Designer protein delivery: From natural to engineered affinity-controlled release systems

Rational design of diblock copolymer enables efficient cytosolic protein delivery

Polymer-mediated cytosolic protein delivery demonstrates a promising strategy for the development of protein therapeutics. Here, we propose a new designed diblock copolymer which realizes efficient cytosolic protein delivery both in vitro and in vivo. The polymer contains one protein-binding block composed of phenylboronic acid (PBA) and N-(3-dimethylaminopropyl) (DMAP) pendant units for protein binding and endosomal escape, respectively, followed by the response to ATP enriched in the cytosol which triggers the protein release. The other block is PEG designed to improve particle size control and circulation in vivo. By optimizing the block composition, sequence and length of the copolymer, the optimal one (BP20) was identified with the binding block containing 20 units of both PBA and DMAP, randomly distributed along the chain. When mixed with proteins, the BP20 forms stable nanoparticles and mediates efficient cytosolic delivery of a wide range of proteins including enzymes, toxic proteins and CRISPR/Cas9 ribonucleoproteins (RNP), to various cell lines. The PEG block, especially when further modified with folic acid (FA), enables tumor-targeted delivery of Saporin in vivo, which significantly suppresses the tumor growth. Our results shall inspire the design of novel polymeric vehicles with robust capability for cytosolic protein delivery, which holds great potential for both biological research and therapeutic applications.

Delivery Strategies of Growth Factors in Cartilage Tissue Engineering

Cartilage plays an important role in supporting soft tissues, reducing joint friction, and distributing pressure. However, its self-repair capacity is limited due to the lack of blood vessels, nerves, and lymphatic systems. Tissue engineering offers a potential solution to promote cartilage regeneration by combining scaffolds, seed cells, and growth factors. Among these, growth factors play a critical role in regulating cell proliferation, differentiation, and extracellular matrix remodeling. However, their instability, susceptibility to degradation and potential side effects limit their effectiveness. This article reviews the main growth factors used in cartilage tissue engineering and their delivery strategies, including affinity-based delivery, carrier-assisted delivery, stimuli-responsive delivery, spatial structure-based delivery, and cell system-based delivery. Each method shows unique advantages in enhancing the delivery efficiency and specificity of growth factors but also faces challenges such as cost, biocompatibility, and safety. Future research needs to further optimize these strategies to achieve more efficient, safe, and economical delivery of growth factors, thereby advancing the clinical application of cartilage tissue engineering.

Colloidal Hydrogel with Staged Sequestration and Release of Molecules Undergoing Competitive Binding

Competitive binding of distinct molecules in the hydrogel interior can facilitate dynamic exchange between the hydrogel and the surrounding environment. The ability to control the rates of sequestration and release of these molecules would enhance the hydrogel's functionality and enable targeting of a specific task. Here, we report the design of a colloidal hydrogel with two distinct pore dimensions to achieve staged, diffusion-controlled scavenging and release dynamics of molecules undergoing competitive binding. The staged scavenging and release strategy was shown for CpG oligodeoxynucleotide (ODN) and human epidermal growth factor (hEGF), two molecules exhibiting different affinities to the quaternary ammonium groups of the hydrogel. Fast ODN scavenging from the ambient environment occurred via diffusion through submicrometer-size hydrogel pores, while delayed hEGF release from the hydrogel was governed by its diffusion through nanometer-size pores. The results of the experiments were in agreement with simulation results. The significance of staged ODN-hEGF exchange was highlighted by the dual anti-inflammation and tissue proliferation hydrogel performance.

Formation of Nanofibrillar Self-Healing Hydrogels Using Antimicrobial Peptides

The rise of drug-resistant microorganisms has prompted the development of innovative strategies with the aim of addressing this challenge. Among the alternative approaches gaining increased attention are antimicrobial peptides (AMPs), a group of peptides with the ability to combat microbial pathogens. Here, we investigated a small peptide, KLVFF, derived from the Alzheimer's amyloid-β (Aβ) protein. While Aβ has been associated with the development of neurodegenerative diseases, the core part of the Aβ protein, namely the Aβ 16-20 fragment, has also been exploited to obtain highly functional biomaterials. In this study we found that KLVFF is capable of self-assembling into a fibrillar network to form a self-healing hydrogel. Moreover, this small peptide can undergo a transition from a gel to a liquid state following application of shear stress, in a reversible manner. As an AMP, this material exhibited both antibacterial and antifungal properties while remaining highly biocompatible and noncytotoxic toward mammalian cells. The propensity of the KLVFF hydrogel to rapidly assemble into highly ordered macroscopic structures makes it an ideal candidate for biomedical applications necessitating antimicrobial activity, such as wound healing.

Subcellular targeting strategies for protein and peptide delivery

Cytosolic delivery of proteins and peptides provides opportunities for effective disease treatment, as they can specifically modulate intracellular processes. However, most of protein-based therapeutics only have extracellular targets and are cell-membrane impermeable due to relatively large size and hydrophilicity. The use of organelle-targeting strategy offers great potential to overcome extracellular and cell membrane barriers, and enables localization of protein and peptide therapeutics in the organelles. Although progresses have been made in the recent years, organelle-targeted protein and peptide delivery is still challenging and under exploration. We reviewed recent advances in subcellular targeted delivery of proteins/peptides with a focus on targeting mechanisms and strategies, and highlight recent examples of active and passive organelle-specific protein and peptide delivery systems. This emerging platform could open a new avenue to develop more effective protein and peptide therapeutics.

Dual Functional Microcapsule based on Monodisperse Short PEG Amphiphile for Drug Encapsulation and Protein Affinity Controlled Release

A short monodisperse poly(ethylene glycol) (PEG) and a neutral organic rotamer conjugate TEG-BTA-2 amphiphile was designed for the construction of a stimuli-responsive switchable self-assembled structure for drug encapsulation by noncovalent interaction and targeted controlled delivery. A short PEG, tetraethylene glycol (TEG) was covalently attached with a neutral organic rotamer benzothiazole dye (BTA-2) affording the neutral TEG-BTA-2 (<500 D). The TEG-BTA-2 is self-assembled into a microsphere in an aqueous medium, but remarkably undergoes morphology change switching to a rice-like microcapsule for curcumin encapsulation. Curcumin-loaded microcapsules were stable in an aqueous solution, however, were noticed disintegrating upon the addition of BSA protein. This is possibly due to an interaction with BSA protein leading to a protein affinity-controlled curcumin release in a neutral PBS buffer. Moreover, cell internalization of the neutral amphiphile TEG-BTA-2 into A549 cells was observed by fluorescence microscopy, providing an opportunity for application as a molecular vehicle for targeted drug delivery and monitoring.

Hydrogel-Based Growth Factor Delivery Platforms: Strategies and Recent Advances

Growth factors play a crucial role in regulating a broad variety of biological processes and are regarded as powerful therapeutic agents in tissue engineering and regenerative medicine in the past decades. However, their application is limited by their short half-lives and potential side effects in physiological environments. Hydrogels are identified as having the promising potential to prolong the half-lives of growth factors and mitigate their adverse effects by restricting them within the matrix to reduce their rapid proteolysis, burst release, and unwanted diffusion. This review discusses recent progress in the development of growth factor-containing hydrogels for various biomedical applications, including wound healing, brain tissue repair, cartilage and bone regeneration, and spinal cord injury repair. In addition, the review introduces strategies for optimizing growth factor release including affinity-based delivery, carrier-assisted delivery, stimuli-responsive delivery, spatial structure-based delivery, and cellular system-based delivery. Finally, the review presents current limitations and future research directions for growth factor-delivering hydrogels.

Sustainable Janus lignin-based polyurethane biofoams with robust antibacterial activity and long-term biofilm resistance

Conventional antibiotic therapies have been becoming less efficient due to increasingly, and sometimes fully, antibiotic-resistant bacterial strains, sometimes known as "superbacteria" or "superbugs." Thus, novel antibacterial materials to effectively inhibit or kill bacteria are crucial for humanity. As a broad-spectrum antimicrobial agent, silver nanoparticles (Ag NPs) have been the most widely commercialized of biomedical materials. However, long-term use of significant amounts of Ag NPs can be potentially harmful to human health through a condition known as argyria, in addition to being toxic to many environmental systems. It is, thus, highly necessary to reduce the amount of Ag NPs employed in medical treatments while also ensuring maintenance of antimicrobial properties, in addition to reducing the overall cost of treatment for humanitarian utilization. For this purpose, naturally sourced antimicrobial polylysine (PL) is used to partially replace Ag NPs within the materials composition. Accordingly, a series of PL, Ag NPs, and lignin-based polyurethane (LPU) composite biofoams (LPU-PL-Ag) were prepared. These proposed composite biofoams, containing at most only 2 % PL and 0.03 % Ag NPs, significantly inhibited the growth of both Gram-positive and Gram-negative bacteria within 1 h and caused irreversibly destructive bactericidal effects. Additionally, with a layer of polydimethylsiloxane (PDMS) on the surface, PDMS-LPU-PL(2 %)-Ag(0.03 %) can effectively prevent bacterial adhesion with a clearance rate of about 70 % for both bacterial biofilms within three days and a growth rate of more than 80 % for mouse fibroblasts NIH 3 T3. These lignin-based polyurethane biofoam dressings, with shorter antiseptic sterilization times and broad-spectrum antibacterial effects, are extremely advantageous for infected wound treatment and healing in clinical use.

Rational Design and Development of Polymeric Nanogels as Protein Carriers

Proteins have gained significant attention as potential therapeutic agents owing to their high specificity and reduced toxicity. Nevertheless, their clinical utility is hindered by inherent challenges associated with stability during storage and after in vivo administration. To overcome these limitations, polymeric nanogels (NGs) have emerged as promising carriers. These colloidal systems are capable of efficient encapsulation and stabilization of protein cargoes while improving their bioavailability and targeted delivery. The design of such delivery systems requires a comprehensive understanding of how the synthesis and formulation processes affect the final performance of the protein. This review highlights critical aspects involved in the development of NGs for protein delivery, with specific emphasis on loading strategies and evaluation techniques. For example, factors influencing loading efficiency and release kinetics are discussed, along with strategies to optimize protein encapsulation through protein-carrier interactions to achieve the desired therapeutic outcomes. The discussion is based on recent literature examples and aims to provide valuable insights for researchers working toward the advancement of protein-based therapeutics.

Quantifying and Modulating Protein Encapsulation in Guanosine-Based Supramolecular Particles

The encapsulation of proteins is an effective way to preserve their structure and enhance their function. One exciting possibility is adjusting the protective agent to match the specific protein's characteristics to influence its properties. In a recent study, we developed a flow cytometry-based method to quantify the encapsulation of small-molecule dyes in colloidal particles made from guanosine derivatives (supramolecular hacky sacks (SHS) particles). We aimed to determine whether this method could quantify protein encapsulation and track changes and if the particles could be tuned to bind to specific proteins. Our results showed that fluorescein isothiocyanate (FITC)-labeled proteins had apparent association constants in the micromolar range with hydrophobicity as the dominant factor enhancing the affinities. Confocal laser scanning microscopy (CLSM) imaging supported these results and provided additional information about the protein distribution within the particles. We also tested the feasibility of tuning the avidin affinity (AVI) for SHS particles with a biotin ligand. We found that increasing the amount of biotin initially enhanced AVI binding, but then reached saturation, which we hypothesize results from noncovalent cross-linking caused by strong biotin/AVI interactions. CLSM images showed that the linker also impacted the AVI distribution within the particles. Our strategy provides an advantage over other methods for quantifying protein encapsulation by being suitable for high-throughput analysis with high reproducibility. We anticipate that future efforts to use lower-affinity ligands would result in better strategies for modulating protein affinity for drug delivery applications.

Engineering Nucleotidoproteins for Base-Pairing-Assisted Cytosolic Delivery and Genome Editing

Protein therapeutics targeting intracellular machineries hold profound potential for disease treatment, and hence robust cytosolic protein delivery technologies are imperatively demanded. Inspired by the super-negatively charged, nucleotide-enriched structure of nucleic acids, adenylated pro-proteins (A-proteins) with dramatically enhanced negative surface charges have been engineered for the first time via facile green synthesis. Then, thymidine-modified polyethyleneimine is developed, which exhibits strong electrostatic attraction, complementary base pairing, and hydrophobic interaction with A-proteins to form salt-resistant nanocomplexes with robust cytosolic delivery efficiencies. The acidic endolysosomal environment enables traceless restoration of the A-proteins and consequently promotes the intracellular release of the native proteins. This strategy shows high efficiency and universality for a variety of proteins with different molecular weights and isoelectric points in mammalian cells. Moreover, it enables highly efficient delivery of CRISPR-Cas9 ribonucleoproteins targeting fusion oncogene EWSR1-FLI1, leading to pronounced anti-tumor efficacy against Ewing sarcoma. This study provides a potent and versatile platform for cytosolic protein delivery and gene editing, and may benefit the development of protein pharmaceuticals.

Electrospinning and Cell Fibers in Biomedical Applications

Human body tissues such as muscle, blood vessels, tendon/ligaments, and nerves have fiber-like fascicle morphologies, where ordered organization of cells and extracellular matrix (ECM) within the bundles in specific 3D manners orchestrates cells and ECM to provide tissue functions. Through engineering cell fibers (which are fibers containing living cells) as living building blocks with the help of emerging "bottom-up" biomanufacturing technologies, it is now possible to reconstitute/recreate the fiber-like fascicle morphologies and their spatiotemporally specific cell-cell/cell-ECM interactions in vitro, thereby enabling the modeling, therapy, or repair of these fibrous tissues. In this article, a concise review is provided of the "bottom-up" biomanufacturing technologies and materials usable for fabricating cell fibers, with an emphasis on electrospinning that can effectively and efficiently produce thin cell fibers and with properly designed processes, 3D cell-laden structures that mimic those of native fibrous tissues. The importance and applications of cell fibers as models, therapeutic platforms, or analogs/replacements for tissues for areas such as drug testing, cell therapy, and tissue engineering are highlighted. Challenges, in terms of biomimicry of high-order hierarchical structures and complex dynamic cellular microenvironments of native tissues, as well as opportunities for cell fibers in a myriad of biomedical applications, are discussed.

Supramolecular nanoarchitectonics of phenolic-based nanofiller for controlled diffusion of versatile drugs in hydrogels

Drug-dependent design of hydrogels is currently required for engineering the controlled release of therapeutics, which is a major contributor to the technical challenges relating to the clinical translation of hydrogel-drug systems. Herein, by integrating supramolecular phenolic-based nanofillers (SPFs) into hydrogel microstructures we developed a facile strategy to endow a range of clinically relevant hydrogels with controlled release properties for diverse therapeutic agents. The assembly of multiscale SPF aggregates leads to tunable mesh size and multiple dynamic interactions between SPF aggregates and drugs, which relaxes the available choices of drugs and hydrogels. This simple approach allowed for the controlled release of 12 representative drugs evaluated with 8 commonly used hydrogels. Moreover, the anesthetic drug lidocaine was loaded into SPF-integrated alginate hydrogel and demonstrated sustained release for 14 days in vivo, validating the potential for long-term anesthesia in patients.

Intracellular delivery of therapeutic proteins. New advancements and future directions

Achieving the full potential of therapeutic proteins to access and target intracellular receptors will have enormous benefits in advancing human health and fighting disease. Existing strategies for intracellular protein delivery, such as chemical modification and nanocarrier-based protein delivery approaches, have shown promise but with limited efficiency and safety concerns. The development of more effective and versatile delivery tools is crucial for the safe and effective use of protein drugs. Nanosystems that can trigger endocytosis and endosomal disruption, or directly deliver proteins into the cytosol, are essential for successful therapeutic effects. This article aims to provide a brief overview of the current methods for intracellular protein delivery to mammalian cells, highlighting current challenges, new developments, and future research opportunities.

Functional advantages of building nanosystems using multiple molecular components

Over half of all the natural nanomachines in living organisms are multimeric and likely exploit the self-assembly of their components to provide functional benefits. However, the advantages and disadvantages of building nanosystems using multiple molecular components remain relatively unexplored at the thermodynamic, kinetic and functional levels. In this study we used theory and a simple DNA-based model that forms the same nanostructures with different numbers of components to advance our knowledge in this area. Despite its lower assembly rate, we found that a system built with three components may undergo a more cooperative assembly transition from less preorganized components, which facilitates the emergence of functionalities. Using simple variations of its components, we also found that trimeric nanosystems display a much higher level of programmability than their dimeric counterparts because they can assemble with various levels of cooperativity, self-inhibition and time-dependent properties. We show here how two simple strategies (for example, cutting and adding components) can be employed to efficiently programme the regulatory function of a more complex, artificially selected, RNA-cleaving catalytic nanosystem.

A comprehensive review of protein-based carriers with simple structures for the co-encapsulation of bioactive agents

The rational design and fabrication of edible codelivery carriers are important to develop functional foods fortified with a plurality of bioactive agents, which may produce synergistic effects in increasing bioactivity and functionality to target specific health benefits. Food proteins possess considerable functional attributes that make them suitable for the delivery of a single bioactive agent in a wide range of platforms. Among the different types of protein-based carriers, protein-ligand nanocomplexes, micro/nanoparticles, and oil-in-water (O/W) emulsions have increasingly attracted attention in the codelivery of multiple bioactive agents, due to the simple and convenient preparation procedure, high stability, matrix compatibility, and dosage flexibility. However, the successful codelivery of bioactive agents with diverse physicochemical properties by using these simple-structure carriers is a daunting task. In this review, some effective strategies such as combined functional properties of proteins, self-assembly, composite, layer-by-layer, and interfacial engineering are introduced to redesign the carrier structure and explore the encapsulation of multiple bioactive agents. It then highlights success stories and challenges in the co-encapsulation of multiple bioactive agents within protein-based carriers with a simple structure. The partition, protection, and release of bioactive agents in these protein-based codelivery carriers are considered and discussed. Finally, safety and application as well as challenges of co-encapsulated bioactive agents in the food industry are also discussed. This work provides a state-of-the-art overview of protein-based particles and O/W emulsions in co-encapsulating bioactive agents, which is essential for the design and development of novel functional foods containing multiple bioactive agents.

Affinity-controlled release of rod-derived cone viability factor enhances cone photoreceptor survival

Retinitis pigmentosa (RP) is a group of genetic diseases that results in rod photoreceptor cell degeneration, which subsequently leads to cone photoreceptor cell death, impaired vision and eventual blindness. Rod-derived cone viability factor (RdCVF) is a protein which has two isoforms: a short form (RdCVF) and a long form (RdCVFL) which act on cone photoreceptors in the retina. RdCVFL protects photoreceptors by reducing hyperoxia in the retina; however, sustained delivery of RdCVFL remains challenging. We developed an affinity-controlled release strategy for RdCVFL. An injectable physical blend of hyaluronan and methylcellulose (HAMC) was covalently modified with a peptide binding partner of the Src homology 3 (SH3) domain. This domain was expressed as a fusion protein with RdCVFL, thereby enabling its controlled release from HAMC-binding peptide. Sustained release of RdCVFL was demonstrated for the first time as RdCVFL-SH3 from HAMC-binding peptide for 7 d in vitro. To assess bioactivity, chick retinal dissociates were harvested and treated with the affinity-released recombinant protein from the HAMC-binding peptide vehicle. After 6 d in culture, cone cell viability was greater when cultured with released RdCVFL-SH3 relative to controls. We utilized computational fluid dynamics to model release of RdCVFL-SH3 from our delivery vehicle in the vitreous of the human eye. We demonstrate that our delivery vehicle can prolong the bioavailability of RdCVFL-SH3 in the retina, potentially enhancing its therapeutic effects. Our affinity-based system constitutes a versatile delivery platform for ultimate intraocular injection in the treatment of retinal degenerative diseases. STATEMENT OF SIGNIFICANCE: Retinitis pigmentosa (RP) is the leading cause of inherited blindness in the world. Rod-derived cone viability factor (RdCVF), a novel protein paracrine factor, is effective in preclinical models of RP. To extend its therapeutic effects, we developed an affinity-controlled release strategy for the long form of RdCVF, RdCVFL. We expressed RdCVFL as a fusion protein with an Src homology 3 domain (SH3). We then utilized a hydrogel composed of hyaluronan and methylcellulose (HAMC) and modified it with SH3 binding peptides to investigate its release in vitro. Furthermore, we designed a mathematical model of the human eye to investigate delivery of the protein from the delivery vehicle. This work paves the way for future investigation of controlled release RdCVF.

Directed Evolution Enables Simultaneous Controlled Release of Multiple Therapeutic Proteins from Biopolymer-Based Hydrogels

With the advent of increasingly complex combination strategies of biologics, independent control over their delivery is the key to their efficacy; however, current approaches are hindered by the limited independent tunability of their release rates. To overcome these limitations, directed evolution is used to engineer highly specific, low affinity affibody binding partners to multiple therapeutic proteins to independently control protein release rates. As a proof-of-concept, specific affibody binding partners for two proteins with broad therapeutic utility: insulin-like growth factor-1 (IGF-1) and pigment epithelium-derived factor (PEDF) are identified. Protein-affibody binding interactions specific to these target proteins with equilibrium dissociation constants (K_D ) between 10^-7 and 10^-8 m are discovered. The affibodies are covalently bound to the backbone of crosslinked hydrogels using click chemistry, enabling sustained, independent, and simultaneous release of bioactive IGF-1 and PEDF over 7 days. The system is tested with C57BL/6J mice in vivo, and the affibody-controlled release of IGF-1 results in sustained activity when compared to bolus IGF-1 delivery. This work demonstrates a new, broadly applicable approach to tune the release of therapeutic proteins simultaneously and independently and thus the way for precise control over the delivery of multicomponent therapies is paved.

General Method for Pesticide Recognition Using Albumin-Based Host-Guest Ensembles

The massive use of pesticides nowadays has led to serious consequences for the environment and public health. Fluorescence analytical methods for pesticides are particularly advantageous with respect to simplicity and portability; however, currently available fluorescence methods (enzyme-based assays and indicator displacement assays) with poor universality are only able to detect few specific pesticides (e.g., organophosphorus). Making use of the multiple flexible and asymmetrical binding sites in albumin, we herein report a set of multicolor albumin-based host-guest ensembles. These ensembles exhibit a universal but distinctive fluorescent response to most of the common pesticides and allow array-based identification of pesticides with high accuracy. Furthermore, the simplicity, portability, and visualization of this method enable on-site determination of pesticides in a practical setting. This albumin host strategy largely expands the toolbox of traditional indicator displacement assays (synthetic macrocycles as hosts), and we expect it to inspire a series of sensor designs for pesticide detection.

Therapeutic angiogenesis-based strategy for peripheral artery disease

Peripheral artery disease (PAD) poses a great challenge to society, with a growing prevalence in the upcoming years. Patients in the severe stages of PAD are prone to amputation and death, leading to poor quality of life and a great socioeconomic burden. Furthermore, PAD is one of the major complications of diabetic patients, who have higher risk to develop critical limb ischemia, the most severe manifestation of PAD, and thus have a poor prognosis. Hence, there is an urgent need to develop an effective therapeutic strategy to treat this disease. Therapeutic angiogenesis has raised concerns for more than two decades as a potential strategy for treating PAD, especially in patients without option for surgery-based therapies. Since the discovery of gene-based therapy for therapeutic angiogenesis, several approaches have been developed, including cell-, protein-, and small molecule drug-based therapeutic strategies, some of which have progressed into the clinical trial phase. Despite its promising potential, efforts are still needed to improve the efficacy of this strategy, reduce its cost, and promote its worldwide application. In this review, we highlight the current progress of therapeutic angiogenesis and the issues that need to be overcome prior to its clinical application.

3D Printing of PLLA/Biomineral Composite Bone Tissue Engineering Scaffolds

Tissue engineering is one of the most effective ways to treat bone defects in recent years. However, current highly active bone tissue engineering (BTE) scaffolds are mainly based on the addition of active biological components (such as growth factors) to promote bone repair. High cost, easy inactivation and complex regulatory requirements greatly limit their practical applications. In addition, conventional fabrication methods make it difficult to meet the needs of personalized customization for the macroscopic and internal structure of tissue engineering scaffolds. Herein, this paper proposes to select five natural biominerals (eggshell, pearl, turtle shell, degelatinated deer antler and cuttlebone) with widely available sources, low price and potential osteo-inductive activity as functional particles. Subsequently compounding them into L-polylactic acid (PLLA) biomaterial ink to further explore 3D printing processes of the composite scaffold, and reveal their potential as biomimetic 3D scaffolds for bone tissue repair. The research results of this project provide a new idea for the construction of a 3D scaffold with growth-factor-free biomimetic structure, personalized customization ability and osteo-inductive activity.

Real-time evaluation of a hydrogel delivery vehicle for cancer immunotherapeutics within embedded spheroid cultures

Many protein immunotherapeutics are hindered by transport barriers that prevent the obtainment of minimum effective concentrations (MECs) in solid tumors. Local delivery vehicles with tunable release (infusion) rates for immunotherapeutics are being developed to achieve local and sustained release. To expedite their discovery and translation, in vitro models can identify promising delivery vehicles and immunotherapies that benefit from sustained release by evaluating cancer spheroid killing in real-time. Using displacement affinity release (DAR) within a hydrogel, we tuned the release of a CD133 targeting dual antigen T cell engager (DATE) without the need for further DATE or hydrogel modifications, yielding an injectable vehicle that acts as a tunable infusion pump. To quantify bioactivity benefits, a 3D embedded cancer spheroid model was developed for the evaluation of sustained protein release and combination therapies on T cell mediated spheroid killing. Using automated brightfield and fluorescent microscopy, the size of red fluorescent protein (iRFP670) expressing spheroids were tracked to quantify spheroid growth or killing over time as a function of controlled delivery. We demonstrate that sustained DATE release enhanced T cell mediated killing of embedded glioblastoma spheroids at longer timepoints, killing was further enhanced with the addition of anti-PD1 antibody (αPD1). The multi-cellular embedded spheroid model with automated microscopy demonstrated the benefit of extended bispecific release on T cell mediated killing, which will expedite the identification and translation of delivery vehicles such as DAR for immunotherapeutics.

A general carbon dot-based platform for intracellular delivery of proteins

The shortcomings of proteins, such as poor stability in biological environments, the impermeability of the membrane and the susceptibility to enzymolysis, restrict their potential applications. Therefore, constructing universal nanocarriers for intracellular delivery of a variety of proteins remains a great challenge. In this work, gallic acid (GA) and L-lysine were used as starting materials to synthesize carbon dots (CDs). The CDs were used as carriers to interact with bovine serum albumin (BSA), enhanced green fluorescent protein (EGFP) and glucose oxidase (GOx) via supramolecular interaction to construct CDs-protein nanocomposites CDs-BSA, CDs-EGFP and CDs-GOx. Furthermore, CDs-EGFP and CDs-GOx can achieve intracellular protein delivery and maintain 89% of the biological activity of GOx. In this work, the latency of CDs is projected as a universal platform for effective intracellular delivery of proteins.

Osteogenic Differentiation of Human Adipose-Derived Stem Cells Seeded on a Biomimetic Spongiosa-like Scaffold: Bone Morphogenetic Protein-2 Delivery by Overexpressing Fascia

Human adipose-derived stem cells (hADSCs) have the capacity for osteogenic differentiation and, in combination with suitable biomaterials and growth factors, the regeneration of bone defects. In order to differentiate hADSCs into the osteogenic lineage, bone morphogenetic proteins (BMPs) have been proven to be highly effective, especially when expressed locally by route of gene transfer, providing a constant stimulus over an extended period of time. However, the creation of genetically modified hADSCs is laborious and time-consuming, which hinders clinical translation of the approach. Instead, expedited single-surgery gene therapy strategies must be developed. Therefore, in an in vitro experiment, we evaluated a novel growth factor delivery system, comprising adenoviral BMP-2 transduced fascia tissue in terms of BMP-2 release kinetics and osteogenic effects, on hADSCs seeded on an innovative biomimetic spongiosa-like scaffold. As compared to direct BMP-2 transduction of hADSCs or addition of recombinant BMP-2, overexpressing fascia provided a more uniform, constant level of BMP-2 over 30 days. Despite considerably higher BMP-2 peak levels in the comparison groups, delivery by overexpressing fascia led to a strong osteogenic response of hADSCs. The use of BMP-2 transduced fascia in combination with hADSCs may evolve into an expedited single-surgery gene transfer approach to bone repair.

Tailoring Hyperbranched Poly(β-amino ester) as a Robust and Universal Platform for Cytosolic Protein Delivery

Cytosolic protein delivery is a prerequisite for protein-based biotechnologies and therapeutics on intracellular targets. Polymers that can complex with proteins to form nano-assemblies represent one of the most important categories of materials, because of the ease of nano-fabrication, high protein loading efficiency, no need for purification, and maintenance of protein bioactivity. Stable protein encapsulation and efficient intracellular liberation are two critical yet opposite processes toward cytosolic delivery, and polymers that can resolve these two conflicting challenges are still lacking. Herein, hyperbranched poly(β-amino ester) (HPAE) with backbone-embedded phenylboronic acid (PBA) is developed to synchronize these two processes, wherein PBA enhanced protein encapsulation via nitrogen-boronate (N-B) coordination while triggered polymer degradation and protein release upon oxidation by H₂ O₂ in cancer cells. Upon optimization of the branching degree, charge density, and PBA distribution, the best-performing A2-B3-C2-S₂ -P₂ is identified, which mediates robust delivery of various native proteins/peptides with distinct molecular weights (1.6-430 kDa) and isoelectric points (4.1-10.3) into cancer cells, including enzymes, toxins, antibodies, and CRISPR-Cas9 ribonucleoproteins (RNPs). Moreover, A2-B3-C2-S₂ -P₂ mediates effective cytosolic delivery of saporin both in vitro and in vivo to provoke remarkable anti-tumor efficacy. Such a potent and universal platform holds transformative potentials for protein pharmaceuticals.

Spontaneous desorption of protein from self-assembled monolayer (SAM)-coated gold nanoparticles induced by high temperature

The nonspecific binding of proteins with nanomaterials (NMs) is a dynamic reversible process including both protein adsorption and desorption parts, which is crucial for controlled release of protein drug loaded by nanocarriers. The nonspecific binding of proteins is susceptible to high temperature, whereas its underlying mechanism still remains elusive. Here, the binding behavior of human serum albumin (HSA) with an amino-terminated self-assembled monolayer (SAM)-coated gold (111) surface was investigated by using molecular dynamics (MD) simulations. HSA binds to the SAM surface through salt bridges at 300 K. As the temperature increases to 350 K, HSA maintains its native structure, while the salt bridges largely diminish owing to the considerable lateral diffusion of HSA on the SAM. Moreover, the interfacial water located between HSA and the SAM gets increased and prevents the reformation of the salt bridges of HSA with the SAM, which reduces the binding affinity of HSA. And HSA eventually desorbs from the SAM. The depiction of thermally induced spontaneous protein desorption enriches our understanding of reversible binding behavior of protein with NMs, and may provide new insights into the controlled release of protein drugs delivered by using nanocarriers under the regulation of high temperature.

Peptide hydrogels for affinity-controlled release of therapeutic cargo: Current and potential strategies

The development of devices for the precise and controlled delivery of therapeutics has grown rapidly over the last few decades. Drug delivery materials must provide a depot with delivery profiles that satisfy pharmacodynamic and pharmacokinetic requirements resulting in clinical benefit. Therapeutic efficacy can be limited due to short half-life and poor stability. Thus, to compensate for this, frequent administration and high doses are often required to achieve therapeutic effect, which in turn increases potential side effects and systemic toxicity. This can potentially be mitigated by using materials that can deliver drugs at controlled rates, and material design principles that allow this are continuously evolving. Affinity-based release strategies incorporate a myriad of reversible interactions into a gel network, which have affinities for the therapeutic of interest. Reversible binding to the gel network impacts the release profile of the drug. Such affinity-based interactions can be modulated to control the release profile to meet pharmacokinetic benchmarks. Much work has been done developing affinity-based control in the context of polymer-based materials. However, this strategy has not been widely implemented in peptide-based hydrogels. Herein, we present recent advances in the use of affinity-controlled peptide gel release systems and their associated mechanisms for applications in drug delivery.

Reversible immobilization of laccase onto glycopolymer microspheres via protein-carbohydrate interaction for biodegradation of phenolic compounds

It is challenging to regenerate enzyme carriers when covalently immobilized enzymes suffered from inactivation during continuous operations. Hence, it is urgent to develop a facile strategy to immobilize enzymes reversibly. Herein, the non-covalent interaction between protein and carbohydrate was used to adsorb and desorb enzymes reversibly. Laccase was immobilized onto glycopolymer microspheres via protein-carbohydrate interaction using lectins as the intermediates. The enzyme loading and immobilization yield were up to 49 mg/g and 77.1% with highly expressed activity of 107.9 U/mg. The immobilized laccase exhibited enhanced pH stability and high activity in catalyzing the biodegradation of paracetamol. During ten successive recoveries, the immobilized laccases could be recycled while maintaining relatively high enzyme activity. The glycopolymer microspheres could be efficiently regenerated by elution with an aqueous solution of mannose or acid for further enzyme immobilization. This glycopolymer microspheres has excellent potential to act as reusable carriers for the non-covalent immobilization of different enzymes.

Amphiphilic and Biocompatible DNA Origami-Based Emulsion Formation and Nanopore Release for Anti-Melanogenesis Therapy

Programmable engineered DNA origami provides infinite possibilities for customizing nanostructures with controllable precision and configurable functionality. Here, a strategy for fabricating an amphiphilic triangular DNA origami with a central nanopore that integrates phase-stabilizing, porous-gated, and affinity-delivering effects is presented. By introducing the DNA origami as a single-component surfactant, the water-in-oil-in-water (W/O/W) emulsion is effectively stabilized with decreased interfacial tension. Microscopic observation validates the attachment of the DNA origami onto the water-in-oil and oil-in-water interfaces. Furthermore, fluorescence studies and molecular docking simulations indicate the binding interactions of DNA origami with arbutin and coumaric acid at docking sites within central nanopores. These central nanopores are functionalized as molecular gates and affinity-based scaffold for the zero-order release of arbutin and coumaric acid at a constant rate regardless of concentration gradient throughout the whole releasing period. In vivo zebrafish results illustrate the advantages of this zero-order release for anti-melanogenesis therapy over direct exposure or Fickian diffusion. The DNA origami-based W/O/W emulsion presents anti-melanogenic effects against UV-B exposure without cardiotoxicity or motor toxicity. These results demonstrate that this non-toxic amphiphilic triangular DNA origami is capable of solely stabilizing the W/O/W emulsion as well as serving as nanopore gates and affinity-based scaffold for constant release.

Modeling bioaffinity-based targeted delivery of antimicrobials to Escherichia coli biofilms using yeast microparticles. Part II: Parameter evaluation and validation

The design of bioaffinity-based targeted delivery systems for biofilm inactivation may require a comprehensive understanding of physicochemical and biochemical properties of biobased antimicrobial particles and their interactions with biofilm. In this study, Escherichia coli biofilm inactivation by chlorine-charged yeast microparticles was numerically simulated, and the roles of chemical stability, binding affinity, and controlled release of this targeted delivery system were assessed using this numerical simulation. The simulation results were experimentally validated using two different types of yeast microparticles. The results of this study illustrate that chorine stability achieved by yeast microparticles was a key factor for improved biofilm inactivation in an organic-rich environment (>6 additional log reduction in 20 min compared to the free chlorine treatment). Moreover, the binding affinity of yeast microparticles to E. coli biofilms was another key factor for an enhanced inactivation of biofilm, as a 10-fold increase in binding rate resulted in a 4.2-fold faster inactivation. Overall, the mechanistic modeling framework developed in this study could guide the design and development of biobased particles for targeted inactivation of biofilms.

Affinity-Controlled Double-Network Hydrogel Facilitates Long-Term Release of Anti-Human Papillomavirus Protein

Hydrogels have recently received attention as delivery carriers owing to their good biocompatibility and structural similarity to natural extracellular matrices. However, the utilization of traditional single-network (SN) hydrogels is limited by poor mechanical properties and burst drug release. Therefore, we developed a novel double-network (DN) hydrogel, which employs an alginate (ALG)/polyethylene glycol diacrylate (PEGDA) network to adjust the mechanical strength and a positively charged monomer AETAC (2-(acryloyloxy)ethyl]trimethyl-ammonium chloride) to regulate the release curve of the electronegative anti-human papillomavirus (HPV) protein (bovine β-lactoglobulin modified with 3-hydroxyphthalic anhydride) based on an affinity-controlled delivery mechanism. The results show that the double-network hydrogel strongly inhibits the burst release, and the burst release amount is about one-third of that of the single-network hydrogel. By changing the concentration of the photoinitiator, the mechanical strength of the DN hydrogels can be adjusted to meet the stiffness requirements for various tissues within the range of 0.71 kPa to 10.30 kPa. Compared with the SN hydrogels, the DN hydrogels exhibit almost twice the mechanical strength and have smaller micropores. Cytotoxicity tests indicated that these SN and DN hydrogels were not cytotoxic with the result of over 100% relative proliferation rate of the HUVECs. Furthermore, DN hydrogels can significantly alleviate the burst release of antiviral proteins and prolong the release time to more than 14 days. Finally, we utilized digital light processing (DLP) technology to verify the printability of the DN hydrogel. Our study indicates that ALG/PEGDA-AETAC DN hydrogels could serve as platforms for delivering proteins and show promise for diverse tissue engineering applications.

Translational Applications of Hydrogels

Advances in hydrogel technology have unlocked unique and valuable capabilities that are being applied to a diverse set of translational applications. Hydrogels perform functions relevant to a range of biomedical purposes-they can deliver drugs or cells, regenerate hard and soft tissues, adhere to wet tissues, prevent bleeding, provide contrast during imaging, protect tissues or organs during radiotherapy, and improve the biocompatibility of medical implants. These capabilities make hydrogels useful for many distinct and pressing diseases and medical conditions and even for less conventional areas such as environmental engineering. In this review, we cover the major capabilities of hydrogels, with a focus on the novel benefits of injectable hydrogels, and how they relate to translational applications in medicine and the environment. We pay close attention to how the development of contemporary hydrogels requires extensive interdisciplinary collaboration to accomplish highly specific and complex biological tasks that range from cancer immunotherapy to tissue engineering to vaccination. We complement our discussion of preclinical and clinical development of hydrogels with mechanical design considerations needed for scaling injectable hydrogel technologies for clinical application. We anticipate that readers will gain a more complete picture of the expansive possibilities for hydrogels to make practical and impactful differences across numerous fields and biomedical applications.

Peptide-Enabled Targeted Delivery Systems for Therapeutic Applications

Receptor-targeting peptides have been extensively pursued for improving binding specificity and effective accumulation of drugs at the site of interest, and have remained challenging for extensive research efforts relating to chemotherapy in cancer treatments. By chemically linking a ligand of interest to drug-loaded nanocarriers, active targeting systems could be constructed. Peptide-functionalized nanostructures have been extensively pursued for biomedical applications, including drug delivery, biological imaging, liquid biopsy, and targeted therapies, and widely recognized as candidates of novel therapeutics due to their high specificity, well biocompatibility, and easy availability. We will endeavor to review a variety of strategies that have been demonstrated for improving receptor-specificity of the drug-loaded nanoscale structures using peptide ligands targeting tumor-related receptors. The effort could illustrate that the synergism of nano-sized structures with receptor-targeting peptides could lead to enrichment of biofunctions of nanostructures.

BMP-2 delivery strategy modulates local bone regeneration and systemic immune responses to complex extremity trauma

Bone nonunions arising from large bone defects and composite injuries remain compelling challenges for orthopedic surgeons. Biological changes associated with nonunions, such as systemic immune dysregulation, can contribute to an adverse healing environment. Bone morphogenetic protein 2 (BMP-2), an osteoinductive and potentially immunomodulatory growth factor, is a promising strategy; however, burst release from the clinical standard collagen sponge delivery vehicle can result in adverse side effects such as heterotopic ossification (HO) and irregular bone structure, especially when using supraphysiological BMP-2 doses for complex injuries at high risk for nonunion. To address this challenge, biomaterials that strongly bind BMP-2, such as heparin methacrylamide microparticles (HMPs), may be used to limit exposure and spatially constrain proteins within the injury site. Here, we investigate moderately high dose BMP-2 delivered in HMPs within an injectable hydrogel system in two challenging nonunion models exhibiting characteristics of systemic immune dysregulation. The HMP delivery system increased total bone volume and decreased peak HO compared to collagen sponge delivery of the same BMP-2 dose. Multivariate analyses of systemic immune markers showed the collagen sponge group correlated with markers that are hallmarks of systemic immune dysregulation, including immunosuppressive myeloid-derived suppressor cells, whereas the HMP groups were associated with immune effector cells, including T cells, and cytokines linked to robust bone regeneration. Overall, our results demonstrate that HMP delivery of moderately high doses of BMP-2 promotes repair of complex bone nonunion injuries and that local delivery strategies for potent growth factors like BMP-2 may positively affect the systemic immune response to traumatic injury.

Injectable Supramolecular Polymer-Nanoparticle Hydrogels for Cell and Drug Delivery Applications

These methods describe how to formulate injectable, supramolecular polymer-nanoparticle (PNP) hydrogels for use as biomaterials. PNP hydrogels are composed of two components: hydrophobically modified cellulose as the network polymer and self-assembled core-shell nanoparticles that act as non-covalent cross linkers through dynamic, multivalent interactions. These methods describe both the formation of these self-assembled nanoparticles through nanoprecipitation as well as the formulation and mixing of the two components to form hydrogels with tunable mechanical properties. The use of dynamic light scattering (DLS) and rheology to characterize the quality of the synthesized materials is also detailed. Finally, the utility of these hydrogels for drug delivery, biopharmaceutical stabilization, and cell encapsulation and delivery is demonstrated through in vitro experiments to characterize drug release, thermal stability, and cell settling and viability. Due to its biocompatibility, injectability, and mild gel formation conditions, this hydrogel system is a readily tunable platform suitable for a range of biomedical applications.

Encapsulation of BSA in hybrid PEG hydrogels: stability and controlled release

Hybrid hydrogels based on silylated polyethylene glycol, Si-PEG, were evaluated as hybrid matrices able to trap, stabilize and release bovine serum albumin (BSA) in a controlled manner. Parameters of the inorganic condensation reaction leading to a siloxane (Si–O–Si) three dimensional network were carefully investigated, in particular the temperature, the surrounding hygrometry and the Si-PEG concentration. The resulting hydrogel structural features affected the stability, swelling, and mechanical properties of the network, leading to different protein release profiles. Elongated polymer assemblies were observed, the length of which ranged from 150 nm to over 5 μm. The length could be correlated to the Si–O–Si condensation rate from 60% (hydrogels obtained at 24 °C) to about 90% (xerogels obtained at 24 °C), respectively. Consequently, the controlled release of BSA could be achieved from hours to several weeks, with respect to the fibers' length and the condensation rate. The protein stability was evaluated by means of a thermal study. The main results gave insight into the biomolecule structure preservation during polymerisation, with ΔG < 0 for encapsulated BSA in any conditions, below the melting temperature (65 °C).

Silylated hybrid hydrogels of polyethylene glycol were designed to trap, stabilize and release a model protein (bovine serum albumin). Fine-tuning sol–gel reactions lead to sustained release of BSA over weeks, with good insight of protein stability.

Effects of Biotin-Avidin Interactions on Hydrogel Swelling

Affinity interactions between the small molecule biotin and the protein avidin have been used extensively to functionalize biomaterials. More recently, researchers have leveraged the changes in biotin-avidin affinity that occur upon biotin conjugation to larger molecules to control the release of biotinylated drugs and proteins. However, the effects of biotin-avidin interactions on hydrogel properties have not been thoroughly investigated. The objective of this study was to evaluate the effect of increasing biotin and avidin concentrations on hydrogel swelling properties, as an indicator of crosslinking. Gelatin, selected as a model hydrogel material, was biotinylated at increasing fold molar excesses of biotin with a PEG linker using N-hydroxysuccinimide chemistry. Afterwards, biotinylated gelatin was formed into hydrogels and stabilized with glutaraldehyde. Swelling properties of the biotinylated hydrogels were investigated by conducting swelling studies in different avidin solutions. Increasing the degree of biotinylation caused significant decreases in swelling ratios of the hydrogels in a dose-dependent manner, suggesting increases in crosslinking of the hydrogels. However, increasing avidin concentrations in excess of biotin content did not significantly affect swelling ratios. Moving hydrogels to phosphate-buffered saline following avidin incorporation resulted in increased swelling ratios for hydrogels prepared with a lower concentration of biotin. However, hydrogels prepared with the highest concentration of biotin did not experience increased swelling ratios, implying that the stability of biotin-avidin-mediated crosslinking depends on the number of biotin molecules available for binding. Collectively, these results demonstrate that biotin-avidin interactions control hydrogel swelling properties, and that the magnitude and stability of the effects depend on the biotin concentration. These results have important implications for affinity-based controlled release of biotinylated drugs or proteins from biotin-avidin-crosslinked hydrogels.

Magnetically Driven Nanotransporter-Assisted Intracellular Delivery and Autonomous Release of Proteins

Biofunctional proteins such as active enzymes and therapeutic proteins show tremendous promise in disease treatment. However, intracellular delivery of proteins is facing substantial challenges owing to their vulnerability to degradation and denaturation and the presence of various biological barriers such as their low membrane transport efficiency. Herein, we report a magnetically driven and redox-responsive nanotransporter (MRNT) for highly efficient intracellular delivery of biofunctional proteins. The MRNT has remarkably high cargo capacity, compared with that without nanoscale cargo compartments. We have demonstrated the directional and dynamic motion of the MRNT using both nanoparticle tracking analysis and magnetic driving evaluation. Moreover, the active MRNT can translocate into the cytosol and sense the reducing cytosolic environment to discharge protein cargoes autonomously. The internalization mechanism of the MRNT has been studied using endocytosis inhibitors. Under the magnetic drive, the MRNT can promote a protein transduction efficiency of over 95%, and the intracellular protein delivery by the active MRNT shows significantly higher (∼4 times) enzymatic activity and therapeutic efficiency than those achieved by the static ones. Our proof-of-concept study provides a valuable tool for intracellular protein transduction and contributes to biotechnology and protein therapeutics.

An orally available hypoglycaemic peptide taken up by caveolae transcytosis displays improved hypoglycaemic effects and body weight control in db/db mice

BACKGROUND AND PURPOSE

Type 2 diabetes is one of the most severe chronic diseases and is an increasingly important public health problem worldwide. Several agonists of the glucagon-like peptide-1 (GLP-1) receptor have been developed to treat Type 2 diabetes but most of them are administered by injection. This mode of administration seriously reduces patient compliance and increases the risk of infection. Here, we describe the actions of a novel, orally available, GLP-1 receptor agonist - oral hypoglycaemic peptide 2 (OHP2) - derived from exendin-4 by replacing amino acids. We have also investigated its pharmacokinetic profiles, therapeutic effects and absorption mechanism.

EXPERIMENTAL APPROACH

Healthy Wistar rats were used for pharmacokinetic analyses. In diabetic db/db mice. OHP2 was given for 8 weeks to evaluate its effects on hyperglycaemia, dyslipidaemia, basal metabolism and tissue injury. Possible endocytosis and transcytosis mechanisms of OHP2 uptake were explored in Caco-2 cell monolayers.

KEY RESULTS

In rats, the absolute bioavailability of orally administered OHP2 was 20-fold greater than that of orally administered exendin-4. In db/db mice, OHP2 dose-dependently exhibits good potential in glucose-lowering and weight loss after oral administration. OHP2 also alleviated hyperlipidaemia, ameliorated energy metabolism and promoted tissue repair in diabetic mice. Furthermore, uptake of OHP2 by Caco-2 cells was dependent on caveolae-mediated transcytosis rather than endocytosis mediated by GLP-1 receptors.

CONCLUSIONS AND IMPLICATIONS

OHP2 is a potential, orally bioavailable, candidate drug for the treatment of Type 2 diabetes. Its transcytosis mechanism of uptake could help in the development of absorption enhancers of OHP2.

Protein-ligand binding with the coarse-grained Martini model

The detailed understanding of the binding of small molecules to proteins is the key for the development of novel drugs or to increase the acceptance of substrates by enzymes. Nowadays, computer-aided design of protein–ligand binding is an important tool to accomplish this task. Current approaches typically rely on high-throughput docking essays or computationally expensive atomistic molecular dynamics simulations. Here, we present an approach to use the recently re-parametrized coarse-grained Martini model to perform unbiased millisecond sampling of protein–ligand interactions of small drug-like molecules. Remarkably, we achieve high accuracy without the need of any a priori knowledge of binding pockets or pathways. Our approach is applied to a range of systems from the well-characterized T4 lysozyme over members of the GPCR family and nuclear receptors to a variety of enzymes. The presented results open the way to high-throughput screening of ligand libraries or protein mutations using the coarse-grained Martini model.

Computer-aided design of protein-ligand binding is important for the development of novel drugs. Here authors present an approach to use the recently re-parametrized coarse-grained Martini model to perform unbiased millisecond sampling of protein-ligand binding interactions of small drug-like molecules.

Coaxial mussel-inspired biofibers: making of a robust and efficacious depot for cancer drug delivery

Biopolymer-based hydrogels have emerged as promising platforms for drug delivery systems (DDSs) due to their inherent biocompatibility, tunable physical properties and controllable degradability. Yet, drug release in majority of these systems is solely contingent on diffusion of drug molecules through the hydrogel, which often leads to burst release of drugs from these systems. Herein, inspired by the chemistry of mussel adhesive proteins, a new generation of coaxial hydrogel fibers was developed that could simultaneously exert both affinity and diffusion control over the release of chemotherapeutic drugs. Specifically, dopamine-modified alginate hydrogel along with chemotherapeutic drugs (doxorubicin or gemcitabine) was used as the main core component to confer affinity-controlled release, while a methacrylated-alginate hydrogel was used as the shell composition to provide the controlled diffusion barrier. It was shown that our coaxial mussel-inspired biofibers yielded biocompatible hydrogel fibers (as indicated by comprehensive in vitro and in vivo experiments) with favourable properties including controlled swelling, and enhanced mechanical properties, when compared against single fibers made from unmodified alginate. Notably, it was observed that these coaxial fibers were capable of releasing the two drugs in a slower manner, when compared to single fibers made from pure alginate, which was partly attributed to stronger interactions of drugs with dopamine-modified alginate (the core element of coaxial fibers) as observed from zeta-potential measurements. It was further shown that these drug-loaded coaxial fibers had optimal anticancer activity both in vitro and in vivo using various pancreatic cancer cell lines. Most remarkably, drug loaded coaxial fibers, particularly doxorubicin-containing fibers, had higher anticancer effect in vivo compared to systemic injection of equivalent dosage of the drugs. Altogether, these biocompatible and robust hydrogel fibers may be further used as neoadjuvant or adjuvant therapies for controlled delivery of chemotherapeutic drugs locally to the tumor sites.

ATP-Charged Nanoclusters Enable Intracellular Protein Delivery and Activity Modulation for Cancer Theranostics

Protein drugs own a large share in the market and hold great prospects for the treatment of many diseases. However, the available protein drugs are limited to the extracellular target, owing to the inefficient transduction and activity modulation of proteins targeting intracellular environment. In this study, we constructed ATP-charged platforms to overcome the above-mentioned barriers for cancer theranostics. The phenylboronic acid-modified polycations (PCD) were synthesized to assemble with enzymes and shield its activity in the blood circulation. When the PCD nanoclusters reached tumor site, they effectively transported the enzymes into the cells, followed by recovering its catalytic activity after being charged with ATP. Importantly, the cascaded enzyme systems (GOx&HRPA) selectively induced starvation therapy as well as photoacoustic imaging of tumor. Our results revealed that the intelligent nanoclusters were broadly applicable for protein transduction and enzyme activity modulation, which could accelerate the clinical translation of protein drugs toward intracellular target.

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ATP-charged nanoclusters capable of enzyme activity modulation

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Universal platform for intracellular protein delivery

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Selective cellular cascaded catalysis for cancer theranostics

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Photoacoustic (PA) imaging and starvation therapy of breast cancer