (from < 5 to > 90%). Stable vesicle morphologies were verified by cryo-TEM; the suspensions also displayed no signs of aggregate formation for > 2 weeks as assessed by DLS. "Progressive saturation" was further utilized for the encapsulation of a variety of other proteins, ranging in size from 17 to 450 kDa.

CONCLUSIONS

Compared to established vesicle formation methods, "progressive saturation" increases the quantities of functional proteins that may be encapsulated in nanoscale polymersomes.

A novel artificial red blood cell substitute: grafted starch-encapsulated hemoglobin

GSEHb induced no histological variations of the main organs including the hearts, kidneys, lungs and livers of the control and GSEHb treated rats in rat model with hemorrhagic shock.

Biodegradable dextran vesicles for effective haemoglobin encapsulation

Biocompatible and biodegradable dextran–PLA copolymer self-assembled into polymeric vesicles, which could encapsulate the hemoglobin. The encapsulated hemoglobin retained biological activity and could be potentially used as blood substitute.

PEG-stabilized bilayer nanodisks as carriers for doxorubicin delivery

Spherical nanoparticles as a classic delivery vehicle for anticancer drugs have been extensively investigated, but study on the shape of nanoparticles has received little attention until now. Here, a nonspherical poly(ethylene glycol) (PEG)-stabilized bilayer nanodisk consisting of 1,2-distearyl-sn-glycero-3-phosphocholine (DSPC) and PEG5000-glyceryl distearate (PEG5K-GCDS) was prepared for doxorubicin delivery, called DOX-Disks. The prepared disks were open bilayer structures, with a hydrophobic discoid center built by DSPC and a hydrophilic PEG edge. Mean particle diameter of the disk was 80.14 nm, and the disk height was about 6 nm with aspect ratio about 12. Encapsulation efficiency of DOX-Disks was as high as 96.1%, and DOX release from DOX-Disks was pH-dependent (25.6% of total DOX released at 24 h in pH 7.4). The pharmacokinetic performances showed that DOX-Disks demonstrated long circulation time in blood and larger AUC (11.7-fold of t1/2 and 31.7-fold of AUC) in rats compared with DOX solutions (DOX-Sol). Tissue distribution in H22 tumor bearing mice demonstrated higher tumor accumulation (9.7-fold) and lower heart toxicities (25.7-fold) at 48 h after iv administration, in comparison with DOX-Sol. In addition, DOX-Disks exhibited much effectiveness in inhibiting tumor cell growth, and the IC50 values were 2.03, 0.85, and 0.86 μg/mL for DOX-Sol and 0.23, 0.24, and 0.20 μg/mL for DOX-Disks after treatment for 48, 72, and 96 h against MCF-7/Adr cells, respectively. DOX-Disks were taken up into MCF-7/Adr cells via energy-dependent endocytosis processes, involved in clathrin-mediated, macropinocytosis-mediated, and non-clathrin- and non-caveolae-mediated endocytosis pathways. In summary, such PEG-stabilized bilayer nanodisks could be one of the promising carriers for antitumor drugs via extended blood circulation and improved tumor distribution.

Polyprodrug amphiphiles: hierarchical assemblies for shape-regulated cellular internalization, trafficking, and drug delivery

Solution self-assembly of block copolymers (BCPs) typically generates spheres, rods, and vesicles. The reproducible bottom-up fabrication of stable planar nanostructures remains elusive due to their tendency to bend into closed bilayers. This morphological vacancy renders the study of shape effects on BCP nanocarrier-cell interactions incomplete. Furthermore, the fabrication of single BCP assemblies with built-in drug delivery functions and geometry-optimized performance remains a major challenge. We demonstrate that PEG-b-PCPTM polyprodrug amphiphiles, where PEG is poly(ethylene glycol) and PCPTM is polymerized block of reduction-cleavable camptothecin (CPT) prodrug monomer, with >50 wt % CPT loading content can self-assemble into four types of uniform nanostructures including spheres, large compound vesicles, smooth disks, and unprecedented staggered lamellae with spiked periphery. Staggered lamellae outperform the other three nanostructure types, exhibiting extended blood circulation duration, the fastest cellular uptake, and unique internalization pathways. We also explore shape-modulated CPT release kinetics, nanostructure degradation, and in vitro cytotoxicities. The controlled hierarchical organization of polyprodrug amphiphiles and shape-tunable biological performance opens up new horizons for exploring next-generation BCP-based drug delivery systems with improved efficacy.

Factors controlling the pharmacokinetics, biodistribution and intratumoral penetration of nanoparticles

Nanoparticle drug delivery to the tumor is impacted by multiple factors: nanoparticles must evade clearance by renal filtration and the reticuloendothelial system, extravasate through the enlarged endothelial gaps in tumors, penetrate through dense stroma in the tumor microenvironment to reach the tumor cells, remain in the tumor tissue for a prolonged period of time, and finally release the active agent to induce pharmacological effect. The physicochemical properties of nanoparticles such as size, shape, surface charge, surface chemistry (PEGylation, ligand conjugation) and composition affect the pharmacokinetics, biodistribution, intratumoral penetration and tumor bioavailability. On the other hand, tumor biology (blood flow, perfusion, permeability, interstitial fluid pressure and stroma content) and patient characteristics (age, gender, tumor type, tumor location, body composition and prior treatments) also have impact on drug delivery by nanoparticles. It is now believed that both nanoparticles and the tumor microenvironment have to be optimized or adjusted for optimal delivery. This review provides a comprehensive summary of how these nanoparticle and biological factors impact nanoparticle delivery to tumors, with discussion on how the tumor microenvironment can be adjusted and how patients can be stratified by imaging methods to receive the maximal benefit of nanomedicine. Perspectives and future directions are also provided.

Modulation of oxidative stability of haemoglobin inside liposome-encapsulated haemoglobin

The major hurdle in the formulation of liposome-encapsulated haemoglobin (LEH) is the oxidation of haemoglobin (Hb) into methaemoglobin during storage and after administration. In order to reduce this oxidative degradation, we tested various reducing conditions in the presence of catalase. We found that at 37°C more than 50% of Hb oxidized to methaemoglobin within 24 h, whereas in presence of catalase, the oxidation was significantly reduced. The effect of catalase was further enhanced by a reduction mixture containing β-NAD, d-glucose, adenine, inosine, MgCl2, KCl, KH2PO4 and Na2HPO4; only 14% methaemoglobin was generated in the presence of catalase and reduction mixture. Contrary to the expectation, glutathione, deferoxamine and homocysteine enhanced Hb oxidation. The presence of CRM inside liposomes (250 nm) significantly decreased Hb oxidation. The results suggest that catalase and a well-defined mixture of co-factors may help control Hb oxidation for improvement in the functional life of LEH.

Polymer nanoreactors with dual functionality: simultaneous detoxification of peroxynitrite and oxygen transport

The design of multifunctional systems is in focus today as a key strategy for coping with complex challenges in various domains that include chemistry, medicine, environmental sciences, and technology. Herein, we introduce protein-containing polymer nanoreactors with dual functionality: peroxynitrite degradation and oxygen transport. Vesicles made of poly-(2-methyloxazoline)-poly(dimethylsiloxane)-poly(2-methyloxazoline) successfully encapsulated hemoglobin (Hb), which serves as a model protein because of its dual function in oxygen transport and peroxynitrite degradation. By inserting channel proteins, the polymer membranes of vesicles permitted passage of various compounds that served for the assessment of in situ Hb activity. The requisite conformational changes in the protein structure and the change in oxidation states that took place within the confined space of the vesicle cavity demonstrated that Hb preserved its dual functionality: peroxynitrite degradation and oxygen transport. The functionality of our nanoreactor, combined with its simple procedure of production and extensive stability over several months, supports it as a promising system for further medical applications.

Supramolecular core-shell nanosilica@liposome nanocapsules for drug delivery

The fabrication of core-shell structural nanosilica@liposome nanocapsules as a drug delivery vehicle is reported. SiO(2) nanoparticles are encapsulated within liposomes by a W/O/W emulsion approach to form supramolecular assemblies with a core of colloidal particles enveloped by a lipid bilayer shell. A nanosilica core provides charge compensation and architectural support for the lipid bilayer, which significantly improves their physical stability. A preliminary application of these core-shell nanocapsules for hemoglobin (Hb) delivery is described. Through the H-bonding interaction between the hydroxyl groups on nanosilicas and the amino nitrogens of Hb, Hb-SiO(2) nanocomplexes in which the saturated adsorption amount of Hb on SiO(2) is 0.47 g g(-1) are coated with lipids to generate core-shell Hb-SiO(2)@liposome nanocapsules with mean diameters of 60-500 nm and Hb encapsulation efficiency of 48.4-87.9%. Hb-SiO(2)@liposome supramolecular nanovehicles create a mode of delivery that stabilizes the encapsulated Hb and achieves long-lasting release, thereby improving the efficacy of the drug. Compared with liposome-encapsulated Hb and Hb-loaded SiO(2) particles, such core-shell nanovehicles show substantially enhanced release performance of Hb in vitro. This finding opens up a new window of liposome-based formulations as drug delivery nanovehicles for widespread pharmaceutical applications.

Novel approaches for drug delivery systems in nanomedicine: effects of particle design and shape

The identification of novel drug candidates for the treatment of diseases like cancer, infectious diseases, or allergies (especially asthma) assigns new tasks for pharmaceutical technology. With respect to drug delivery several problems occur such as low solubility and hence low bioavailability or restriction to inconvenient routes of administration. Nanotechnological approaches promise to circumvent some of these problems, therefore being well suited for future applications as nanomedicines. Furthermore, efficient and sufficient loading is a critical issue that is approached through mesoporous particles and/or through nonspherical particles both offering larger volumes and surfaces. Special interest is laid on the effect of shape of particulate materials on the body and related physiological mechanisms. The modified response of biological systems on different shapes opens a new dimension to adjust particle system interaction. Finally, the biological response to these systems will determine the fate with respect to their therapeutic value. Therefore, the interaction pattern between nonspherical particulate materials and biological systems as well as the production processes are highlighted.

Application of flow field-flow fractionation for the characterization of macromolecules of biological interest: a review

An overview is given of the recent literature on (bio) analytical applications of flow field-flow fractionation (FlFFF). FlFFF is a liquid-phase separation technique that can separate macromolecules and particles according to size. The technique is increasingly used on a routine basis in a variety of application fields. In food analysis, FlFFF is applied to determine the molecular size distribution of starches and modified celluloses, or to study protein aggregation during food processing. In industrial analysis, it is applied for the characterization of polysaccharides that are used as thickeners and dispersing agents. In pharmaceutical and biomedical laboratories, FlFFF is used to monitor the refolding of recombinant proteins, to detect aggregates of antibodies, or to determine the size distribution of drug carrier particles. In environmental studies, FlFFF is used to characterize natural colloids in water streams, and especially to study trace metal distributions over colloidal particles. In this review, first a short discussion of the state of the art in instrumentation is given. Developments in the coupling of FlFFF to various detection modes are then highlighted. Finally, application studies are discussed and ordered according to the type of (bio) macromolecules or bioparticles that are fractionated.

Large scale production of vesicles by hollow fiber extrusion: a novel method for generating polymersome encapsulated hemoglobin dispersions

Vesicles, which include both liposomes and polymersomes (polymer vesicles), are being developed as therapeutic drug carriers. In this study, we present a fully scalable low pressure extrusion methodology for preparing vesicles. Vesicles were generated by continuous extrusion through a 200 nm pore diameter hollow fiber (HF) membrane. The first half of this study describes a method for generating empty polymersomes composed of different molecular weight amphiphilic poly(butadiene-b-ethylene oxide) (PBD-b-PEO) diblock copolymers on a large scale (50-100 mL) using a HF membrane. Monodisperse empty polymersomes were formed with particle diameters slightly less than 200 nm, which were close to the rated 200 nm pore size of the HF membrane. The second half of this study describes the successful encapsulation of hemoglobin (Hb) inside the aqueous core of polymersomes using the HF extrusion methodology. We demonstrate that polymersome encapsulated hemoglobin (PEH) particles formed by this technique had similar oxygen affinity, cooperativity coefficient, and methemoglobin (metHb) level compared to PEH particles formed by the 1 mL volume small scale manual extrusion method. Most notably, Hb encapsulation inside the polymer vesicles formed by the HF extrusion method increased 2-fold compared to the manual extrusion method. This work is important, since it will enable facile scale-up of homogeneous vesicle dispersions that are typically required for preclinical and clinical studies as well as industrial use.

Purification of hemoglobin by tangential flow filtration with diafiltration

A recent study by Palmer, Sun, and Harris (Biotechnol. Prog., 25:189-199, 2009) demonstrated that tangential flow filtration (TFF) can be used to produce HPLC-grade bovine and human hemoglobin (Hb). In this current study, we assessed the quality of bovine Hb (bHb) purified by introducing a 10 L batch-mode diafiltration step to the previously mentioned TFF Hb purification process. The bHb was purified from bovine red blood cells (RBCs) by filtering clarified RBC lysate through 50 nm (stage I) and 500 kDa (stage II) hollow fiber (HF) membranes. The filtrate was then passed through a 100 kDa (stage III) HF membrane with or without an additional 10 L diafiltration step to potentially remove additional small molecular weight impurities. Protein assays, SDS-PAGE, and LC-MS of the purified bHb (stage III retentate) reveal that addition of a diafiltration step has no effect on bHb purity or yield; however, it does increase the methemoglobin level and oxygen affinity of purified bHb. Therefore, we conclude that no additional benefit is gained from diafiltration at stage III and a three stage TFF process is sufficient to produce HPLC-grade bHb.

Porosity and semipermeability of hemoglobin-loaded polymeric nanoparticles as potential blood substitutes

Porosity and semipermeability, allowing life-sustaining small molecules to penetrate, but hemoglobin (Hb) and other enzymes to cut off, predominantly affect the functionalities of the Hb-loaded polymeric nanoparticles (HbPNPs) as blood substitutes. In this article, HbPNPs formulated in the size range of 110-122 nm were prepared by a modified double-emulsion method with poly(lactic acid) (PLA)-based polymers. The influences of the main preparation conditions, including solvent composition, stirring speed, Hb concentration and polymer matrix, on the porosity were investigated in details. To evaluate the porosity of HbPNPs, a novel nondestructive testing method based on molecular weight cut-off (MWCO) was developed, and an effusion approach was applied to investigate the pore size in the particle shells with poly(ethylene glycol)s (PEGs) of different molecular weights (PEG200, PEG400, PEG600) as probes. Moreover, in vitro diffusion behaviors of ascorbic acid and reduced glutathione from HbPNPs fabricated with various polymer matrices were studied. The MWCO of HbPNPs by changing solvent composition, stirring speed, Hb concentration, and polymer composition varied from 200 to 600, especially the PEGylation of the polymer, which exhibited obvious influence on the MWCO of HbPNPs. Ascorbic acid with molecular weight 176.1 could diffuse into PEGylated nanoparticles with mPEG content of 5-30 wt % freely, while reduced glutathione with molecular weight 307.3 could not penetrate when mPEG content reached 30 wt %. These results suggest that the HbPNPs optimized with MWCO between 400 and 600 can facilitate the transport of all those life-sustaining small molecules.

Trapping Hemoglobin in Rigid Matrices: Fine Tuning of Oxygen Binding Properties by Modulation of Encapsulation Protocols

Encapsulation of hemoglobin in a biocompatible matrix is a potential strategy for obtaining blood substitutes. Such a system would retain most of the immunogenic and functional properties of the physiologically relevant oxygen carrier but would prevent protein extravasation and dimer/dimer dissociation. We applied this approach by entrapping hemoglobin in wet nanoporous silica gel, in the presence and absence of allosteric effectors. Silica gels, although not suitable for intravenous perfusion, are inert and optically transparent, thus allowing a full characterization of the functional and structural properties of encapsulated hemoglobin by spectroscopic techniques. Results indicate that hemoglobin molecules, entrapped using different protocols, exhibit an oxygen affinity that can be modulated between 12 and 140 torr. This tunability could be exploited to meet distinct clinical needs.

A noninvasive method for measuring the oxygen binding-releasing capacity of hemoglobin-loaded polymeric nanoparticles as oxygen carrier

Based on the strong penetration capacity of near infrared lights (NIRs) and different absorption of oxyhemoglobin and deoxyhemoglobin in NIRs region, a novel noninvasive method, with the aid of an airproof-equilibrium apparatus, was developed to determine the oxygen binding-releasing capacity, including oxygen dissociation curve (ODC) and P(50), of the hemoglobin-loaded polymeric nanoparticles (HbP) in this study. The measured ODC of the PLA-PEG HbP was very close to that of the native hemoglobin, and the corresponding P(50) (26.1 mmHg) was also near to the native precursor protein (27.3 mmHg), indicative of the validity of the method proposed. To further verify the method proposed, the oxygen binding-releasing capacity of the HbPs prepared by PCL, PCL-PEG, PLA were also investigated with human blood as control. These results indicated that the method developed here enabled accurate and noninvasive determination of the oxygen binding-releasing capacity of the biodegradable polymeric oxygen carriers.

Tangential flow filtration of hemoglobin

Bovine and human hemoglobin (bHb and hHb, respectively) was purified from bovine and human red blood cells via tangential flow filtration (TFF) in four successive stages. TFF is a fast and simple method to purify Hb from RBCs using filtration through hollow fiber (HF) membranes. Most of the Hb was retained in stage III (100 kDa HF membrane) and displayed methemoglobin levels less than 1%, yielding final concentrations of 318 and 300 mg/mL for bHb and hHb, respectively. Purified Hb exhibited much lower endotoxin levels than their respective RBCs. The purity of Hb was initially assessed via SDS-PAGE, and showed tiny impurity bands for the stage III retentate. The oxygen affinity (P(50)) and cooperativity coefficient (n) were regressed from the measured oxygen-RBC/Hb equilibrium curves of RBCs and purified Hb. These results suggest that TFF yielded oxygen affinities of bHb and hHb that are comparable to values in the literature. LC-MS was used to measure the molecular weight of the alpha (alpha) and beta (beta) globin chains of purified Hb. No impurity peaks were present in the HPLC chromatograms of purified Hb. The mass of the molecular ions corresponding to the alpha and beta globin chains agreed well with the calculated theoretical mass of the alpha- and beta- globin chains. Taken together, our results demonstrate that HPLC-grade Hb can be generated via TFF. In general, this method can be more broadly applied to purify Hb from any source of RBCs. This work is significant, since it outlines a simple method for generating Hb for synthesis and/or formulation of Hb-based oxygen carriers.