Polymeric Nanoparticles with Neglectable Protein Corona

Polymer Brushes on Nanoparticles for Controlling the Interaction with Protein-Rich Physiological Media

The interaction of nanoparticles (NPs) with biological environments triggers the formation of a protein corona (PC), which significantly influences their behavior in vivo. This review explores the evolving understanding of PC formation, focusing on the opportunity for decreasing or suppressing protein-NP interactions by macromolecular engineering of NP shells. The functionalization of NPs with a dense, hydrated polymer brush shell is a powerful strategy for imparting stealth properties in order to elude recognition by the immune system. While poly(ethylene glycol) (PEG) has been extensively used for this purpose, concerns regarding its stability and immunogenicity have prompted the exploration of alternative polymers. The stealth properties of brush shells can be enhanced by tailoring functionalities and structural parameters, including the molar mass, grafting density, and polymer topology. Determining correlations between these parameters and biopassivity has enabled us to obtain polymer-grafted NPs with high colloidal stability and prolonged circulation time in biological media.

Modular Synthesis of Semiconducting Graft Copolymers to Achieve "Clickable" Fluorescent Nanoparticles with Long Circulation and Specific Cancer Targeting

Semiconducting polymer nanoparticles (SPNs) are explored for applications in cancer theranostics because of their high absorption coefficients, photostability, and biocompatibility. However, SPNs are susceptible to aggregation and protein fouling in physiological conditions, which can be detrimental for in vivo applications. Here, a method for achieving colloidally stable and low-fouling SPNs is described by grafting poly(ethylene glycol) (PEG) onto the backbone of the fluorescent semiconducting polymer, poly(9,9'-dioctylfluorene-5-fluoro-2,1,3-benzothiadiazole), in a simple one-step substitution reaction, postpolymerization. Further, by utilizing azide-functionalized PEG, anti-human epidermal growth factor receptor 2 (HER2) antibodies, antibody fragments, or affibodies are site-specifically "clicked" onto the SPN surface, which allows the functionalized SPNs to specifically target HER2-positive cancer cells. In vivo, the PEGylated SPNs are found to have excellent circulation efficiencies in zebrafish embryos for up to seven days postinjection. SPNs functionalized with affibodies are then shown to be able to target HER2 expressing cancer cells in a zebrafish xenograft model. The covalent PEGylated SPN system described herein shows great potential for cancer theranostics.

Polysarcosine as PEG Alternative for Enhanced Camptothecin-Induced Cancer Immunogenic Cell Death

Nanomedicine-enhanced immunogenic cell death (ICD) has attracted considerable attention for its great potential in cancer treatment. Even though polyethylene glycol (PEG) is widely recognized as the gold standard for surface modification of nanomedicines, some shortcomings associated with this PEGylation, such as hindered cell endocytosis and accelerated blood clearance phenomenon, have been revealed in recent years. Notably, polysarcosine (PSar) as a highly biocompatible polymer can be finely synthesized by mild ring-opening polymerization (ROP) of sarcosine N-carboxyanhydrides (Sar-NCAs) and exhibit great potential as an alternative to PEG. In this article, PSar-b-polycamptothecin block copolymers are synthesized by sequential ROP of camptothecin-based NCAs (CPT-NCAs) and Sar-NCAs. Then, the detailed and systematic comparison between PEGylation and PSarylation against the 4T1 tumor model indicates that PSar decoration can facilitate the cell endocytosis, greatly enhancing the ICD effects and antitumor efficacy. Therefore, it is believed that this well-developed PSarylation technique will achieve effective and precise cancer treatment in the near future.

Advancing In Situ Analysis of Biomolecular Corona: Opportunities and Challenges in Utilizing Field-Flow Fractionation

The biomolecular corona, a complex layer of biological molecules, envelops nanoparticles (NPs) upon exposure to biological fluids including blood. This dynamic interface is pivotal for the advancement of nanomedicine, particularly in areas of therapy and diagnostics. In situ analysis of the biomolecular corona is crucial, as it can substantially improve our ability to accurately predict the biological fate of nanomedicine and, therefore, enable development of more effective, safe, and precisely targeted nanomedicines. Despite its importance, the repertoire of techniques available for in situ analysis of the biomolecular corona is surprisingly limited. This tutorial review provides an overview of the available techniques for in situ analysis of biomolecular corona with a particular focus on exploring both the advantages and the limitations inherent in the use of field-flow fractionation (FFF) for in situ analysis of the biomolecular corona. It delves into how FFF can unravel the complexities of the corona, enhancing our understanding and guiding the design of next-generation nanomedicines for medical use.

Unveiling the challenges of engineered protein corona from the proteins' perspective

It is well known that protein corona affects the "biological identity" of nanoparticles (NPs), which has been seen as both a challenge and an opportunity. Approaches have moved from avoiding protein adsorption to trying to direct it, taking advantage of the formation of a protein corona to favorably modify the pharmacokinetic parameters of NPs. Although promising, the results obtained with engineered NPs still need to be completely understood. While much effort has been put into understanding how the surface of nanomaterials affects protein absorption, less is known about how proteins can affect corona formation due to their specific physicochemical properties. This review addresses this knowledge gap, examining key protein factors influencing corona formation, highlighting current challenges in studying protein-protein interactions, and discussing future perspectives in the field.

Personalized Cancer Nanomedicine: Overcoming Biological Barriers for Intracellular Delivery of Biopharmaceuticals

The success of personalized medicine in oncology relies on using highly effective and precise therapeutic modalities such as small interfering RNA (siRNA) and monoclonal antibodies (mAbs). Unfortunately, the clinical exploitation of these biological drugs has encountered obstacles in overcoming intricate biological barriers. Drug delivery technologies represent a plausible strategy to overcome such barriers, ultimately facilitating the access to intracellular domains. Here, an overview of the current landscape on how nanotechnology has dealt with protein corona phenomena as a first and determinant biological barrier is presented. This continues with the analysis of strategies facilitating access to the tumor, along with conceivable methods for enhanced tumor penetration. As a final step, the cellular barriers that nanocarriers must confront in order for their biological cargo to reach their target are deeply analyzed. This review concludes with a critical analysis and future perspectives of the translational advances in personalized oncological nanomedicine.

Nano-Bio Interactions: Exploring the Biological Behavior and the Fate of Lipid-Based Gene Delivery Systems

Gene therapy for many diseases is rapidly becoming a reality, as demonstrated by the recent approval of various nucleic acid-based therapeutics. Non-viral systems such as lipid-based carriers, lipid nanoparticles (LNPs), for delivering different payloads including small interfering RNA, plasmid DNA, and messenger RNA have been particularly extensively explored and developed for clinical uses. One of the most important issues in LNP development is delivery to extrahepatic tissues. To achieve this, various lipids and lipid-like materials are being examined and screened. Several LNP formulations that target extrahepatic tissues, such as the spleen and the lungs have been developed by adjusting the lipid compositions of LNPs. However, mechanistic details of how the characteristics of LNPs affect delivery efficiency remains unclear. The purpose of this review is to provide an overview of LNP-based nucleic acid delivery focusing on LNP components and their structures, as well as discussing biological factors, such as biomolecular corona and cellular responses related to the delivery efficiency.

Nanomedicine Tumor Targeting

Nanomedicines are extensively explored for cancer therapy. By delivering drug molecules more efficiently to pathological sites and by attenuating their accumulation in healthy organs and tissues, nanomedicine formulations aim to improve the balance between drug efficacy and toxicity. More than 20 cancer nanomedicines are approved for clinical use, and hundreds of formulations are in (pre)clinical development. Over the years, several key pitfalls have been identified as bottlenecks in nanomedicine tumor targeting and translation. These go beyond materials- and production-related issues, and particularly also encompass biological barriers and pathophysiological heterogeneity. In this manuscript, the author describes the most important principles, progress, and products in nanomedicine tumor targeting, delineates key current problems and challenges, and discuss the most promising future prospects to create clinical impact.

Polyethylene glycol (PEG) as a broad applicability marker for LC-MS/MS-based biodistribution analysis of nanomedicines

Polyethylene glycol (PEG) conjugation (PEGylation) is a well-established strategy to improve the pharmacokinetic and biocompatibility properties of a wide variety of nanomedicines and therapeutic peptides and proteins. This broad use makes PEG an attractive 'allround' candidate marker for the biodistribution of such PEGylated compounds. This paper presents the development of a novel strategy for PEG quantification in biological matrices. The methodology is based on sample hydrolysis which both decomposes the sample matrix and degrades PEGylated analytes to specific molecular fragments more suitable for detection by LC-MS/MS. Method versatility was demonstrated by applying it to a wide variety of PEGylated compounds, including polymeric poly(ethylbutyl cyanoacrylate) (PEBCA) nanoparticles, lipidic nanoparticles (Doxil®, LipImage 815™ and lipid nanoparticles for nucleic acid delivery) and the antibody Cimzia®. Method applicability was assessed by analyzing plasma and tissue samples from a comprehensive drug biodistribution study in rats, of both PEBCA and LipImage 815™ nanoparticles. The results demonstrated the method's utility for biodistribution studies on PEG. Importantly, by using the method described herein in tandem with quantification of nanoparticle payloads, we showed that this approach can provide detailed understanding of various critical aspects of the in vivo behavior of PEGylated nanomedicines, such as drug release and particle stability. Together, the presented results demonstrate the novel method as a robust, versatile and generic approach for biodistribution analysis of PEGylated therapeutics.

Effect of ligand and shell densities on the surface structure of core-shell nanoparticles self-assembled from function-spacer-lipid constructs

Biomolecular corona is the major obstacle to the clinical translation of nanomedicines. Since corona formation is governed by molecular interactions at the nano-bio interface, nanoparticle surface properties such as topography, charge and surface chemistry can be tuned to manipulate biomolecular corona formation. To this end, as the first step towards a deep understanding of the processes of corona formation, it is necessary to develop nanoparticles employing various biocompatible materials and characterize their surface structure and dynamics at the molecular level. In this work, we applied molecular dynamics simulation to study the surface structure of organic core-shell nanoparticles formed by the self-assembly of synthetic molecules composed of a DOPE lipid, a carboxymethylglycine spacer and biotin. Lipid moieties form the hydrophobic core, spacer motifs serve as a hydrophilic shell and biotin residues function as a targeting ligand. By mixing such function-spacer-lipid, spacer-lipid and lipid-only constructs at various molar ratios, densities of the ligand and spacer on the nanoparticle surface were modified. For convenient analysis of the structure and dynamics of all regions of the nanoparticle surface, we compiled topography maps based on atomic coordinates. It was shown that an increase in the density of the shell does not reduce exposure of the core, but increases shell average thickness. Biotin, due to its alkyl valeric acid chain and spacer flexibility, is localized primarily near the hydrophobic core and its partial presentation on the surface occurs only in nanoparticles with higher ligand densities. However, an increase in biotin density leads to its clustering. In turn, ligand clustering diminishes the stealth properties of the shell and targeting efficiency. Based on nanoparticle surface structures, we determined the optimal density of biotin. Experimental studies reported in the literature confirm these conclusions. We also suggest design tips to achieve the preferred biotin presentation. Simulation results are consistent with the synchrotron SAXS profile. We believe that such studies will contribute to a better understanding of nano-bio interactions towards the rational design of efficient drug delivery systems.

Nanoparticular Carriers As Objects to Study Intentional and Unintentional Bioconjugation

Synthetic nanoparticles are interesting to use in the study of ligation with natural biorelevant structures. That is because they present an intermediate situation between reactions onto soluble polymers or onto solid surfaces. In addition, differently functionalized nanoparticles can be separated and studied independently thereafter. So what would be a "patchy functionalization" on a macroscopic surface results in differently functionalized nanoparticles, which can be separated after the interaction with body fluids. This paper will review bioconjugation of such nanoparticles with a special focus on recent results concerning the formation of a protein corona by unspecific adsorption (lower lines of TOC), which presents an unintentional bioconjugation, and on new aspects of intentionally performed bioconjugation by covalent chemistry (upper line). For this purpose, it is important that polymeric nanoparticles without a protein corona can be prepared. This opens, e.g., the possibility to look for special proteins adsorbed as a result of the natural compound ligated to the nanoparticle by covalent chemistry, like the Fc part of antibodies. At the same time, the use of highly reactive, bioorthogonal functional groups (inverse electron demand Diels-Alder cycloaddition) on the nanoparticles allows an efficient ligation after administration inside the body, i.e., in vivo.

Enhancing near-infrared fluorescence intensity and stability of PLGA-b-PEG micelles by introducing Gd-DOTA at the core boundary

Micelles have been extensively used in biomedicine as potential carriers of hydrophobic fluorescent dyes. Their small diameters can potentially enable them to evade recognition by the reticuloendothelial system, resulting in prolonged circulation. Nevertheless, their lack of stability in physiological environments limits the imaging utility of micelles. In particular, when a dye sensitive to water, such as IR-1061, is encapsulated in the micelle core, the destabilized structure leads to interactions between water and dye, degrading the fluorescence. In this study, we investigated a method to improve micelle stability utilizing the electrical effect of gadolinium (Gd3+ ) and tetraazacyclododecane tetraacetic acid (DOTA), introduced into the micelles. Three micellar structures, one containing a poly(lactic-co-glycolic acid)-block-poly(ethylene glycol) (PLGA-b-PEG) block copolymer, and two other structures, including PLGA-b-PEG with DOTA or Gd-DOTA introduced at the boundary of PLGA and PEG, were prepared with IR-1061 in the core. Structures that contained DOTA at the border of the PLGA core and PEG shell exhibited much higher fluorescence intensity than probes without DOTA. With Gd3+ ions at the DOTA center, fluorescence stability was enhanced remarkably in physiological environments. Most interesting is the finding that fluorescence is enhanced with increased Gd-DOTA concentrations. In conclusion, we found that overall fluorescence and stability are improved by introducing Gd-DOTA at the boundary of the PLGA core and PEG shell. Improving micelle stability is crucial for further biomedical applications of micellar probes such as bimodal fluorescence and magnetic resonance imaging.

Differential cellular responses to FDA-approved nanomedicines: an exploration of albumin-based nanocarriers and liposomes in protein corona formation

Albumin nanoparticles (NPs) and PEGylated liposomes have garnered tremendous interest as therapeutic drug carriers due to their unique physicochemical properties. These unique properties also have significant effects on the composition and structure of the protein corona formed around these NPs in a biological environment. Herein, protein corona formation on albumin NPs and liposomes was simultaneously evaluated through in vitro and simulation studies. The sizes of both types of NPs increased with more negatively charged interfaces upon being introduced into fetal bovine serum. Gel electrophoresis and label-free quantitative proteomics were performed to identify proteins recruited to the hard corona, and fewer proteins were found in albumin NPs than in liposomes, which is in accordance with isothermal titration calorimetry. The cellular uptake efficiency of the two NPs significantly differed in different serum concentrations, which was further scrutinized by loading an anticancer compound into albumin NPs. The presence of the hard protein corona increased the cellular uptake of albumin NPs in comparison with liposomes. In our simulation study, a specific receptor present in the membrane was greatly attracted to the albumin-apolipoprotein E complex. Overall, this study not only evaluated protein corona formation on albumin NPs, but also made promising advancements toward albumin- and liposome-based therapeutic systems.

Peptide-Conjugated Micelles Make Effective Mimics of the TRAIL Protein for Driving Apoptosis in Colon Cancer

Tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) drives apoptosis selectively in cancer cells by clustering death receptors (DR4 and DR5). While it has excellent in vitro selectivity and toxicity, the TRAIL protein has a very low circulation half-life in vivo, which has hampered clinical development. Here, we developed core-cross-linked micelles that present multiple copies of a TRAIL-mimicking peptide at its surface. These micelles successfully induce apoptosis in a colon cancer cell line (COLO205) via DR4/5 clustering. Micelles with a peptide density of 15% (roughly 1 peptide/45 nm2) displayed the strongest activity with an IC50 value of 0.8 μM (relative to peptide), demonstrating that the precise spatial arrangement of ligands imparted by a protein such as a TRAIL may not be necessary for DR4/5/signaling and that a statistical network of monomeric ligands may suffice. As micelles have long circulation half-lives, we propose that this could provide a potential alternative drug to TRAIL and stimulate the use of micelles in other membrane receptor clustering networks.

Orthogonal Covalent Entrapment of Cargo into Biodegradable Polymeric Micelles via Native Chemical Ligation

Polymeric micelles (PMs) are promising platforms for enhanced tissue targeting of entrapped therapeutic agents. Strategies to circumvent premature release of entrapped drugs include cross-linking of the micellar core as well as covalent attachment of the drug cargo. The chemistry employed to obtain cross-linked micelles needs to be mild to also allow entrapment of fragile molecules, such as certain peptides, proteins, oligonucleotides, and fluorescent dyes. Native chemical ligation (NCL) is a mild bio-orthogonal reaction between a N-terminal cysteine residue and a thioester that proceeds under physiological conditions. Here, we designed a trifunctional cross-linker containing two cysteine residues for the micelle core-cross-linking reaction and an azide residue for ring-strained alkyne conjugation of fluorescent dyes. We applied this approach to thermosensitive methoxypolyethylene glycol-b-N-(2-hydroxypropyl)methacrylamide-lactate (mPEG-b-HPMAmLacn) based block copolymers of a core-cross-linked polymeric micelle (CCPM) system by attaching thioester residues (using ethyl thioglycolate-succinic anhydride, ETSA) for NCL cross-linking with the trifunctional cross-linker under physiological conditions. By use of mild copper-free click chemistry, we coupled fluorescent dyes, Sulfo.Cy5 and BODIPY, to the core via the azide residue present on the cross-linker by triazole ring formation. In addition, we employed a recently developed cycloheptyne strain promoted click reagent (TMTHSI, CliCr) in comparison to the frequently employed cyclooctyne derivative (DBCO), both achieving successful dye entrapment. The size of the resulting CCPMs could be tuned between 50 and 100 nm by varying the molecular weight of the thermosensitive block and ETSA content. In vitro cell experiments showed successful internalization of the dye entrapped CCPMs, which did not affect cell viability up to a polymer concentration of 2 mg/mL in PC3 cells. These fluorescent dye entrapped CCPMs can be applied in diagnostic imaging and the chemistry developed in this study serves as a steppingstone toward covalently entrapped fragile drug compounds with tunable release in CCPMs.

Chain-extension in hyperbranched polymers alters tissue distribution and cytotoxicity profiles in orthotopic models of triple negative breast cancers

The therapeutic efficacy of nanomedicines is highly dependent on their access to target sites in the body, and this in turn is markedly affected by their size, shape and transport properties in tissue. Although there have been many studies in this area, the ability to design nanomaterials with optimal physicochemical properties for in vivo efficacy remains a significant challenge. In particular, it is often difficult to quantify the detailed effects of cancer drug delivery systems in vivo as tumour volume reduction, a commonly reported marker of efficacy, does not always correlate with cytotoxicity in tumour tissue. Here, we studied the behaviour in vivo of two specific poly(2-hydroxypropyl methacrylamide) (pHPMA) pro-drugs, with hyperbranched and chain-extended branched architectures, redox-responsive backbone components, and pH-sensitive linkers to the anti-cancer drug doxorubicin. Evaluation of the biodistribution of these polymers following systemic injection indicated differences in the circulation time and organ distribution of the two polymers, despite their very similar hydrodynamic radii (∼10 and 15 nm) and architectures. In addition, both polymers showed improved tumour accumulation in orthotopic triple-negative breast cancers in mice, and decreased accumulation in healthy tissue, as compared to free doxorubicin, even though neither polymer-doxorubicin pro-drug decreased overall tumour volume as much as the free drug under the dosing regimens selected. However, the results of histopathological examinations by haematoxylin and eosin, and TUNEL staining indicated a higher population of apoptotic cells in the tumours for both polymer pro-drug treatments, and in turn a lower population of apoptotic cells in the heart, liver and spleen, as compared to free doxorubicin treatment. These data suggest that the penetration of these polymer pro-drugs was enhanced in tumour tissue relative to free doxorubicin, and that the combination of size, architecture, bioresponsive backbone and drug linker degradation yielded greater efficacy for the polymers as measured by biomarkers than that of tumour volume. We suggest therefore that the effects of nanomedicines may be different at various length scales relative to small molecule free drugs, and that penetration into tumour tissue for some nanomedicines may not be as problematic as prior reports have suggested. Furthermore, the data indicate that dual-responsive crosslinked polymer-prodrugs in this study may be effective nanomedicines for breast cancer chemotherapy, and that endpoints beyond tumour volume reduction can be valuable in selecting candidates for pre-clinical trials.

Tuning the Cross-Linking Density and Cross-Linker in Core Cross-Linked Polymeric Micelles and Its Effects on the Particle Stability in Human Blood Plasma and Mice

Core cross-linked polymeric micelles (CCPMs) are designed to improve the therapeutic profile of hydrophobic drugs, reduce or completely avoid protein corona formation, and offer prolonged circulation times, a prerequisite for passive or active targeting. In this study, we tuned the CCPM stability by using bifunctional or trifunctional cross-linkers and varying the cross-linkable polymer block length. For CCPMs, amphiphilic thiol-reactive polypept(o)ides of polysarcosine-block-poly(S-ethylsulfonyl-l-cysteine) [pSar-b-pCys(SO2Et)] were employed. While the pCys(SO2Et) chain lengths varied from Xn = 17 to 30, bivalent (derivatives of dihydrolipoic acid) and trivalent (sarcosine/cysteine pentapeptide) cross-linkers have been applied. Asymmetrical flow field-flow fraction (AF4) displayed the absence of aggregates in human plasma, yet for non-cross-linked PM and CCPMs cross-linked with dihydrolipoic acid at [pCys(SO2Et)]17, increasing the cross-linking density or the pCys(SO2Et) chain lengths led to stable CCPMs. Interestingly, circulation time and biodistribution in mice of non-cross-linked and bivalently cross-linked CCPMs are comparable, while the trivalent peptide cross-linkers enhance the circulation half-life from 11 to 19 h.

Polymeric Nanoparticles and Nanogels: How Do They Interact with Proteins?

Polymeric nanomaterials, nanogels, and solid nanoparticles can be fabricated using single or double emulsion methods. These materials hold great promise for various biomedical applications due to their biocompatibility, biodegradability, and their ability to control interactions with body fluids and cells. Despite the increasing use of nanoparticles in biomedicine and the plethora of publications on the topic, the biological behavior and efficacy of polymeric nanoparticles (PNPs) have not been as extensively studied as those of other nanoparticles. The gap between the potential of PNPs and their applications can mainly be attributed to the incomplete understanding of their biological identity. Under physiological conditions, such as specific temperatures and adequate protein concentrations, PNPs become coated with a "protein corona" (PC), rendering them potent tools for proteomics studies. In this review, we initially investigate the synthesis routes and chemical composition of conventional PNPs to better comprehend how they interact with proteins. Subsequently, we comprehensively explore the effects of material and biological parameters on the interactions between nanoparticles and proteins, encompassing reactions such as hydrophobic bonding and electrostatic interactions. Moreover, we delve into recent advances in PNP-based models that can be applied to nanoproteomics, discussing the new opportunities they offer for the clinical translation of nanoparticles and early prediction of diseases. By addressing these essential aspects, we aim to shed light on the potential of polymeric nanoparticles for biomedical applications and foster further research in this critical area.

Transformative Materials for Interfacial Drug Delivery

Drug delivery systems (DDS) are designed to temporally and spatially control drug availability and activity. They assist in improving the balance between on-target therapeutic efficacy and off-target toxic side effects. DDS aid in overcoming biological barriers encountered by drug molecules upon applying them via various routes of administration. They are furthermore increasingly explored for modulating the interface between implanted (bio)medical materials and host tissue. Herein, an overview of the biological barriers and host-material interfaces encountered by DDS upon oral, intravenous, and local administration is provided, and material engineering advances at different time and space scales to exemplify how current and future DDS can contribute to improved disease treatment are highlighted.

Differences in Human Plasma Protein Interactions between Various Polymersomes and Stealth Liposomes as Observed by Fluorescence Correlation Spectroscopy

A significant factor hindering the clinical translation of polymersomes as vesicular nanocarriers is the limited availability of comparative studies detailing their interaction with blood plasma proteins compared to liposomes. Here, polymersomes are self-assembled via film rehydration, solvent exchange, and polymerization-induced self-assembly using five different block copolymers. The hydrophilic blocks are composed of anti-fouling polymers, poly(ethylene glycol) (PEG) or poly(2-methyl-2-oxazoline) (PMOXA), and all the data is benchmarked to PEGylated "stealth" liposomes. High colloidal stability in human plasma (HP) is confirmed for all but two tested nanovesicles. In situ fluorescence correlation spectroscopy measurements are then performed after incubating unlabeled nanovesicles with fluorescently labeled HP or the specific labeled plasma proteins, human serum albumin, and clusterin (apolipoprotein J). The binding of HP to PMOXA-polymersomes could explain their relatively short circulation times found previously. In contrast, PEGylated liposomes also interact with HP but accumulate high levels of clusterin, providing them with their known prolonged circulation time. The absence of significant protein binding for most PEG-polymersomes indicates mechanistic differences in protein interactions and associated downstream effects, such as cell uptake and circulation time, compared to PEGylated liposomes. These are key observations for bringing polymersomes closer to clinical translation and highlighting the importance of such comparative studies.

Identification of the Proteins Determining the Blood Circulation Time of Nanoparticles

The therapeutic efficacy and adverse impacts of nanoparticles (NPs) are strongly dependent on their systemic circulation time. The corona proteins adsorbed on the NPs determine their plasma half-lives, and hence, it is crucial to identify the proteins shortening or extending their circulation time. In this work, the in vivo circulation time and corona composition of superparamagnetic iron oxide nanoparticles (SPIONs) with different surface charges/chemistries were analyzed over time. SPIONs with neutral and positive charges showed the longest and shortest circulation times, respectively. The most striking observation was that corona-coated NPs with similar opsonin/dysopsonin content showed different circulation times, implying these biomolecules are not the only contributing factors. Long-circulating NPs adsorb higher concentrations of osteopontin, lipoprotein lipase, coagulation factor VII, matrix Gla protein, secreted phosphoprotein 24, alpha-2-HS-glycoprotein, and apolipoprotein C-I, while short-circulating NPs adsorb higher amounts of hemoglobin. Therefore, these proteins may be considered to be determining factors governing the NP systemic circulation time.

Complex Structures Made Simple - Continuous Flow Production of Core Cross-Linked Polymeric Micelles for Paclitaxel Pro-Drug-Delivery

Translating innovative nanomaterials to medical products requires efficient manufacturing techniques that enable large-scale high-throughput synthesis with high reproducibility. Drug carriers in medicine embrace a complex subset of tasks calling for multifunctionality. Here, the synthesisof pro-drug-loaded core cross-linked polymeric micelles (CCPMs) in a continuous flow processis reported, which combines the commonly separated steps of micelle formation, core cross-linking, functionalization, and purification into a single process. Redox-responsive CCPMs are formed from thiol-reactive polypept(o)ides of polysarcosine-block-poly(S-ethylsulfonyl-l-cysteine) and functional cross-linkers based on dihydrolipoic acid hydrazide for pH-dependent release of paclitaxel. The precisely controlled microfluidic process allows the production of spherical micelles (D_h  = 35 nm) with low polydispersity values (PDI < 0.1) while avoiding toxic organic solvents and additives with unfavorable safety profiles. Self-assembly and cross-linking via slit interdigital micromixers produces 350-700 mg of CCPMs/h per single system, while purification by online tangential flow filtration successfully removes impurities (unimer ≤ 0.5%). The formed paclitaxel-loaded CCPMs possess the desired pH-responsive release profile, display stable drug encapsulation, an improved toxicity profile compared to Abraxane (a trademark of Bristol-Myers Squibb), and therapeutic efficiency in the B16F1-xenotransplanted zebrafish model. The combination of reactive polymers, functional cross-linkers, and microfluidics enables the continuous-flow synthesis of therapeutically active CCPMs in a single process.

Mechanistic Understanding of Protein Corona Formation around Nanoparticles: Old Puzzles and New Insights

Although a wide variety of nanoparticles (NPs) have been engineered for use as disease markers or drug delivery agents, the number of nanomedicines in clinical use has hitherto remained small. A key obstacle in nanomedicine development is the lack of a deep mechanistic understanding of NP interactions in the bio-environment. Here, the focus is on the biomolecular adsorption layer (protein corona), which quickly enshrouds a pristine NP exposed to a biofluid and modifies the way the NP interacts with the bio-environment. After a brief introduction of NPs for nanomedicine, proteins, and their mutual interactions, research aimed at addressing fundamental properties of the protein corona, specifically its mono-/multilayer structure, reversibility and irreversibility, time dependence, as well as its role in NP agglomeration, is critically reviewed. It becomes quite evident that the knowledge of the protein corona is still fragmented, and conflicting results on fundamental issues call for further mechanistic studies. The article concludes with a discussion of future research directions that should be taken to advance the understanding of the protein corona around NPs. This knowledge will provide NP developers with the predictive power to account for these interactions in the design of efficacious nanomedicines.

Polymer-Based mRNA Delivery Strategies for Advanced Therapies

Messenger RNA (mRNA)-based therapies offer great promise for the treatment of a variety of diseases. In 2020, two FDA approvals of mRNA-based vaccines have elevated mRNA vaccines to global recognition. However, the therapeutic capabilities of mRNA extend far beyond vaccines against infectious diseases. They hold potential for cancer vaccines, protein replacement therapies, gene editing therapies, and immunotherapies. For realizing such advanced therapies, it is crucial to develop effective carrier systems. Recent advances in materials science have led to the development of promising nonviral mRNA delivery systems. In comparison to other carriers like lipid nanoparticles, polymer-based delivery systems often receive less attention, despite their unique ability to carefully tune their chemical features to promote mRNA protection, their favorable pharmacokinetics, and their potential for targeting delivery. In this review, the central features of polymer-based systems for mRNA delivery highlighting the molecular design criteria, stability, and biodistribution are discussed. Finally, the role of targeting ligands for the future of RNA therapies is analyzed.

Π-Π interactions stabilize PeptoMicelle-based formulations of Pretomanid derivatives leading to promising therapy against tuberculosis in zebrafish and mouse models

Tuberculosis is the deadliest bacterial disease globally, threatening the lives of millions every year. New antibiotic therapies that can shorten the duration of treatment, improve cure rates, and impede the development of drug resistance are desperately needed. Here, we used polymeric micelles to encapsulate four second-generation derivatives of the antitubercular drug pretomanid that had previously displayed much better in vivo activity against Mycobacterium tuberculosis than pretomanid itself. Because these compounds were relatively hydrophobic and had limited bioavailability, we expected that their micellar formulations would overcome these limitations, reduce toxicities, and improve therapeutic outcomes. The polymeric micelles were based on polypept(o)ides (PeptoMicelles) and were stabilized in their hydrophobic core by π-π interactions, allowing the efficient encapsulation of aromatic pretomanid derivatives. The stability of these π-π-stabilized PeptoMicelles was demonstrated in water, blood plasma, and lung surfactant by fluorescence cross-correlation spectroscopy and was further supported by prolonged circulation times of several days in the vasculature of zebrafish larvae. The most efficacious PeptoMicelle formulation tested in the zebrafish larvae infection model almost completely eradicated the bacteria at non-toxic doses. This lead formulation was further assessed against Mycobacterium tuberculosis in the susceptible C3HeB/FeJ mouse model, which develops human-like necrotic granulomas. Following intravenous administration, the drug-loaded PeptoMicelles significantly reduced bacterial burden and inflammatory responses in the lungs and spleens of infected mice.

Incubating Green Synthesized Iron Oxide Nanorods for Proteomics-Derived Motif Exploration: A Fusion to Deep Learning Oncogenesis

The nanotechnological arena has revolutionized the diagnostic efficacies by investigating the protein corona. This displays provoking proficiencies in determining biomarkers and diagnostic fingerprints for early detection and advanced therapeutics. The green synthesized iron oxide nanoparticles were prepared via Withania coagulans and were well characterized using UV-visible spectroscopy, X-ray diffraction analysis, Fourier transform infrared spectroscopy, and nano-LC mass spectrophotometry. Iron oxides were rod-shaped with an average size of 17.32 nm and have crystalline properties. The as-synthesized nanotool mediated firm nano biointeraction with the proteins in treatment with nine different cancers. The resultant of the proteome series was filtered oddly that highlighted the variant proteins within the differentially expressed proteins on behalf of nano-bioinformatics. Further magnification focused on S13_N, RS15, RAB, and 14_3_3 domains and few abundant motifs that aid scanning biomarkers. The entire set of variant proteins contracting to common proteins elucidates the underlining mechanical proteins that are marginally assessed using the robotic nanotechnology. Additionally, the iron rods indirectly possess a prognostic effect in manipulating expression of proteins through a smarter route. Thereby, such biologically designed nanotools provide a dual approach for medical studies.

Comment on "Optimal centrifugal isolating of liposome-protein complexes from human plasma" by L. Digiacomo, F. Giulimondi, A. L. Capriotti, S. Piovesana, C. M. Montone, R. Z. Chiozzi, A. Laganá, M. Mahmoudi, D. Pozzi and G. Caracciolo, Nanoscale Adv., 2021, , 3824

In a recent paper in Nanoscale Advances, Digiacomo et al. conclude that centrifugation should be the method of choice for researchers who want to investigate the protein corona of liposomes for drug delivery in human plasma. In this Comment, we however propose the opposite - that centrifugation, in most cases, is unsuitable for isolating liposomes from human plasma. Our conclusion is based on the bulk literature on this and similar topics, and new experimental data based on formulations and protocols like the ones used by Digiacomo et al.

How Nanoparticles Open the Paracellular Route of Biological Barriers: Mechanisms, Applications, and Prospects

Biological barriers are essential physiological protective systems and obstacles to drug delivery. Nanoparticles (NPs) can access the paracellular route of biological barriers, either causing adverse health impacts on humans or producing therapeutic opportunities. This Review introduces the structural and functional influences of NPs on the key components that govern the paracellular route, mainly tight junctions, adherens junctions, and cytoskeletons. Furthermore, we evaluate their interaction mechanisms and address the influencing factors that determine the ability of NPs to open the paracellular route, which provides a better knowledge of how NPs can open the paracellular route in a safer and more controllable way. Finally, we summarize limitations in the research models and methodologies of the existing research in the field and provide future research direction. This Review demonstrates the in-depth causes for the reversible opening or destruction of the integrity of barriers generated by NPs; more importantly, it contributes insights into the design of NP-based medications to boost paracellular drug delivery efficiency.

The effect of Gd-DOTA locations within PLGA-b-PEG micelle encapsulated IR-1061 on bimodal over-1000 nm near-infrared fluorescence and magnetic resonance imaging

Multimodal imaging is attractive in biomedical research because it can provide multidimensional information about objects that individual techniques cannot accomplish. In particular, combining over one-thousand-nanometer near-infrared (OTN-NIR) fluorescence and magnetic resonance (MR) imaging is promising for detecting lesions with high sensitivity and structural information. Herein, we describe the development of a bimodal OTN-NIR/MRI probe from gadolinium-tetraazacyclododecanetetraacetic acid (Gd-DOTA) conjugated poly(lactic-co-glycolic acid)-block-poly(ethylene glycol) copolymer (PLGA-b-PEG) micelle encapsulated IR-1061 at two different locations. One configuration contains Gd-DOTA at the end of the PEG of the hydrophilic shell and the other contains Gd-DOTA at the border of PLGA/PEG. The two structures show remarkable differences in fluorescence and R₁ relaxation rates in biological environments; the structure with Gd-DOTA at the border of PLGA/PEG exhibits stable fluorescence and T₁ signal distribution in live mice. The introduction ratio of Gd-DOTA to PEG is significant for controlling the properties of both structures; a higher Gd-DOTA ratio is preferable for the contrast enhancement effect. We found that Gd-DOTA ratios higher than 10% degraded the fluorescence intensity when Gd-DOTA was bound to the end of PEG. In contrast, the introduction of 70% Gd-DOTA at the border of PLGA/PEG did not exhibit a degraded signal, and the structural stability was enhanced with higher ratios of Gd-DOTA. In conclusion, we confirmed that the location of Gd-DOTA is a crucial factor in designing high-performance probes. The overall properties improve when Gd-DOTA is set on the border of PLGA/PEG. These improvements in the properties by controlling the probe structures are promising for future biomedical applications.

Profiling target engagement and cellular uptake of cRGD-decorated clinical-stage core-crosslinked polymeric micelles

Polymeric micelles are increasingly explored for tumor-targeted drug delivery. CriPec® technology enables the generation of core-crosslinked polymeric micelles (CCPMs) based on thermosensitive (mPEG-b-pHPMAmLac_n) block copolymers, with high drug loading capacity, tailorable size, and controlled drug release kinetics. In this study, we decorated clinical-stage CCPM with the α_vβ₃ integrin-targeted cyclic arginine-glycine-aspartic acid (cRGD) peptide, which is one of the most well-known active targeting ligands evaluated preclinically and clinically. Using a panel of cell lines with different expression levels of the α_vβ₃ integrin receptor and exploring both static and dynamic incubation conditions, we studied the benefit of decorating CCPM with different densities of cRGD. We show that incubation time and temperature, as well as the expression levels of α_vβ₃ integrin by target cells, positively influence cRGD-CCPM uptake, as demonstated by immunofluorescence staining and fluorescence microscopy. We demonstrate that even very low decoration densities (i.e., 1 mol % cRGD) result in increased engagement and uptake by target cells as compared to peptide-free control CCPM, and that high cRGD decoration densities do not result in a proportional increase in internalization. In this context, it should be kept in mind that a more extensive presence of targeting ligands on the surface of nanomedicines may affect their pharmacokinetic and biodistribution profile. Thus, we suggest a relatively low cRGD decoration density as most suitable for in vivo application.

Block Length-Dependent Protein Fouling on Poly(2-oxazoline)-Based Polymersomes: Influence on Macrophage Association and Circulation Behavior

Polymersomes are vesicular structures self-assembled from amphiphilic block copolymers and are considered an alternative to liposomes for applications in drug delivery, immunotherapy, biosensing, and as nanoreactors and artificial organelles. However, the limited availability of systematic stability, protein fouling (protein corona formation), and blood circulation studies hampers their clinical translation. Poly(2-oxazoline)s (POx) are valuable antifouling hydrophilic polymers that can replace the current gold-standard, poly(ethylene glycol) (PEG), yet investigations of POx functionality on nanoparticles are relatively sparse. Herein, a systematic study is reported of the structural, dynamic and antifouling properties of polymersomes made of poly(2-methyl-2-oxazoline)-block-poly(dimethylsiloxane)-block-poly(2-methyl-2-oxazoline) (PMOXA-b-PDMS-b-PMOXA). The study relates in vitro antifouling performance of the polymersomes to atomistic molecular dynamics simulations of polymersome membrane hydration behavior. These observations support the experimentally demonstrated benefit of maximizing the length of PMOXA (degree of polymerization (DP) > 6) while keeping PDMS at a minimal length that still provides sufficient membrane stability (DP > 19). In vitro macrophage association and in vivo blood circulation evaluation of polymersomes in zebrafish embryos corroborate these findings. They further suggest that single copolymer presentation on polymersomes is outperformed by blends of varied copolymer lengths. This study helps to rationalize design rules for stable and low-fouling polymersomes for future medical applications.

Versatile Protein Coronation Approach with Multiple Depleted Serum for Creating Biocompatible, Precision Nanomedicine

The protein corona effect has long been treated as the evil source behind delivery efficacy issues. In this study, this concept is challenged by showcasing that the protein corona can serve as a versatile functionalization approach to improve the delivery efficacy or mitigate nanocytotoxicity. To this end, the depleted serum is introduced to create nanomaterials carrying functionally distinct protein corona, referred to as PCylated nanomaterials. It is confirmed that the passivation with depleted serum helps reduce the toxicity and pro-inflammatory response. Furthermore, the same method can be leveraged to enhance the capacity of nanomaterials to undergo endocytosis as well as their potential as an agonist for the NF-κB pathways. The comparable stability of protein corona created by late and early-stage serum reveals that the chanceless interaction with nanomaterials, rather than an inadequate binding strength, may be behind the failure of enriching certain components. The PCylation strategy is extended to cancer patient-derived fluid, creating a set of T1 and T3-stage cancer-specific nanotherapeutics to retard the metastasis of cancer cells, while leaving normal endothelial negligibly affected. It is hoped the novel PCylation approach validated here can shed light on the future development of precision nanomedicine with improved delivery efficacy.

The effects of protein corona on in vivo fate of nanocarriers

With the emerging advances in utilizing nanocarriers for biomedical applications, a molecular-level understanding of the in vivo fate of nanocarriers is necessary. After administration into human fluids, nanocarriers can attract proteins onto their surfaces, forming an assembled adsorption layer called protein corona (PC). The formed PC can influence the physicochemical properties and subsequently determine nanocarriers' biological behaviors. Therefore, an in-depth understanding of the features and effects of the PC on the nanocarriers' surface is the first and most important step towards controlling their in vivo fate. This review introduces fundamental knowledge such as the definition, formation, composition, conformation, and characterization of the PC, emphasizing the in vivo environmental factors that control the PC formation. The effect of PC on the physicochemical properties and thus biological behaviors of nanocarriers was then presented and thoroughly discussed. Finally, we proposed the design strategies available for engineering PC onto nanocarriers to manipulate them with the desired surface properties and achieve the best biomedical outcomes.

Squaric Ester-Based Nanogels Induce No Distinct Protein Corona but Entrap Plasma Proteins into their Porous Hydrogel Network

After intravenous administration of nanocarriers, plasma proteins may rapidly adsorb onto their surfaces. This process hampers the prediction of the nanocarriers' pharmacokinetics as it determines their physiological identity in a complex biological environment. Toward clinical translation it is therefore an essential prerequisite to investigate the nanocarriers' interaction with plasma proteins. Here, this work evaluates a highly "PEGylated" squaric ester-based nanogel with inherent prolonged blood circulation properties. After incubation with human blood plasma, the nanogels are isolated by asymmetrical flow-field flow fractionation. Multiangle light scattering measurements confirm the absence of significant size increases as well as aggregation upon plasma incubation. However, proteomic analyses by gel electrophoresis find minor absolute amounts of proteins (3 wt%), whereas label-free liquid chromatography mass spectrometry identify 65 enriched proteins. Interestingly, the relative abundance of these proteins is almost similar to their proportion in pure native plasma. Due to the nanogels' hydrated and porous network morphology, it is concluded that the detected proteins rather result from passive diffusion into the nanogel network than from specific interactions at the plasma particle interface. Consequently, these results do not indicate a classical surface protein corona but rather reflect the highly outer and inner stealth-like behavior of the porous hydrogel network.

Artificial engineering of the protein corona at bio-nano interfaces for improved cancer-targeted nanotherapy

Nanoparticles (NPs) have been demonstrated in numerous applications as anticancer, antibacterial and antioxidant agents. Artificial engineering of protein interactions with NPs in biological systems is crucial to develop potential NPs for drug delivery and cancer nanotherapy. The protein corona (PC) on the NP surface, displays an interface between biomacromolecules and NPs, governing their pharmacokinetics and pharmacodynamics. Upon interaction of proteins with the NP surface, their surface features are modified and they can easily be removed from the circulation by the mononuclear phagocytic system (MPS). PC properties heavily depend on the biological microenvironment and NP surface physicochemical parameters. Based on this context, we have surveyed different approaches that have been used for artificial engineering of the PC composition on NP surfaces. We discuss the effects of NP size, shape, surface modifications (PEGylation, self-peptide, other polymers), and protein pre-coating on the PC properties. Additionally, other factors including protein source and structure, intravenous injection and the subsequent shear flow, plasma protein gradients, temperature and local heat transfer, and washing media are considered in the context of their effects on the PC properties and overall target cellular effects. Moreover, the effects of NP-PC complexes on cancer cells based on cellular interactions, organization of intracellular PC (IPC), targeted drug delivery (TDD) and regulation of burst drug release profile of nanoplatforms, enhanced biocompatibility, and clinical applications were discussed followed by challenges and future perspective of the field. In conclusion, this paper can provide useful information to manipulate PC properties on the NP surface, thus trying to provide a literature survey to shorten their shipping from preclinical to clinical trials and to lay the basis for a personalized PC.

Multiplexed Analysis of the Cellular Uptake of Polymeric Nanocarriers

Polymeric nanocarriers (PNCs) are versatile drug delivery vehicles capable of delivering a variety of therapeutics. Quantitatively monitoring their uptake in biological systems is essential for realizing their potential as next-generation delivery systems; however, existing quantification strategies are limited due to the challenges of detecting polymeric materials in complex biological samples. Here, we describe a metal-coded mass tagging approach that enables the multiplexed quantification of the PNC uptake in cells using mass spectrometry (MS). In this approach, PNCs are conjugated with ligands that bind strongly to lanthanide ions, allowing the PNCs to be sensitively quantitated by inductively coupled plasma-MS. The metal-coded tags have little effect on the properties or toxicity of the PNCs, making them biocompatible. We demonstrate that the conjugation of different metals to the PNCs enables the multiplexed analysis of cellular uptake of multiple distinct PNCs at the same time. This multiplexing capability should improve the design and optimization of PNCs by minimizing biological variability and reducing analysis time, effort, and cost.

Local detection of pH-induced disaggregation of biocompatible micelles by fluorescence switch ON

Fluorogenic nanoparticles (NPs) able to sense different physiological environments and respond with disaggregation and fluorescence switching OFF/ON are powerful tools in nanomedicine as they can combine diagnostics with therapeutic action. pH-responsive NPs are particularly interesting as they can differentiate cancer tissues from healthy ones, they can drive selective intracellular drug release and they can act as pH biosensors. Controlled polymerization techniques are the basis of such materials as they provide solid routes towards the synthesis of pH-responsive block copolymers that are able to assemble/disassemble following protonation/deprotonation. Ring opening metathesis polymerization (ROMP), in particular, has been recently exploited for the development of experimental nanomedicines owing to the efficient direct polymerization of both natural and synthetic functionalities. Here, we capitalize on these features and provide synthetic routes for the design of pH-responsive fluorogenic micelles via the assembly of ROMP block-copolymers. While detailed photophysical characterization validates the pH response, a proof of concept experiment in a model cancer cell line confirmed the activity of the biocompatible micelles in relevant biological environments, therefore pointing out the potential of this approach in the development of novel nano-theranostic agents.

PET-CT Imaging of Polymeric Nanoparticle Tumor Accumulation in Patients

Several FDA/EMA-approved nanomedicines have demonstrated improved pharmacokinetics and toxicity profiles compared to their conventional chemotherapeutic counterparts. The next step to increase therapeutic efficacy depends on tumor accumulation, which can be highly heterogeneous. A clinical tool for patient stratification is urgently awaited. Therefore, a docetaxel-entrapping polymeric nanoparticle (⁸⁹ Zr-CPC634) is radiolabeled, and positron emission tomography/computed tomography (PET/CT) imaging is performed in seven patients with solid tumors with two different doses of CPC634: an on-treatment (containing 60 mg m^-2 docetaxel) and a diagnostic (1-2 mg docetaxel) dose (NCT03712423). Pharmacokinetic half-life for ⁸⁹ Zr-CPC634 is mean 97.0 ± 14.4 h on-treatment, and 62.4 ± 12.9 h for the diagnostic dose (p = 0.003). At these doses accumulation is observed in 46% and 41% of tumor lesions with a median accumulation in positive lesions 96 h post-injection of 4.94 and 4.45%IA kg^-1 (p = 0.91), respectively. In conclusion, PET/CT imaging with a diagnostic dose of ⁸⁹ Zr-CPC634 accurately reflects on-treatment tumor accumulation and thus opens the possibility for patient stratification in cancer nanomedicine with polymeric nanoparticles.

Effect of dopamine-functionalization, charge and pH on protein corona formation around TiO2 nanoparticles

Inorganic nanoparticles (NPs) are gaining increasing attention in nanomedicine because of their stimuli responsiveness, which allows combining therapy with diagnosis. However, little information is known about their interaction with intracellular or plasma proteins when they are introduced in a biological environment. Here we present atomistic molecular dynamics (MD) simulations investigating the case study of dopamine-functionalized TiO₂ nanoparticles and two proteins that are overexpressed in cancer cells, i.e. PARP1 and HSP90, since experiments proved them to be the main components of the corona in cell cultures. The mechanism and the nature of the interaction (electrostatic, van der Waals, H-bonds, etc.) is unravelled by defining the protein residues that are more frequently in contact with the NPs, the extent of contact surface area and the variations in the protein secondary structures, at different pH and ionic strength conditions of the solution where they are immersed to simulate a realistic biological environment. The effects of the NP surface functionalization and charge are also considered. Our MD results suggest that less acidic intracellular pH conditions in the presence of cytosolic ionic strength enhance PARP1 interaction with the nanoparticle, whereas the HSP90 contribution is partly weakened, providing a rational explanation to existing experimental observations.

Influence of surface chemistry and morphology of nanoparticles on protein corona formation

Nanomaterials offer promising solutions as drug delivery systems and imaging agents in response to the demand for better therapeutics and diagnostics. However, the limited understanding of the interaction between nanoparticles and biological entities is currently hampering the development of new systems and their applications in clinical settings. Proteins and lipids in biological fluids are known to complex with nanoparticles to form a "biomolecular corona". This has been shown to affect particles' morphology and behavior in biological systems and their interactions with cells. Hence, understanding how nanomaterials' physicochemical properties affect the formation and composition of this biocorona is a crucial step. This work evaluates existing literature on how morphology (size and shape), and surface chemistry (charge and hydrophobicity) of nanoparticles influence the formation of protein corona. The latest evidence suggest that although surface charge promotes the interaction with proteins and lipids, surface chemistry plays a leading role in determining the affinity of the nanoparticle for biomolecules and, ultimately, the composition of the corona. More recently the study of additional nanoparticles' properties like shape and surface chirality have demonstrated a significant effect on protein corona architecture, providing new tools to tailor biomolecular corona formation. This article is categorized under: Therapeutic Approaches and Drug Discovery > Emerging Technologies Toxicology and Regulatory Issues in Nanomedicine > Toxicology of Nanomaterials.

Performance of nanoparticles for biomedical applications: The in vitro/in vivo discrepancy

Nanomedicine has a great potential to revolutionize the therapeutic landscape. However, up-to-date results obtained from in vitro experiments predict the in vivo performance of nanoparticles weakly or not at all. There is a need for in vitro experiments that better resemble the in vivo reality. As a result, animal experiments can be reduced, and potent in vivo candidates will not be missed. It is important to gain a deeper knowledge about nanoparticle characteristics in physiological environment. In this context, the protein corona plays a crucial role. Its formation process including driving forces, kinetics, and influencing factors has to be explored in more detail. There exist different methods for the investigation of the protein corona and its impact on physico-chemical and biological properties of nanoparticles, which are compiled and critically reflected in this review article. The obtained information about the protein corona can be exploited to optimize nanoparticles for in vivo application. Still the translation from in vitro to in vivo remains challenging. Functional in vitro screening under physiological conditions such as in full serum, in 3D multicellular spheroids/organoids, or under flow conditions is recommended. Innovative in vivo screening using barcoded nanoparticles can simultaneously test more than hundred samples regarding biodistribution and functional delivery within a single mouse.

Current hurdles to the translation of nanomedicines from bench to the clinic

The field of nanomedicine has significantly influenced research areas such as drug delivery, diagnostics, theranostics, and regenerative medicine; however, the further development of this field will face significant challenges at the regulatory level if related guidance remains unclear and unconsolidated. This review describes those features and pathways crucial to the clinical translation of nanomedicine and highlights considerations for early-stage product development. These include identifying those critical quality attributes of the drug product essential for activity and safety, appropriate analytical methods (physical, chemical, biological) for characterization, important process parameters, and adequate pre-clinical models. Additional concerns include the evaluation of batch-to-batch consistency and considerations regarding scaling up that will ensure a successful reproducible manufacturing process. Furthermore, we advise close collaboration with regulatory agencies from the early stages of development to assure an aligned position to accelerate the development of future nanomedicines.

Shining Light on Polymeric Drug Nanocarriers with Fluorescence Correlation Spectroscopy

The use of nanoparticles as carriers is an extremely promising way for administration of therapeutic agents, such as drug molecules, proteins and nucleic acids. Such nanocarriers (NCs) can increase the solubility of hydrophobic compounds, protect their cargo from the environment, and if properly functionalized, deliver it to specific target cells and tissues. Polymer-based NCs are especially promising, because they offer high degree of versatility and tunability. However, in order to get a full advantage of this therapeutic approach and develop efficient delivery systems, a careful characterization of the NCs is needed. This Feature Article highlights the fluorescence correlation spectroscopy (FCS) technique as a powerful and versatile tool for NCs characterization at all stages of the drug delivery process. In particular, FCS can monitor and quantify the size of the NCs and the drug loading efficiency after preparation, the NCs stability and possible interactions with, e.g., plasma proteins in the blood stream and the kinetic of drug release in the cytoplasm of the target cells. This article is protected by copyright. All rights reserved.

Revisiting the outstanding questions in cancer nanomedicine with a future outlook

The field of cancer nanomedicine has been fueled by the expectation of mitigating the inefficiencies and life-threatening side effects of conventional chemotherapy. Nanomedicine proposes to utilize the unique nanoscale properties of nanoparticles to address the most pressing questions in cancer treatment and diagnosis. The approval of nano-based products in the 1990s inspired scientific explorations in this direction. However, despite significant progress in the understanding of nanoscale properties, there are only very few success stories in terms of substantial increase in clinical efficacy and overall patient survival. All existing paradigms such as the concept of enhanced permeability and retention (EPR), the stealth effect and immunocompatibility of nanomedicine have been questioned in recent times. In this review we critically examine impediments posed by biological factors to the clinical success of nanomedicine. We put forth current observations on critical outstanding questions in nanomedicine. We also provide the promising side of cancer nanomedicine as we move forward in nanomedicine research. This would provide a future direction for research in nanomedicine and inspire ongoing investigations.

Opportunities and Challenges for Nanotherapeutics for the Aging Population

Nanotherapeutics utilize the properties of nanomaterials to alter the pharmacology of the drugs and therapies being transported, leading to changes in their biological disposition (absorption, distribution, cellular uptake, metabolism and elimination) and ultimately, their pharmacological effect. This provides an opportunity to optimize the pharmacology of drugs, particularly for those that are dependent on hepatic action. Old age is associated with changes in many pharmacokinetic processes which tend to impair drug efficacy and increase risk of toxicity. While these age-related changes are drug-specific they could be directly addressed using nanotechnology and precision targeting. The benefits of nanotherapeutics needs to be balanced against toxicity, with future use in humans dependent upon the gathering of information about the clearance and long-term safety of nanomaterials.

The influence of Gd-DOTA ratios conjugating PLGA-PEG micelles encapsulated IR-1061 in bimodal over–1000 nm near–infrared fluorescence and magnetic resonance imaging

Multimodal imaging can provide multidimensional information for understanding concealed microstructures or bioprocesses in biological objects. The combination of over–1000 nm near–infrared (OTN–NIR) fluorescence imaging and magnetic resonance (MR) imaging is...