Controlling the Biological Fate of Micellar Nanoparticles: Balancing Stealth and Targeting

Stealth Nanocarriers in Cancer Therapy: a Comprehensive Review of Design, Functionality, and Clinical Applications

Nanotechnology has significantly transformed cancer treatment by introducing innovative methods for delivering drugs effectively. This literature review provided an in-depth analysis of the role of nanocarriers in cancer therapy, with a particular focus on the critical concept of the 'stealth effect.' The stealth effect refers to the ability of nanocarriers to evade the immune system and overcome physiological barriers. The review investigated the design and composition of various nanocarriers, such as liposomes, micelles, and inorganic nanoparticles, highlighting the importance of surface modifications and functionalization. The complex interaction between the immune system, opsonization, phagocytosis, and the protein corona was examined to understand the stealth effect. The review carefully evaluated strategies to enhance the stealth effect, including surface coating with polymers, biomimetic camouflage, and targeting ligands. The in vivo behavior of stealth nanocarriers and their impact on pharmacokinetics, biodistribution, and toxicity were also systematically examined. Additionally, the review presented clinical applications, case studies of approved nanocarrier-based cancer therapies, and emerging formulations in clinical trials. Future directions and obstacles in the field, such as advancements in nanocarrier engineering, personalized nanomedicine, regulatory considerations, and ethical implications, were discussed in detail. The review concluded by summarizing key findings and emphasizing the transformative potential of stealth nanocarriers in revolutionizing cancer therapy. This review enhanced the comprehension of nanocarrier-based cancer therapies and their potential impact by providing insights into advanced studies, clinical applications, and regulatory considerations.

Pharmacokinetic Analyses of a Lipid Nanoparticle-Encapsulated mRNA-Encoded Antibody against Rift Valley Fever Virus

Rift Valley fever virus (RVFV) could cause an emergency illness characterized by fever, muscle pain, and even death in humans or ruminants. However, there are no approved antiviral drugs that prevent or treat RVFV infection. While therapeutic antibodies have shown promising potential for prevention or treatment in several studies, many studies are ongoing, especially in the field of infectious diseases. Among these studies, the mRNA-LNP platform shows great potential for application, following the COVID-19 pandemic. Previously, we have obtained a neutralizing antibody against RVFV, which was named A38 protein and verified to have a high binding and neutralization ability. In this study, we aimed to identify an effectively optimized sequence and expressed the prioritized mRNA-encoded antibody in vitro. Notably, we effectively expressed mRNA-encoded protein and used the mRNA-LNP platform to generate A38-mRNA-LNP. Pharmacokinetic experiments were conducted in vivo and set up in two groups of mRNA-A38 group and A38 protein group, which were derived from mRNA-LNP and plasmid DNA-expressed proteins, respectively. A38-mRNA-LNPs were administrated by intramuscular injection, A38 proteins were administrated by intravenous administration, and their unique ability to maintain long-lasting protein concentrations by mRNA-encoded protein was demonstrated with the mRNA-encoded protein providing a longer circulating half-life compared to injection of the free A38 protein. These preclinical data on the mRNA-encoded antibody highlighted its potential to prevent infectious diseases in the future.

Targeted delivery of polo-like kinase 1 siRNA nanoparticles using an EGFR-PEG bispecific antibody inhibits proliferation of high-risk neuroblastoma

High-risk neuroblastoma has poor survival due to treatment failure and off-target side effects of therapy. Small molecule inhibitors have shown therapeutic efficacy at targeting oncogenic cell cycle dysregulators, such as polo-like kinase 1 (PLK1). However, their clinical success is limited by a lack of efficacy and specificity, causing off-target toxicity. Herein, we investigate a new treatment strategy whereby a bispecific antibody (BsAb) with dual recognition of methoxy polyethylene glycol (PEG) and a neuroblastoma cell-surface receptor, epidermal growth factor receptor (EGFR), is combined with a PEGylated small interfering RNA (siRNA) lipid nanoparticle, forming BsAb-nanoparticle RNA-interference complexes for targeted PLK1 inhibition against high-risk neuroblastoma. Therapeutic efficacy of this strategy was explored in neuroblastoma cell lines and a tumor xenograft model. Using ionizable lipid-based nanoparticles as a low-toxicity and clinically safe approach for siRNA delivery, we identified that their complexing with EGFR-PEG BsAb resulted in increases in cell targeting (1.2 to >4.5-fold) and PLK1 gene silencing (>2-fold) against EGFR+ high-risk neuroblastoma cells, and enhancements correlated with EGFR expression on the cells (r > 0.94). Through formulating nanoparticles with PEG-lipids ranging in diffusivity, we further identified a highly diffusible PEG-lipid which provided the most pronounced neuroblastoma cell binding, PLK1 silencing, and significantly reduced cancer growth in vitro in high-risk neuroblastoma cell cultures and in vivo in a tumor-xenograft mouse model of the disease. Together, this work provides an insight on the role of PEG-lipid diffusivity and EGFR targeting as potentially relevant variables influencing the therapeutic efficacy of siRNA nanoparticles in high-risk neuroblastoma.

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.

Targeted Hyperbranched Nanoparticles for Delivery of Doxorubicin in Breast Cancer Brain Metastasis

Breast cancer brain metastases (BM) are associated with a dismal prognosis and very limited treatment options. Standard chemotherapy is challenging in BM patients because the high dosage required for an effective outcome causes unacceptable systemic toxicities, a consequence of poor brain penetration, and a short physiological half-life. Nanomedicines have the potential to circumvent off-target toxicities and factors limiting the efficacy of conventional chemotherapy. The HER3 receptor is commonly expressed in breast cancer BM. Here, we investigate the use of hyperbranched polymers (HBP) functionalized with a HER3 bispecific-antibody fragment for cancer cell-specific targeting and pH-responsive release of doxorubicin (DOX) to selectively deliver and treat BM. We demonstrated that DOX-release from the HBP carrier was controlled, gradual, and greater in endosomal acidic conditions (pH 5.5) relative to physiologic pH (pH 7.4). We showed that the HER3-targeted HBP with DOX payload was HER3-specific and induced cytotoxicity in BT474 breast cancer cells (IC50: 17.6 μg/mL). Therapeutic testing in a BM mouse model showed that HER3-targeted HBP with DOX payload impacted tumor proliferation, reduced tumor size, and prolonged overall survival. HER3-targeted HBP level detected in ex vivo brain samples was 14-fold more than untargeted-HBP. The HBP treatments were well tolerated, with less cardiac and oocyte toxicity compared to free DOX. Taken together, our HER3-targeted HBP nanomedicine has the potential to deliver chemotherapy to BM while reducing chemotherapy-associated toxicities.

Exploring the impact of severity in hepatic fibrosis disease on the intrahepatic distribution of novel biodegradable nanoparticles targeted towards different disease biomarkers

Nanoparticle-based drug delivery systems (DDS) have shown promising results in reversing hepatic fibrosis, a common pathological basis of chronic liver diseases (CLDs), in preclinical animal models. However, none of these nanoparticle formulations has transitioned to clinical usage and there are currently no FDA-approved drugs available for liver fibrosis. This highlights the need for a better understanding of the challenges faced by nanoparticles in this complex disease setting. Here, we have systematically studied the impact of targeting strategy, the degree of macrophage infiltration during fibrosis, and the severity of fibrosis, on the liver uptake and intrahepatic distribution of nanocarriers. When tested in mice with advanced liver fibrosis, we demonstrated that the targeting ligand density plays a significant role in determining the uptake and retention of the nanoparticles in the fibrotic liver whilst the type of targeting ligand modulates the trafficking of these nanoparticles into the cell population of interest - activated hepatic stellate cells (aHSCs). Engineering the targeting strategy indeed reduced the uptake of nanoparticles in typical mononuclear phagocyte (MPS) cell populations, but not the infiltrated macrophages. Meanwhile, additional functionalization may be required to enhance the efficacy of DDS in end-stage fibrosis/cirrhosis compared to early stages.

Tumor Abnormality-Oriented Nanomedicine Design

Anticancer nanomedicines have been proven effective in mitigating the side effects of chemotherapeutic drugs. However, challenges remain in augmenting their therapeutic efficacy. Nanomedicines responsive to the pathological abnormalities in the tumor microenvironment (TME) are expected to overcome the biological limitations of conventional nanomedicines, enhance the therapeutic efficacies, and further reduce the side effects. This Review aims to quantitate the various pathological abnormalities in the TME, which may serve as unique endogenous stimuli for the design of stimuli-responsive nanomedicines, and to provide a broad and objective perspective on the current understanding of stimuli-responsive nanomedicines for cancer treatment. We dissect the typical transport process and barriers of cancer drug delivery, highlight the key design principles of stimuli-responsive nanomedicines designed to tackle the series of barriers in the typical drug delivery process, and discuss the "all-into-one" and "one-for-all" strategies for integrating the needed properties for nanomedicines. Ultimately, we provide insight into the challenges and future perspectives toward the clinical translation of stimuli-responsive nanomedicines.

The interplay between PEGylated nanoparticles and blood immune system

During the last two decades, an increasing number of reports have pointed out that the immunogenicity of polyethylene glycol (PEG) may trigger accelerated blood clearance (ABC) and hypersensitivity reaction (HSR) to PEGylated nanoparticles, which could make PEG modification counterproductive. These phenomena would be detrimental to the efficacy of the load and even life-threatening to patients. Consequently, further elucidation of the interplay between PEGylated nanoparticles and the blood immune system will be beneficial to developing and applying related formulations. Many groups have worked to unveil the relevance of structural factors, dosing schedule, and other factors to the ABC phenomenon and hypersensitivity reaction. Interestingly, the results of some reports seem to be difficult to interpret or contradict with other reports. In this review, we summarize the physiological mechanisms of PEG-specific immune response. Moreover, we speculate on the potential relationship between the induction phase and the effectuation phase to explain the divergent results in published reports. In addition, the role of nanoparticle-associated factors is discussed based on the classification of the action phase. This review may help researchers to develop PEGylated nanoparticles to avoid unfavorable immune responses based on the underlying mechanism.

Controlled spatial characteristics of ligands on nanoparticles: Determinant of cellular functions

Interactions of various ligands and receptors have been extensively investigated because they regulate a series of signal transduction leading to various functional cellular outcomes. The receptors on cell membrane recognize their specific ligands, resulting in specific binding between ligands and receptors. Accumulating evidence reveals that the receptors recognize the difference on the spatial characteristics of ligands as well as the types of ligands. Thus, control on spatial characteristics of multiple ligands presented on therapeutic nanoparticles is believed to impact the cellular functions. Specifically, the localized and multivalent distribution of ligands on nanoparticles can induce receptor oligomerization and receptor clustering, controlling intensity or direction of signal transduction cascades. Here, we will introduce recent studies on the use of material-based nanotechnology to control spatial characteristics of ligands and their effect on cellular functions. These therapeutic nanoparticles with controlled spatial characteristics of ligands may be a promising strategy for maximized therapeutic outcome.

Novel Combination Therapy for Triple-Negative Breast Cancer based on an Intelligent Hollow Carbon Sphere

Triple-negative breast cancer (TNBC) is a subtype of breast cancer with high mortality, and the efficacy of monotherapy for TNBC is still disappointing. Here, we developed a novel combination therapy for TNBC based on a multifunctional nanohollow carbon sphere. This intelligent material contains a superadsorbed silicon dioxide sphere, sufficient loading space, a nanoscale hole on its surface, a robust shell, and an outer bilayer, and it could load both programmed cell death protein 1/programmed cell death ligand 1 (PD-1/PD-L1) small-molecule immune checkpoints and small-molecule photosensitizers with excellent loading contents, protect these small molecules during the systemic circulation, and achieve accumulation of them in tumor sites after systemic administration followed by the application of laser irradiation, thereby realizing dual attack of photodynamic therapy and immunotherapy on tumors. Importantly, we integrated the fasting-mimicking diet condition that can further enhance the cellular uptake efficiency of nanoparticles in tumor cells and amplify the immune responses, further enhancing the therapeutic effect. Thus, a novel combination therapy "PD-1/PD-L1 immune checkpoint blockade + photodynamic therapy + fasting-mimicking diet"was developed with the aid of our materials, which eventually achieved a marked therapeutic effect in 4T1-tumor-bearing mice. The concept can also be applied to the clinical treatment of human TNBC with guiding significance in the future.

Progress in nanoparticle-based regulation of immune cells

Immune cells are indispensable defenders of the human body, clearing exogenous pathogens and toxicities or endogenous malignant and aging cells. Immune cell dysfunction can cause an inability to recognize, react, and remove these hazards, resulting in cancers, inflammatory diseases, autoimmune diseases, and infections. Immune cells regulation has shown great promise in treating disease, and immune agonists are usually used to treat cancers and infections caused by immune suppression. In contrast, immunosuppressants are used to treat inflammatory and autoimmune diseases. However, the key to maintaining health is to restore balance to the immune system, as excessive activation or inhibition of immune cells is a common complication of immunotherapy. Nanoparticles are efficient drug delivery systems widely used to deliver small molecule inhibitors, nucleic acid, and proteins. Using nanoparticles for the targeted delivery of drugs to immune cells provides opportunities to regulate immune cell function. In this review, we summarize the current progress of nanoparticle-based strategies for regulating immune function and discuss the prospects of future nanoparticle design to improve immunotherapy.

Photothermal Attenuation of Cancer Cell Stemness, Chemoresistance, and Migration Using CD44-Targeted MoS2 Nanosheets

Cancer stem-like cells (CSCs) play key roles in chemoresistance, tumor metastasis, and clinical relapse. However, current CSC inhibitors lack specificity, efficacy, and applicability to different cancers. Herein, we introduce a nanomaterial-based approach to photothermally induce the differentiation of CSCs, termed "photothermal differentiation", leading to the attenuation of cancer cell stemness, chemoresistance, and metastasis. MoS2 nanosheets and a moderate photothermal treatment were applied to target a CSC surface receptor (i.e., CD44) and modulate its downstream signaling pathway. This treatment forces the more stem-like cancer cells to lose the mesenchymal phenotype and adopt an epithelial, less stem-like state, which shows attenuated self-renewal capacity, more response to anticancer drugs, and less invasiveness. This approach could be applicable to various cancers due to the broad availability of the CD44 biomarker. The concept of using photothermal nanomaterials to regulate specific cellular activities driving the differentiation of CSCs offers a new avenue for treating refractory cancers.

The Impact of Nanobody Density on the Targeting Efficiency of PEGylated Liposomes

Nanoparticles (NPs) are commonly modified with tumor-targeting moieties that recognize proteins overexpressed on the extracellular membrane to increase their specific interaction with target cells. Nanobodies (Nbs), the variable domain of heavy chain-only antibodies, are a robust targeting ligand due to their small size, superior stability, and strong binding affinity. For the clinical translation of targeted Nb-NPs, it is essential to understand how the number of Nbs per NP impacts the receptor recognition on cells. To study this, Nbs targeting the hepatocyte growth factor receptor (MET-Nbs) were conjugated to PEGylated liposomes at a density from 20 to 800 per liposome and their targeting efficiency was evaluated in vitro. MET-targeted liposomes (MET-TLs) associated more profoundly with MET-expressing cells than non-targeted liposomes (NTLs). MET-TLs with approximately 150-300 Nbs per liposome exhibited the highest association and specificity towards MET-expressing cells and retained their targeting capacity when pre-incubated with proteins from different sources. Furthermore, a MET-Nb density above 300 Nbs per liposome increased the interaction of MET-TLs with phagocytic cells by 2-fold in ex vivo human blood compared to NTLs. Overall, this study demonstrates that adjusting the MET-Nb density can increase the specificity of NPs towards their intended cellular target and reduce NP interaction with phagocytic cells.

Metabolic Signatures of Surface-Modified Poly(lactic-co-glycolic acid) Nanoparticles in Differentiated THP-1 Cells Derived with Liquid Chromatography-Mass Spectrometry-based Metabolomics

Polymeric nanoparticles (NPs) are widely used in preclinical drug delivery investigations, and some formulations are now in the clinic. However, the detailed effects of many NPs at the subcellular level have not been fully investigated. In this study, we used differentiated THP-1 macrophage cells, as a model, to investigate the metabolic changes associated with the use of poly (lactic-co-glycolic acid) (PLGA) NPs with different surface coating or conjugation chemistries. Liquid chromatography-mass spectrometry-based metabolic profiling was performed on the extracts (n = 6) of the differentiated THP-1 cells treated with plain, Pluronic (F-127, F-68, and P-85)-coated and PEG-PLGA NPs and control (no treatment). Principal component analysis and orthogonal partial least squares-discriminant analysis (OPLS-DA) in conjunction with univariate and pathway analyses were performed to identify significantly changed metabolites and pathways related to exposure of the cells to NPs. OPLS-DA of each class in the study compared to the control showed clear separation and clustering with cross-validation values of R ² and Q ² > 0.5. A total of 105 metabolites and lipids were found to be significantly altered in the differentiated THP-1 cell profiles due to the NP exposure, whereas more than 20 metabolic pathways were found to be affected. These pathways included glycerophospholipid, sphingolipid, linoleic acid, arginine and proline, and alpha-linolenic acid metabolisms. PLGA NPs were found to perturb some amino acid metabolic pathways and altered membrane lipids to a different degree. The metabolic effect of the PLGA NPs on the cells were comparable to those caused by silver oxide NPs and other inorganic nanomaterials. However, PEG-PLGA NPs demonstrated a reduced impact on the cellular metabolism compared to Pluronic copolymer-coated PLGA and plain PLGA NPs.

Pre-targeting of polymeric nanomaterials to balance tumour accumulation and clearance

Pre-targeting of bispecific antibodies is probed to enhance tumour retention while limiting clearance of administered multifunctional branched PEGylated nanomedicines. The temporal influence of pre-targeting on polymer interaction with tumour cells and tissue is explored using in vitro assays through to preclinical validation.

Controlling the Biological Behaviors of Polymer-Coated Upconverting Nanoparticles by Adjusting the Linker Length of Estrone Ligands

The estrone ligand is used for modifying nanoparticle surfaces to improve their targeting effect on cancer cell lines. However, to date, there is no common agreement on the ideal linker length to be used for the optimum targeting performance. In this study, we aimed to investigate the impact of poly(poly ethylene glycol methyl ether methacrylate) (PPEGMEMA) linker length on the cellular uptake behavior of polymer-coated upconverting nanoparticles (UCNPs). Different triblock terpolymers, poly(poly (ethylene glycol) methyl ether methacrylate)-block-polymethacrylic acid-block-polyethylene glycol methacrylate phosphate (PPEGMEMA_x-b-PMAA_y-b-PEGMP₃: x = 7, 15, 33, and 80; y = 16, 20, 18, and 18), were synthesized with different polymer linker chain lengths between the surface and the targeting ligand by reversible addition-fragmentation chain transfer polymerization. The estrone ligand was attached to the polymer via specific terminal conjugation. The cellular association of polymer-coated UCNPs with linker chain lengths was evaluated in MCF-7 cells by flow cytometry. Our results showed that the bioactivity of ligand modification is dependent on the length of the polymer linker. The shortest polymer PPEGMEMA₇-b-PMAA₁₆-b-PEGMP₃ with estrone at the end of the polymer chain was found to have the best cellular association behavior in the estrogen receptor (ER)α-positive expression cell line MCF-7. Additionally, the anticancer drug doxorubicin•HCl was encapsulated in the nanocarrier to evaluate the 2D and 3D cytotoxicity. The results showed that estrone modification could efficiently improve the cellular uptake in ERα-positive expression cell lines and in 3D spheroid models.

Nanoparticle based medicines: approaches for evading and manipulating the mononuclear phagocyte system and potential for clinical translation

For decades, nanomedicines have been reported as a potential means to overcome the limitations of conventional drug delivery systems by reducing side effects, toxicity and the non-ideal pharmacokinetic behaviour typically exhibited by small molecule drugs. However, upon administration many nanoparticles prompt induction of host inflammatory responses due to recognition and uptake by macrophages, eliminating up to 95% of the administered dose. While significant advances in nanoparticle engineering and consequent therapeutic efficacy have been made, it is becoming clear that nanoparticle recognition by the mononuclear phagocyte system (MPS) poses an impassable junction in the current framework of nanoparticle development. Hence, this has negative consequences on the clinical translation of nanotechnology with respect to therapeutic efficacy, systemic toxicity and economic benefit. In order to improve the translation of nanomedicines from bench-to-bedside, there is a requirement to either modify nanomedicines in terms of how they interact with intrinsic processes in the body, or modulate the body to be more accommodating for nanomedicine treatments. Here we provide an overview of the current standard for design elements of nanoparticles, as well as factors to consider when producing nanomedicines that have minimal MPS-nanoparticle interactions; we explore this landscape across the cellular to tissue and organ levels. Further, rather than designing materials to suit the body, a growing research niche involves modulating biological responses to administered nanomaterials. We here discuss how developing strategic methods of MPS 'pre-conditioning' with small molecule or biological drugs, as well as implementing strategic dosing regimens, such as 'decoy' nanoparticles, is essential to increasing nanoparticle therapeutic efficacy. By adopting such a perspective, we hope to highlight the increasing trends in research dedicated to improving nanomedicine translation, and subsequently making a positive clinical impact.

Alginate-enabled green synthesis of S/Ag1.93S nanoparticles, their photothermal property and in-vitro assessment of their anti-skin-cancer effects augmented by a NIR laser

We report herein the design and synthesis of colloidally-stable S/Ag_1.93S nanoparticles, their photothermal conversion properties and in vitro cytotoxicity toward A431 skin cancer cells under the excitation of a minimally-invasive 980 nm near-infrared (NIR) laser. Micron-sized S particles were first synthesized via acidifying Na₂S₂O₃ using biocompatible sodium alginate as a surfactant. In the presence of AgNO₃ and under rapid microwave-induced heating, alginate reduced AgNO₃ to nascent Ag which reacted with molten S in situ to S/Ag_1.93S nanoparticles. The nanoparticles were characterized using a combination of X-ray diffraction, electron microscopies, elemental analysis, zeta-potential analysis and UV-VIS-NIR spectroscopy. The average particles size was controlled between 40 and 60 nm by fixing the mole ratio of Ag⁺:S₂O₃^2-. When excited by a 980 nm laser, S/Ag_1.93S nanoparticles (~40 nm) produced with the least amount of AgNO₃ exhibited a respectable photothermal conversion efficiency of circa 62% with the test aqueous solution heated to a hyperthermia-inducing 52 °C in 15 min. At 0.7 W/cm², the viability of A431 skin cancer cells incubated with 7.0 ± 0.2 μg/mL of S/Ag_1.93S nanoparticles reduced to 14 ± 0.6%, while an A431 cell control maintained an 80% cell viability. These results suggested that S/Ag_1.93S nanoparticles may have good potential in reducing metastatic skin carcinoma.

Nanoparticle/Nanocarrier Formulation as an Antigen: The Immunogenicity and Antigenicity of Itself

In antibody preparation, the immunogenicity of small molecules is limited due to the instability of adjuvant/hapten emulsions. Nanoparticle-based adjuvants overcome instability and effectively improve immune responses. Immunogenicity and antigenicity are fundamentally important, yet understudied, facets of nanoparticle formulations themselves. Herein, we studied the immunogenicity and antigenicity of nanoparticle formulations. In experiments in a rabbit model, simple inorganic nanoparticle (e.g., gold nanoparticle (AuNP) and silver nanoparticle (AgNP)) immunogens induced higher titers of antiserum. Moreover, several promising nanoparticle drug carrier immunogens (e.g., SiO₂, oleylamine graft polysuccinimide (PSI_OAm), oleylamine and N-(3-aminopropyl)imidazole cograft polysuccinimide (PSI_OAm-NAPI), Fe₃O₄@O-dextran, etc.) showed excellent immunogenicity. Cross-reactivity calculations revealed that the antigenicity properties of AgNP and AuNP antigens are highly size-dependent. Meanwhile, four nanoparticle drug carriers generate antibody-specific immune responses to their antigens. The reactivity of the anti-NP antibodies with nanoparticle antigens was confirmed using immunoassays. This study systematically identified the immunogenicity and antigenicity of the nanoparticle formulation itself. These findings provide insights into the immunological properties of the nanoparticle formulation itself in an organism.

Development of targeted micelles and polymersomes prepared from degradable RAFT-based diblock copolymers and their potential role as nanocarriers for chemotherapeutics

Modern polymerisation techniques allow synthesis of functional block copolymers that can self-assemble into degradable nanoparticles (NPs) of different sizes and conformations.

Density of Conjugated Antibody Determines the Extent of Fc Receptor Dependent Capture of Nanoparticles by Liver Sinusoidal Endothelial Cells

Despite considerable progress in the design of multifunctionalized nanoparticles (NPs) that selectively target specific cell types, their systemic application often results in unwanted liver accumulation. The exact mechanisms for this general observation are still unclear. Here we asked whether the number of cell-targeting antibodies per NP determines the extent of NP liver accumulation and also addressed the mechanisms by which antibody-coated NPs are retained in the liver. We used polysarcosine-based peptobrushes (PBs), which in an unmodified form remain in the circulation for >24 h due to the absence of a protein corona formation and low unspecific cell binding, and conjugated them with specific average numbers (2, 6, and 12) of antibodies specific for the dendritic cell (DC) surface receptor, DEC205. We assessed the time-dependent biodistribution of PB-antibody conjugates by in vivo imaging and flow cytometry. We observed that PB-antibody conjugates were trapped in the liver and that the extent of liver accumulation strongly increased with the number of attached antibodies. PB-antibody conjugates were selectively captured in the liver via Fc receptors (FcR) on liver sinusoidal endothelial cells, since systemic administration of FcR-blocking agents or the use of F(ab')₂ fragments prevented liver accumulation. Cumulatively, our study demonstrates that liver endothelial cells play a yet scarcely acknowledged role in liver entrapment of antibody-coated NPs and that low antibody numbers on NPs and the use of F(ab')₂ antibody fragments are both sufficient for cell type-specific targeting of secondary lymphoid organs and necessary to minimize unwanted liver accumulation.

Non-Viral Vector-Mediated Gene Therapy for ALS: Challenges and Future Perspectives

Amyotrophic lateral sclerosis (ALS) is a devastating neurodegenerative disease, for which no effective treatment is yet available to either slow or terminate it. Recent advances in gene therapy renew hope for developing an effective approach to control this disease. Non-viral vectors, such as lipid- and polymer-based nanoparticles, cationic polymers, and exosomes, can effectively transfer genes into primary neurons. The resulting gene expression can be long-term, stable, and without immunological complications, which is essential for the effective management of neurological disorders. This Review will first describe the current research and clinical stage of novel therapies for ALS. It will then touch on the journey of non-viral vector use in ALS, subsequently highlighting the application of non-viral vector-mediated gene therapy. The bottlenecks in the translation of non-viral vectors for ALS treatment are also discussed, including the biological barriers of systemic administration and the issues of "when, where, and how much?" for effective gene delivery. The prospect of employing emerging techniques, such as CRISPR-Cas9 gene editing, stem cell methodology, and low-intensity focused ultrasound for fueling the transport of non-viral vectors to the central nervous system for personalized gene therapy, is briefly discussed in the context of ALS. Despite the challenging road that lies ahead, with the current expansion in interest and technological advancement in non-viral vector-delivered gene therapy for ALS, we hold hope that the field is headed toward a positive future.

Interactions of core cross-linked poly(2-oxazoline) and poly(2-oxazine) micelles with immune cells in human blood

Water-soluble poly(cyclic imino ether)s (PCIEs) have emerged as promising biocompatible polymers for nanomedicine applications in recent years. Despite their generally accepted stealth properties, there has been no comprehensive evaluation of their interactions with primary immune cells in human blood. Here we present a library of core cross-linked micelles (CCMs) containing various PCIE shells. Well-defined high molar mass CCMs (M_n > 175 kDa, Р< 1.2) of similar diameter (~20 nm) were synthesised using a cationic ring-opening polymerisation (CROP) - surfactant-free reversible addition-fragmentation chain-transfer (RAFT) emulsion polymerisation strategy. The stealth properties of the different PCIE CCMs were assessed employing a whole human blood assay simulating the complex blood environment. Cell association studies revealed lower associations of poly(2-methyl-2-oxazoline) (PMeOx) and poly(2-ethyl-2-oxazoline) (PEtOx) CCMs with blood immune cells compared to the respective poly(2-oxazine) (POz) CCMs. Noteworthy, PMeOx CCMs outperformed all other reported CCMs, showing overall low associations and only negligible differences in the presence and absence of serum proteins. This study highlights the importance of investigating individual nanomaterials under physiologically relevant conditions and further strengthens the position of PMeOx as a highly promising stealth material for biomedical applications.

In Vivo T Cell-Targeting Nanoparticle Drug Delivery Systems: Considerations for Rational Design

T cells play an important role in immunity and repair and are implicated in diseases, including blood cancers, viral infections, and inflammation, making them attractive targets for the treatment and prevention of diseases. Over recent years, the advent of nanomedicine has shown an increase in studies that use nanoparticles as carriers to deliver therapeutic cargo to T cells for ex vivo and in vivo applications. Nanoparticle-based delivery has several advantages, including the ability to load and protect a variety of drugs, control drug release, improve drug pharmacokinetics and biodistribution, and site- or cell-specific targeting. However, the delivery of nanoparticles to T cells remains a major technological challenge, which is primarily due to the nonphagocytic nature of T cells. In this review, we discuss the physiological barriers to effective T cell targeting and describe the different approaches used to deliver cargo-loaded nanoparticles to T cells for the treatment of disease such as T cell lymphoma and human immunodeficiency virus (HIV). In particular, engineering strategies that aim to improve nanoparticle internalization by T cells, including ligand-based targeting, will be highlighted. These nanoparticle engineering approaches are expected to inspire the development of effective nanomaterials that can target or manipulate the function of T cells for the treatment of T cell-related diseases.