Albumin as a "Trojan Horse" for polymeric nanoconjugate transendothelial transport across tumor vasculatures for improved cancer targeting

Investigation of the interaction between S-isoalkyl derivatives of the thiosalicylic acid and human serum albumin

S-isoalkyl derivatives of thiosalicylic acid (isopropyl-(L1), isobutyl-(L2) and isoamyl-(L3)) were selected in order to investigate the binding interaction with the human serum albumin (HSA) using different spectroscopic methods and molecular docking simulation. Association constants and number of binding sites were used to analyze the quenching mechanism. The experimental results showed that the fluorescence quenching of HSA by L1, L2 and L3 occurs because of static quenching and that binding processes were spontaneous, with the leading forces in bonding by hydrogen bonding, hydrophobic interactions, and electrostatic interactions. Fluorescence spectroscopy, UV-Vis spectroscopy and synchronous fluorescence spectroscopy showed that ligands (L1, L2 and L3) can bind to HSA and that the binding of ligands induced some microenvironmental and conformational changes in HSA. The calculated distance between the donor and the acceptor according to fiFörster's theory confirms the energy transfer efficiency between the acceptor and HSA. Results of site marker competitive experiments showed that the tested compounds bind to HSA in domain IIA (Site I). Molecular dynamics and docking calculations demonstrated that L3 binds to the Sudlow site I of HSA with lower values of binding energies compared to L1 and L2, indicating the formation of the most stable ligand-HSA complex. Understanding the binding mechanisms of S-isoalkyl derivatives of the thiosalicylic acid to HSA may provide valuable data for the future studies of their biological activity and application as potential antitumor drugs.Communicated by Ramaswamy H. Sarma.

Applications of human and bovine serum albumins in biomedical engineering: A review

Serum albumin, commonly recognized as a predominant major plasma protein, is ubiquitously distributed among vertebrates, demonstrating versatility and widespread accessibility. Numerous studies have discussed the composition and attributes of human and bovine serum albumin; nonetheless, few systematic and comprehensive summaries on human and bovine serum albumin exist. This paper reviews the applications of human and bovine serum albumin in biomedical engineering. First, we introduce the differences in the structure of human and bovine serum albumin. Next, we describe the extraction methods for human and bovine serum albumin (fractionation process separation, magnetic adsorption, reverse micellar (RM) extraction, and genetic engineering) and the advantages and disadvantages of recently developed extraction methods. The characteristics of different processing forms of human and bovine serum albumin are also discussed, concomitantly elucidating their intrinsic properties, functions, and applications in biomedicine. Notably, their pivotal functions as carriers for drugs and tissue-engineered scaffolds, as well as their contributions to cell reproduction and bioimaging, are critically examined. Finally, to provide guidance for researchers in their future work, this review summarizes the current state of human and bovine serum albumin research and outlines potential future research topics.

Layer-by-Layer Nanoassemblies for Vaccination Purposes

In recent years, the availability of effective vaccines has become a public health challenge due to the proliferation of different pandemic outbreaks which are a risk for the world population health. Therefore, the manufacturing of new formulations providing a robust immune response against specific diseases is of paramount importance. This can be partially faced by introducing vaccination systems based on nanostructured materials, and in particular, nanoassemblies obtained by the Layer-by-Layer (LbL) method. This has emerged, in recent years, as a very promising alternative for the design and optimization of effective vaccination platforms. In particular, the versatility and modularity of the LbL method provide very powerful tools for fabricating functional materials, opening new avenues on the design of different biomedical tools, including very specific vaccination platforms. Moreover, the possibility to control the shape, size, and chemical composition of the supramolecular nanoassemblies obtained by the LbL method offers new opportunities for manufacturing materials which can be administered following specific routes and present very specific targeting. Thus, it will be possible to increase the patient convenience and the efficacy of the vaccination programs. This review presents a general overview on the state of the art of the fabrication of vaccination platforms based on LbL materials, trying to highlight some important advantages offered by these systems.

Polysaccharide-based nanocarriers for efficient transvascular drug delivery

Polysaccharide-based nanocarriers (PBNs) are the focus of extensive investigation because of their biocompatibility, low cost, wide availability, and chemical versatility, which allow a wide range of anticancer agents to be loaded within the nanocarriers. Similar to other nanocarriers, most PBNs are designed to extravasate out of tumor vessels, depending on the enhanced permeability and retention (EPR) effect. However, the EPR effect is compromised in some tumors due to the heterogeneity of tumor structures. Transvascular transport efficacy is decreased by complex blood vessels and condensed tumor stroma. The limited extravasation impedes efficient drug delivery into tumor parenchyma, and thus affects the subsequent tumor accumulation, which hinders the therapeutic effect of PBNs. Therefore, overcoming the biological barriers that restrict extravasation from tumor vessels is of great importance in PBN design. Many strategies have been developed to enhance the EPR effect that involve nanocarrier property regulation and tumor structure remodeling. Moreover, some researchers have proposed active transcytosis pathways that are complementary to the paracellular EPR effect to increase the transvascular extravasation efficiency of PBNs. In this review, we summarize the recent advances in the design of PBNs with enhanced transvascular transport to enable optimization of PBNs in the extravasation of the drug delivery process. We also discuss the obstacles and challenges that need to be addressed to clarify the transendothemial mechanism of PBNs and the potential interactions between extravasation and other drug delivery steps.

Transcytosis-enabled active extravasation of tumor nanomedicine

Extravasation is the first step for nanomedicines in circulation to reach targeted solid tumors. Traditional nanomedicines have been designed to extravasate into tumor interstitium through the interendothelial gaps previously assumed rich in tumor blood vessels, i.e., the enhanced permeability and retention (EPR) effect. While the EPR effect has been validated in animal xenograft tumor models, accumulating evidence implies that the EPR effect is very limited and highly heterogeneous in human tumors, leading to highly unpredictable and inefficient extravasation and thus limited therapeutic efficacy of nanomedicines, including those approved in clinics. Enabling EPR-independent extravasation is the key to develop new generation of nanomedicine with enhanced efficacy. Transcytosis of tumor endothelial cells can confer nanomedicines to actively extravasate into solid tumors without relying on the EPR effect. Here, we review and prospectthe development of transcytosis-inducing nanomedicines, in hope of providing instructive insights for design of nanomedicines that can undergo selective transcellular transport across tumor endothelial cells, and thus inspiring the development of next-generation nanomedicines for clinical translation.

Development of an Integrated High Serum Stability Zwitterionic Polypeptide-Based Nanodrug with Both Rapid Internalization and Endocellular Drug Releasing for Efficient Targeted Chemotherapy

Chemotherapeutic nanodrugs have to penetrate through many biological barriers before reaching the tumor cells. Thus, high stability of the nanocarrier before reaching tumor cells and fast release of the carried drugs in targeted tumor cells are required. In this work, inspired by the intrinsic zwitterionic surface property, mainly formed by glutamic acid and lysine residues, of the plasma protein surface, the zwitterionic poly(glutamyl lysine-co-aspartic acid-co-cysteine) peptide (P(EK-D-C)) was synthesized for conjugating n-mercaptoalkanoic acid (MA) with different chain lengths on cysteine residues through a disulfide linkage to load hydrophobic doxorubicin (DOX). The results showed that the slightly negative-biased zwitterionic nanodrugs were very stable in both resistance to nonspecific plasma protein adsorption and prevention of premature DOX release at physiological pH 7.4 due to the zwitterionic polypeptide shell and the sharp contrast in polarity between the shell and DOX-loaded core, while they can quickly release the loaded DOX through responding to both low pH values in the endosome/lysosome and high glutathione concentrations in the tumor cell cytoplasm. Furthermore, the enhanced internalization of these nanodrugs led to about 60% higher in vitro cytotoxicity against MCF-7 cells at pH 6.7 than at pH 7.4, whereas the in vitro cytotoxicity of DOX·HCl at pH 6.7 was only 75% of the value at pH 7.4. In vivo results revealed that the stable nanodrugs conjugated with the long hydrophobic 12-mercaptododecanoic acid had higher tumor inhibition rate and lower systematic toxicity on MCF-7 tumor-bearing mice than the less stable nanodrugs conjugated with the short 8-mercaptooctaoic acid and were significantly superior to DOX·HCl. These results indicate that the combination of high stability in circulation and fast release in tumor cells of nanodrugs can enhance high efficacy targeted chemotherapy. This pH/redox-sensitive zwitterionic polypeptide nanocarrier might provide an excellent vehicle for solid tumor treatment.

Challenges towards Targeted Drug Delivery in Cancer Nanomedicines

Despite cancer nanomedicine celebrates already thirty years since its introduction, together with the achievements and progress in cancer treatment area, it still undergoes serious disadvantages that must be addressed. Since the first observation that macromolecules tend to accumulate in tumor tissue due to fenestrated endothelial of vasculature, considered as the “royal gate” in drug delivery field, more than dozens of nanoformulations have been approved and introduced into the practice for cancer treatment. Lipid, polymeric, and hybrid nanocarriers are biocompatible nano-drug delivery systems (NDDs) having suitable physicochemical properties and modulate payload release in response to specific chemical or physical stimuli. Biopharmaceutical properties of NDDs and their efficacy in animal models and humans can significantly affect their impact and perspective in nanomedicine. One of the future directions could be focusing on personalized cancer treatment, considering the heterogeneity and complexity of each patient tumor tissue and the designing of multifunctional targeted NDDs combining synthetic nanomaterials and biological components, like cellular membranes, circulating proteins, RNAi/DNAi, which enforce the efficacy of NDDs and boost their therapeutic effect.

Lignin, lipid, protein, hyaluronic acid, starch, cellulose, gum, pectin, alginate and chitosan-based nanomaterials for cancer nanotherapy: Challenges and opportunities

Although nanotechnology-driven drug delivery systems are relatively new, they are rapidly evolving since the nanomaterials are deployed as effective means of diagnosis and delivery of assorted therapeutic agents to targeted intracellular sites in a controlled release manner. Nanomedicine and nanoparticulate drug delivery systems are rapidly developing as they play crucial roles in the development of therapeutic strategies for various types of cancer and malignancy. Nevertheless, high costs, associated toxicity and production of complexities are some of the critical barriers for their applications. Green nanomedicines have continually been improved as one of the viable approaches towards tumor drug delivery, thus making a notable impact on which considerably affect cancer treatment. In this regard, the utilization of natural and renewable feedstocks as a starting point for the fabrication of nanosystems can considerably contribute to the development of green nanomedicines. Nanostructures and biopolymers derived from natural and biorenewable resources such as proteins, lipids, lignin, hyaluronic acid, starch, cellulose, gum, pectin, alginate, and chitosan play vital roles in the development of cancer nanotherapy, imaging and management. This review uncovers recent investigations on diverse nanoarchitectures fabricated from natural and renewable feedstocks for the controlled/sustained and targeted drug/gene delivery systems against cancers including an outlook on some of the scientific challenges and opportunities in this field. Various important natural biopolymers and nanomaterials for cancer nanotherapy are covered and the scientific challenges and opportunities in this field are reviewed.

Application of advances in endocytosis and membrane trafficking to drug delivery

Multidisciplinary research efforts in the field of drug delivery have led to the development of a variety of drug delivery systems (DDS) designed for site-specific delivery of diagnostic and therapeutic agents. Since efficient uptake of drug carriers into target cells is central to effective drug delivery, a comprehensive understanding of the biological pathways for cellular internalization of DDS can facilitate the development of DDS capable of precise tissue targeting and enhanced therapeutic outcomes. Diverse methods have been applied to study the internalization mechanisms responsible for endocytotic uptake of extracellular materials, which are also the principal pathways exploited by many DDS. Chemical inhibitors remain the most commonly used method to explore endocytotic internalization mechanisms, although genetic methods are increasingly accessible and may constitute more specific approaches. This review highlights the molecular basis of internalization pathways most relevant to internalization of DDS, and the principal methods used to study each route. This review also showcases examples of DDS that are internalized by each route, and reviews the general effects of biophysical properties of DDS on the internalization efficiency. Finally, options for intracellular trafficking and targeting of internalized DDS are briefly reviewed, representing an additional opportunity for multi-level targeting to achieve further specificity and therapeutic efficacy.

Co-delivery of dual chemo-drugs with precisely controlled, high drug loading polymeric micelles for synergistic anti-cancer therapy

Simultaneous delivery of multiple chemotherapeutics using polymeric micelles often suffers from unsatisfactory drug loading, drug ratio management, and drug release. Herein, we report a feasible strategy to prepare micelles with ultra-high drug loading and a controllable drug ratio through the introduction of donor-acceptor interactions between drugs and polymeric carriers. An amphiphilic copolymer modified with phenylboronic acid moieties on the hydrophobic segment was synthesized, in which phenylboronic acid functioned as an electron acceptor and formed donor-acceptor coordination with doxorubicin (DOX) and irinotecan (IR). The obtained dual-drug-loaded micelles possessed high drug loading (up to 50%), a tunable drug ratio, and a uniform particle size. Furthermore, both of the encapsulated drug cargoes could be effectively and selectively released in cancer cells with over-produced reactive oxygen species (ROS), and thus the drug-loaded micelles exhibited synergistic anticancer efficacy and reduced systemic toxicity.

Harnessing the layer-by-layer assembly technique to design biomaterials vaccines for immune modulation in translational applications

The existence of challenging diseases such as cancers, HIV and Zika requires developing new vaccines that can generate tunable and robust immune responses against the diseases. Biomaterials-based techniques have been broadly explored for designing vaccines that can produce controllable and potent immunity. Among the existing biomaterials-based strategies, the layer-by-layer (LbL) assembly technique is remarkably attractive in vaccine design due to its unique features such as programmed and versatile cargo loading, cargo protection, co-delivery, juxtaposing of immune signals, etc. In this work, we reviewed the existing LbL-based vaccine design techniques for translational applications. Specifically, we discussed nanovaccines constructed by coating polyelectrolyte multilayers (PEMs) on nanoparticles, microcapsule vaccines assembled from PEMs, polyplex/complex vaccines condensed from charged materials and microneedle vaccines deposited with PEMs, highlighting the employment of these techniques to promote immunity against diseases ranging from cancers to infectious and autoimmune diseases (i.e., HIV, influenza, multiple sclerosis, etc.). Additionally, the review specifically emphasized using LbL-based vaccine technologies for tuning the cellular and molecular pathways, demonstrating the unique advantages presented by these vaccination strategies. These studies showed the versatility and potency of using LbL-based techniques for designing the next generation of biomaterials vaccines for translational purposes.

Enhanced cytotoxic T lymphocytes recruitment targeting tumor vasculatures by endoglin aptamer and IP-10 plasmid presenting liposome-based nanocarriers

Background: Adequate recruitment of highly active tumor antigen-specific cytotoxic T lymphocytes (CTLs) remains a major challenge in cancer immunotherapy.

Objective: To construct liposome (LP)-based nanocapsules with surface endoglin aptamer (ENG-Apt) encapsulating mouse interferon-inducible protein-10 (mIP-10), with the ability to target mouse tumor vascular endothelial cells (mTECs) and enhance CTLs targeting and recruitment to the tumor vasculature.

Methods: ENG-Apt/mIP-10-LP nanocapsules were prepared by grafting DSPE-PEG₂₀₀₀-ENG-Apt on the surface of liposomes containing mIP-10 plasmids, characterized and assessed for the cell binding specificity in vitro. The tumor-targeting ability of ENG-Apt/mIP-10-LP nanocapsules was evaluated in vivo. The anti-tumor efficacy of ENG-Apt/mIP-10-LP nanocapsules treatment, as well as the combination treatment of ENG-Apt/mIP-10-LP nanocapsules and adoptive TRP2CD8⁺ T cells, were both tested in melanoma-bearing mice, by evaluation of the tumor volume and the mouse survival time. To discuss the anti-tumoral mechanism of ENG-Apt/mIP-10-LP nanocapsules-based therapies, IFN-γ secretion, proportion of TRP2CD8⁺ T cells among TILs, MDSCs in the tumor microenvironment and Tregs in the spleen, were determined after the treatments. Proliferation and apoptosis of tumor cells, and tumor angiogenesis were also assessed.

Results: The prepared ENG-Apt/mIP-10-LP nanocapsules possess an adequate nanometric size, good stability, high specificity to mTECs and tumor sites, along with the ability to induce mIP-10 expression in vitro and in vivo. Treatment of ENG-Apt/mIP-10-LP nanocapsules demonstrated CTLs enrichment into the tumor site, which inhibited tumor cell proliferation and angiogenesis, as well as promoted tumor-cell apoptosis, leading to a decrease in tumor progression and prolonged survival time in melanoma tumor-bearing mice. In addition, the proportion of MDSCs and Tregs was found to decrease. The combination of ENG-Apt/mIP-10-LP nanocapsules with adoptive TRP2CD8⁺ T cells, showed stronger abilities in inhibiting tumor growth and increasing animal survival time, thereby displayed an enhanced anti-melanoma tumor efficacy, due to the recruitment of both endogenous CD8⁺ T cells and exogenous TRP2CD8⁺ T cells in vivo.

Conclusion: ENG-Apt/mIP-10-LP nanocapsules could enhance the recruitment of both endogenous and exogenous CTLs specifically targeting melanoma tumor vasculatures and exert anti-tumoral effect, therefore provides a potentially novel strategy for tumor immunotherapy.

Co-delivery of Cyclopamine and Doxorubicin Mediated by Bovine Serum Albumin Nanoparticles Reverses Doxorubicin Resistance in Breast Cancer by Down-regulating P-glycoprotein Expression

Combination chemotherapy is considered to be one of the most effective treatments for breast cancer by reducing the emergence of drug resistance. In this study, a novel drug delivery system based on bovine serum albumin nanoparticles (BSA NPs) was successfully developed. Doxorubicin (DOX) and cyclopamine (CYC), a potential anti-cancer agent that inhibits the hedgehog signaling pathway were entrapped into BSA NPs through electrostatic interactions and hydrophobic interactions, respectively. Rather than simple combination of two different chemotherapeutics, the CYC also increased the intracellular DOX accumulation by decreasing the expression of P-glycoprotein (P-gp), which could thus reverse the DOX resistance. Tumor-targeting property of nanoparticles was the prerequisite for its further application. Interestingly, retention of fluorescently-labeled particles in vivo indicated that the dual-drug-loaded BSA NPs could not only target the primary tumors, but also target the metastatic lymph nodes, which would simultaneously inhibit the tumor growth and distant metastasis. Taken together, this study provides a promising strategy for co-delivery of drugs, tumor and metastatic lymph node targeting, and DOX resistance reversing in breast cancer chemotherapy.

Paclitaxel-loaded pH responsive hydrogel based on self-assembled peptides for tumor targeting

Intratumoral delivery of chemotherapeutic agents may permit the localization of drugs in tumors, decrease nonspecific targeting and increase efficacy.

Polymer–antibiotic conjugates as antibacterial additives in dental resins

Dental resins containing polymer–antibiotic conjugates (PACs) demonstrate significant antibacterial properties.

Cancer nanomedicine: focus on recent developments and self-assembled peptide nanocarriers

The applications of nanoparticulate drug delivery have received abundant interest in the field of cancer diagnosis and treatment.

Understanding the effect of alkyl chains of gemini cations on the physicochemical and cellular properties of polyurethane micelles

Cationic gemini quaternary ammonium (GQA) has been used as a cell internalization promoter to improve the permeability of the cell membrane and enhance the cellular uptake. However, the effect of the alkyl chain length on the cellular properties of nanocarriers has not been elucidated yet. In this study, we developed a series of polyurethane micelles containing GQAs with various alkyl chain lengths. The alteration of the gemini alkyl chain length was found to change the distribution of GQA surfactants in the micellar structure and affect the surface charge exposure, stability, and the protein absorption properties of nanocarriers. Moreover, we also clarified the role of the alkyl chain length in tumor cell internalization and macrophage uptake of polyurethane micelles. This work provides a new understanding on the effect of the GQA alkyl chain length on the physicochemical and biological properties of nanomedicines, and offers guidance on the rational design of effective drug delivery systems where the issue of functional group exposure at the micellar surface should be considered.