Polymer conjugates: nanosized medicines for treating cancer

Polysaccharide mediated nanodrug delivery: A review

Polysaccharides have drawn a lot of attention due to their potential as carriers for drugs and other bioactive chemicals. In drug delivery systems, natural macromolecules such as polysaccharides are widely utilized as polymers. This utilization extends to various polysaccharides employed in the development of nanoparticles for medicinal administration, with the goal of enhancing therapeutic efficacy while minimizing side effects. This study not only offers an overview of the existing challenges faced by these materials but also provides detailed information on key polysaccharides expertly engineered into nanoparticles. Noteworthy examples include Bael Fruit Gum, Guar Gum, Pectin, Agar, Cellulose, Alginate, Chitin, and Gum Acacia, each selected for their distinctive properties and strategically integrated into nanoparticles. The exploration of these natural macromolecules illuminates their diverse applications and underscores their potential as effective carriers in drug delivery systems. By delving into the unique attributes of each polysaccharide, this review aims to contribute valuable insights to the ongoing advancements in nanomedicine and pharmaceutical technologies. The overarching objective of this review research is to assess the utilization and comprehension of polysaccharides in nanoapplications, further striving to promote their continued integration in contemporary therapeutics and industrial practices.

Gastric cancer specific drug delivery with hydrophilic peptide probe conjugation

Cancer-specific diagnosis is challenging. Phage display is an approach that could contribute to finding new specific biomarkers. In this study, we developed a new peptide probe specific for gastric cancer and validated it for gastric cancer-specific theranostics. We isolated linear peptides by screening a combinatorial phage library for a cancer stem cell marker, LGR5 protein. Among these, peptides with high selectivity against gastric cancer cells were selected and examined for therapeutic poteintial in vitro as well as in vivo. Through leucine-rich G protein-coupled receptor 5 (LGR5) protein-based phage display, we obtained a hydrophilic 7-mer peptide sequence (STCTRSR, named STC). Both the STC-peptide-conjugated fluorescent dye and chlorin e6 (Ce6) displayed a significantly higher intensity in gastric cancer cells compared to that in healthy cells. In mice with gastric cancer, the fluorescence in the tumors was 3.4× more intense when treated with the Ce6-STC conjugate compared to that with free Ce6 and conferred higher phototoxicity after single laser irradiation. Repeated photodynamic therapy could further reduce the tumor volume after treating these mice with the Ce6-STC conjugate. The treatment with the Ce6-STC conjugate exhibited a significantly lower fluorescence in the liver than that with free Ce6. In conclusion, we confirmed that the STC peptide is a gastric cancer-specific probe that could be useful in gastric cancer theranostics. In conclusion, considering its targeting ability and hydrophilicity, various hydrophobic chemotherapeutic agents could be revisited for gastric cancer treatment in combination with the probe described in this study.

FhuA: From Iron-Transporting Transmembrane Protein to Versatile Scaffolds through Protein Engineering

ConspectusProtein engineering has emerged as a powerful methodology to tailor the properties of proteins. It empowers the design of biohybrid catalysts and materials, thereby enabling the convergence of materials science, chemistry, and medicine. The choice of a protein scaffold is an important factor for performance and potential applications. In the past two decades, we utilized the ferric hydroxamate uptake protein FhuA. FhuA is, from our point of view, a versatile scaffold due to its comparably large cavity and robustness toward temperature as well as organic cosolvents. FhuA is a natural iron transporter located in the outer membrane of Escherichia coli (E. coli). Wild-type FhuA consists of 714 amino acids and has a β-barrel structure composed of 22 antiparallel β-sheets, closed by an internal globular "cork" domain (amino acids 1-160). FhuA is robust in a broad pH range and toward organic cosolvents; therefore, we envisioned FhuA to be a suitable platform for various applications in (i) biocatalysis, (ii) materials science, and (iii) the construction of artificial metalloenzymes.(i) Applications in biocatalysis were achieved by removing the globular cork domain (FhuA_Δ1-160), thereby creating a large pore for the passive transport of otherwise difficult-to-import molecules through diffusion. Introducing this FhuA variant into the outer membrane of E. coli facilitates the uptake of substrates for downstream biocatalytic conversion. Furthermore, removing the globular "cork" domain without structural collapse of the ß-barrel protein allowed the use of FhuA as a membrane filter, exhibiting a preference for d-arginine over l-arginine.(ii) FhuA is a transmembrane protein, which makes it attractive to be used for applications in non-natural polymeric membranes. Inserting FhuA into polymer vesicles yielded so-called synthosomes (i.e., catalytic synthetic vesicles in which the transmembrane protein acted as a switchable gate or filter). Our work in this direction enables polymersomes to be used in biocatalysis, DNA recovery, and the controlled (triggered) release of molecules. Furthermore, FhuA can be used as a building block to create protein-polymer conjugates to generate membranes.(iii) Artificial metalloenzymes (ArMs) are formed by incorporating a non-native metal ion or metal complex into a protein. This combines the best of two worlds: the vast reaction and substrate scope of chemocatalysis and the selectivity and evolvability of enzymes. With its large inner diameter, FhuA can harbor (bulky) metal catalysts. Among others, we covalently attached a Grubbs-Hoveyda-type catalyst for olefin metathesis to FhuA. This artificial metathease was then used in various chemical transformations, ranging from polymerizations (ring-opening metathesis polymerization) to enzymatic cascades involving cross-metathesis. Ultimately, we generated a catalytically active membrane by copolymerizing FhuA and pyrrole. The resulting biohybrid material was then equipped with the Grubbs-Hoveyda-type catalyst and used in ring-closing metathesis.The number of reports on FhuA and its various applications indicates that it is a versatile building block to generate hybrid catalysts and materials. We hope that our research will inspire future research efforts at the interface of biotechnology, catalysis, and material science in order to create biohybrid systems that offer smart solutions for current challenges in catalysis, material science, and medicine.

Hidden hydrophobicity impacts polymer immunogenicity

Antibodies against poly(ethylene glycol) (PEG) have been found to be the culprit of side reactions and efficacy loss of a number of PEGylated drugs. Fundamental mechanisms of PEG immunogenicity and design principles for PEG alternatives still have not been fully explored. By using hydrophobic interaction chromatography (HIC) under varied salt conditions, we reveal the "hidden" hydrophobicity of those polymers which are generally considered as hydrophilic. A correlation between the hidden hydrophobicity of a polymer and its polymer immunogenicity is observed when this polymer is conjugated with an immunogenic protein. Such a correlation of hidden hydrophobicity vs. immunogenicity for a polymer also applies to corresponding polymer-protein conjugates. Atomistic molecular dynamics (MD) simulation results show a similar trend. Based on polyzwitterion modification and with this HIC technique, we are able to produce extremely low-immunogenic protein conjugates as their hydrophilicity is pushed to the limit and their hydrophobicity is eliminated, breaking the current barriers of eliminating anti-drug and anti-polymer antibodies.

A Multifunctional Conjugated Polymer Developed as an Efficient System for Differentiation of SH-SY5Y Tumour Cells

Polymer-based systems have been demonstrated in novel therapeutic and diagnostic (theranostic) treatments for cancer and other diseases. Polymers provide a useful scaffold to develop multifunctional nanosystems that combine various beneficial properties such as drug delivery, bioavailability, and photosensitivity. For example, to provide passive tumour targeting of small drug molecules, polymers have been used to modify and functionalise the surface of water-insoluble drugs. This approach also allows the reduction of adverse side effects, such as retinoids. However, multifunctional polymer conjugates containing several moieties with distinct features have not been investigated in depth. This report describes the development of a one-pot approach to produce a novel multifunctional polymer conjugate. As a proof of concept, we synthesised polyvinyl alcohol (PVA) covalently conjugated with rhodamine B (a tracking agent), folic acid (a targeting agent), and all-trans retinoic acid (ATRA, a drug). The obtained polymer (PVA@RhodFR) was characterised by MALDI-TOF mass spectrometry, gel permeation chromatography, thermal analysis, dynamic light-scattering, NMR, UV-Vis, and fluorescence spectroscopy. Finally, to evaluate the efficiency of the multifunctional polymer conjugate, cellular differentiation treatments were performed on the neuroblastoma SH-SY5Y cell line. In comparison with standard ATRA-based conditions used to promote cell differentiation, the results revealed the high capability of the new PVA@RhodFR to induce neuroblastoma cells differentiation, even with a short incubation time and low ATRA concentration.

Poly(Styrene-Co-Maleic Acid)-Conjugated 6-Aminofluorescein and Rhodamine Micelle as Macromolecular Fluorescent Probes for Micro-Tumors Detection and Imaging

Styrene-co-maleic acid (SMA) copolymer was evaluated as a polymer platform to conjugate with two fluorescent dyes, i.e., 6-aminofluorescein (AF) and Rhodamine (Rho); which spontaneously self-assembles in an aqueous medium and forms a micelle through a non-covalent interaction. These SMA-dye conjugates showed the nanosized micelle formation through dynamic light scattering (DLS) with discrete distributions having mean particle sizes of 135.3 nm, and 190.9 nm for SMA-AF, and SMA-Rho, respectively. The apparent molecular weight of the micelle was evaluated using Sephadex G-100 gel chromatography and it was found that the 49.3 kDa, and 28.7 kDa for SMA-AF, and SMA-Rho, respectively. Moreover, the biodistribution study showed the selective accumulation of the SMA-dye conjugates in the tumor of mice. Taken together, the SMA-dye conjugated micelles appear in high concentrations in the tumor by utilizing the enhanced permeability and retention (EPR) effect of the tumor-targeted delivery. These results indicate that SMA-dye conjugates have the advanced potential as macromolecular fluorescent probes for microtumor imaging by means of a photodynamic diagnosis.

Embelin and Its Derivatives: Design, Synthesis, and Potential Delivery Systems for Cancer Therapy

Embelin is a naturally occurring benzoquinone that inhibits the growth of cancer cells, making it a potent anticancer drug. However, the low water solubility of embelin restricts its clinical applicability. This review provides a concise summary and in-depth analysis of the published literature on the design and synthesis of embelin derivatives possessing increased aqueous solubility and superior therapeutic efficacy. In addition, the potential of drug delivery systems to improve the anticancer capabilities of embelin and its derivatives is discussed.

Nanomedicine and versatile therapies for cancer treatment

The higher prevalence of cancer is related to high rates of mortality and morbidity worldwide. By virtue of the properties of matter at the nanoscale, nanomedicine is proven to be a powerful tool to develop innovative drug carriers with greater efficacies and fewer side effects than conventional therapies. In this review, different nanocarriers for controlled drug release and their routes of administration have been discussed in detail, especially for cancer treatment. Special emphasis has been given on the design of drug delivery vehicles for sustained release and specific application methods for targeted delivery to the affected areas. Different polymeric vehicles designed for the delivery of chemotherapeutics have been discussed, including graft copolymers, liposomes, hydrogels, dendrimers, micelles, and nanoparticles. Furthermore, the effect of dimensional properties on chemotherapy is vividly described. Another integral section of the review focuses on the modes of administration of nanomedicines and emerging therapies, such as photothermal, photodynamic, immunotherapy, chemodynamic, and gas therapy, for cancer treatment. The properties, therapeutic value, advantages, and limitations of these nanomedicines are highlighted, with a focus on their increased performance versus conventional molecular anticancer therapies.

Polylactide Perspectives in Biomedicine: From Novel Synthesis to the Application Performance

The incessant developments in the pharmaceutical and biomedical fields, particularly, customised solutions for specific diseases with targeted therapeutic treatments, require the design of multicomponent materials with multifunctional capabilities. Biodegradable polymers offer a variety of tailored physicochemical properties minimising health adverse side effects at a low price and weight, which are ideal to design matrices for hybrid materials. PLAs emerge as an ideal candidate to develop novel materials as are endowed withcombined ambivalent performance parameters. The state-of-the-art of use of PLA-based materials aimed at pharmaceutical and biomedical applications is reviewed, with an emphasis on the correlation between the synthesis and the processing conditions that define the nanostructure generated, with the final performance studies typically conducted with either therapeutic agents by in vitro and/or in vivo experiments or biomedical devices.

Polyprodrug Nanomedicines: An Emerging Paradigm for Cancer Therapy

Nanomedicines have the potential to provide advanced therapeutic strategies in combating tumors. Polymer-prodrug-based nanomedicines are particularly attractive in cancer therapies owing to the maximum drug loading, prolonged blood circulation, and reduced premature leakage and side effects in comparison with conventional nanomaterials. However, the difficulty in precisely tuning the composition and drug loading of polymer-drug conjugates leads to batch-to-batch variations of the prodrugs, thus significantly restricting their clinical translation. Polyprodrug nanomedicines inherit the numerous intrinsic advantages of polymer-drug conjugates and exhibit well-controlled composition and drug loading via direct polymerization of therapeutic monomers, representing a promising nanomedicine for clinical tumor therapies. In this review, recent advances in the development of polyprodrug nanomedicines are summarized for tumor elimination. Various types of polyprodrug nanomedicines and the corresponding properties are first summarized. The unique advantages of polyprodrug nanomedicines and their key roles in various tumor therapies are further highlighted. Finally, current challenges and the perspectives on future research of polyprodrug nanomedicines are discussed.

Chitosan-Coated-PLGA Nanoparticles Enhance the Antitumor and Antimigration Activity of Stattic – A STAT3 Dimerization Blocker

Purpose

The use of nanocarriers to improve the delivery and efficacy of antimetastatic agents is less explored when compared to cytotoxic agents. This study reports the entrapment of an antimetastatic Signal Transducer and Activator of Transcription 3 (STAT3) dimerization blocker, Stattic (S) into a chitosan-coated-poly(lactic-co-glycolic acid) (C-PLGA) nanocarrier and the improvement on the drug’s physicochemical, in vitro and in vivo antimetastatic properties post entrapment.

Methods

In vitro, physicochemical properties of the Stattic-entrapped C-PLGA nanoparticles (S@C-PLGA) and Stattic-entrapped PLGA nanoparticles (S@PLGA, control) in terms of size, zeta potential, polydispersity index, drug loading, entrapment efficiency, Stattic release in different medium and cytotoxicity were firstly evaluated. The in vitro antimigration properties of the nanoparticles on breast cancer cell lines were then studied by Scratch assay and Transwell assay. Study on the in vivo antitumor efficacy and antimetastatic properties of S@C-PLGA compared to Stattic were then performed on 4T1 tumor bearing mice.

Results

The S@C-PLGA nanoparticles (141.8 ± 2.3 nm) was hemocompatible and exhibited low Stattic release (12%) in plasma. S@C-PLGA also exhibited enhanced in vitro anti-cell migration potency (by >10-fold in MDA-MB-231 and 5-fold in 4T1 cells) and in vivo tumor growth suppression (by 33.6%) in 4T1 murine metastatic mammary tumor bearing mice when compared to that of the Stattic-treated group. Interestingly, the number of lung and liver metastatic foci was found to reduce by 50% and 56.6%, respectively, and the average size of the lung metastatic foci was reduced by 75.4% in 4T1 tumor-bearing mice treated with S@C-PLGA compared to Stattic-treated group (p < 0.001).

Conclusion

These findings suggest the usage of C-PLGA nanocarrier to improve the delivery and efficacy of antimetastatic agents, such as Stattic, in cancer therapy.

Bioactive Synthetic Polymers

Synthetic polymers are omnipresent in society as textiles and packaging materials, in construction and medicine, among many other important applications. Alternatively, natural polymers play a crucial role in sustaining life and allowing organisms to adapt to their environments by performing key biological functions such as molecular recognition and transmission of genetic information. In general, the synthetic and natural polymer worlds are completely separated due to the inability for synthetic polymers to perform specific biological functions; in some cases, synthetic polymers cause uncontrolled and unwanted biological responses. However, owing to the advancement of synthetic polymerization techniques in recent years, new synthetic polymers have emerged that provide specific biological functions such as targeted molecular recognition of peptides, or present antiviral, anticancer, and antimicrobial activities. In this review, the emergence of this generation of bioactive synthetic polymers and their bioapplications are summarized. Finally, the future opportunities in this area are discussed.

Synthesis, cytotoxicity assay, pharmacokinetics, biodistribution and modeling study of cabazitaxel-dextran nanoconjugates: targeted vs non targeted delivery

Cabazitaxel (CTX) is an anti-neoplastic agent of second-generation taxane derivatives, characterized by very low water solubility. The currently marketed formulation of CTX contains high concentrations of surfactant and ethanol, which causes severe hypersensitivity reactions in patients. To deal with aforementioned side effects, our previous study attempted to develop the prodrugs of CTX with dextran. Here our approach differs through synthesizing folate containing prodrug and also investigating cytotoxicity and pharmacokinetics parameters obtained with dextran and dextran-folate nanoconjugates versus free CTX. MCF-7 with medium folate receptor expression and MDA-MB-231 as high folate receptor expression cell lines were selected for cytotoxicity assay. Pharmacokinetics properties were studied by injecting prodrugs and CTX to Wistar rats, analyzing serum and selected tissue samples and the obtained results were sibjected to data modeling study. The size of synthesized prodrugs was mostly less than 90 nm. Folate conjugates provided higher toxicity in comparison with dextran conjugates on both cell lines. In vivo non-compartmental pharmacokinetics analysis revealed enhanced area under the curve (about 3-5 fold for different samples) and longer half-life (approximately 1.3-1.8 fold higher) which led to increased serum residence time of prodrugs in comparison to free CTX. Tissue accumulation data showed that liver was the major organ with high accumulation of CTX. The accumulation of folate conjugates was remarkably higher than dextran samples (p < 0.05 in samples of 2, 10 and 24 h). Data modeling by Principal Component Analysis (PCA) and Hierarchical Cluster models showed a significant difference between pharmacokinetics properties of CTX and prodrugs. In summary, prodrugs seem to be proper and promising CTX delivery systems as substitution for the current market formulation.

Hurdles for the wide implementation of photoimmunotherapy

Near infrared photoimmunotherapy (NIR-PIT) is a molecularly targeted treatment for cancers achieved by injecting a conjugate of IRDye700DX^® (IR700), a water-soluble silicon phthalocyanine derivative in the near infrared, and a monoclonal antibody that targets cancer cell antigens. NIR-PIT is a highly specific treatment with few side effects that results in rapid immunogenic cell death. Despite it being a very effective and innovative therapy, there are a few challenges preventing full implementation in clinical practice. These include the limits of near infrared light penetration, selection of targets, concerns about tumor lysis syndrome and drug costs. However, NIR-PIT has been approved by the regulatory authorities in Japan, allowing for exploration of how to mitigate challenges while maximizing the benefits of this treatment modality.

ASP-Enzymosomes with Saccharomyces cerevisiae Asparaginase II Expressed in Pichia pastoris: Formulation Design and In Vitro Studies of a Potential Antileukemic Drug

The bacterial enzyme asparaginase is the main treatment option for acute lymphoblastic leukemia. However, it causes side effects, such as immunological reactions, and presents undesirable glutaminase activity. As an alternative, we have been studying asparaginase II from Saccharomyces cerevisiae, coded by ASP3 gene, which was cloned and expressed in Pichia pastoris. The recombinant asparaginase (ASP) presented antileukemic activity and a glutaminase activity 100 times lower in comparison to its asparaginase activity. In this work, we describe the development of a delivery system for ASP via its covalent attachment to functionalized polyethylene glycol (PEG) polymer chains in the outer surface of liposomes (ASP-enzymosomes). This new delivery system demonstrated antiproliferative activity against K562 (chronic myeloid leukemia) and Jurkat (acute lymphocytic leukemia) cell lines similar to that of ASP. The antiproliferative response of the ASP-enzymosomes against the Jurkat cells suggests equivalence to that of the free Escherichia coli commercial asparaginase (Aginasa^®). Moreover, the ASP-enzymosomes were stable at 4 °C with no significant loss of activity within 4 days and retained 82% activity up to 37 days. Therefore, ASP-enzymosomes are a promising antileukemic drug.

Nanotechnologies for the delivery of biologicals: Historical perspective and current landscape

Biological macromolecule-based therapeutics irrupted in the pharmaceutical scene generating a great hope due to their outstanding specificity and potency. However, given their susceptibility to degradation and limited capacity to overcome biological barriers new delivery technologies had to be developed for them to reach their targets. This review aims at analyzing the historical seminal advances that shaped the development of the protein/peptide delivery field, along with the emerging technologies on the lead of the current landscape. Particularly, focus is made on technologies with a potential for transmucosal systemic delivery of protein/peptide drugs, followed by approaches for the delivery of antigens as new vaccination strategies, and formulations of biological drugs in oncology, with special emphasis on mAbs. Finally, a discussion of the key challenges the field is facing, along with an overview of prospective advances are provided.

Preparation and Characterization of Palladium Derivate-Loaded Micelle Formulation in Vitro as an Innovative Therapy Option against Non-Small Cell Lung Cancer Cells

Nanoparticles have been used in cancer treatments to target tumor and reduce side effects. In this study, we aimed to increase the effectiveness of palladium(II) complex [PdCl(terpy)](sac) ⋅ 2H₂ O, which previously showed anticancer potential, by preparing the nanoparticle formulation. An inhalable micellar dispersion containing a palladium(II) complex (PdNP) was prepared and its physicochemical characteristics were evaluated using in vitro tests. Morphology, size and surface charges of particle and loading/encapsulation efficiency of PdNP were analyzed by scanning electron microscopy, zeta sizer and inductively coupled plasma mass spectrometry while aerosol properties of PdNP were measured by the next generation impactor. A549 and H1299 non-small lung cancer cell types were used for cytotoxicity using SRB and ATP assays. Fluorescent staining and M30 antigen assay were carried out for cell death evaluation. Apoptosis was confirmed by flow cytometry analyses. SEM, particle size, and zeta potential results showed the particles have inhalable properties. The amount of the palladium(II) complex loaded into the particles was quantified which indicated high encapsulation efficiencies (97 %). The micellar dispersion expected to reach the alveolar region and the brachial region was determined 35 % and 47 %, respectively. PdNP showed an anti-growth effect by increasing reactive oxygen species that is followed by the induction of mitochondria-dependent apoptosis that is evidenced by pyknotic nuclei and M30 antigen level increments and disruption of polarization of membrane in mitochondria (Δψm). The results show that PdNP might be a promising inhalable novel complex to be used in non-small cell lung cancer, which warrants animal studies in further.

Stimuli-Responsive Polymeric Nanoplatforms for Cancer Therapy

Polymeric nanoparticles have been widely used as carriers of drugs and bioimaging agents due to their excellent biocompatibility, biodegradability, and structural versatility. The principal application of polymeric nanoparticles in medicine is for cancer therapy, with increased tumor accumulation, precision delivery of anticancer drugs to target sites, higher solubility of pharmaceutical properties and lower systemic toxicity. Recently, the stimuli-responsive polymeric nanoplatforms attracted more and more attention because they can change their physicochemical properties responding to the stimuli conditions, such as low pH, enzyme, redox agents, hypoxia, light, temperature, magnetic field, ultrasound, and so on. Moreover, the unique properties of stimuli-responsive polymeric nanocarriers in target tissues may significantly improve the bioactivity of delivered agents for cancer treatment. This review introduces stimuli-responsive polymeric nanoparticles and their applications in tumor theranostics with the loading of chemical drugs, nucleic drugs and imaging molecules. In addition, we discuss the strategy for designing multifunctional polymeric nanocarriers and provide the perspective for the clinical applications of these stimuli-responsive polymeric nanoplatforms.

Polymer encapsulated clinical ICG nanoparticles for enhanced photothermal therapy and NIR fluorescence imaging in cervical cancer

Photothermal therapy (PTT) is a popular tumor therapy method, which is based on efficient photothermal nanoagents (PTNs). Clinical Indocyanine Green (ICG), as a Food and Drug Administration (FDA) approved agent, is an often-used PTN, meanwhile it is also a good near-infrared (NIR) fluorescence contrast agent. However, the further applications of ICG in biomedical fields are limited due to its poor stability. In this study, ICG was encapsulated by the amphiphilic polymer poly(styrene-co-maleic anhydride) (PSMA) to form ICG@PSMA nanoparticles. Furthermore, optical and thermal characteristics of ICG@PSMA nanoparticles were studied in detail. Strong NIR fluorescence and excellent photothermal properties of ICG@PSMA nanoparticles under 808 nm laser irradiation were measured. Besides, favorable biocompatibility of ICG@PSMA nanoparticles was demonstrated on a human cervical cancer cell line (HeLa) via cell viability studies. Hence, ICG@PSMA nanoparticles were further applied to enhanced PTT of living HeLa cells under 808 nm excitation, and a high PTT efficiency of ∼70% was obtained. The novel ICG nanoparticles as a promising PTT nanoplatform could offer an opportunity for further tumour treatments.

PSMA encapsulated Clinical ICG to form ICG@PSMA nanoparticles. ICG@PSMA nanoparticles showed strong NIR fluorescence and excellent photothermal properties.

Biomaterials-Based Delivery of Therapeutic Antibodies for Cancer Therapy

Considerable breakthroughs in the treatment of malignant tumors using antibody drugs, especially immunomodulating monoclonal antibodies (mAbs), have been made in the past decade. Despite technological advancements in antibody design and manufacture, multiple challenges face antibody-mediated cancer therapy, such as instability in vivo, poor tumor penetration, limited response rate, and undesirable off-target cytotoxicity. In recent years, an increasing number of biomaterials-based delivery systems have been reported to enhance the antitumor efficacy of antibody drugs. This review summarizes the advances and breakthroughs in integrating biomaterials with therapeutic antibodies for enhanced cancer therapy. A brief introduction to the principal mechanism of antibody-based cancer therapy is first established, and then various antibody immobilization strategies are provided. Finally, the current state-of-the-art in biomaterials-based antibody delivery systems and their applications in cancer treatment are summarized, highlighting how the delivery systems augment the therapeutic efficacy of antibody drugs. The outlook and perspective on biomaterials-based delivery of antitumor antibodies are also discussed.

Cell membrane cloaked nanomedicines for bio-imaging and immunotherapy of cancer: Improved pharmacokinetics, cell internalization and anticancer efficacy

Despite enormous advancements in the field of oncology, the innocuous and effectual treatment of various types of malignancies remained a colossal challenge. The conventional modalities such as chemotherapy, radiotherapy, and surgery have been remained the most viable options for cancer treatment, but lacking of target-specificity, optimum safety and efficacy, and pharmacokinetic disparities are their impliable shortcomings. Though, in recent decades, numerous encroachments in the field of onco-targeted drug delivery have been adapted but several limitations (i.e., short plasma half-life, early clearance by reticuloendothelial system, immunogenicity, inadequate internalization and localization into the onco-tissues, chemoresistance, and deficient therapeutic efficacy) associated with these onco-targeted delivery systems limits their clinical viability. To abolish the aforementioned inadequacies, a promising approach has been emerged in which stealthing of synthetic nanocarriers has been attained by cloaking them into the natural cell membranes. These biomimetic nanomedicines not only retain characteristics features of the synthetic nanocarriers but also inherit the cell-membrane intrinsic functionalities. In this review, we have summarized preparation methods, mechanism of cloaking, and pharmaceutical and therapeutic superiority of cell-membrane camouflaged nanomedicines in improving the bio-imaging and immunotherapy against various types of malignancies. These pliable adaptations have revolutionized the current drug delivery strategies by optimizing the plasma circulation time, improving the permeation into the cancerous microenvironment, escaping the immune evasion and rapid clearance from the systemic circulation, minimizing the immunogenicity, and enabling the cell-cell communication via cell membrane markers of biomimetic nanomedicines. Moreover, the preeminence of cell-membrane cloaked nanomedicines in improving the bio-imaging and theranostic applications, alone or in combination with phototherapy or radiotherapy, have also been pondered.

Dual Antibody-Conjugated Amyloid Nanorods to Promote Selective Cell-Cell Interactions

Grafting biomolecules on nanostructures' surfaces is an increasingly used strategy to target pathogenic cells, with both diagnostic and therapeutic applications. However, nanomaterials monofunctionalized by conjugating a single type of ligand find limited uses in pathologies/therapies that require two or more targets/receptors to be targeted and/or activated with a single molecular entity simultaneously. Therefore, multivalent nanomaterials for dual- or multitargeting are attracting significant interest. This study provides a proof of concept of such nanostructures. We have recently developed a modular methodology that allows obtaining amyloid-based materials decorated with active globular domains. Here, this approach is exploited to generate functional amyloid fibrils displaying antibody capture moieties. A high antibody binding affinity and capacity for the resulting nanofibrils, whose size can be manipulated to obtain homogeneous nanorods with high biocompatibility, are demonstrated. These nanorods are then used for specific antibody-mediated targeting of different cell types. Simultaneous conjugation of these nanorods with different antibodies allows obtaining a mimic of a bispecific antibody that redirects T lymphocytes to tumoral cells, holding high potential for immunotherapy. Overall, the work illustrates a modular and straightforward strategy to obtain preparative quantities of multivalent antibody-functionalized nanomaterials with multitargeting properties without the need for covalent modification.

Antibody-drug nanoparticle induces synergistic treatment efficacies in HER2 positive breast cancer cells

Chemotherapeutic drugs suffer from non-specific binding, undesired toxicity, and poor blood circulation which contribute to poor therapeutic efficacy. In this study, antibody–drug nanoparticles (ADNs) are engineered by synthesizing pure anti-cancer drug nanorods (NRs) in the core of nanoparticles with a therapeutic monoclonal antibody, Trastuzumab on the surface of NRs for specific targeting and synergistic treatments of human epidermal growth factor receptor 2 (HER2) positive breast cancer cells. ADNs were designed by first synthesizing ~ 95 nm diameter × ~ 500 nm long paclitaxel (PTX) NRs using the nanoprecipitation method. The surface of PTXNRs was functionalized at 2′ OH nucleophilic site using carbonyldiimidazole and conjugated to TTZ through the lysine residue interaction forming PTXNR-TTZ conjugates (ADNs). The size, shape, and surface charge of ADNs were characterized using scanning electron microscopy (SEM), SEM, and zeta potential, respectively. Using fluorophore labeling and response surface analysis, the percentage conjugation efficiency was found > 95% with a PTX to TTZ mass ratio of 4 (molar ratio ≈ 682). In vitro therapeutic efficiency of PTXNR-TTZ was evaluated in two HER2 positive breast cancer cell lines: BT-474 and SK-BR-3, and a HER2 negative MDA-MB-231 breast cancer cell using MTT assay. PTXNR-TTZ inhibited > 80% of BT-474 and SK-BR-3 cells at a higher efficiency than individual PTX and TTZ treatments alone after 72 h. A combination index analysis indicated a synergistic combination of PTXNR-TTZ compared with the doses of single-drug treatment. Relatively lower cytotoxicity was observed in MCF-10A human breast epithelial cell control. The molecular mechanisms of PTXNR-TTZ were investigated using cell cycle and Western blot analyses. The cell cycle analysis showed PTXNR-TTZ arrested > 80% of BT-474 breast cancer cells in the G2/M phase, while > 70% of untreated cells were found in the G0/G1 phase indicating that G2/M arrest induced apoptosis. A similar percentage of G2/M arrested cells was found to induce caspase-dependent apoptosis in PTXNR-TTZ treated BT-474 cells as revealed using Western blot analysis. PTXNR-TTZ treated BT-474 cells showed ~ 1.3, 1.4, and 1.6-fold higher expressions of cleaved caspase-9, cytochrome C, and cleaved caspase-3, respectively than untreated cells, indicating up-regulation of caspase-dependent activation of apoptotic pathways. The PTXNR-TTZ ADN represents a novel nanoparticle design that holds promise for targeted and efficient anti-cancer therapy by selective targeting and cancer cell death via apoptosis and mitotic cell cycle arrest.

Robotics, microfluidics, nanotechnology and AI in the synthesis and evaluation of liposomes and polymeric drug delivery systems

The field of nanotechnology and personalised medicine is undergoing drastic changes in the approach and efficiency of experimentation. The COVID-19 pandemic has spiralled into mass stagnation of major laboratories around the globe and led to increased investment into remote systems for nanoparticle experiments. A significant number of laboratories now operate using automated systems; however, the extension to nanoparticle preparation and artificial intelligence-dependent databases holds great translational promise. The strive to combine automation with artificial intelligence (AI) grants the ability to optimise targeted therapeutic nanoparticles for unique cell types and patients. In this perspective, the current and future trends of automated approaches to nanomedicine synthesis are discussed and compared with traditional methods.

Nanomedicine Reformulation of Chloroquine and Hydroxychloroquine

The chloroquine family of antimalarials has a long history of use, spanning many decades. Despite this extensive clinical experience, novel applications, including use in autoimmune disorders, infectious disease, and cancer, have only recently been identified. While short term use of chloroquine or hydroxychloroquine is safe at traditional therapeutic doses in patients without predisposing conditions, administration of higher doses and for longer durations are associated with toxicity, including retinotoxicity. Additional liabilities of these medications include pharmacokinetic profiles that require extended dosing to achieve therapeutic tissue concentrations. To improve chloroquine therapy, researchers have turned toward nanomedicine reformulation of chloroquine and hydroxychloroquine to increase exposure of target tissues relative to off-target tissues, thereby improving the therapeutic index. This review highlights these reformulation efforts to date, identifying issues in experimental designs leading to ambiguity regarding the nanoformulation improvements and lack of thorough pharmacokinetics and safety evaluation. Gaps in our current understanding of these formulations, as well as recommendations for future formulation efforts, are presented.

Redox-sensitive polyglutamic acid-platinum(IV) prodrug grafted nanoconjugates for efficient delivery of cisplatin into breast tumor

Targeting cisplatin to the sites of action and decreasing its side effects are still major challenges. Here, we introduced a polyglutamic acid-platinum(IV) prodrug nanoconjugates (γ-PGA-CA-Pt(IV)) constructed by polyglutamic acid and modified platinum(IV) prodrug to reserve the anti-tumor efficacy of cisplatin with decreased side effects. We describe the synthesis, physico-chemical characterization, and redox- and pH-sensitive releasing behavior of the nanoconjugate. In vitro studies revealed that, when incubated with glutathione in advance, the γ-PGA-CA-Pt(IV) nanoconjugate induced significant apoptosis in human breast carcinoma MCF-7 cells. From in vivo antitumor efficacy evaluation, the γ-PGA-CA-Pt(IV) nanoconjugate obviously improved the survival rate of tumor-bearing mice with inhibition of the tumor growth compared with cisplatin. Meanwhile, the nanoconjugates showed remarkable improved safety profile than the free cisplatin.

A dual-functional buformin-mimicking poly(amido amine) for efficient and safe gene delivery

Biguanides (i.e. metformin, phenformin and buformin) are antidiabetic drugs with potential antitumor effects. Herein, a polycationic polymer, N,N'-bis(cystamine)acrylamide-buformin (CBA-Bu), containing multiple biodegradable disulphide bonds and buformin-mimicking side chains was synthesised. CBA-Bu was equipped with high efficiency and safety profile for gene delivery, meanwhile exhibiting potential antitumor efficacy. As a gene vector, CBA-Bu was able to condense plasmid DNA (pDNA) into nano-sized (<200 nm), positively-charged (>30 mV) uniform polyplexes that were well resistant to heparin and DNase I. Due to the reduction responsiveness of the disulphide bonds, CBA-Bu/pDNA polyplexes could release the loaded pDNA in the presence of dithiothreitol, and induce extremely low cytotoxicity in NIH/3T3 and U87 MG cells. The transfection results showed that CBA-Bu had a cellular uptake efficiency comparable to 25 kDa PEI, while a significantly higher gene expression level. Additionally, CBA-Bu had a lower IC50 value than its non-biguanide counterpart in two cancer cell lines. Furthermore, CBA-Bu could activate AMPK and inhibit mTOR pathways in U87 MG cells, a mechanism involved in the antitumor effect of biguanides. Taken together, CBA-Bu represented an advanced gene vector combining desirable gene delivery capability with potential antitumor activity, which was promising to achieve enhanced therapeutic efficacy in antitumor gene therapy.

Design, in silico modelling and functionality theory of folate-receptor-targeted myricetin-loaded bovine serum albumin nanoparticle formulation for cancer treatment

Targeted drug delivery systems are a promising field of research. Nano-engineered material-mediated drug delivery possesses remarkable potential for the treatment of various malignancies. Here, folic acid (FA)-conjugated bovine serum albumin (BSA) nanoparticles (NPs) were used to encapsulate myricetin (Myr). Subsequently, the delivery of Myr via naturally overexpressed folate receptor (FR) to FR-positive breast cancer cells was studied. Myr-loaded BSA NPs were assembled by modified desolvation cross-linking technique. An FA-conjugated carrier, N-hydroxysuccinimide (NHS)-FA ester, was successfully synthesized. Its functional and structural characteristics were confirmed by ultraviolet, Fourier-transform infrared, and proton nuclear magnetic resonance spectroscopy. Biocompatible FA-conjugated, Myr-loaded BSA NPs (FA-Myr-BSA NPs) were successfully formulated using a carbonate/bicarbonate buffer. Their morphology, size, shape, physiological stability, and drug release kinetics were studied. Molecular docking studies revealed that FA-Myr-BSA NPs readily bound non-covalently to folate receptors and facilitated active drug endocytosis. FA-Myr-BSA NPs could trigger fast release of Myr in an acidic medium (pH 5.4), and showed high biocompatibility in a physiological medium. FA-Myr-BSA NPs effectively decreased the viability of MCF-7 cells after 24 h with 72.45 μg ml^-1 IC₅₀ value. In addition, FA-Myr-BSA NPs enhanced the uptake of Myr in MCF-7 cells. After incubation, a typical apoptotic morphology of condensed nuclei and distorted membrane bodies was observed. The NPs also targeted mitochondria of MCF-7 cells, significantly increasing reactive oxygen species release and contributing to the loss of mitochondrial membrane integrity. The observed results confirm that the newly developed FA-Myr-BSA NPs can serve as a potential carrier for Myr to increase the anticancer activity of this chemotherapeutic.

Highly effective anti-tumor nanomedicines based on HPMA copolymer conjugates with pirarubicin prepared by controlled RAFT polymerization

Here, we describe innovative synthesis of well-defined biocompatible N-(2-hydroxypropyl) methacrylamide (HPMA)-based polymer carriers and their drug conjugates with pirarubicin intended for controlled drug delivery and pH-triggered drug activation in tumor tissue. Polymer carrier synthesis was optimized to obtain well-defined linear HPMA-based polymer precursor with dispersity close to 1 and molar mass close to renal threshold with minimal synthesis steps. The developed synthesis enables preparation of tailored polymer nanomedicines with highly enhanced biological behavior in vivo, especially the biodistribution, urine elimination, tumor accumulation and anticancer activity. STATEMENT OF SIGNIFICANCE: The manuscript reports on novel synthesis and detailed physicochemical characterization and in vivo evaluation of well-defined biocompatible hydrophilic copolymers based on N-(2-hydroxypropyl)methacrylamide (HPMA) and their drug conjugates with pirarubicin enabling controlled drug delivery and pH-triggered drug activation in tumor tissue. Polymer carrier synthesis was optimized to obtain well-defined linear HPMA-based polymer precursor with minimal synthesis steps using controlled polymerization. Compared to previously published HPMA-based polymer drug conjugates whose polymer carriers were prepared by classical route via free radical polymerization, the newly prepared polymer drug conjugates exhibited enhanced biological behavior in vivo, especially the prolonged blood circulation, urine elimination, tumor accumulation and excellent anticancer activity. We believe that the newly prepared well-defined polymer conjugates could significantly enhance tumor therapy in humans.

Effects of molecular weight and structural conformation of multivalent-based elastin-like polypeptides on tumor accumulation and tissue biodistribution

In order to improve clinical outcomes for novel drug delivery systems, distinct optimization of size, shape, multifunctionality, and site-specificity are of utmost importance. In this study, we designed various multivalent elastin-like polypeptide (ELP)-based tumor-targeting polymers in which multiple copies of IL-4 receptor (IL-4R)-targeting ligand (AP1 peptide) were periodically incorporated into the ELP polymer backbone to enhance the affinity and avidity towards tumor cells expressing high levels of IL-4R. Several ELPs with different molecular sizes and structures ranging from unimer to micelle-forming polymers were evaluated for their tumor accumulation as well as in vivo bio-distribution patterns. Different percentages of cell binding and uptake were detected corresponding to polymer size, number of targeting peptides, or unimer versus micelle structure. As compared to low molecular weight polypeptides, high molecular weight AP1-ELP showed superior binding activity with faster entry and efficient processing in the IL-4R-dependent endocytic pathway. In addition, in vivo studies revealed that the high molecular weight micelle-forming AP1-ELPs (A86 and A100) displayed better tumor penetration and extensive retention in tumor tissue along with reduced non-specific accumulation in vital organs, when compared to low molecular weight non-micelle forming AP1-ELPs. It is suggested that the superior binding activities shown by A86 and A100 may depend on the multiple presentation of ligands upon transition to a micelle-like structure rather than a larger molecular weight. Thus, this study has significance in elucidating the different patterns underlying unimer and micelle-forming ELP-mediated tumor targeting as well as the in vivo biodistribution.

Multicomponent Conjugates of Anticancer Drugs and Monoclonal Antibody with PAMAM Dendrimers to Increase Efficacy of HER-2 Positive Breast Cancer Therapy

Purpose

Conjugation of nanocarriers with antibodies that bind to specific membrane receptors that are overexpressed in cancer cells enables targeted delivery. In the present study, we developed and synthesised two PAMAM dendrimer-trastuzumab conjugates that carried docetaxel or paclitaxel, specifically targeted to cells which overexpressed HER-2.

Methods

The ¹H NMR, ¹³C NMR, FTIR and RP-HPLC were used to analyse the characteristics of the products and assess their purity. The toxicity of PAMAM-trastuzumab, PAMAM-doc-trastuzumab and PAMAM-ptx-trastuzumab conjugates was determined using MTT assay and compared with free trastuzumab, docetaxel and paclitaxel toward HER-2-positive (SKBR-3) and negative (MCF-7) human breast cancer cell lines. The cellular uptake and internal localisation were studied using flow cytometry and confocal microscopy, respectively.

Results

The PAMAM-drug-trastuzumab conjugates in particular showed extremely high toxicity toward the HER-2-positive SKBR-3 cells and very low toxicity towards to HER-2-negative MCF-7 cells. As expected, the HER-2-positive SKBR-3 cell line accumulated trastuzumab from both conjugates rapidly; but surprisingly, although a large amount of PAMAM-ptx-trastuzumab conjugate was observed in the HER-2-negative MCF-7 cells. Confocal microscopy confirmed the intracellular localisation of analysed compounds. The key result of fluorescent imaging was the identification of strong selective binding of the PAMAM-doc-trastuzumab conjugate with HER-2-positive SKBR-3 cells only.

Conclusions

Our results confirm the high selectivity of PAMAM-doc-trastuzumab and PAMAM-ptx-trastuzumab conjugates for HER-2-positive cells, and demonstrate the utility of trastuzumab as a targeting agent. Therefore, the analysed conjugates present an promising approach for the improvement of efficacy of targeted delivery of anticancer drugs such as docetaxel or paclitaxel.

Electronic supplementary material

The online version of this article (10.1007/s11095-019-2683-7) contains supplementary material, which is available to authorized users.

Efficient Photodynamic Therapy of Prostate Cancer Cells through an Improved Targeting of the Cation-Independent Mannose 6-Phosphate Receptor

The aim of the present work is the development of highly efficient targeting molecules to specifically address mesoporous silica nanoparticles (MSNs) designed for the photodynamic therapy (PDT) of prostate cancer. We chose the strategy to develop a novel compound that allows the improvement of the targeting of the cation-independent mannose 6-phosphate receptor, which is overexpressed in prostate cancer. This original sugar, a dimannoside-carboxylate (M6C-Man) grafted on the surface of MSN for PDT applications, leads to a higher endocytosis and thus increases the efficacy of MSNs.

Polycation-globular protein complex: Ionic strength and chain length effects on the structure and properties

The effect of high salt concentration and pH on the binding of globular protein to polycation at different molar masses has been investigated by dynamic light scattering (DLS), turbidimetry and electrostatic modeling for the protein. In dilute concentration regime, DLS and pH titrations showed three remarkable pH transitions: pHc, the pH where soluble complexes of bovine serum albumin (BSA) and linear synthetic Polyethylenemine (PEI) are formed, pHc’ presents the end of primary soluble complex and pHφ presents the first appearance of microcoacervate droplets. All pH transitions increase with increasing NaCl concentration. The Adaptive Poisson-Boltzmann Solver (APBS) identify with precision the functional sites at the surface of BSA and shows that the strength of electrostatic interactions depends hugely on the variation of pH and ionic strength. At a very high concentration of salt, no remarkable effect on a mixture formed of a long chain of polycation and globular protein.

Stressing the Role of DNA as a Drug Carrier: Synthesis of DNA-Drug Conjugates through Grafting Chemotherapeutics onto Phosphorothioate Oligonucleotides

To stress the role of deoxyribonucleic acid (DNA) as a drug carrier, an efficient conjugation strategy in which chemotherapeutics can be grafted onto a phosphorothiolated DNA backbone through the reaction between the phosphorothioate group (PS) and a benzyl bromide group is proposed. As a proof of concept, benzyl-bromide-modified paclitaxel (PTX) is employed to graft onto the DNA backbone at the PS modification sites. Due to the easy preparation of phosphorothiolated DNA at any desired position during its solid-phase synthesis, diblock DNA strands containing both normal phosphodiester segment (^PO DNA) and phosphorothiolate segment (^PS DNA) are directly grafted with a multitude of PTXs without using complicated and exogenous linkers. Then, the resulting amphiphilic ^PO DNA-blocked-(^PS DNA-grafted PTX) conjugates (^PO DNA-b-(^PS DNA-g-PTX)) assemble into PTX-loaded spherical nucleic acid (SNA)-like micellar nanoparticles (PTX-SNAs) with a high drug loading ratio up to ≈53%. Importantly, the ^PO DNA segment maintains its molecular recognition property and biological functions, which allows the as-prepared PTX-SNAs to be further functionalized with tumor-targeting aptamers, fluorescent probe strands, or antisense sequences. These multifunctional PTX-SNAs demonstrate active tumor-targeting delivery, efficient inhibition of tumor growth, and the reversal of drug resistance both in vitro and in vivo for comprehensive antitumor therapy.

Challenges and Opportunities from Basic Cancer Biology for Nanomedicine for Targeted Drug Delivery

Background:

Effective cancer therapy is still a great challenge for modern medical research due to the complex underlying mechanisms of tumorigenesis and tumor metastasis, and the limitations commonly associated with currently used cancer therapeutic options. Nanotechnology has been implemented in cancer therapeutics with immense potential for improving cancer treatment.

Objective:

Through information about the recent advances regarding cancer hallmarks, we could comprehensively understand the pharmacological effects and explore the mechanisms of the interaction between the nanomaterials, which could provide opportunities to develop mechanism-based nanomedicine to treat human cancers.

Methods:

We collected related information and data from articles.

Results:

In this review, we discussed the characteristics of cancer including tumor angiogenesis, abnormalities in tumor blood vessels, uncontrolled cell proliferation markers, multidrug resistance, tumor metastasis, cancer cell metabolism, and tumor immune system that provide opportunities and challenges for nanomedicine to be directed to specific cancer cells and portray the progress that has been accomplished in application of nanotechnology for cancer treatment.

Conclusion:

The information presented in this review can provide useful references for further studies on developing effective nanomedicine for the treatment of cancer.

Bioconjugation in Drug Delivery: Practical Perspectives and Future Perceptions

For the past three decades, pharmaceutical research has been mainly converging to novel carrier systems and nanoparticulate colloidal technologies for drug delivery, such as nanoparticles, nanospheres, vesicular systems, liposomes, or nanocapsules to impart novel functions and targeting abilities. Such technologies opened the gate towards more sophisticated and effective multi-acting platform(s) which can offer site-targeting, imaging, and treatment using a single multifunctional system. Unfortunately, such technologies faced major intrinsic hurdles including high cost, low stability profile, short shelf-life, and poor reproducibility across and within production batches leading to harsh bench-to-bedside transformation.Currently, pharmaceutical industry along with academic research is investing heavily in bioconjugate structures as an appealing and advantageous alternative to nanoparticulate delivery systems with all its flexible benefits when it comes to custom design and tailor grafting along with avoiding most of its shortcomings. Bioconjugation is a ubiquitous technique that finds a multitude of applications in different branches of life sciences, including drug and gene delivery applications, biological assays, imaging, and biosensing.Bioconjugation is simple, easy, and generally a one-step drug (active pharmaceutical ingredient) conjugation, using various smart biocompatible, bioreducible, or biodegradable linkers, to targeting agents, PEG layer, or another drug. In this chapter, the different types of bioconjugates, the techniques used throughout the course of their synthesis and characterization, as well as the well-established synthetic approaches used for their formulation are presented. In addition, some exemplary representatives are outlined with greater emphasis on the practical tips and tricks of the most prominent techniques such as click chemistry, carbodiimide coupling, and avidin-biotin system.