Versatile Protein Nanogels Prepared by In Situ Polymerization

Polymeric Nanoparticles for Delivery of Natural Bioactive Agents: Recent Advances and Challenges

In the last few decades, several natural bioactive agents have been widely utilized in the treatment and prevention of many diseases owing to their unique and versatile therapeutic effects, including antioxidant, anti-inflammatory, anticancer, and neuroprotective action. However, their poor aqueous solubility, poor bioavailability, low GIT stability, extensive metabolism as well as short duration of action are the most shortfalls hampering their biomedical/pharmaceutical applications. Different drug delivery platforms have developed in this regard, and a captivating tool of this has been the fabrication of nanocarriers. In particular, polymeric nanoparticles were reported to offer proficient delivery of various natural bioactive agents with good entrapment potential and stability, an efficiently controlled release, improved bioavailability, and fascinating therapeutic efficacy. In addition, surface decoration and polymer functionalization have opened the door to improving the characteristics of polymeric nanoparticles and alleviating the reported toxicity. Herein, a review of the state of knowledge on polymeric nanoparticles loaded with natural bioactive agents is presented. The review focuses on frequently used polymeric materials and their corresponding methods of fabrication, the needs of such systems for natural bioactive agents, polymeric nanoparticles loaded with natural bioactive agents in the literature, and the potential role of polymer functionalization, hybrid systems, and stimuli-responsive systems in overcoming most of the system drawbacks. This exploration may offer a thorough idea of viewing the polymeric nanoparticles as a potential candidate for the delivery of natural bioactive agents as well as the challenges and the combating tools used to overcome any hurdles.

Recent advances in microencapsulation of drugs for veterinary applications

Microencapsulation is a process where very minute droplets or particles of solid or liquid or gas are trapped with a polymer to isolate the internal core material from external environmental hazards. Microencapsulation is applied mostly for flavor masking, fortification, and sustained and control release. It improves palatability, absorption, and bioavailability of drugs with good conformity. Microencapsulation has been widely studied in numerous drug delivery systems for human health. The application of microcapsules in the veterinary pharmaceutical sciences is increasing day by day. The treatment systems for humans and animals are likely to be similar, but more complex in the veterinary field due to the diversity of the species, breeds, body size, biotransformation rate, and other factors associated with animal physiology. Commercially viable, economically profitable, and therapeutically effective microencapsulated vaccine, anthelmintic, antibacterial, and other therapeutics have a great demand for livestock and poultry production. Nowadays, researchers emphasize the controlled and sustained-release dosage form of drugs in the veterinary field. This paper has highlighted the microencapsulation materials, preparation techniques, characteristics, roles, and the application of microcapsules in veterinary medicine.

Recent Advances in Polymeric Nanoparticle-Encapsulated Drugs against Intracellular Infections

Polymeric nanocarriers (PNs) have demonstrated to be a promising alternative to treat intracellular infections. They have outstanding performance in delivering antimicrobials intracellularly to reach an adequate dose level and improve their therapeutic efficacy. PNs offer opportunities for preventing unwanted drug interactions and degradation before reaching the target cell of tissue and thus decreasing the development of resistance in microorganisms. The use of PNs has the potential to reduce the dose and adverse side effects, providing better efficiency and effectiveness of therapeutic regimens, especially in drugs having high toxicity, low solubility in the physiological environment and low bioavailability. This review provides an overview of nanoparticles made of different polymeric precursors and the main methodologies to nanofabricate platforms of tuned physicochemical and morphological properties and surface chemistry for controlled release of antimicrobials in the target. It highlights the versatility of these nanosystems and their challenges and opportunities to deliver antimicrobial drugs to treat intracellular infections and mentions nanotoxicology aspects and future outlooks.

Biomimetic Presentation of Cryptic Ligands via Single-Chain Nanogels for Synergistic Regulation of Stem Cells

Dynamic controlling the nanoscale presentation of synergistic ligands to stem cells by biomimetic single-chain materials can provide critical insights to understand the molecular crosstalk underlying cells and their extracellular matrix. Here, a stimuli-responsive single-chain macromolecular nanoregulator with conformational dynamics is fabricated based on an advanced scale-up single polymeric chain nanogel (SCNG). Such a carefully designed SCNG is capable of mediating a triggered copresentation of the master and cryptic ligands in a single molecule to elicit the synergistic crosstalk between different intracellular signaling pathways, thereby considerably boosting the bioactivity of the presented ligands. This controllable nanoswitching-on of cell-adhesive ligands' presentation allows the regulation of cell adhesion and fate from molecular scale. The modular nature of this synthetic macromolecular nanoregulator makes it a versatile nanomaterial platform to assist basic and fundamental studies in a wide array of research topics.

Stimuli-responsive biohybrid nanogels with self-immolative linkers for protein protection and traceless release

Nanogels have been applied in protein delivery due to the nanoscale sizes and the crosslinked structures. However, the release of protein molecules from the nanogels without damages to the structures and functionalities is quite a challenging research subject. In this research, responsive self-immolative linker dithioethyl carbamate bond is introduced to connect protein and polymer in the nanogel so that traceless release of protein occurs upon addition of glutathione (GSH) or dithiothreitol (DTT). Thermoresponsive polymer poly(di(ethylene glycol) methyl ether methacrylate-co-2-(2-(2-hydroxyethyl) disulfanyl) ethyl methacrylate) was synthesized by reversible addition-fragmentation chain transfer (RAFT) polymerization, and was modified with 4-nitrophenyl chloroformate yielding polymer chains with pendant dithioethyl carbonate groups. The dithioethyl carbonate groups were reacted with amine groups of lipases resulting in the formation of dithioethyl carbamate bonds. Meanwhile, biohybrid nanogels were prepared by crosslinking the polymer chains with lipases. The immobilized lipase in the nanogels exhibited enhanced heat and acid resistance. Once the nanogels were treated with GSH or DTT, lipase could be released with no residual groups and most of its bioactivity was recovered.

Peroxidase-Mediated In Situ Fabrication of Multi-Stimuli-Responsive and Dynamic Protein Nanogels from Tyrosine-Conjugated Biodynamer and Ovablumin

Horseradish peroxidase (HRP)-mediated oxidation of tyrosine-conjugated biodynamer containing acylhydrazone linkages and ovalbumin (OVA)/reduced ovalbumin (rOVA) generated protein nanogels through simultaneous tyrosine coupling and thiol cross-linking in the presence of H₂O₂. The obtained nanogels are multi-stimuli-responsive to temperature, pH, and glutathione (GSH) and possess the dynamic character of reversible covalent bonds. The OVA-based or rOVA-based protein nanogels can be utilized as cargoes of anticancer drug curcumin (Cur). The Cur-loaded protein nanogels rapidly released Cur in intracellular-mimicking acidic and reductive environment, thus, making these protein nanogels promising nanocarriers for intracellular drug delivery. HRP-mediated cross-linking of the tyrosine-conjugated biodynamer and proteins provides a facile and versatile approach for fabrication of responsive and adaptive biohybrid nanogels under mild conditions.

Polypeptide Nanogels With Different Functional Cores Promote Chemotherapy of Lung Carcinoma

Two kinds of tumor microenvironment-responsive polypeptide nanogels were developed for intracellular delivery of cytotoxics to enhance the antitumor efficacies and reduce the side effects in the chemotherapy of lung carcinoma. The sizes of both doxorubicin (DOX)-loaded nanogels methoxy poly(ethylene glycol)-poly(L-phenylalanine-co-L-cystine) [mPEG-P(LP-co-LC)] and methoxy poly(ethylene glycol)-poly(L-glutamic acid-co-L-cystine) [mPEG-P(LG-co-LC)] (NGP/DOX and NGG/DOX) were less than 100 nm, which was appropriate for the enhanced permeability and retention (EPR) effect. The bigger and smaller scale of nanoparticle could induce the elimination of reticuloendothelial system (RES) and decrease the in vivo circulating half-life, respectively. The loading nanogels were stable in the neutral environment while quickly degraded in the mimic intracellular microenvironment. Furthermore, the DOX-loaded reduction-responsive nanogels showed significantly higher tumor cell uptake than free DOX⋅HCl as time went on from 2 to 6 h. In addition, these DOX-loaded nanogels showed efficient antitumor effects in vivo, which was verified by the obviously increased necrosis areas in the tumor tissues. Furthermore, these DOX-loaded nanogels efficiently reduced the side effects of DOX. In conclusion, these reduction-responsive polypeptides based nanogels are suitable for the efficient therapy of lung carcinoma.

Poly(trimesoyl chloride-melamine) grafted on palygorskite for simultaneous ultra-trace removal of methylene blue and toxic metals

Poly(trimesoyl chloride-melamine) was grafted on palygorskite via in situ interfacial polymerization. The poly(trimesoyl chloride-melamine)-grafted palygorskite (PTMP) composite was characterized by Fourier transform infrared spectroscopy (FTIR), Energy Dispersive X-Ray Spectroscopy (EDX), N₂-physisorption, and scanning electron microscope (SEM). The performance of PTMP as an adsorbent was evaluated for the removal of methylene blue dye (MB) in batch and column systems. The effects of initial dye concentration, contact time, temperature and initial pH on the efficiency of MB removal were investigated. A high adsorption efficiency (≈100%) was shown by PTMP removal within 8 min with high Langmuir monolayer capacity of 64.5 mg/g at 25 °C. The mechanisms of adsorption were evaluated by isotherm and kinetic models. The activation energy E_a and different thermodynamic parameters, for example, ΔG^o, ΔS^o, and ΔH^o were calculated. The prepared composite demonstrated to be an efficient adsorbent for simultaneous removal of dye and toxic metals such as As(III), Cr(III), Mo(II), Co(III), Ni(II), and Hg(II). The dye removal was evaluated by a packed bed column system and showed an excellent adsorption performance with 90 min breakthrough at 160 ppm of initial dye concentration.

Bio-Inspired Protein-Based Nanoformulations for Cancer Theranostics

Over the past decade, more interests have been aroused in engineering protein-based nanoformulations for cancer treatment. This excitement originates from the success of FDA approved Abraxane (Albumin-based paclitaxel nanoparticles) in 2005. The new generation of biocompatible endogenous protein-based nanoformulations is currently constructed through delivering cancer therapeutic and diagnostic agents simultaneously, as named potential theranostics. Protein nanoformulations are commonly incorporated with dyes, contrast agents, drug payloads or inorganic nanoclusters, serving as imaging-guided combinatorial cancer therapeutics. Employing the nature identity of proteins, the theranostics, escape the clearance by reticuloendothelial cells and have a long blood circulation time. The nanoscale sizet allows them to be penetrated deeply into tumor tissues. In addition, stimuli release and targeted molecules are incorporated to improve the delivery efficiency. The ongoing advancement of protein-based nanoformulations for cancer theranostics in recent 5 years is reviewed in this paper. Fine-designed nanoformulations based on albumin, ferritin, gelatin, and transferrin are highlighted from the literature. Finally, the current challenges are identified in translating protein-based nanoformulations from laboratory to clinical trials.

Polymeric microneedles for transdermal protein delivery

The intrinsic properties of therapeutic proteins generally present a major impediment for transdermal delivery, including their relatively large molecule size and susceptibility to degradation. One solution is to utilize microneedles (MNs), which are capable of painlessly traversing the stratum corneum and directly translocating protein drugs into the systematic circulation. MNs can be designed to incorporate appropriate structural materials as well as therapeutics or formulations with tailored physicochemical properties. This platform technique has been applied to deliver drugs both locally and systemically in applications ranging from vaccination to diabetes and cancer therapy. This review surveys the current design and use of polymeric MNs for transdermal protein delivery. The clinical potential and future translation of MNs are also discussed.

Enhanced Cancer Immunotherapy by Microneedle Patch-Assisted Delivery of Anti-PD1 Antibody

Despite recent advances in melanoma treatment through the use of anti-PD-1 (aPD1) immunotherapy, the efficacy of this method remains to be improved. Here we report an innovative self-degradable microneedle (MN) patch for the sustained delivery of aPD1 in a physiologically controllable manner. The microneedle is composed of biocompatible hyaluronic acid integrated with pH-sensitive dextran nanoparticles (NPs) that encapsulate aPD1 and glucose oxidase (GOx), which converts blood glucose to gluconic acid. The generation of acidic environment promotes the self-dissociation of NPs and subsequently results in the substantial release of aPD1. We find that a single administration of the MN patch induces robust immune responses in a B16F10 mouse melanoma model compared to MN without degradation trigger or intratumoral injection of free aPD1 with the same dose. Moreover, this administration strategy can integrate with other immunomodulators (such as anti-CTLA-4) to achieve combination therapy for enhancing antitumor efficacy.