Poly(ethylene glycol)-Prodrug Conjugates: Concept, Design, and Applications

The synergistic anti-leishmanial effect of photodynamic therapy employing chemotherapy-mediated nanocomposites

Cutaneous leishmaniasis (CL) presents a significant therapeutic challenge due to limitations of current treatments like meglumine antimoniate (MAT), including drug resistance and adverse side effects. Photodynamic therapy (PDT) has emerged as a promising, non-invasive alternative. This study explored the synergistic potential of combining PDT with chemotherapy using novel MAT-loaded nanocomposites for enhanced anti-leishmanial activity. A novel nanocomposite, Co-Fe2O4@GO-poly(AMPS-co-AM), was synthesized and characterized using energy-dispersive X-ray spectroscopy (EDX), elemental mapping, and high-resolution transmission electron microscopy (HR-TEM). MAT was immobilized onto the nanocomposite, forming NCMAT. The in vitro anti-leishmanial efficacy of NCMAT against L. tropica was evaluated using flow cytometry, MTT assays, and real-time polymerase chain reaction (PCR) to assess gene expression. The characterization techniques confirmed the successful synthesis and MAT loading of the nanocomposite. In vitro studies demonstrated that NCMAT combined with PDT resulted in a 78% increase in hydroxyl radical production and exhibited a significant reduction (X%) in parasite viability compared to MAT alone. This enhanced activity is likely attributed to increased reactive oxygen species (ROS) production and immunomodulation. Combining nanotechnology with PDT offers a promising approach for treating CL. The Co-Fe2O4@GO-poly(AMPS-co-AM) nanocomposites demonstrated improved therapeutic outcomes in vitro. While these results are encouraging, further research is crucial to evaluate the clinical safety and efficacy of this combined therapeutic strategy.

Preparation of Wood Fiber-Polyurethane Plastic Composite with Water Resistance and High Strength

The current widespread use of plastics is a significant source of environmental pollution and increases the carbon load in the atmosphere, which has precipitated an urgent drive to replace plastics with biomass-based materials. In this paper, we prepared a lignocellulose-based, high-strength, water-resistant composite based on eucalyptus waste sawdust combined with a polyurethane prepolymer. The preparation process included pretreating sawdust with deep eutectic solvents (DESs) to remove some of the lignin and hemicellulose. A prepolymer preparation involving isocyanate groups using the prepolymerization of polyethylene glycol (PEG) with hexamethylene diisocyanate (HDI) grafted the prepolymers to the hydroxyl of the pretreated wood fibers, which were subsequently blended with acetylated pretreated sawdust to create the composite. The composite contained 67% wood fibers, possessed good tensile strength, and exhibited Young's moduli of 18 MPa and 484 MPa. It was water-resistant with a contact angle of 92° and had a low water absorption of 32%, and it maintained a wet tensile strength of 5.71 MPa. The composite offers several advantages, including UV protection and thermal stability. This high-performance wood waste composite provides an alternative green production option for producing plastic materials.

Scaling analytical RP-HPLC to semi-preparative for fractionation and characterization of pegfilgrastim oxidized variants

Pegfilgrastim, a 40 kDa PEGylated form of recombinant human granulocyte colony-stimulating factor (rhG-CSF), is a biotherapeutic protein used to treat chemotherapy-induced neutropenia. To ensure the product is safe and effective, stringent monitoring of product-related impurities, particularly those arising from oxidative degradation, is necessary. This study focuses on the isolation and characterization of oxidized variants in pegfilgrastim using a multi-step approach that includes method transfer to semi-preparative High-Performance Liquid Chromatography (HPLC), mass spectrometry, and an in vitro cell-based potency assay (CBPA). The analytical reversed-phase (RP)-HPLC method was successfully scaled up and optimized for isolating oxidized variants in H2O2-treated pegfilgrastim. Mass spectrometry analysis identified the degree and specific sites of oxidation, with Met1 being the most susceptible. CBPA showed that oxidation at Met1 alone had minimal impact on functional activity, while oxidation at both Met127 and Met138 led to significant reductions in activity. The impact of oxidation at all four sites in pegfilgrastim could not be assessed due to significant degradation. These findings highlight the importance of robust analytical strategies in the characterization and control of pegfilgrastim impurities.

Oligoethylene Phosphoramidate-Based Kinase Inhibitor Prodrugs - Solubility, Enzyme Inhibition, and Hydrolysis

The efficiency of kinase inhibiting cancer therapeutics is often limited by their poor solubility in water. PEGylation is one possible strategy to improve the solubility of the drug, however, means to cleave off the PEG after reaching the target is important to make use of the therapeutic effects of the native drug. Moreover, the length of the PEG chains will have an effect on the solubility and binding. In this study, we want to extend our understanding of solubilizing oligo ethylene glycol (OEG) chains connected to kinase inhibitors using a pH labile phosphoramidate linker. We synthesize a library of drug-OEG conjugates for Ceritinib, Crizotinib, Palbociclib, and Ribocilib kinase inhibitors with n=2, 3, 4 and 8 OEG repeat units. We study the influence on water solubility, enzyme inhibition, and pH induced hydrolysis. A maximum in solubility is obtained for n=3 or 4. We show that small differences in chain length can strongly influence the water solubility, while all other properties remain relatively comparable.

Advancements in nose-to-brain drug targeting for Alzheimer's disease: a review of nanocarriers and clinical insights

Alzheimer's disease (AD) is a type of neurodegenerative disease that describes cognitive decline and memory loss resulting in disability in movement, memory, speech etc. Which first affects the hippocampal and entorhinal cortex regions of brain. Pathogenesis of AD depends on Amyloid-β, hyper-phosphorylation of tau protein, mitochondrial dysfunction, cholinergic hypothesis and oxidative stress. In comparison with males, females are more prone to AD due to reduced estrogen level. Some of the FDA-approved drugs and their conventional formulations available in the market are discussed in this review. Nose-to-brain delivery system provides the target specific drug delivery via olfactory and trigeminal nerve (active and passive drug targeting strategies) and bypassing the Blood Brain Barrier. Mucoadhesive agents and permeation enhancers are mostly utilized to enhance the retention time and bioavailability of the drugs. Liposomes, niosomes, cubosomes, solid lipid nanoparticles, nanoemulsions, micelles, and many more nanocarriers for nose-to-brain delivery of drugs are also described thoroughly in this review. It also covers the clinical trials and patents for nose-to-brain delivery. In this article, we investigate the nose-to-brain pathways for AD treatment strategies.

PEGylated ATP-Independent Luciferins for Noninvasive High-Sensitivity High-Speed Bioluminescence Imaging

Bioluminescence imaging (BLI) is a powerful, noninvasive imaging method for animal studies. NanoLuc luciferase and its derivatives are attractive bioluminescent reporters recognized for their efficient photon production and ATP independence. However, utilizing them for animal imaging poses notable challenges. Low substrate solubility has been a prominent problem, limiting in vivo brightness, while the susceptibility of luciferins to auto-oxidation by molecular oxygen in air increases handling complexity and poses an obstacle to obtaining consistent results. To address these issues, we developed a range of caged PEGylated luciferins with increased auto-oxidation resistance and water solubility of up to 25 mM, resulting in substantial in vivo bioluminescence increases in mouse models. This advancement has created the brightest and most sensitive luciferase-luciferin combination, enabling high-speed video-rate imaging of freely moving mice with brain-expressed luciferase. These innovative substrates offer new possibilities for investigating a wide range of biological processes and are poised to become invaluable resources for chemical, biological, and biomedical fields.

Highly Active Oligoethylene Glycol Pleuromutilins via Systematic Linker Synthesis/One-Pot Attachment and a Microscale Solubility Method

The semisynthetic derivatization of natural products is crucial for their continued development as antibiotics. While commercial pleuromutilin derivatives depend on amines for solubility, we demonstrate the high activity and solubility of oligoethylene glycol-substituted pleuromutilins achieved via a one-pot deprotection/attachment approach using thiolates protected as thioesters. The bifunctional linker synthesis is versatile and can be broadly applied to other chemistries. Antibacterial assays revealed this simple glycolate modification enhanced inhibition 4-8-fold relative to that of pleuromutilin. A new microscale solubility method is also introduced.

Advancing Therapeutic Strategies with Polymeric Drug Conjugates for Nucleic Acid Delivery and Treatment

The effective clinical translation of messenger RNA (mRNA), small interfering RNA (siRNA), and microRNA (miRNA) for therapeutic purposes hinges on the development of efficient delivery systems. Key challenges include their susceptibility to degradation, limited cellular uptake, and inefficient intracellular release. Polymeric drug conjugates (PDCs) offer a promising solution, combining the benefits of polymeric carriers and therapeutic agents for targeted delivery and treatment. This comprehensive review explores the clinical translation of nucleic acid therapeutics, focusing on polymeric drug conjugates. It investigates how these conjugates address delivery obstacles, enhance systemic circulation, reduce immunogenicity, and provide controlled release, improving safety profiles. The review delves into the conjugation strategies, preparation methods, and various classes of PDCs, as well as strategic design, highlighting their role in nucleic acid delivery. Applications of PDCs in treating diseases such as cancer, immune disorders, and fibrosis are also discussed. Despite significant advancements, challenges in clinical adoption persist. The review concludes with insights into future directions for this transformative technology, underscoring the potential of PDCs to advance nucleic acid-based therapies and combat infectious diseases significantly.

Phytophenols as Promoieties for Prodrug Design

One lucrative method for overcoming challenges in drug discovery or for enhancing undesirable properties of already-approved medications is prodrug design. The goal of this review is to present researchers with a profile of naturally occurring Phytophenols as carriers that would be used for prodrug synthesis as well as their advantages. Phytophenols offer several advantages when used as promoieties as they also possess antioxidant and analgesic properties, they are obtained naturally and their safety profile is well established. Several phytophenols like menthol, thymol, eugenol, guaiacol, sesamol, vanillin, and umbelliferone are some of the phytophenols having several beneficial properties and are extensively employed in the field of food processing and medicine. In the current review, we have listed all types of promoieties that are used for prodrug synthesis and phytophenols are reviewed, which may help researchers to select phytophenols based on their need and suitability for drug candidates.

Magnesium Nanocomposite Hydrogel Reverses the Pathologies to Enhance Mandible Regeneration

The healing of bone defects after debridement in medication-related osteonecrosis of the jaw (MRONJ) is a challenging medical condition with impaired angiogenesis, susceptible infection, and pro-inflammatory responses. Magnesium (Mg) nanocomposite hydrogel is developed to specifically tackle multiple factors involved in MRONJ. Mg-oxide nanoparticles tune the gelation kinetics in the reaction between N-hydroxysuccinimide-functionalized hyperbranched poly (ethylene glycol) and proteins. This reaction allows an enhanced mechanical property after instant solidification and, more importantly, also stable gelation in challenging environments such as wet and hemorrhagic conditions. The synthesized hydrogel guides mandible regeneration in MRONJ rats by triggering the formation of type H vessels, activating Osterix+ osteoprogenitor cells, and generating anti-inflammatory microenvironments. Additionally, this approach demonstrates its ability to suppress infection by inhibiting specific pathogens while strengthening stress tolerance in the affected alveolar bone. Furthermore, the enhanced osteogenic properties and feasibility of implantation of the hydrogel are validated in mandible defect and iliac crest defect created in minipigs, respectively. Collectively, this study offers an injectable and innovative bone substitute to enhance mandible defect healing by tackling multiple detrimental pathologies.

Regenerative Medicine and Nanotechnology Approaches against Cardiovascular Diseases: Recent Advances and Future Prospective

Regenerative medicine refers to medical research focusing on repairing, replacing, or regenerating damaged or diseased tissues or organs. Cardiovascular disease (CVDs) is a significant health issue globally and is the leading cause of death in many countries. According to the Centers for Disease Control and Prevention (CDC), one person dies every 34 seconds in the United States from cardiovascular diseases, and according to a World Health Organization (WHO) report, cardiovascular diseases are the leading cause of death globally, taking an estimated 17.9 million lives each year. Many conventional treatments are available using different drugs for cardiovascular diseases, but these treatments are inadequate. Stem cells and nanotechnology are promising research areas for regenerative medicine treating CVDs. Regenerative medicines are a revolutionary strategy for advancing and successfully treating various diseases, intending to control cardiovascular disorders. This review is a comprehensive study of different treatment methods for cardiovascular diseases using different types of biomaterials as regenerative medicines, the importance of different stem cells in therapeutics, the expanded role of nanotechnology in treatment, the administration of several types of stem cells, their tracking, imaging, and the final observation of clinical trials on many different levels as well as it aims to keep readers up to pace on emerging therapeutic applications of some specific organs and disorders that may improve from regenerative medicine shortly.

l-Type amino acid transporter 1-targeting nanoparticles for antisense oligonucleotide delivery to the CNS

l-Type amino acid transporter 1 (LAT1)-specific ligands and polyion complexes are used as brain-specific targets to deliver RNA-based drugs across the blood-brain barrier. We characterized an LAT1-targeting antisense oligonucleotide (ASO)-encapsulated nanoparticle, Phe-NPs/ASO. A 25% density of phenylalanine effectively binds to the surface of LAT1-targeting NPs in the GL261-Luc cells, and Phe-NPs/ASO shows higher binding affinity compared to that without phenylalanine by cellular binding assay. To further characterize the blood-brain barrier-targeting effect and tissue distribution following a single-dose intravenous injection in mice, we performed in vivo biodistribution studies using fluorescence imaging. The Phe-NPs/ASOs were detected in the brain tissue 1 h post-intravenous injection at an approximately 64-fold higher ratio than that of the same ASOs administered in the absence of any NP carrier. The brain tissue delivery of ASO-loaded Phe-NPs was also confirmed in a fluorescence imaging study performed in non-human primates. These results demonstrate that Phe-NPs may successfully deliver an ASO to the brain tissue across brain regions. Phe-NPs loaded with RNA-based drugs have the potential to treat diseases of the CNS, including all forms of neurodegenerative diseases.

Megamolecule Self-Assembly Networks: A Combined Computational and Experimental Design Strategy

This work describes the use of computational strategies to design megamolecule building blocks for the self-assembly of lattice networks. The megamolecules are prepared by attaching four Cutinase-SnapTag fusion proteins (CS fusions) to a four-armed linker, followed by functionalizing each fusion with a terpyridine linker. This functionality is designed to participate in a metal-mediated self-assembly process to give networks. This article describes a simulation-guided strategy for the design of megamolecules to optimize the peptide linker in the fusion protein to give conformations that are best suited for self-assembly and therefore streamlines the typically time-consuming and labor-intensive experimental process. We designed 11 candidate megamolecules and identified the most promising linker, (EAAAK)2, along with the optimal experimental conditions through a combination of all-atom molecular dynamics, enhanced sampling, and larger-scale coarse-grained molecular dynamics simulations. Our simulation findings were validated and found to be consistent with the experimental results. Significantly, this study offers valuable insight into the self-assembly of megamolecule networks and provides a novel and general strategy for large biomolecular material designs by using systematic bottom-up coarse-grained simulations.

Resveratrol: Challenges and prospects in extraction and hybridization with nanoparticles, polymers, and bio-ceramics

Resveratrol (RSV), a bioactive natural phenolic compound found in plants, fruits, and vegetables, has garnered significant attention in pharmaceutical, food, and cosmetic industries due to its remarkable biological and pharmacological activities. Despite its potential in treating various diseases, its poor pharmacokinetic properties, such as low solubility, stability, bioavailability, and susceptibility to rapid oxidation, limit its biomedical applications. Recent advancements focus on incorporating resveratrol into innovative materials like nanoparticles, polymers, and bio-ceramics to enhance its properties and bioavailability. In this review, an exhaustive literature search was conducted from PubMed, Google Scholar, Science Direct, Scopus, and Web of Science databases to explore these advancements, to compares conventional and innovative extraction methods, and to highlights resveratrol's therapeutic potential, including its anti-inflammatory, anti-oxidative, anti-cancerogenic, antidiabetic, neuroprotective, and cardio-protective properties. Additionally, we discuss the challenges and prospects of hybrid materials combining resveratrol with nanoparticles, polymers, and bio-ceramics for therapeutic applications. Rigorous studies are still needed to confirm their clinical efficacy.

Challenges and recent advances in erythropoietin stability

Erythropoietin (EPO) is a pivotal hormone that regulates red blood cell production, predominantly synthesized by the kidneys and also produced by the liver. Since the introduction of recombinant human EPO (rh-EPO) in 1989 through recombinant DNA technology, the therapeutic landscape for anemia has been improved. rh-EPO's market expansion has been substantial, with its application extending across various conditions such as chronic kidney disease, cancer-related anemia, and other disorders. Despite its success, significant concerns remain regarding the stability of EPO, which is critical for preserving its biological activity and ensuring therapeutic efficacy under diverse environmental conditions. Instability issues, including degradation and loss of biological activity, challenge both drug development and treatment outcomes. Factors contributing to EPO instability include temperature fluctuations, light exposure, and interactions with other substances. To overcome these challenges, pharmaceutical research has focused on developing innovative strategies such as stabilizing agents, advanced formulation techniques, and optimized storage conditions. This review article explores the multifaceted aspects of EPO stability, examining the impact of instability on clinical efficacy and drug development. It also provides a comprehensive review of current stabilization strategies, including the use of excipients, lyophilization, and novel delivery systems.

Fluorogenic chemical tools to shed light on CES1-mediated adverse drug interactions

Studying factors that cause interindividual variability of carboxylesterase 1 (CES1) activity is currently difficult due to limited methods. Here, fluorogenic tools for measuring CES1 activity are developed and demonstrated to report on these factors in living cells. These tools enable experiments that will develop a deeper understanding of CES1 metabolism.

Polyethylene Glycol-Based Polymer-Drug Conjugates: Novel Design and Synthesis Strategies for Enhanced Therapeutic Efficacy and Targeted Drug Delivery

Due to their potential to enhance therapeutic results and enable targeted drug administration, polymer-drug conjugates that use polyethylene glycol (PEG) as both the polymer and the linker for drug conjugation have attracted much research. This study seeks to investigate recent developments in the design and synthesis of PEG-based polymer-drug conjugates, emphasizing fresh ideas that fill in existing knowledge gaps and satisfy the increasing need for more potent drug delivery methods. Through an extensive review of the existing literature, this study identifies key challenges and proposes innovative strategies for future investigations. The paper presents a comprehensive framework for designing and synthesizing PEG-based polymer-drug conjugates, including rational molecular design, linker selection, conjugation methods, and characterization techniques. To further emphasize the importance and adaptability of PEG-based polymer-drug conjugates, prospective applications are highlighted, including cancer treatment, infectious disorders, and chronic ailments.

Engineering a 3D Biomimetic Peptides Functionalized-Polyethylene Glycol Hydrogel Model Cocultured with Endothelial Cells and Astrocytes: Enhancing In Vitro Blood-Brain Barrier Biomimicry

The blood-brain barrier (BBB) poses a significant challenge for drug delivery and is linked to various neurovascular disorders. In vitro BBB models provide a tool to investigate drug permeation across the BBB and the barrier's response to external injury events. Yet, existing models lack fidelity in replicating the BBB's complexity, hindering a comprehensive understanding of its functions. This study introduces a three-dimensional (3D) model using polyethylene glycol (PEG) hydrogels modified with biomimetic peptides that represent recognition sequences of key proteins in the brain. Hydrogels were functionalized with recognition sequences for laminin (IKVAV) and fibronectin peptides (RGD) and chemically cross-linked with matrix metalloprotease-sensitive peptides (MMPs) to mimic the extracellular matrix of the BBB. Astrocytes and endothelial cells were seeded within and on the surface of the hydrogels, respectively. The barrier integrity was assessed through different tests including transendothelial electrical resistance (TEER), the permeability of sodium fluorescence (Na-F), the permeability of Evan's blue bound to albumin (EBA), and the expression of zonula occluden-1 (ZO-1) in seeded endothelial cells. Hydrogels with a combination of RGD and IKVAV peptides displayed superior performance, exhibiting significantly higher TEER values (55.33 ± 1.47 Ω·cm2) at day 5 compared to other 2D controls including HAECs-monoculture and HAECs-cocultured with NHAs seeded on well inserts and 3D controls including RGD hydrogel and RGD-IKVAV monoculture with HAECs and RGD hydrogel cocultured with HAECs and NHAs. The designed 3D system resulted in the lowest Evan's blue permeability at 120 min (0.215 ± 0.055 μg/mL) compared to controls. ZO-1 expression was significantly higher and formed a relatively larger network in the functionalized hydrogel cocultured with astrocytes and endothelial cells compared to the controls. Thus, the designed 3D model effectively recapitulates the main BBB structure and function in vitro and is expected to contribute to a deeper understanding of pathological CNS angiogenesis and the development of effective CNS medications.

Surface Modifications of Superparamagnetic Iron Oxide Nanoparticles with Chitosan, Polyethylene Glycol, Polyvinyl Alcohol, and Polyvinylpyrrolidone as Methylene Blue Adsorbent Beads

Due to the negative impacts the dye may have on aquatic habitats and human health, it is often found in industrial effluent and poses a threat to public health. Hence, to solve this problem, this study developed magnetic adsorbents that can remove synthetic dyes like methylene blue. The adsorbent, in the form of beads, consists of a polymer blend of chitosan, polyethylene glycol, polyvinyl alcohol, polyvinylpyrrolidone, and superparamagnetic iron oxide nanoparticles (average size of 19.03 ± 4.25 nm). The adsorption and desorption of MB from beads were carried out at pH values of 7 and 3.85, respectively. At a concentration of 9 mg/L, the loading capacity and the loading amount of MB after 5 days peaked at 29.75 ± 1.53% and 297.48 ± 15.34 mg/g, respectively. Meanwhile, the entrapment efficiency of MB reached 29.42 ± 2.19% at a concentration of 8 mg/L. The cumulative desorption capacity of the adsorbent after 13 days was at its maximum at 7.72 ± 0.5%. The adsorption and desorption kinetics were evaluated.

Investigation of the structure of protein-polymer conjugates in solution reveals the impact of protein deuteration and the size of the polymer on its thermal stability

The conjugation of proteins with polymers offers immense biotechnological potential by creating novel macromolecules. This article presents experimental findings on the structural properties of maltose-binding protein (MBP) conjugated with linear biodegradable polyphosphoester polymers with different molecular weights. We studied isotopic effects on both proteins and polymers. Circular dichroism and fluorescence spectroscopy and small-angle neutron scattering reveal that the conjugation process destabilizes the protein, affecting the secondary more than the tertiary structure, even at room temperature, and that the presence of two domains in the MBP may contribute to its observed instability. Notably, unfolding temperatures differ between native MBP and the conjugates. In particular, this study sheds light on the complex interplay of factors such as the deuteration influencing protein stability and conformational changes in the conjugation processes. The perdeuteration influences the hydrogen bond network and hydrophobic interactions in the case of the MBP protein. The perdeuteration of the protein influences the hydrogen bond network and hydrophobic interactions. This is evident in the decreased thermal stability of deuterated MBP protein, in the conjugate, especially with high-molecular-mass polymers.

Striving for Uniformity: A Review on Advances and Challenges To Achieve Uniform Polyethylene Glycol

Poly(ethylene glycol) (PEG) is the polymer of choice in drug delivery systems due to its biocompatibility and hydrophilicity. For over 20 years, this polymer has been widely used in the drug delivery of small drugs, proteins, oligonucleotides, and liposomes, improving the stability and pharmacokinetics of many drugs. However, despite the extensive clinical experience with PEG, concerns have emerged related to its use. These include hypersensitivity, purity, and nonbiodegradability. Moreover, conventional PEG is a mixture of polymers that can complicate drug synthesis and purification leading to unwanted immunogenic reactions. Studies have shown that uniform PEGylated drugs may be more effective than conventional PEGylated drugs as they can overcome issues related to molecular heterogeneity and immunogenicity. This has led to significant research efforts to develop synthetic procedures to produce uniform PEGs (monodisperse PEGs). As a result, iterative step-by-step controlled synthesis methods have been created over time and have shown promising results. Nonetheless, these procedures have presented numerous challenges due to their iterative nature and the requirement for multiple purification steps, resulting in increased costs and time consumption. Despite these challenges, the synthetic procedures went through several improvements. This review summarizes and discusses recent advances in the synthesis of uniform PEGs and its derivatives with a focus on overall yields, scalability, and purity of the polymers. Additionally, the available characterization methods for assessing polymer monodispersity are discussed as well as uniform PEG applications, side effects, and possible alternative polymers that can overcome the drawbacks.

Synthesis of new representatives of A3B-type carboranylporphyrins based on meso-tetra(pentafluorophenyl)porphyrin transformations

A carboranylporphyrin of A3B-type bearing a single pentafluorophenyl ring was prepared through the regioselective nucleophilic aromatic substitution reaction of the p-fluorine atoms in 5,10,15,20-tetrakis(pentafluorophenyl)porphyrin with 9-mercapto-m-carborane. The reaction of this porphyrin with sodium azide led to the selective substitution of the p-fluorine atom in the pentafluorophenyl substituent with an azide functionality which upon reduction with SnCl2 resulted in the formation of the corresponding porphyrin with an amino group. Pentafluorophenyl-substituted A3B-porphyrins were studied and transformed to thiol and amino-substituted compounds allowing for the preparation of porphyrins with different reactive groups such as hydroxy and amino derivatives capable for further functionalization and conjugation of these porphyrins to other substrates. In addition, conjugates containing maleimide or biotin entities in the structure of carborane A3B-porphyrin were also synthesized based on the amino-substituted A3B-porphyrin. The structures of the prepared carboranylporphyrins were determined by UV-vis, IR, 1H, 19F, 11B NMR spectroscopic data and MALDI mass spectrometry.

Characterization of PEGylation sites in Neulasta and a biosimilar candidate with a combined fragmentation strategy in mass spectrometry analysis

In the development of biosimilar products to Neulasta, it is essential to determine the intact molecular mass and confirm precise PEGylation sites. In this study, we applied a combination of techniques, including post-column addition of triethylamine in reversed-phase liquid chromatography-mass spectrometry (RPLC-MS) to determine the intact molecular mass, and in-source fragmentation (ISF) and higher-energy collision dissociation-tandem mass spectrometry (HCD-MS/MS) to identify the PEGylation site. Our results show that both the pegfilgrastim biosimilar candidate and Neulasta lots are mono-PEGylated at the N-terminal end. Furthermore, we show that the combined ISF and HCD-MS/MS method can be used for identifying the PEGylation sites in the diPEGylated variant of pegfilgrastim. The diPEGylated variant has modification sites at the N-terminal end and a lysine at position 35 in the protein sequence.

Functionalisation of brush polyethylene glycol polymers with specific lipids extends their elimination half-life through association with natural lipid trafficking pathways

Polymeric prodrugs have been applied to control the delivery of various types of therapeutics. Similarly, conjugation of peptide therapeutics to lipids has been used to prolong systemic exposure. Here, we extend on these two approaches by conjugating brush polyethylene glycol (PEG) polymers with different lipid components including short-chain (1C2) or medium-chain (1C12) monoalkyl hydrocarbon tails, cholesterol (Cho), and diacylglycerols composed of two medium-chain (2C12) or long-chain (2C18) fatty acids. We uniquely evaluate the integration of these lipid-polymers into endogenous lipid trafficking pathways (albumin and lipoproteins) and the impact of lipid conjugation on plasma pharmacokinetics after intravenous (IV) and subcutaneous (SC) dosing to cannulated rats. The IV and SC elimination half-lives of Cho-PEG (13 and 22 h, respectively), 2C12-PEG (11 and 17 h, respectively) and 2C18-PEG (12 h for both) were prolonged compared to 1C2-PEG (3 h for both) and 1C12-PEG (4 h for both). Interestingly, 1C2-PEG and 1C12-PEG had higher SC bioavailability (40 % and 52 %, respectively) compared to Cho-PEG, 2C12-PEG and 2C18-PEG (25 %, 24 % and 23 %, respectively). These differences in pharmacokinetics may be explained by the different association patterns of the polymers with rat serum albumin (RSA), bovine serum albumin (BSA) and lipoproteins. For example, in pooled plasma (from IV pharmacokinetic studies), 2C18-PEG had the highest recovery in the high-density lipoprotein (HDL) fraction. In conclusion, the pharmacokinetics of brush PEG polymers can be tuned via conjugation with different lipids, which can be utilised to tune the elimination half-life, biodistribution and effect of therapeutics for a range of medical applications. STATEMENT OF SIGNIFICANCE: Lipidation of therapeutics such as peptides has been employed to extend their plasma half-life by promoting binding to serum albumin, providing protection against rapid clearance. Here we design and evaluate innovative biomaterials consisting of brush polyethylene glycol polymers conjugated with different lipids. Importantly, we show for the first time that lipidated polymeric materials associate with endogenous lipoprotein trafficking pathways and this, in addition to albumin binding, controls their plasma pharmacokinetics. We find that conjugation to dialkyl lipids and cholesterol leads to higher association with lipid trafficking pathways, and more sustained plasma exposure, compared to conjugation to short and monoalkyl lipids. Our lipidated polymers can thus be utilised as delivery platforms to tune the plasma half-life of various pharmaceuticals.

Unnatural Amino Acid Engineering for Intracellular Delivery of Protein Therapeutics

Protein drugs are a critically important therapeutic modality due to the sophisticated binding recognition, catalytic properties, and disease relevance of proteins. There is a clear need for new strategies able to improve pharmacokinetics, bioavailability, and/or intracellular delivery of therapeutic proteins, as stability limitations have significantly hindered clinical advancement, and most proteins are membrane impermeable. Bioconjugation strategies able to site-specifically modify proteins with cell binding, and other ligands offer a particularly valuable approach to facilitate protein delivery due to the importance of ligand presentation on protein bioactivity and cellular uptake. We explored unnatural amino acid (UAA) incorporation as a novel strategy to tunably incorporate clustered cell-binding ligands in fluorescent proteins and suicide enzymes, resulting in substantial increases in cell-specific uptake and targeted cell-killing activity. These approaches offer a valuable and versatile method to modify a variety of proteins and enable improved clinical potential.

A bio-instructive parylene-based conformal coating suppresses thrombosis and intimal hyperplasia of implantable vascular devices

Implantable vascular devices are widely used in clinical treatments for various vascular diseases. However, current approved clinical implantable vascular devices generally have high failure rates primarily due to their surface lacking inherent functional endothelium. Here, inspired by the pathological mechanisms of vascular device failure and physiological functions of native endothelium, we developed a new generation of bioactive parylene (poly(p-xylylene))-based conformal coating to address these challenges of the vascular devices. This coating used a polyethylene glycol (PEG) linker to introduce an endothelial progenitor cell (EPC) specific binding ligand LXW7 (cGRGDdvc) onto the vascular devices for preventing platelet adhesion and selectively capturing endogenous EPCs. Also, we confirmed the long-term stability and function of this coating in human serum. Using two vascular disease-related large animal models, a porcine carotid artery interposition model and a porcine carotid artery-jugular vein arteriovenous graft model, we demonstrated that this coating enabled rapid generation of self-renewable "living" endothelium on the blood contacting surface of the expanded polytetrafluoroethylene (ePTFE) grafts after implantation. We expect this easy-to-apply conformal coating will present a promising avenue to engineer surface properties of "off-the-shelf" implantable vascular devices for long-lasting performance in the clinical settings.

3D-Printed Microcubes for Catalase Drug Delivery

Oxidative stress, i.e., excessive production of reactive oxygen species (ROS), plays an important role in the pathogenesis of inflammatory diseases such as cardiovascular diseases, cancer, and neurodegenerative diseases. Catalase, an antioxidant enzyme, has great therapeutic potential; however, its efficacy is limited by its delivery to target cells or tissues. In order to achieve efficient delivery, consistent drug distribution, and drug activity, small and uniformly sized drug delivery vehicles are needed. Here, three-dimensional (3D) microcubes were printed by Nanoscribe Photonic Professional GT2, a high-resolution 3D printer, and the characteristics of 3D-printed microcubes as drug delivery vehicles for the delivery of catalase were investigated. The size of the 3D-printed microcubes was 800 nm in length of a square and 600 nm in height, which is suitable for targeting macrophages passively. Microcubes were also tunable in shape and size, and high-resolution 3D printing could provide microparticles with little variation in shape and size. Catalase was loaded on 3D-printed microcubes by nonspecific adsorption, and catalase on 3D-printed microcubes (CAT-MC) retained 83.1 ± 1.3% activity of intact catalase. CAT-MC also saved macrophages, RAW 264.7, from the cytotoxicity of H2O2 by 86.4 ± 4.1%. As drug delivery vehicles, 3D-printed microparticles are very promising due to their small and uniform size, which provides consistent drug distribution and drug activity. Therefore, we anticipate numerous applications of 3D-printed microparticles for delivering therapeutic proteins.

Contrasting Properties of Polymeric Nanocarriers for MRI-Guided Drug Delivery

Poor pharmacokinetics and low aqueous solubility combined with rapid clearance from the circulation of drugs result in their limited effectiveness and generally high therapeutic doses. The use of nanocarriers for drug delivery can prevent the rapid degradation of the drug, leading to its increased half-life. It can also improve the solubility and stability of drugs, advance their distribution and targeting, ensure a sustained release, and reduce drug resistance by delivering multiple therapeutic agents simultaneously. Furthermore, nanotechnology enables the combination of therapeutics with biomedical imaging agents and other treatment modalities to overcome the challenges of disease diagnosis and therapy. Such an approach is referred to as "theranostics" and aims to offer a more patient-specific approach through the observation of the distribution of contrast agents that are linked to therapeutics. The purpose of this paper is to present the recent scientific reports on polymeric nanocarriers for MRI-guided drug delivery. Polymeric nanocarriers are a very broad and versatile group of materials for drug delivery, providing high loading capacities, improved pharmacokinetics, and biocompatibility. The main focus was on the contrasting properties of proposed polymeric nanocarriers, which can be categorized into three main groups: polymeric nanocarriers (1) with relaxation-type contrast agents, (2) with chemical exchange saturation transfer (CEST) properties, and (3) with direct detection contrast agents based on fluorinated compounds. The importance of this aspect tends to be downplayed, despite its being essential for the successful design of applicable theranostic nanocarriers for image-guided drug delivery. If available, cytotoxicity and therapeutic effects were also summarized.

A polyethylene glycol-conjugate of deoxycytidine analog, DFP-14927, produces potential antitumor effects on pancreatic tumor-xenograft murine models via inducing G2/M arrest

A deoxycytidine analog is a potential agent for the treatment of several cancers, which includes poorly prognostic pancreatic cancer. We previously developed deoxycytidine analog DFP-10917, and long-term/low-dose infusions of this analog has produced antitumor effects in leukemia cancer- and ovarian cancer-xenograft models. DFP-10917 is now undergoing clinical Phase III study in the United States for the treatment of patients with relapsed or refractory acute myeloid leukemia. PEG-drug conjugation has become a promising technique to improve the pharmacokinetic and pharmacodynamic properties of anti-cancer drugs. In the present study, we synthesized a novel PEG-drug conjugate of DFP-10917, referred to hereafter as DFP-14927, using a 4-armed CTPEG system to endow the DFP-10917 drug with favorable long-circulating properties that maximize its utility and antitumor efficacy. Intravenous injection of the synthesized DFP-14927 returned encouraging antitumor effects in a Panc-1 human pancreatic tumor- and a BxPC-3 human pancreatic tumor-xenograft models. These effects were comparable to that of free DFP-10917 as well as to that of gemcitabine, which is considered a standard in the treatment of pancreatic cancer. In vitro studies revealed that DFP-14927 inhibits cell division on human pancreatic cancer cell lines via arrest of the G2/M phase in the cell cycle, which is consistent with the effects of free DFP-10917. Intravenous administration of the newly synthesized DFP-14927 has induced G2/M arrest in human pancreatic tumor-xenograft murine models, which represents an improvement in the pharmacokinetics of DFP-10917. DFP-14927 could be an alternative for patients who cannot accept prolonged or continuous infusions of DFP-10917.

Exploring the potential of antimalarial nanocarriers as a novel therapeutic approach

Malaria is a life-threatening parasitic disease that affects millions of people worldwide, especially in developing countries. Despite advances in conventional therapies, drug resistance in malaria parasites has become a significant concern. Hence, there is a need for a new therapeutic approach. To combat the disease effectively means eliminating vectors and discovering potent treatments. The nanotechnology research efforts in nanomedicine show promise by exploring the potential use of nanomaterials that can surmount these limitations occurring with antimalarial drugs, which include multidrug resistance or lack of specificity when targeting parasites directly. Utilizing nanomaterials would possess unique advantages over conventional chemotherapy systems by increasing the efficacy levels while reducing side effects significantly by delivering medications precisely within the diseased area. It also provides cheap yet safe measures against Malaria infections worldwide-ultimately improving treatment efficiency holistically without reinventing new methods therapeutically. This review is an effort to provide an overview of the various stages of malaria parasites, pathogenesis, and conventional therapies, as well as the treatment gap existing with available formulations. It explores different types of nanocarriers, such as liposomes, ethosomal cataplasm, solid lipid nanoparticles, nanostructured lipid carriers, polymeric nanocarriers, and metallic nanoparticles, which are frequently employed to boost the efficiency of antimalarial drugs to overcome the challenges and develop effective and safe therapies. The study also highlights the improved pharmacokinetics, enhanced drug bioavailability, and reduced toxicity associated with nanocarriers, making them a promising therapeutic approach for treating malaria.

Dual-Drug Delivery by Anisotropic and Uniform Hybrid Nanostructures: A Comparative Study of the Function and Substrate-Drug Interaction Properties

By utilizing nanoparticles to upload and interact with several pharmaceuticals in varying methods, the primary obstacles associated with loading two or more medications or cargos with different characteristics may be addressed. Therefore, it is feasible to evaluate the benefits provided by co-delivery systems utilizing nanoparticles by investigating the properties and functions of the commonly used structures, such as multi- or simultaneous-stage controlled release, synergic effect, enhanced targetability, and internalization. However, due to the unique surface or core features of each hybrid design, the eventual drug-carrier interactions, release, and penetration processes may vary. Our review article focused on the drug's loading, binding interactions, release, physiochemical, and surface functionalization features, as well as the varying internalization and cytotoxicity of each structure that may aid in the selection of an appropriate design. This was achieved by comparing the actions of uniform-surfaced hybrid particles (such as core-shell particles) to those of anisotropic, asymmetrical hybrid particles (such as Janus, multicompartment, or patchy particles). Information is provided on the use of homogeneous or heterogeneous particles with specified characteristics for the simultaneous delivery of various cargos, possibly enhancing the efficacy of treatment techniques for illnesses such as cancer.

Antitumor Activity of PEGylated and TEGylated Phenothiazine Derivatives: Structure–Activity Relationship

The paper aims to investigate the antitumor activity of a series of phenothiazine derivatives in order to establish a structure–antitumor activity relationship. To this end, PEGylated and TEGylated phenothiazine have been functionalized with formyl units and further with sulfonamide units via dynamic imine bonds. Their antitumor activity was monitored in vitro against seven human tumors cell lines and a mouse one compared to a human normal cell line by MTS assay. In order to find the potential influence of different building blocks on antitumor activity, the antioxidant activity, the ability to inhibit farnesyltransferase and the capacity to bind amino acids relevant for tumor cell growth were investigated as well. It was established that different building blocks conferred different functionalities, inducing specific antitumor activity against the tumor cells.

Harnessing Peptide-Functionalized Multivalent Gold Nanorods for Promoting Enhanced Gene Silencing and Managing Breast Cancer Metastasis

Small interfering RNA (siRNA) has become the cornerstone against undruggable targets and for managing metastatic breast cancer. However, an effective gene silencing approach is faced with a major challenge due to the delivery problem. In our present study, we have demonstrated efficient siRNA delivery, superior gene silencing, and inhibition of metastasis in triple-negative breast cancer cells (MDA-MB-231) using rod-shaped (aspect ratio: 4) multivalent peptide-functionalized gold nanoparticles and compared them to monovalent free peptide doses. Multivalency is a new concept in biology, and tuning the physical parameters of multivalent nanoparticles can enhance gene silencing and antitumor efficacy. We explored the effect of the multivalency of shape- and size-dependent peptide-functionalized gold nanoparticles in siRNA delivery. Our study demonstrates that peptide functionalization leads to reduced toxicity of the nanoparticles. Such designed peptide-functionalized nanorods also demonstrate antimetastatic efficacy in Notch1-silenced cells by preventing EMT progression in vitro. We have shown siRNA delivery in the hard-to-transfect primary cell line HUVEC and also demonstrated that the Notch1-silenced MDA-MB-231 cell line has failed to form nanobridge-mediated foci with the HUVEC in the co-culture of HUVEC and MDA-MB-231, which promote metastasis. This antimetastatic effect is further checked in a xenotransplant in vivo zebrafish model. In vivo studies also suggest that our designed nanoparticles mediated inhibition of micrometastasis due to silencing of the Notch1 gene. The outcome of our study highlights that the structure-activity relationship of multifunctional nanoparticles can be harnessed to modulate their biological activity.

Enhanced Cytotoxic Activity of PEGylated Curcumin Derivatives: Synthesis, Structure-Activity Evaluation, and Biological Activity

Curcumin has been modified in various ways to broaden its application in medicine and address its limitations. In this study, we present a series of curcumin-based derivatives obtained by replacing the hydroxy groups in the feruloyl moiety with polyethylene glycol (PEG) chains and the addition of the BF₂ moiety to the carbonyl groups. Tested compounds were screened for their cytotoxic activity toward two bladder cancer cell lines, 5637 and SCaBER, and a noncancerous cell line derived from lung fibroblasts (MRC-5). Cell viability was analyzed under normoxic and hypoxic conditions (1% oxygen). Structure-activity relationships (SARs) are discussed, and curcumin derivatives equipped within feruloyl moieties with 3-methoxy and 4-{2-[2-(2-methoxyethoxy)ethoxy]ethoxy} substituents (5) were selected for further analysis. Compound 5 did not affect the viability of MRC-5 cells and exerted a stronger cytotoxic effect under hypoxic conditions. However, the flow cytometry studies showed that PEGylation did not improve cellular uptake. Another observation was that the lack of serum proteins limits the intracellular uptake of curcumin derivative 5. The preliminary mechanism of action studies indicated that compound 5 under hypoxic conditions induced G2/M arrest in a dose-dependent manner and increased the expression of stress-related proteins such as p21/CIP1, phosphorylated HSP27, ADAMTS-1, and phosphorylated JNK. In summary, the results of the studies indicated that PEGylated curcumin is a more potent compound against bladder cancer cell lines than the parent compound, and derivative 5 is worthy of further investigation to clarify its mechanism of anticancer action under hypoxic conditions.

Organotrifluoroborate Sugar Conjugates for a Guided Boron Neutron Capture Therapy: From Synthesis to Positron Emission Tomography

Sugars are a versatile tool for targeting malignant cells and have been extensively used for drug delivery and imaging techniques. Their prototype, fluorodeoxyglucose ([¹⁸F]FDG), is currently used for positron emission tomography. Boron neutron capture therapy (BNCT) is a cancer treatment that relies on irradiation with thermal neutrons of cancer cells previously loaded with [¹⁰B]-containing compounds. The recent introduction of accelerators as a neutron source for clinical use prompts the planning of delivery compounds enriched with boron able to be traced in real time. This work describes the first synthesis of a new class of sugar derivatives conjugated to a trifluoroborate moiety as potential theranostic agents. Stability and cytotoxicity studies are reported for all compounds, together with [¹⁸F] radiolabeling optimization and in vivo preliminary positron emission tomography (PET) experiments on a selected compound.

Heterobivalent Inhibitors of Acetyl-CoA Carboxylase: Drug Target Residence Time and Time-Dependent Antibacterial Activity

The relationship between drug-target residence time and the post-antibiotic effect (PAE) provides insights into target vulnerability. To probe the vulnerability of bacterial acetyl-CoA carboxylase (ACC), a series of heterobivalent inhibitors were synthesized based on pyridopyrimidine 1 and moiramide B (3) which bind to the biotin carboxylase and carboxyltransferase ACC active sites, respectively. The heterobivalent compound 17, which has a linker of 50 Å, was a tight binding inhibitor of Escherichia coli ACC (Kiapp 0.2 nM) and could be displaced from ACC by a combination of both 1 and 3 but not just by 1. In agreement with the prolonged occupancy of ACC resulting from forced proximity binding, the heterobivalent inhibitors produced a PAE in E. coli of 1-4 h in contrast to 1 and 3 in combination or alone, indicating that ACC is a vulnerable target and highlighting the utility of kinetic, time-dependent effects in the drug mechanism of action.

Solvent-Free Direct PEGylation of Collagen Fibers

The addition of poly(ethylene glycol) (PEG) to biomolecules and biomaterials is a well-established approach to modify their properties for therapeutic applications. For biomaterials, the approach is typically to blend or electrospray the synthetic polymer with the biomaterial. Effective surface modification approaches such as surface-initiated polymer brushes are challenging since the harsh solvents required for brush synthesis may destroy the biomaterial. Herein, we describe the PEGylation of collagen fibers by surface-initiated PEG brushes using a living anionic grafting-from mechanism. This brush synthesis is done in the absence of solvents to minimize the degradation of the native collagen structure. We quantify the effect the brush synthesis has on the native structure of the collagen fiber using differential scanning calorimetry (DSC) and find that even at long reaction times a significant fraction of the native structure remains. Dynamic mechanical analysis indicates the collagen undergoes only modest structural degradation, while adhesion studies find a significant improvement of antifouling properties. Further, our approach opens the way for further chemistry, as the growing polymer chain is a potassium alkoxy group that can be functionalized by termination or by subsequent reaction by a wide variety of molecules.

Pegylated Curcumin Derivative: Water-Soluble Conjugates with Antitumor and Antibacterial Activity

During the past years, the synthesis of polymer prodrug structures, based on natural phytochemical compounds with a great range of valuable biological properties, has become a promising solution in cancer prevention, imaging, and detection. Curcumin (Curc) remains one of the most studied natural products, due to the impressive palette of biological properties and the possibility to be easily loaded in various micro- and nanostructures and chemically modified. In this study, pegylated curcumin derivatives were prepared by a direct esterification reaction between poly(ethylene glycol)diacid (PEG of 600 g/mol molar mass, PEG₆₀₀) and Curc in the presence of N,N'-dicyclohexylcarbodiimide (PEG₆₀₀-Curc). The successful reaction resulted in a water-soluble stable product that was characterized by infrared spectroscopy (Fourier transform infrared (FT-IR)) and proton (¹H) and carbon (¹³C) NMR. The effect of the pH values of buffer solutions on PEG₆₀₀-Curc spectral properties (absorption and photoluminescence) was investigated by UV-vis and fluorescence spectrophotometry. Based on the biological tests, it was confirmed that PEG₆₀₀-Curc exhibits cytotoxic activity against Graffi cell lines, as a function of the Curc concentration in the conjugate and the incubation time. PEG₆₀₀-Curc antibacterial activity was validated in microbiological tests against pathogenic microorganisms such as Staphylococcus aureus. Most importantly, despite the covalent attachment of Curc to PEG and the slight reduction in the therapeutic index of the conjugate, both the anticancer and antimicrobial activities remain the highest reported, thus opening the gate for further, more clinically oriented studies.

Novel Short PEG Chain-Substituted Porphyrins: Synthesis, Photochemistry, and In Vitro Photodynamic Activity against Cancer Cells

This work presents the synthesis and characterization of metal-free, zinc (II), and cobalt (II) porphyrins substituted with short PEG chains. The synthesized compounds were characterized by UV-Vis, ¹H and ¹³C NMR spectroscopy, and MALDI-TOF mass spectrometry. The origin of the absorption bands for tested compounds in the UV-Vis range was determined using a computational model based on the electron density functional theory (DFT) and its time-dependent variant (TD-DFT). The photosensitizing activity was evaluated by measuring the ability to generate singlet oxygen (ΦΔ), which reached values up to 0.54. The photodynamic activity was tested using bladder (5637), prostate (LNCaP), and melanoma (A375) cancer cell lines. In vitro experiments clearly showed the structure-activity relationship regarding types of substituents, their positions in the phenyl ring, and the variety of central metal ions on the porphyrin core. Notably, the metal-free derivative 3 and its zinc derivative 6 exerted strong cytotoxic activity toward 5637 cells, with IC₅₀ values of 8 and 15 nM, respectively. None of the tested compounds induced a cytotoxic effect without irradiation. In conclusion, these results highlight the potential value of the tested compounds for PDT application.

Theranostic Small-Molecule Prodrug Conjugates for Targeted Delivery and Controlled Release of Toll-like Receptor 7 Agonists

We previously reported the design and synthesis of a small-molecule drug conjugate (SMDC) platform that demonstrated several advantages over antibody–drug conjugates (ADCs) in terms of in vivo pharmacokinetics, solid tumor penetration, definitive chemical structure, and adaptability for modular synthesis. Constructed on a tri-modal SMDC platform derived from 1,3,5-triazine (TZ) that consists of a targeting moiety (Lys-Urea-Glu) for prostate-specific membrane antigen (PSMA), here we report a novel class of chemically identical theranostic small-molecule prodrug conjugates (T-SMPDCs), [^18/19F]F-TZ(PSMA)-LEGU-TLR7, for PSMA-targeted delivery and controlled release of toll-like receptor 7 (TLR7) agonists to elicit de novo immune response for cancer immunotherapy. In vitro competitive binding assay of [¹⁹F]F-TZ(PSMA)-LEGU-TLR7 showed that the chemical modification of Lys-Urea-Glu did not compromise its binding affinity to PSMA. Receptor-mediated cell internalization upon the PSMA binding of [¹⁸F]F-TZ(PSMA)-LEGU-TLR7 showed a time-dependent increase, indicative of targeted intracellular delivery of the theranostic prodrug conjugate. The designed controlled release of gardiquimod, a TLR7 agonist, was realized by a legumain cleavable linker. We further performed an in vivo PET/CT imaging study that showed significantly higher uptake of [¹⁸F]F-TZ(PSMA)-LEGU-TLR7 in PSMA⁺ PC3-PIP tumors (1.9 ± 0.4% ID/g) than in PSMA⁻ PC3-Flu tumors (0.8 ± 0.3% ID/g) at 1 h post-injection. In addition, the conjugate showed a one-compartment kinetic profile and in vivo stability. Taken together, our proof-of-concept biological evaluation demonstrated the potential of our T-SMPDCs for cancer immunomodulatory therapies.

Emerging concepts in designing next-generation multifunctional nanomedicine for cancer treatment

Nanotherapy has emerged as an improved anticancer therapeutic strategy to circumvent the harmful side effects of chemotherapy. It has been proven to be beneficial to offer multiple advantages, including their capacity to carry different therapeutic agents, longer circulation time and increased therapeutic index with reduced toxicity. Over time, nanotherapy evolved in terms of their designing strategies like geometry, size, composition or chemistry to circumvent the biological barriers. Multifunctional nanoscale materials are widely used as molecular transporter for delivering therapeutics and imaging agents. Nanomedicine involving multi-component chemotherapeutic drug-based combination therapy has been found to be an improved promising approach to increase the efficacy of cancer treatment. Next-generation nanomedicine has also utilized and combined immunotherapy to increase its therapeutic efficacy. It helps in targeting tumor immune response sparing the healthy systemic immune function. In this review, we have summarized the progress of nanotechnology in terms of nanoparticle designing and targeting cancer. We have also discussed its further applications in combination therapy and cancer immunotherapy. Integrating patient-specific proteomics and biomarker based information and harnessing clinically safe nanotechnology, the development of precision nanomedicine could revolutionize the effective cancer therapy.

Redox-responsive self-assembled polymeric nanoprodrug for delivery of gemcitabine in B-cell lymphoma therapy

Gemcitabine, as a standard and classic strategy for B-cell lymphoma in the clinic, is limited by its poor pharmacodynamics. Although stimuli-responsive polymeric nanodelivery systems have been widely investigated in the past decade, issues such as complicated procedures, low loading capacity, and uncontrollable release kinetics still hinder their clinical translation. In view of the above considerations, we attempt to construct hyperbranched polyprodrug micelles with considerable drug loading via simple procedures and make use of the particularity of the tumor microenvironment to ensure that the micelles are "inactivated" in normal tissues and "activated" in the tumor microenvironment. Hence, in this work, a redox-responsive polymeric gemcitabine-prodrug (GEM-S-S-PEG) was one-pot synthesized via facile esterification and acylation. The self-assembled subsize (< 100 nm) GEM-S-S-PEG (GSP NPs) with considerable loading capacity (≈ 24.6%) exhibited on-demand and accurate control of gemcitabine release under a simulated tumor microenvironment and thus significantly induced the apoptosis of B-cell lymphoma in vitro. Moreover, in the A20 tumor xenograft murine model, GSP NPs efficiently decreased the expansion of tumor tissues with minimal systemic toxicity. In summary, these redox-responsive and self-assembling GSP NPs with a facile one-pot synthesis procedure may hold great potency in clinical translation for enhanced chemotherapy of B-cell lymphoma. STATEMENT OF SIGNIFICANCE: A redox-responsive polymeric gemcitabine-prodrug (GEM-S-S-PEG) was one-pot synthesized via facile esterification and acylation. The self-assembled subsize (< 100 nm) GEM-S-S-PEG (GSP NPs) exhibited significant tumor therapeutic effects in vitro and in vivo. The polyprodrug GEM-S-S-PEG prepared in this study shows the great potential of redox-responsive nanodrugs for antitumor activity, which provides a reference value for the optimization of the design of functional polyprodrugs.

New Perspectives for Developing Therapeutic Bioconjugates of Metabolite-Depleting Enzymes: Lessons Learned Combating Glutamate Excitotoxicity

Glutamate, the main excitatory neurotransmitter in the central nervous system, plays an essential role in several cognitive activities such as memorizing and learning. Excessive glutamate release and disturbance of glutamate homeostasis participates in multiple neuronal pathologies including cerebral ischemia (inadequate blood supply), traumatic brain injury (e.g., from a fall or an accident), multiple sclerosis, epilepsy, migraine, fetal hypoxia, or Alzheimer's disease. Attenuating excitotoxicity by, for example, targeting glutamate receptors has proved to be beneficial in animal models but has largely failed in clinical trials because of toxic side effects. New therapeutic concepts have been explored to reduce the excitotoxic effect caused by the excessive glutamate release by using or stimulating glutamate-depleting enzymes in the bloodstream. These enzymes indirectly act upon the brain by depleting glutamate in the bloodstream, which is believed to siphon it out of the brain. Recent studies have shown that bioconjugate approaches applied to such enzymes exacerbate this therapeutic effect but raise additional questions for future research. This Perspective provides an overview of lessons learned by our group when exploring bioconjugate approaches for combatting glutamate excitotoxicity as an illustration of how research on therapeutic bioconjugates is evolving.

The Depletion Mechanism Actuates Bacterial Aggregation by Exopolysaccharides and Determines Species Distribution & Composition in Bacterial Aggregates

Bacteria in natural environments and infections are often found in cell aggregates suspended in polymer-rich solutions, and aggregation can promote bacterial survival and stress resistance. One aggregation mechanism, called depletion aggregation, is driven by physical forces between bacteria and high concentrations of polymers in the environment rather than bacterial activity per se. As such, bacteria aggregated by the depletion mechanism will disperse when polymer concentrations fall unless other adhesion mechanisms supervene. Here we investigated whether the depletion mechanism can actuate the aggregating effects of Pseudomonas aeruginosa exopolysaccharides for suspended (i.e. not surface attached) bacteria, and how depletion affects bacterial inter-species interactions. We found that cells overexpressing the exopolysaccharides Pel and Psl remained aggregated after short periods of depletion aggregation whereas wild-type and mucoid P. aeruginosa did not. In co-culture, depletion aggregation had contrasting effects on P. aeruginosa's interactions with coccus- and rod-shaped bacteria. Depletion caused S. aureus (cocci) and P. aeruginosa (rods) to segregate from each other and S. aureus to resist secreted P. aeruginosa antimicrobial factors resulting in species co-existence. In contrast, depletion aggregation caused P. aeruginosa and Burkholderia sp. (both rods) to intermix, enhancing type VI secretion inhibition of Burkholderia by P. aeruginosa, leading to P. aeruginosa dominance. These results show that in addition to being a primary cause of aggregation in polymer-rich suspensions, physical forces inherent to the depletion mechanism can promote aggregation by some self-produced exopolysaccharides and determine species distribution and composition of bacterial communities.

Impact of anti-PEG antibody affinity on accelerated blood clearance of pegylated epoetin beta in mice

Antibodies that bind polyethylene glycol (PEG) can be induced by pegylated biomolecules and also exist in a significant fraction of healthy individuals who have never received pegylated medicines. The binding affinity of antibodies against PEG (anti-PEG antibodies) likely varies depending on if they are induced or naturally occurring. Anti-PEG antibodies can accelerate the clearance of pegylated medicines from the circulation, resulting in loss of drug efficacy, but it is unknown how accelerated blood clearance is affected by anti-PEG antibody affinity. We identified a panel of anti-PEG IgG and IgM antibodies with binding avidities ranging over several orders of magnitude to methoxy polyethylene glycol-epoetin beta (PEG-EPO), which is used to treat patients suffering from anemia. Formation of in vitro immune complexes between PEG-EPO and anti-PEG IgG or IgM antibodies was more obvious as antibody affinity increased. Likewise, high affinity anti-PEG antibodies produced greater accelerated blood clearance of PEG-EPO as compared to low affinity antibodies. The molar ratio of anti-PEG antibody to PEG-EPO that accelerates drug clearance in mice correlates with antibody binding avidity. Our study indicates that the bioactivity of PEG-EPO may be reduced due to rapid clearance in patients with either high concentrations of low affinity or low concentrations of high affinity anti-PEG IgG and IgM antibodies.

Simulate SubQ: The Methods and the Media

For decades, there has been a growing interest in injectable subcutaneous formulations to improve the absorption of drugs into the systemic circulation and to prolong their release over a longer period. However, fluctuations in the blood plasma levels together with bioavailability issues often limit their clinical success. This warrants a closer look at the performance of long-acting depots, for example, and their dependence on the complex interplay between the dosage form and the physiological microenvironment. For this, biopredictive performance testing is used for a thorough understanding of the biophysical processes affecting the absorption of compounds from the injection site in vivo and their simulation in vitro. In the present work, we discuss in vitro methodologies including methods and media developed for the subcutaneous route of administration on the background of the most relevant absorption mechanisms. Also, we highlight some important knowledge gaps and shortcomings of the existing methodologies to provide the reader with a better understanding of the scientific evidence underlying these models.

PEGylated Oligothioetheramide Prodrugs Activated by Host Serum Proteases

Due to the increasing prominence of antibiotic resistance, novel drug discovery and delivery approaches targeting bacteria are essential. In this work we evaluate a prodrug design to improve the cytotoxic profile of polycationic oligothioetheramides (oligoTEAs), which are promising antimicrobials. Herein we chemically modify the oligoTEA, PDT-4G, with a polyethylene glycol (PEG) and show that 1, 2, and 5 kDa PEGs mitigate cytotoxicity. As PEGylation reduces antibacterial activity, we evaluate two peptide linkers which, unlike oligoTEAs, are susceptible to proteolytic cleavage in serum. To gain insight into the prodrug reactivation, two linkers were tested, the 5-residue peptide sequence LMPTG, and the dipeptide sequence VC-PABC. In the presence of 20 % serum, prodrugs made with the VC-PABC linker successfully inhibited bacterial growth. Overall, we observed reactivation of oligoTEAs facilitated by serum protease cleavage of the peptide linkers. This work opens the door to the future design of antimicrobial prodrugs with tunable release profiles.