Ferritin nanoparticle-based SpyTag/SpyCatcher-enabled click vaccine for tumor immunotherapy

Au@Fe₃O₄@PEG nanocubes as photoactive agents in photothermal therapy: An in vitro study

Photothermal therapy (PTT) is an emerging cancer treatment that utilizes near-infrared (NIR) light and photoactive agents to induce localized hyperthermia, leading to cancer cell destruction. Magnetic nanoparticles (MNPs) with plasmonic properties, such as Fe₃O₄@Au hybrids, hold great potential for PTT due to their combined magnetic and optical functionalities. This study investigates the potential of Fe₃O₄@Au@PEG-OH and Fe₃O₄@Au@PEG-NH₂ core-shell nanoparticles as photoactive agents for PTT applications. The nanoparticles were synthesized and characterized for their physicochemical properties, including zeta potential and absorption spectra. Their ability to convert electromagnetic radiation into thermal energy was assessed, and their cytotoxicity was evaluated in normal and cancer cell lines (A549, MRC-5, A375, HaCaT). The effectiveness of PTT was tested at a nanoparticle concentration of 75 μg/mL under NIR laser irradiation. The results demonstrated strong NIR absorption and efficient photothermal conversion, with cytotoxicity tests confirming low toxicity in most cases. PTT treatment significantly reduced cancer cell viability, with up to a 7 % decrease in cell viability, and the highest effect was observed for the A375 cell line. These findings confirm that Fe₃O₄@Au@PEG-OH and Fe₃O₄@Au@PEG-NH₂ nanoparticles are promising photoactive agents for PTT, combining plasmonic and magnetic properties with biocompatibility.

Enhanced Targeted Drug Delivery System to Control Avidity and Drug Encapsulation Using E2 Nanocages and SpyTag/SpyCatcher

Although antibody-drug conjugates offer advanced targeted anticancer therapy that overcomes the limitations of conventional chemotherapy and therapeutic antibodies, they are restricted in their capacity to carry multiple hydrophobic payloads. Protein nanocages have emerged as versatile therapeutic platforms for targeted drug delivery, offering advantages like precise molecular assembly, biocompatibility, and multivalent targeting. This study presents the development of engineered E2 nanocages functionalized with anti-HER2 single-chain variable fragments (scFv) using the SpyTag/SpyCatcher ligation system to achieve controlled scFv display valency. The results demonstrate that increasing anti-HER2 scFv valency enhances HER2 binding affinity via avidity effects, with the highest valency nanocages showing the highest binding avidity. Furthermore, cysteine residues were introduced into the E2 nanocages to enable conjugation with monomethyl auristatin E (MMAE) through maleimide chemistry, achieving efficient drug loading. The resulting MMAE-conjugated nanocages displayed potent, subnanomolar cytotoxicity in HER2-positive SKBR3 and BT-474 cell lines while sparing HER2-negative MDA-MB-231 cells at concentrations up to 1 nM. These results underscore the critical role of scFv valency in enhancing HER2 targeting and highlight the potential of E2 protein nanocages as specific, potent platforms for targeted cancer therapy. In this study, we developed an enhanced targeted drug delivery system using E2 nanocages and scFv with SpyCatcher/SpyTag ligation to regulate binding avidity and encapsulate hydrophobic drugs. The modular design and pH-sensitive dissociation of these nanocages establish a foundation for next-generation precision medicine strategies.

A combined adjuvant and ferritin nanocage based mucosal vaccine against Streptococcus pneumoniae induces protective immune responses in a murine model

Protein nanocages are multimeric structures that can be engineered to mimic the molecular conformation of microorganisms. Based on previous findings showing that a mucosal FlaB-tPspA fusion (flagellin fused with truncated PspA antigen of Streptococcus pneumoniae) vaccine-induced protective immune response against S. pneumoniae, we develop a ferritin nanocage vaccine displaying multivalent presentation of both antigen and adjuvant on a nanocarrier using the SpyTag/SpyCatcher strategy. The 1:1 antigen/adjuvant nanocage is further used as a mucosal vaccine, which can translocate to draining lymph nodes with higher efficiency than fusion vaccine. Moreover, intranasal immunization with the nanocage vaccine significantly enhances mucosal immune responses with more efficient B-cell memory generation and antibody maturation, as well as more balanced (Th1/Th2) immune responses with increased IFN-γ and IL-17 production, comparing with fusion vaccine. Mice immunized with the nanocage vaccine exhibited enhanced protection against lethal infection compare to the FlaB-tPspA fusion group. Our study thus demonstrates the effectiveness of an all-in-one nanocage mucosal vaccine platform, which guarantees enhanced protection with balanced immune responses.

Integrated Analysis of Bulk and Single-Cell RNA Sequencing Data Reveal a Novel Prognostic Signature of Combining Cuproptosis- and Ferroptosis-Related Genes in Hepatocellular Carcinoma

As a common malignancy, hepatocellular carcinoma (HCC) proliferation and metastasis could be promoted by ferroptosis and cuproptosis. In this study, we screened out the differentially expressed cuproptosis- and ferroptosis-related genes (CFRGs) and identified the 17 informative prognosis-associated genes. A CFRG scoring model was constructed based on the subtypes identified by consensus clustering analysis and principal component analysis (PCA). Furthermore, the immune profile, expression of immune checkpoint genes (ICGs) and drug susceptibility were also compared between the two CFRG score groups. The results showed that patients with a high CFRG score had higher survival probabilities. The correlation analysis suggested that CFRG scores were negatively correlated with activated CD4.T.cell. The expression patterns of thirty ICGs and the half-maximal inhibitory concentration (IC50) values of 128 drugs displayed significant differences between the two CFRG score groups. A statistically significant difference in the efficacy of sorafenib was found between the two CFRG score groups. Moreover, based on multivariate COX regression analysis and weighted gene co-expression network analysis (WGCNA), we screened DLAT and SLC2A1 as signature genes. Molecular docking analysis revealed that DLAT and SLC2A1 had a strong binding affinity toward camptothecin, rapamycin, dactolisib, and luminespib. The correlation between the CFRG score and single-cell characteristics was further explored. The study depended on our understanding of the biological function of CFRGs in HCC and provided new insights for developing treatment strategies.

Design and application of ferritin-based nanomedicine for targeted cancer therapy

Owing to its unique structure and favorable biocompatibility, ferritin has been widely studied as a promising drug carrier over the past two decades. Since the identification of its inherent tumor-targeting property due to unique recognition ablity of the transferrin receptor 1 (TfR1), ferritin-based nanomedicine has attracted widespread attention and triggered a research surge in the field of targeted cancer therapy. Along with progress in structure studies and modification technology, diverse strategies have been carried out to equip ferritin with on-demand functions, further improving the antitumor efficacy and in vivo safety of ferritin-based cancer therapy. In this review, we highlight the structure-based rational design of ferritin and summarize the design strategies in detail from two main perspectives: multifunctional modification and drug loading. In particular, the critical issues that need attention in the design are discussed in depth. Furthermore, we provide an overview of the latest advances in the application of ferritin-based nanomedicines in chemotherapy, phototherapy and immunotherapy, with particular emphasis on emerging therapeutic approaches among these therapies.

A self-assembled nanoparticle vaccine elicits effective neutralizing antibody response against EBV infection

Background

Epstein-Barr virus (EBV) is a significant global public health concern because of its association with various malignancies and autoimmune diseases. Over 90% of the global population is chronically infected with EBV, impacting numerous cancer-related cases annually. However, none of the effective prophylactic vaccines against EBV is approved at present.

Methods

In this study, we developed a novel vaccine candidate based on epitope peptides from the receptor-binding domain of EBV-encoded gp350 glycoprotein to prevent EBV infection. These epitope peptides detected a binding capability with host cells were then fused by flexibility linkers and expressed in Escherichia coli to reduce the unnecessary glycan modifications to simulate their free-glycan status. The fused recombinant protein (L350) was displayed on the surface of ferritin-based nanoparticle. The immunogenicity of the L350-ferritin nanoparticle was evaluated in Balb/c mice, and the neutralizing titers of sera from immunized mice were detected by means of an infection blocking assay in an in vitro cell model.

Results

All the five epitope peptides could bind to AKATA cells, and their fused recombinant protein (L350) was successfully presented on the surface of self-assembled ferritin nanoparticles. Sera from the L350-ferritin nanoparticle-immunized mice showed high titers of both L350 protein-specific and gp350D123 protein-specific antibodies, and sera from gp350D123 protein-immunized mice could also recognize L350 protein well. Most importantly, the L350-ferritin nanoparticle induced efficient neutralizing antibodies to block EBV-GFP infection in AKATA cells and also constructed a strong antigen-specific B-cell memory in immunized mice. Moreover, histopathological changes of main tissues from all vaccinated mice were not observed.

Conclusion

These data indicate that the L350-ferritin nanoparticle vaccine candidate has considerable potential application in preventing EBV infection and provides a promising basis for developing prophylactic EBV vaccines.

Delivery of dendritic cells targeting 3M2e-HA2 nanoparticles with a CpG adjuvant via lysosomal escape of Salmonella enhances protection against H9N2 avian influenza virus

Avian influenza virus (AIV) subtype H9N2 still poses a great threat to the poultry farming industry and public health worldwide, and the development of a new influenza vaccine that is safe and conservative and able to address influenza virus mutations is highly promising for application. HA2, the neck of the HA protein, and M2e, the extracellular N-terminal structural domain of the M2 protein, are conserved and effective protective antigens. In this study, the HA2 sequences were fused with three M2e copies (H9N2, H1N1 and H5N1) to the norovirus VP1 protein via the SpyTag-SpyCatcher platform to form self-assembled nanoparticles and display antigenic proteins on its surface, yielding pYL262. The chicken dendritic cells (DCs) targeting the nanobody phage-54 were then fused to HA2-3M2e to yield pYL327. Finally, a synthesized 20-repeat CpG adjuvant gene fragment was inserted into pYL327, resulting in the plasmid pYL331. All the constructed plasmids were then transformed into the sifA gene-deficient Salmonella vector χYL56 for oral immunization. The results showed that sifA-deficient Salmonella could efficiently increase antigen-specific mucosal sIgA antibody titers, especially in alveolar lavage samples, whereas the presence of the phage-54 nanobody could dramatically increase intracellular IFN-γ mRNA levels, indicating its ability to enhance the Th1-type immune response. Finally, the presence of the CpG adjuvant clearly increased T-cell proliferation and promoted DC activation, with elevated splenic TLR21 levels observed. Strikingly, after oral immunization with χYL56 (pYL331), chickens were protected against challenge with the G57 genotype H9N2 virus, which presented similar or even better levels of virus shedding and body weight gain compared with the commercial inactivated vaccine, providing a new option for controlling H9N2 virus infection in the future.

Construction of Chitinase Complexes Using Self-Assembly Systems for Efficient Hydrolysis of Chitin

Chitin biomass is the second most abundant natural polysaccharide after cellulose on the earth, yet its recalcitrance to degrade and utilize severely limits its application. However, many microorganisms, such as Serratia marcescen, can secrete a range of free chitinases to degrade chitin, though their activity is typically insufficient to meet industrial demands. In this study, we employed self-assembly systems, named SpyTag/SpyCatcher and SnoopTag/SnoopCatcher, to modularize the molecular design of CHB, ChiB, ChiC, and CBP21 derived from S. marcescens ATCC14756, and we successfully constructed a variety of chitinase complexes. The assembled complexes showed higher chitinolytic activity and stability, compared to free chitinase mixture. Moreover, the distinct arrangements and combinations of chitinases within these complexes led to varied activities, suggesting that the spatial proximity and substrate channeling effects contribute to the synergy of chitinase complexes. The findings lay a solid technical foundation for the application of chitinosome in the industrial production of N-acetylglucosamine and chitooligosaccharides.

Progress on angiogenic and antiangiogenic agents in the tumor microenvironment

The development of tumors and their metastasis relies heavily on the process of angiogenesis. When the volume of a tumor expands, the resulting internal hypoxic conditions trigger the body to enhance the production of various angiogenic factors. These include vascular endothelial growth factor (VEGF), fibroblast growth factor (FGF), platelet-derived growth factor (PDGF), and transforming growth factor-α (TGF-α), all of which work together to stimulate the activation of endothelial cells and catalyze angiogenesis. Antiangiogenic therapy (AAT) aims to normalize tumor blood vessels by inhibiting these angiogenic signals. In this review, we will explore the molecular mechanisms of angiogenesis within the tumor microenvironment, discuss traditional antiangiogenic drugs along with their limitations, examine new antiangiogenic drugs and the advantages of combination therapy, and consider future research directions in the field of antiangiogenic drugs. This comprehensive overview aims to provide insights that may aid in the development of more effective anti-tumor treatments.

Self-assembling nanoparticle engineered from the ferritinophagy complex as a rabies virus vaccine candidate

Over the past decade, there has been a growing interest in ferritin-based vaccines due to their enhanced antigen immunogenicity and favorable safety profiles, with several vaccine candidates targeting various pathogens advancing to phase I clinical trials. Nevertheless, challenges associated with particle heterogeneity, improper assembly and unanticipated immunogenicity due to the bulky protein adaptor have impeded further advancement. To overcome these challenges, we devise a universal ferritin-adaptor delivery platform based on structural insights derived from the natural ferritinophagy complex of the human ferritin heavy chain (FTH1) and the nuclear receptor coactivator 4 (NCOA4). The engineered ferritinophagy (Fagy)-tag peptide demonstrate significantly enhanced binding affinity to the 24-mer ferritin nanoparticle, enabling efficient antigen presentation. Subsequently, we construct a self-assembling rabies virus (RABV) vaccine candidate by noncovalently conjugating the Fagy-tagged glycoprotein domain III (GDIII) of RABV to the ferritin nanoparticle, maintaining superior homogeneity, stability and immunogenicity. This vaccine candidate induces potent, rapid, and durable immune responses, and protects female mice against the authentic RABV challenge after single-dose administration. Furthermore, this universal, ferritin-based antigen conjugating strategy offers significant potential for developing vaccine against diverse pathogens and diseases.

Tyrosinase-Mediated Conjugation for Antigen Display on Ferritin Nanoparticles

Ferritin (Ft) nanoparticles have become versatile platforms for displaying antigens, being a promising technology for vaccine development. While genetic fusion has traditionally been the preferred method for antigen display, concerns about improper folding and steric hindrance that may compromise vaccine efficacy or stability have prompted alternative approaches. Bioconjugation offers the advantage of preserving native protein structure and function, with recent advancements improving efficiency and specificity. In this study, we used tyrosinase (TYR) to bioconjugate the receptor binding domain of the SARS-CoV-2 spike protein, tagged with a tyrosine (RBD-Y), to native cysteines on Ft, resulting in RBD-Y-Ft nanoparticles. We quantified available cysteines on ferritin using Ellman's assay and monitored their reduction during the reactions. Denaturing analytics (via SDS-PAGE, Western blot, and LC-TOF-MS) confirmed the formation of RBD-Y-Ft monomers with an expected molecular weight of 46 kDa. Mass photometry and HPLC estimated a molecular weight of RBD-Y-Ft nanoparticles of 680 kDa, which was higher than that of nonfunctionalized ferritin (480 kDa), indicating successful binding of up to eight RBD-Y antigens per 24-mer Ft nanoparticle. This work enhances our understanding of how Ft nanoparticles can be engineered to present antigens, leveraging them as a robust scaffold for producing tailored-made candidate vaccines in a timely manner.

Recombinant ferritin-based nanoparticles as neoantigen carriers significantly inhibit tumor growth and metastasis

BACKGROUND

Tumor neoantigen peptide-based vaccines, systemic immunotherapies that enhance antitumor immunity by activating and expanding antigen-specific T cells, have achieved remarkable results in the treatment of a variety of solid tumors. However, how to effectively deliver neoantigens to induce robust antitumor immune responses remains a major obstacle.

RESULTS

Here, we developed a safe and effective neoantigen peptide delivery system (neoantigen-ferritin nanoparticles, neoantigen-FNs) that successfully achieved effective lymph node targeting and induced robust antitumor immune responses. The genetically engineered self-assembled particles neoantigen-FNs with a size of 12 nm were obtained by fusing a neoantigen with optimized ferritin, which rapidly drainage to and continuously accumulate in lymph nodes. The neoantigen-FNs vaccine induced a greater quantity and quality of antigen-specific CD8+ T cells and resulted in significant growth control of multiple tumors, dramatic inhibition of melanoma metastasis and regression of established tumors. In addition, no obvious toxic side effects were detected in the various models, indicating the high safety of optimized ferritin as a vaccine carrier.

CONCLUSIONS

Homogeneous and safe neoantigen-FNs could be a very promising system for neoantigen peptide delivery because of their ability to efficiently drainage to lymph nodes and induce efficient antitumor immune responses.

PLGA-Astragalus Polysaccharide Nanovaccines Exert Therapeutic Effect in Colorectal Cancer

Background

Tumor vaccines have achieved remarkable progress in treating patients with various tumors in clinical studies. Nevertheless, extensive research has also revealed that tumor vaccines are not up to expectations for the treatment of solid tumors due to their low immunogenicity. Therefore, there is an urgent need to design a tumor vaccine that can stimulate a broad anti-tumor immune response.

Methods

In this work, we developed a nanovaccine (NP-TCL@APS), which includes nanoparticles loaded with colorectal cancer tumor cell lysates (TCL) and Astragalus polysaccharides (APS) into poly (lactic-co-glycolic acid) to induce a robust innate immune response. The NP-TCL@APS was identified by transmission electron microscopy and Malvern laser particle size analyzer. The killing and immune activation effects of NP-TCL@APS were evaluated in vitro. Finally, safety and anti-tumor efficacy were evaluated in the colorectal cancer tumor-bearing mouse model.

Results

We found that NP-TCL@APS was preferentially uptaken by DC and further promoted the activation of DC in vitro. Additionally, nanoparticles codelivery of TCL and APS enhanced the antigen-specific CD8+ T cell response and suppressed the growth of tumors in mouse models with good biocompatibility.

Conclusion

We successfully prepared a nanovaccine termed NP-TCL@APS, which can promote the maturation of DC and induce strong responses by T lymphocytes to exert anti-tumor effects. The strategy proposed here is promising for generating a tumor vaccine and can be extended to various types of cancers.

Nature-inspired protein mineralization strategies for nanoparticle construction: advancing effective cancer therapy

Recently, nanotechnology has shown great potential in the field of cancer therapy due to its ability to improve the stability and solubility and reduce side effects of drugs. The biomimetic mineralization strategy based on natural proteins and metal ions provides an innovative approach for the synthesis of nanoparticles. This strategy utilizes the unique properties of natural proteins and the mineralization ability of metal ions to combine nanoparticles through biomimetic mineralization processes, achieving the effective treatment of tumors. The precise control of the mineralization process between proteins and metal ions makes it possible to obtain nanoparticles with the ideal size, shape, and surface characteristics, thereby enhancing their stability and targeting ability in vivo. Herein, initially, we analyze the role of protein molecules in biomineralization and comprehensively review the functions, properties, and applications of various common proteins and metal particles. Subsequently, we systematically review and summarize the application directions of nanoparticles synthesized based on protein biomineralization in tumor treatment. Specifically, we discuss their use as efficient drug delivery carriers and role in mediating monotherapy and synergistic therapy using multiple modes. Also, we specifically review the application of nanomedicine constructed through biomimetic mineralization strategies using natural proteins and metal ions in improving the efficiency of tumor immunotherapy.

Development of a PCSK9-targeted nanoparticle vaccine to effectively decrease the hypercholesterolemia

Proprotein convertase subtilisin/kexin type 9 (PCSK9) binds to the low-density lipoprotein receptor (LDLR) and mediates its internalization and degradation, resulting in an increase in LDL cholesterol levels. Recently, PCSK9 emerged as a therapeutic target for hypercholesterolemia and atherosclerosis. In this study, we develop a PCSK9 nanoparticle (NP) vaccine by covalently conjugating the catalytic domain (aa 153-aa 454, D374Y) of PCSK9 to self-assembled 24-mer ferritin NPs. We demonstrate that the PCSK9 NP vaccine effectively induces interfering antibodies against PCSK9 and reduces serum lipids levels in both a high-fat diet-induced hypercholesterolemia model and an adeno-associated virus-hPCSK9D374Y-induced hypercholesterolemia model. Additionally, the vaccine significantly reduces plaque lesion areas in the aorta and macrophages infiltration in an atherosclerosis mouse model. Furthermore, we discover that the vaccine's efficacy relied on T follicular help cells and LDLR. Overall, these findings suggest that the PCSK9 NP vaccine holds promise as an effective treatment for hypercholesterolemia and atherosclerosis.

Ferritin Nanoparticle Delivery of the E2 Protein of Classical Swine Fever Virus Completely Protects Pigs from Lethal Challenge

Classical swine fever (CSF), caused by the classical swine fever virus (CSFV), results in significant economic losses to the swine industry in many countries. Vaccination represents the primary strategy to control CSF and the CSFV E2 protein is known as the major protective antigen. However, the E2 protein expressed or presented by different systems elicits distinct immune responses. In this study, we established a stable CHO cell line to express the E2 protein and delivered it using self-assembled ferritin nanoparticles (NPs). Subsequently, we compared the adaptive immune responses induced by the E2-ferritin NPs and the monomeric E2 protein produced by the CHO cells or a baculovirus expression system. The results revealed that the NP-delivered E2 protein elicited higher titers of neutralizing antibodies than did the monomeric E2 protein in pigs. Importantly, only the NP-delivered E2 protein significantly induced CSFV-specific IFN-γ-secreting cells. Furthermore, all the pigs inoculated with the E2-ferritin NPs were completely protected from a lethal CSFV challenge infection. These findings demonstrate the ability of the E2-ferritin NPs to protect pigs against the lethal CSFV challenge by eliciting robust humoral and cellular immune responses.

Laser-activable murine ferritin nanocage for chemo-photothermal therapy of colorectal cancer

Chemotherapy, as a conventional strategy for tumor therapy, often leads to unsatisfied therapeutic effect due to the multi-drug resistance and the serious side effects. Herein, we genetically engineered a thermal-responsive murine Ferritin (mHFn) to specifically deliver mitoxantrone (MTO, a chemotherapeutic and photothermal agent) to tumor tissue for the chemotherapy and photothermal combined therapy of colorectal cancer, thanks to the high affinity of mHFn to transferrin receptor that highly expressed on tumor cells. The thermal-sensitive channels on mHFn allowed the effective encapsulation of MTO in vitro and the laser-controlled release of MTO in vivo. Upon irradiation with a 660 nm laser, the raised temperature triggered the opening of the thermal-sensitive channel in mHFn nanocage, resulting in the controlled and rapid release of MTO. Consequently, a significant amount of reactive oxygen species was generated, causing mitochondrial collapse and tumor cell death. The photothermal-sensitive controlled release, low systemic cytotoxicity, and excellent synergistic tumor eradication ability in vivo made mHFn@MTO a promising candidate for chemo-photothermal combination therapy against colorectal cancer.

Hepatitis C Virus E1E2 Structure, Diversity, and Implications for Vaccine Development

Hepatitis C virus (HCV) is a major medical health burden and the leading cause of chronic liver disease and cancer worldwide. More than 58 million people are chronically infected with HCV, with 1.5 million new infections occurring each year. An effective HCV vaccine is a major public health and medical need as recognized by the World Health Organization. However, due to the high variability of the virus and its ability to escape the immune response, HCV rapidly accumulates mutations, making vaccine development a formidable challenge. An effective vaccine must elicit broadly neutralizing antibodies (bnAbs) in a consistent fashion. After decades of studies from basic research through clinical development, the antigen of choice is considered the E1E2 envelope glycoprotein due to conserved, broadly neutralizing antigenic domains located in the constituent subunits of E1, E2, and the E1E2 heterodimeric complex itself. The challenge has been elicitation of robust humoral and cellular responses leading to broad virus neutralization due to the relatively low immunogenicity of this antigen. In view of this challenge, structure-based vaccine design approaches to stabilize key antigenic domains have been hampered due to the lack of E1E2 atomic-level resolution structures to guide them. Another challenge has been the development of a delivery platform in which a multivalent form of the antigen can be presented in order to elicit a more robust anti-HCV immune response. Recent nanoparticle vaccines are gaining prominence in the field due to their ability to facilitate a controlled multivalent presentation and trafficking to lymph nodes, where they can interact with both the cellular and humoral components of the immune system. This review focuses on recent advances in understanding the E1E2 heterodimeric structure to facilitate a rational design approach and the potential for development of a multivalent nanoparticle-based HCV E1E2 vaccine. Both aspects are considered important in the development of an effective HCV vaccine that can effectively address viral diversity and escape.

Construction of a versatile fusion protein for targeted therapy and immunotherapy

Antibody (Ab)-based drugs have been widely used in targeted therapies and immunotherapies, leading to significant improvements in tumor therapy. However, the failure of Ab therapy due to the loss of target antigens or Ab modifications that affect its function limits its application. In this study, we expanded the application of antibodies (Abs) by constructing a fusion protein as a versatile tool for Ab-based target cell detection, delivery, and therapy. We first constructed a SpaC Catcher (SpaCC for short) fusion protein that included the C domains of Staphylococcal protein A (SpaC) and the SpyCatcher. SpaCC conjugated with SpyTag-X (S-X) to form the SpaCC-S-X complex, which binds non-covalently to an Ab to form the Ab-SpaCC-S-X protein complex. The "X" can be a variety of small molecules such as fluoresceins, cell-penetrating peptide TAT, Monomethyl auristatin E (MMAE), and DNA. We found that Ab-SpaCC-S-FITC(-TAT) could be used for target cell detection and delivery. Besides, we synthesized the Ab-SpaCC-SN3-MMAE complex by linking Ab with MMAE by SpaCC, which improved the cytotoxicity of small molecule toxins. Moreover, we constructed an Ab-DNA complex by conjugating SpaCC with the aptamer (Ap) and found that Ab-SpaCC-SN3-Ap boosted the tumor-killing function of T-cells by retargeting tumor cells. Thus, we developed a multifunctional tool that could be used for targeted therapies and immunotherapies, providing a cheap and convenient novel drug development strategy.

Nanomaterial Delivery Vehicles for the Development of Neoantigen Tumor Vaccines for Personalized Treatment

Tumor vaccines have been considered a promising therapeutic approach for treating cancer in recent years. With the development of sequencing technologies, tumor vaccines based on neoantigens or genomes specifically expressed in tumor cells, mainly in the form of peptides, nucleic acids, and dendritic cells, are beginning to receive widespread attention. Therefore, in this review, we have introduced different forms of neoantigen vaccines and discussed the development of these vaccines in treating cancer. Furthermore, neoantigen vaccines are influenced by factors such as antigen stability, weak immunogenicity, and biosafety in addition to sequencing technology. Hence, the biological nanomaterials, polymeric nanomaterials, inorganic nanomaterials, etc., used as vaccine carriers are principally summarized here, which may contribute to the design of neoantigen vaccines for improved stability and better efficacy.

Nanoparticle vaccines based on the receptor binding domain of porcine deltacoronavirus elicit robust protective immune responses in mice

Background

Porcine deltacoronavirus (PDCoV), a novel swine enteropathogenic coronavirus, challenges the global swine industry. Currently, there are no approaches preventing swine from PDCoV infection.

Methods

A new PDCoV strain named JS2211 was isolated. Next, the dimer receptor binding domain of PDCoV spike protein (RBD-dimer) was expressed using the prokaryotic expression system, and a novel nanoparticle containing RBD-dimer and ferritin (SC-Fe) was constructed using the SpyTag/SpyCatcher system. Finally, the immunoprotection of RBD-Fe nanoparticles was evaluated in mice.

Results

The novel PDCoV strain was located in the clade of the late Chinese isolate strains and close to the United States strains. The RBD-Fe nanoparticles were successfully established. Immune responses of the homologous prime-boost regime showed that RBD-Fe nanoparticles efficiently elicited specific humoral and cellular immune responses in mice. Notably, high level PDCoV RBD-specific IgG and neutralizing antibody (NA) could be detected, and the histopathological results showed that PDCoV infection was dramatically reduced in mice immunized with RBD-Fe nanoparticles.

Conclusion

This study effectively developed a candidate nanoparticle with receptor binding domain of PDCoV spike protein that offers protection against PDCoV infection in mice.

A modular approach to enhancing cell membrane-coated nanoparticle functionality using genetic engineering

Since their initial development, cell membrane-coated nanoparticles (CNPs) have become increasingly popular in the biomedical field. Despite their inherent versatility and ability to enable complex biological applications, there is considerable interest in augmenting the performance of CNPs through the introduction of additional functionalities. Here we demonstrate a genetic-engineering-based modular approach to CNP functionalization that can encompass a wide range of ligands onto the nanoparticle surface. The cell membrane coating is engineered to express a SpyCatcher membrane anchor that can readily form a covalent bond with any moiety modified with SpyTag. To demonstrate the broad utility of this technique, three unique targeted CNP formulations are generated using different classes of targeting ligands, including a designed ankyrin repeat protein, an affibody and a single-chain variable fragment. In vitro, the modified nanoparticles exhibit enhanced affinity towards cell lines overexpressing the cognate receptors for each ligand. When formulated with a chemotherapeutic payload, the modularly functionalized nanoparticles display strong targeting ability and growth suppression in a murine tumour xenograft model of ovarian cancer. Our data suggest genetic engineering offers a feasible approach for accelerating the development of multifunctional CNPs for a broad range of biomedical applications.

A SARS-CoV-2 nanoparticle vaccine based on chemical conjugation of loxoribine and SpyCatcher/SpyTag

SARS-CoV-2 is a particularly transmissible virus that renders the worldwide COVID-19 pandemic and global severe respiratory distress syndrome. Protein-based vaccines hold great advantages to build the herd immunity for their specificity, effectiveness, and safety. Receptor-binding domain (RBD) of SARS-CoV-2 is an appealing antigen for vaccine development. However, adjuvants and delivery system are necessitated to enhance the immunogenicity of RBD. In the present study, RBD was chemically conjugated with loxoribine and SpyCatcher/SpyTag, followed by assembly to form a nanoparticle vaccine. Loxoribine (a TLR7/8 agonist) acted as an adjuvant, and nanoparticles functioned as delivery system for the antigen and the adjuvant. The nanoparticle vaccine elicited high RBD-specific antibody titers, high neutralizing antibody titer, and strong ACE2-blocking activity. It stimulated high splenic levels of Th1-type cytokines (IFN-γ and IL-2) and Th2-type cytokines (IL-4 and IL-5) in BALB/c mice. It promoted the splenocyte proliferation, enhanced the CD4+ and CD8+ T cell percentage and stimulated the maturation of dendritic cells. The vaccine did not render apparent toxicity to the organs of mice. Thus, the nanoparticle vaccine was of potential to act as a preliminarily safe and effective candidate against SARS-CoV-2.

Prospects for developing an Hepatitis C virus E1E2-based nanoparticle vaccine

Globally, more than 58 million people are chronically infected with Hepatitis C virus (HCV) with 1.5 million new infections occurring each year. An effective vaccine for HCV is therefore a major unmet medical and public health need. Since HCV rapidly accumulates mutations, vaccines must elicit the production of broadly neutralising antibodies (bnAbs) in a reproducible fashion. Decades of research have generated a number of HCV vaccine candidates. Based on the available data and research through clinical development, a vaccine antigen based on the E1E2 glycoprotein complex appears to be the best choice, but robust induction of humoral and cellular responses leading to virus neutralisation has not yet been achieved. One issue that has arisen in developing an HCV vaccine (and many other vaccines as well) is the platform used for antigen delivery. The majority of viral vaccine trials have employed subunit vaccines. However, subunit vaccines often have limited immunogenicity, as seen for HCV, and thus multiple formats must be examined in order to elicit a robust anti-HCV immune response. Nanoparticle vaccines are gaining prominence in the field due to their ability to facilitate a controlled multivalent presentation and trafficking to lymph nodes, where they can interact with both arms of the immune system. This review discusses the potential for development of a nanoparticle-based HCV E1E2 vaccine, with an emphasis on the potential benefits of such an approach along with the major challenges facing the incorporation of E1E2 into nanoparticulate delivery systems and how those challenges can be addressed.

Nanoparticles-induced potential toxicity on human health: Applications, toxicity mechanisms, and evaluation models

Nanoparticles (NPs) have become one of the most popular objects of scientific study during the past decades. However, despite wealth of study reports, still there is a gap, particularly in health toxicology studies, underlying mechanisms, and related evaluation models to deeply understanding the NPs risk effects. In this review, we first present a comprehensive landscape of the applications of NPs on health, especially addressing the role of NPs in medical diagnosis, therapy. Then, the toxicity of NPs on health systems is introduced. We describe in detail the effects of NPs on various systems, including respiratory, nervous, endocrine, immune, and reproductive systems, and the carcinogenicity of NPs. Furthermore, we unravels the underlying mechanisms of NPs including ROS accumulation, mitochondrial damage, inflammatory reaction, apoptosis, DNA damage, cell cycle, and epigenetic regulation. In addition, the classical study models such as cell lines and mice and the emerging models such as 3D organoids used for evaluating the toxicity or scientific study are both introduced. Overall, this review presents a critical summary and evaluation of the state of understanding of NPs, giving readers more better understanding of the NPs toxicology to remedy key gaps in knowledge and techniques.

Cuproptosis/ferroptosis-related gene signature is correlated with immune infiltration and predict the prognosis for patients with breast cancer

Background: Breast invasive carcinoma (BRCA) is a malignant tumor with high morbidity and mortality, and the prognosis is still unsatisfactory. Both ferroptosis and cuproptosis are apoptosis-independent cell deaths caused by the imbalance of corresponding metal components in cells and can affect the proliferation rate of cancer cells. The aim in this study was to develop a prognostic model of cuproptosis/ferroptosis-related genes (CFRGs) to predict survival in BRCA patients. Methods: Transcriptomic and clinical data for breast cancer patients were obtained from The Cancer Genome Atlas (TCGA) and Gene Expression Omnibus (GEO) databases. Cuproptosis and ferroptosis scores were determined for the BRCA samples from the TCGA cohort using Gene Set Variation Analysis (GSVA), followed by weighted gene coexpression network analysis (WGCNA) to screen out the CFRGs. The intersection of the differentially expressed genes grouped by high and low was determined using X-tile. Univariate Cox regression and least absolute shrinkage and selection operator (LASSO) were used in the TGCA cohort to identify the CFRG-related signature. In addition, the relationship between risk scores and immune infiltration levels was investigated using various algorithms, and model genes were analyzed in terms of single-cell sequencing. Finally, the expression of the signature genes was validated with quantitative real-time PCR (qRT‒PCR) and immunohistochemistry (IHC). Results: A total of 5 CFRGs (ANKRD52, HOXC10, KNOP1, SGPP1, TRIM45) were identified and were used to construct proportional hazards regression models. The high-risk groups in the training and validation sets had significantly worse survival rates. Tumor mutational burden (TMB) was positively correlated with the risk score. Conversely, Tumor Immune Dysfunction and Exclusion (TIDE) and tumor purity were inversely associated with risk scores. In addition, the infiltration degree of antitumor immune cells and the expression of immune checkpoints were lower in the high-risk group. In addition, risk scores and mTOR, Hif-1, ErbB, MAPK, PI3K/AKT, TGF-β and other pathway signals were correlated with progression. Conclusion: We can accurately predict the survival of patients through the constructed CFRG-related prognostic model. In addition, we can also predict patient immunotherapy and immune cell infiltration.

Advances in Cancer Nanovaccines: Harnessing Nanotechnology for Broadening Cancer Immune Response

Many advances have been made recently in the field of cancer immunotherapy, particularly with the development of treatments such as immune checkpoint inhibitors and adoptive cellular immunotherapy. The efficacy of immunotherapy is limited, however, owing to high levels of tumor heterogeneity and the immunosuppressive environments of advanced malignant tumors. Therefore, therapeutic anticancer vaccines have gradually become powerful tools for inducing valid antitumor immune responses and regulating the immune microenvironment. Tumor vaccines loaded in nanocarriers have become an indispensable delivery platform for tumor treatment because of their enhanced stability, targeting capability, and high level of safety. Through a unique design, cancer nanovaccines activate innate immunity and tumor-specific immunity simultaneously. For example, the design of cancer vaccines can incorporate strategies such as enhancing the stability and targeting of tumor antigens, combining effective adjuvants, cytokines, and immune microenvironment regulators, and promoting the maturation and cross-presentation of antigen-presenting cells (APCs). In this review, we discuss the design and preparation of nanovaccines for remodeling tumor antigen immunogenicity and regulating the immunosuppressive microenvironment.

Gene-encoded nanoparticle vaccine platforms for in vivo assembly of multimeric antigen to promote adaptive immunity

Nanoparticle vaccines are a diverse category of vaccines for the prophylaxis or treatment of various diseases. Several strategies have been employed for their optimization, especially to enhance vaccine immunogenicity and generate potent B-cell responses. Two major modalities utilized for particulate antigen vaccines include using nanoscale structures for antigen delivery and nanoparticles that are themselves vaccines due to antigen display or scaffolding-the latter of which we will define as "nanovaccines." Multimeric antigen display has a variety of immunological benefits compared to monomeric vaccines mediated through potentiating antigen-presenting cell presentation and enhancing antigen-specific B-cell responses through B-cell activation. The majority of nanovaccine assembly is done in vitro using cell lines. However, in vivo assembly of scaffolded vaccines potentiated using nucleic acids or viral vectors is a burgeoning modality of nanovaccine delivery. Several advantages to in vivo assembly exist, including lower costs of production, fewer production barriers, as well as more rapid development of novel vaccine candidates for emerging diseases such as SARS-CoV-2. This review will characterize the methods for de novo assembly of nanovaccines in the host using methods of gene delivery including nucleic acid and viral vectored vaccines. This article is categorized under: Therapeutic Approaches and Drug Discovery > Nanomedicine for Infectious Disease Biology-Inspired Nanomaterials > Nucleic Acid-Based Structures Biology-Inspired Nanomaterials > Protein and Virus-Based Structures Therapeutic Approaches and Drug Discovery > Emerging Technologies.

Baculovirus-expressed self-assembling SARS-CoV-2 nanoparticle vaccines targeting the S protein induce protective immunity in mice

Spike (S) protein, a homotrimeric glycoprotein, is the most important antigen target for SARS-CoV-2 vaccines. A complete simulation of the advanced structure of this homotrimer during subunit vaccine development is the most likely method to improve its immunoprotective effects. In this study, preparation strategies for the S protein receptor-binding domain, S1 region, and ectodomain trimer nanoparticles were designed using ferritin nanoparticle self-assembly technology. The Bombyx mori baculovirus expression system was used to prepare three nanoparticle vaccines with high expression levels recorded in silkworms. The results in mice showed that the nanoparticle vaccine prepared using this strategy could induce immune responses when administered via both the subcutaneous administration and oral routes. Given the stability of these ferritin-based nanoparticle vaccines, an easy-to-use and low-cost oral immunization strategy can be employed in vaccine blind areas attributed to shortages of ultralow-temperature equipment and medical resources in underdeveloped areas. Oral vaccines are also promising candidates for limiting the spread of SARS-CoV-2 in domestic and farmed animals, especially in stray and wild animals.

Biomimetic nanoparticles for DC vaccination: a versatile approach to boost cancer immunotherapy

Cancer immunotherapy, which harnesses the immune system to fight cancer, has begun to make a breakthrough in clinical applications. Dendritic cells (DCs) are the bridge linking innate and adaptive immunity and the trigger of tumor immune response. Considering the cumbersome process and poor efficacy of classic DC vaccines, there has been interest in transferring the field of in vitro-generated DC vaccines to nanovaccines. Conventional nanoparticles have insufficient targeting ability and are easily cleared by the reticuloendothelial system. Biological components have evolved very specific functions, which are difficult to fully reproduce with synthetic materials, making people interested in using the further understanding of biological systems to prepare nanoparticles with new and enhanced functions. Biomimetic nanoparticles are semi-biological or nature-derived delivery systems comprising one or more natural materials, which have a long circulation time in vivo and excellent performance of targeting DCs, and can mimic the antigen-presenting behavior of DCs. In this review, we introduce the classification, design, preparation, and challenges of different biomimetic nanoparticles, and discuss their application in activating DCs in vivo and stimulating T cell antitumor immunity. Incorporating biomimetic nanoparticles into cancer immunotherapy has shown outstanding advantages in precisely coaxing the immune system against cancer.

Green synthesis of silica-coated magnetic nanocarriers for simultaneous purification-immobilization of β-1,3-xylanase

Tailoring magnetic nanocarriers with tunable properties is of great significance for the development of multifunctional candidate materials in numerous fields. Herein, we report a one-pot biomimetic silicification-based method for the synthesis of silica-coated magnetic nanoparticles. The synthesis process was mild, low cost, and highly efficient, which took only about 21 min compared with 4.5-120 h in other literature. Then, the carriers had been characterized by VSM, SEM, TEM, XRD, FT-IR, and EDS to confirm their function. To evaluate the usefulness of the carriers, they were adopted to couple the purification and immobilization of β-1,3-xylanase from the cell lysate in a single step with high immobilization yield (92.8 %) and high activity recovery (82.4 %). The immobilized enzyme also retained 58.4 % of the initial activity after 10 cycles and displayed good storage properties, and improved thermal stability, which would be promising in algae biomass bioconversion as well as other diverse applications.

Engineered Norovirus-Derived Nanoparticles as a Plug-and-Play Cancer Vaccine Platform

In recent years, virus-derived self-assembled protein nanoparticles (NPs) have emerged as attractive antigen delivery platforms for developing both preventive and therapeutic vaccines. In this study, we exploited the genetically engineered Norovirus S domain (Nov-S) with SpyCatcher003 fused to the C-terminus to develop a robust, modular, and versatile NP-based carrier platform (Nov-S-Catcher003). The NPs can be conveniently armed in a plug-and-play pattern with SpyTag003-linked antigens. Nov-S-Catcher003 was efficiently expressed in Escherichia coli and self-assembled into highly uniform NPs with a purified protein yield of 97.8 mg/L. The NPs presented high stability at different maintained temperatures and after undergoing differing numbers of freeze-thaw cycles. Tumor vaccine candidates were easily obtained by modifying Nov-S-Catcher003 NPs with SpyTag003-linked tumor antigens. Nov-S-Catcher003-antigen NPs significantly promoted the maturation of bone marrow-derived dendritic cells in vitro and were capable of efficiently migrating to lymph nodes in vivo. In TC-1 and B16F10 tumor-bearing mice, the subcutaneous immunization of NPs elicited robust tumor-specific T-cell immunity, reshaped the tumor microenvironment, and inhibited tumor growth. In the TC-1 model, the NPs even completely abolished established tumors. In conclusion, the Nov-S-Catcher003 system is a promising delivery platform for facilitating the development of NP-based cancer vaccines.

Nanoparticle vaccine based on the envelope protein domain III of Japanese encephalitis virus elicits robust protective immune responses in mice

Aim: To develop a vaccine candidate for Japanese encephalitis virus (JEV), for which an effective and safe vaccine is urgently needed. Materials & methods: A vaccine candidate based on domain III of the JEV envelope protein and lumazine synthase (EDIII-LS) was prepared by coupling multivalent ED III to a self-assembling nanoparticle of LS through genetic fusion and self-assembly. Results: High enrichment of ED III was achieved based on the self-assembly of an EDIII-LS polymer. EDIII-LS strongly promoted dendritic cells' internalization and presentation compared with ED III monomer. The cellular and humoral immune responses provoked by EDIII-LS were remarkably higher than those caused by ED III in mice, and conferred complete protection against JEV challenge. Conclusion: The study of ED III-based nanoparticles suggests an effective approach against JEV.

Ferritin-based nanomedicine for disease treatment

Ferritin is an endogenous protein which is self-assembled by 24 subunits into a highly uniform nanocage structure. Due to the drug-encapsulating ability in the hollow inner cavity and abundant modification sites on the outer surface, ferritin nanocage has been demonstrated great potential to become a multi-functional nanomedicine platform. Its good biocompatibility, low toxicity and immunogenicity, intrinsic tumor-targeting ability, high stability, low cost and massive production, together make ferritin nanocage stand out from other nanocarriers. In this review, we summarized ferritin-based nanomedicine in field of disease diagnosis, treatment and prevention. The different types of drugs to be loaded in ferritin, as well as drug-loading methods were classified. The strategies for site-specific and non-specific functional modification of ferritin were investigated, then the application of ferritin for disease imaging, drug delivery and vaccine development were discussed. Finally, the challenges restricting the clinical translation of ferritin-based nanomedicines were analyzed.

Spy&IAC enables specific capture of SpyTagged proteins for rapid assembly of plug-and-display nanoparticle vaccines

From modular vaccine production to protein assembly on nanoparticles, the SpyCatcher/SpyTag system provides a convenient plug-and-display procedure. Here, we established a general-purpose immunoaffinity chromatography (IAC) method for SpyTagged proteins (Spy&IAC). SpyTags are displayed on the surface of nanoparticles to induce high-affinity monoclonal antibodies, allowing the specific capture of the target protein. Taking the key core antigenic regions of two coronaviruses that are currently more threatened in the field of human and animal diseases, the nucleocapsid (N) protein of SARS-CoV-2 and the COE protein of porcine epidemic diarrhea virus (PEDV) as model proteins, a purification model with SpyTag at the N-terminal or C-terminal expressed in E. coli or mammalian cells was constructed. After the efficient elution of Spy&IAC, the final yield of several proteins is about 3.5-15 mg/L culture, and the protein purity is above 90 %. Purification also preserves the assembly function and immunogenicity of the protein to support subsequent modular assembly and immunization programs. This strategy provides a general tool for the efficient purification of SpyTagged proteins from different expression sources and different tag positions, enabling the production of modular vaccines at lower cost and in a shorter time, which will prepare the public health field for potential pandemic threats.

Fluoroalkane modified cationic polymers for personalized mRNA cancer vaccines

Messenger RNA (mRNA) vaccines, while demonstrating great successes in the fight against COVID-19, have been extensively studied in other areas such as personalized cancer immunotherapy based on tumor neoantigens. In addition to the design of mRNA sequences and modifications, the delivery carriers are also critical in the development of mRNA vaccines. In this work, we synthesized fluoroalkane-grafted polyethylenimine (F-PEI) for mRNA delivery. Such F-PEI could promote intracellular delivery of mRNA and activate the Toll-like receptor 4 (TLR4)-mediated signaling pathway. The nanovaccine formed by self-assembly of F-PEI and the tumor antigen-encoding mRNA, without additional adjuvants, could induce the maturation of dendritic cells (DCs) and trigger efficient antigen presentation, thereby eliciting anti-tumor immune responses. Using the mRNA encoding the model antigen ovalbumin (mRNA^OVA), our F-PEI-based mRNA^OVA cancer vaccine could delay the growth of established B16-OVA melanoma. When combined with immune checkpoint blockade therapy, the F-PEI-based MC38 neoantigen mRNA cancer vaccine was able to suppress established MC38 colon cancer and prevent tumor reoccurrence. Our work presents a new tool for mRNA delivery, promising not only for personalized cancer vaccines but also for other mRNA-based immunotherapies.

Protein-based nanocages for vaccine development

Protein nanocages have attracted considerable attention in various fields of nanomedicine due to their intrinsic properties, including biocompatibility, biodegradability, high structural stability, and ease of modification of their surfaces and inner cavities. In vaccine development, these protein nanocages are suited for efficient targeting to and retention in the lymph nodes and can enhance immunogenicity through various mechanisms, including excellent uptake by antigen-presenting cells and crosslinking with multiple B cell receptors. This review highlights the superiority of protein nanocages as antigen delivery carriers based on their physiological and immunological properties such as biodistribution, immunogenicity, stability, and multifunctionality. With a focus on design, we discuss the utilization and efficacy of protein nanocages such as virus-like particles, caged proteins, and artificial caged proteins against cancer and infectious diseases such as coronavirus disease 2019 (COVID-19). In addition, we summarize available knowledge on the protein nanocages that are currently used in clinical trials and provide a general outlook on conventional distribution techniques and hurdles faced, particularly for therapeutic cancer vaccines.

Advanced Nanomedicine for High-Risk HPV-Driven Head and Neck Cancer

The incidence of high-risk Human Papillomavirus (HR-HPV)-driven head and neck squamous cell carcinoma (HNSCC) is on the rise globally. HR-HPV-driven HNSCC displays molecular and clinical characteristics distinct from HPV-uninvolved cases. Therapeutic strategies for HR-HPV-driven HNSCC are under investigation. HR-HPVs encode the oncogenes E6 and E7, which are essential in tumorigenesis. Meanwhile, involvement of E6 and E7 provides attractive targets for developing new therapeutic regimen. Here we will review some of the recent advancements observed in preclinical studies and clinical trials on HR-HPV-driven HNSCC, focusing on nanotechnology related methods. Materials science innovation leads to great improvement for cancer therapeutics including HNSCC. This article discusses HPV-E6 or -E7- based vaccines, based on plasmid, messenger RNA or peptide, at their current stage of development and testing as well as how nanoparticles can be designed to target and access cancer cells and activate certain immunology pathways besides serving as a delivery vehicle. Nanotechnology was also used for chemotherapy and photothermal treatment. Short interference RNA targeting E6/E7 showed some potential in animal models. Gene editing by CRISPR-CAS9 combined with other treatments has also been assessed. These advancements have the potential to improve the outcome in HR-HPV-driven HNSCC, however breakthroughs are still to be awaited with nanomedicine playing an important role.

Macromolecular assembly of bioluminescent protein nanoparticles for enhanced imaging

Bioluminescence imaging has advantages over fluorescence imaging, such as minimal photobleaching and autofluorescence, and greater signal-to-noise ratios in many complex environments. Although significant achievements have been made in luciferase engineering for generating bright and stable reporters, the full capability of luciferases for nanoparticle tracking has not been comprehensively examined. In biocatalysis, enhanced enzyme performance after immobilization on nanoparticles has been reported. Thus, we hypothesized that by assembling luciferases onto a nanoparticle, the resulting complex could lead to substantially improved imaging properties. Using a modular bioconjugation strategy, we attached NanoLuc (NLuc) or Akaluc bioluminescent proteins to a protein nanoparticle platform (E2), yielding nanoparticles NLuc-E2 and Akaluc-E2, both with diameters of ∼45 ​nm. Although no significant differences were observed between different conditions involving Akaluc and Akaluc-E2, free NLuc at pH 5.0 showed significantly lower emission values than free NLuc at pH 7.4. Interestingly, NLuc immobilization on E2 nanoparticles (NLuc-E2) emitted increased luminescence at pH 7.4, and at pH 5.0 showed over two orders of magnitude (>200-fold) higher luminescence (than free NLuc), expanding the potential for imaging detection using the nanoparticle even upon endocytic uptake. After uptake by macrophages, the resulting luminescence with NLuc-E2 nanoparticles was up to 7-fold higher than with free NLuc at 48 ​h. Cells incubated with NLuc-E2 could also be imaged using live bioluminescence microscopy. Finally, biodistribution of nanoparticles into lymph nodes was detected through imaging using NLuc-E2, but not with conventionally-labeled fluorescent E2. Our data demonstrate that NLuc-bound nanoparticles have advantageous properties that can be utilized in applications ranging from single-cell imaging to in vivo biodistribution.

Emerging prospects of protein/peptide-based nanoassemblies for drug delivery and vaccine development

Proteins have been widely used in the biomedical field because of their well-defined architecture, accurate molecular weight, excellent biocompatibility and biodegradability, and easy-to-functionalization. Inspired by the wisdom of nature, increasing proteins/peptides that possess self-assembling capabilities have been explored and designed to generate nanoassemblies with unique structure and function, including spatially organized conformation, passive and active targeting, stimuli-responsiveness, and high stability. These characteristics make protein/peptide-based nanoassembly an ideal platform for drug delivery and vaccine development. In this review, we focus on recent advances in subsistent protein/peptide-based nanoassemblies, including protein nanocages, virus-like particles, self-assemblable natural proteins, and self-assemblable artificial peptides. The origin and characteristics of various protein/peptide-based assemblies and their applications in drug delivery and vaccine development are summarized. In the end, the prospects and challenges are discussed for the further development of protein/peptide-based nanoassemblies.

Potential of Ferritin-Based Platforms for Tumor Immunotherapy

Ferritin is an iron storage protein that plays a key role in iron homeostasis and cellular antioxidant activity. Ferritin has many advantages as a tumor immunotherapy platform, including a small particle size that allows for penetration into tumor-draining lymph nodes or tumor tissue, a unique structure consisting of 24 self-assembled subunits, cavities that can encapsulate drugs, natural targeting functions, and a modifiable outer surface. In this review, we summarize related research applying ferritin as a tumor immune vaccine or a nanocarrier for immunomodulator drugs based on different targeting mechanisms (including dendritic cells, tumor-associated macrophages, tumor-associated fibroblasts, and tumor cells). In addition, a ferritin-based tumor vaccine expected to protect against a wide range of coronaviruses by targeting multiple variants of SARS-CoV-2 has entered phase I clinical trials, and its efficacy is described in this review. Although ferritin is already on the road to transformation, there are still many difficulties to overcome. Therefore, three barriers (drug loading, modification sites, and animal models) are also discussed in this paper. Notwithstanding, the ferritin-based nanoplatform has great potential for tumor immunotherapy, with greater possibility of clinical transformation.

Real-time in vivo imaging reveals specific nanoparticle target binding in a syngeneic glioma mouse model

Nanomaterial-based drug delivery is a promising strategy for glioma treatment. However, the detailed dynamics of nanoparticles in solid glioma are still a mystery, including their intratumoral infiltration depth, penetration, retention time, and distribution. Revealing these processes in detail requires repeated intravital imaging of the corresponding brain tumor regions over time during glioma growth. Hereby, we established a syngeneic orthotopic cerebral glioma mouse model by combining the chronic cranial window and two-photon microscopy. Thus, we were able to investigate the dynamics of the nanoparticles during long-term glioma growth. Three hours after the intravenous (i.v.) injection of integrin α_Vβ₃ binding conjugated silicon nanoparticles (SNPs-PEG-RGD-FITC), green nanoparticles had already infiltrated the brain glioma, and then more nanoparticles penetrated into the solid brain tumor and were retained for at least 8 days. However, the amount of control SNPs-PEG-FITC that infiltrated into the solid brain tumor was very low. Moreover, we found that SNPs-PEG-RGD-FITC were not only located in the tumor border but could also infiltrate into the core region of the solid tumor. In vitro assay also confirmed the high binding affinity between GL-261-Tdtomato cells and SNPs-PEG-RGD-FITC. Our results indicate that SNPs-PEG-RGD-FITC has high penetration and retention in a solid glioma and our model provides novel ideas for the investigation of nanoparticle dynamics in brain tumors.

Protein Cages: From Fundamentals to Advanced Applications

Proteins that self-assemble into polyhedral shell-like structures are useful molecular containers both in nature and in the laboratory. Here we review efforts to repurpose diverse protein cages, including viral capsids, ferritins, bacterial microcompartments, and designed capsules, as vaccines, drug delivery vehicles, targeted imaging agents, nanoreactors, templates for controlled materials synthesis, building blocks for higher-order architectures, and more. A deep understanding of the principles underlying the construction, function, and evolution of natural systems has been key to tailoring selective cargo encapsulation and interactions with both biological systems and synthetic materials through protein engineering and directed evolution. The ability to adapt and design increasingly sophisticated capsid structures and functions stands to benefit the fields of catalysis, materials science, and medicine.

A self-assembling nanoparticle vaccine targeting the conserved epitope of influenza virus hemagglutinin stem elicits a cross-protective immune response

Various vaccine strategies have been developed to provide broad protection against diverse influenza viruses. The hemagglutinin (HA) stem is the major potential target of these vaccines. Enhancing immunogenicity and eliciting cross-protective immune responses are critical for HA stem-based vaccine designs. In this study, the A helix (Ah) and CD helix (CDh) from the HA stem were fused with ferritin, individually, or in tandem, yielding Ah-f, CDh-f and (A + CD)h-f nanoparticles (NPs), respectively. These NPs were produced through a prokaryotic expression system. After three immunizations with AS03-adjuvanted NPs in BALB/c mice via the subcutaneous route, CDh-f and (A + CD)h-f induced robust humoral and cellular immune responses. Furthermore, CDh-f and (A + CD)h-f conferred complete protection against a lethal challenge of H3N2 virus, while no remarkable immune responses and protective effects were detected in the Ah-f group. These results indicate that the CDh-based nanovaccine represents a promising vaccine platform against influenza, and the epitope-conjugated ferritin NPs may be a potential vaccine platform against other infectious viruses, such as SARS-COV-2.

Tag-mediated single-step purification and immobilization of recombinant proteins toward protein-engineered advanced materials

Background

The potential applications of protein-engineered functional materials are so wide and exciting that the interest in these eco-friendly advanced materials will further expand in the future. Tag-mediated protein purification/immobilization technologies have emerged as green and cost-effective approaches for the fabrication of such materials. Strategies that combine the purification and immobilization of recombinant proteins/peptides onto/into natural, synthetic or hybrid materials in a single-step are arising and attracting increasing interest.

Aim of Review

This review highlights the most significant advances of the last 5 years within the scope of tag-mediated protein purification/immobilization and elucidates their contributions for the development of efficient single-step purification and immobilization strategies. Recent progresses in the field of protein-engineered materials created using innovative protein-tag combinations and future opportunities created by these new technologies are also summarized and identified herein.

Key Scientific Concepts of Review

Protein purification/immobilization tags present a remarkable ability to establish specific non-covalent/covalent interactions between solid materials and biological elements, which prompted the creation of tailor-made and advanced functional materials, and of next-generation hybrid materials. Affinity tags can bind to a wide range of materials (of synthetic, natural or hybrid nature), being most suitable for protein purification. Covalently binding tags are most suitable for long-term protein immobilization, but can only bind naturally to protein-based materials. Hybrid affinity-covalently binding tags have allowed efficient one-step purification and immobilization of proteins onto different materials, as well as the development of innovative protein-engineered materials. Self-aggregating tags have been particularly useful in combination with other tags for generating protein-engineered materials with self-assembling, flexible and/or responsive properties. While these tags have been mainly explored for independent protein purification, immobilization or functionalization purposes, efficient strategies that combine tag-mediated purification and immobilization/functionalization in a single-step will be essential to guarantee the sustainable manufacturing of advanced protein-engineered materials.

Neoantigen Cancer Vaccines: Generation, Optimization, and Therapeutic Targeting Strategies

Alternatives to conventional cancer treatments are highly sought after for high-risk malignancies that have a poor response to established treatment modalities. With research advancing rapidly in the past decade, neoantigen-based immunotherapeutic approaches represent an effective and highly tolerable therapeutic option. Neoantigens are tumor-specific antigens that are not expressed in normal cells and possess significant immunogenic potential. Several recent studies have described the conceptual framework and methodologies to generate neoantigen-based vaccines as well as the formulation of appropriate clinical trials to advance this approach for patient care. This review aims to describe some of the key studies in the recent literature in this rapidly evolving field and summarize the current advances in neoantigen identification and selection, vaccine generation and delivery, and the optimization of neoantigen-based therapeutic strategies, including the early data from pivotal clinical studies.

Protein-Based Nanoparticles for the Imaging and Treatment of Solid Tumors: The Case of Ferritin Nanocages, a Narrative Review

Protein nanocages have been studied extensively, due to their unique architecture, exceptional biocompatibility and highly customization capabilities. In particular, ferritin nanocages (FNs) have been employed for the delivery of a vast array of molecules, ranging from chemotherapeutics to imaging agents, among others. One of the main favorable characteristics of FNs is their intrinsic targeting efficiency toward the Transferrin Receptor 1, which is overexpressed in many tumors. Furthermore, genetic manipulation can be employed to introduce novel variants that are able to improve the loading capacity, targeting capabilities and bio-availability of this versatile drug delivery system. In this review, we discuss the main characteristics of FN and the most recent applications of this promising nanotechnology in the field of oncology with a particular emphasis on the imaging and treatment of solid tumors.

Functionalizing Ferritin Nanoparticles for Vaccine Development

In the last decade, the interest in ferritin-based vaccines has been increasing due to their safety and immunogenicity. Candidates against a wide range of pathogens are now on Phase I clinical trials namely for influenza, Epstein-Barr, and SARS-CoV-2 viruses. Manufacturing challenges related to particle heterogeneity, improper folding of fused antigens, and antigen interference with intersubunit interactions still need to be overcome. In addition, protocols need to be standardized so that the production bioprocess becomes reproducible, allowing ferritin-based therapeutics to become readily available. In this review, the building blocks that enable the formulation of ferritin-based vaccines at an experimental stage, including design, production, and purification are presented. Novel bioengineering strategies of functionalizing ferritin nanoparticles based on modular assembly, allowing the challenges associated with genetic fusion to be circumvented, are discussed. Distinct up/down-stream approaches to produce ferritin-based vaccines and their impact on production yield and vaccine efficacy are compared. Finally, ferritin nanoparticles currently used in vaccine development and clinical trials are summarized.