Design of a Multicompartment Hydrogel that Facilitates Time‐Resolved Delivery of Combination Therapy and Synergized Killing of Glioblastoma

Recent Advances in Boosting EGFR Tyrosine Kinase Inhibitors-Based Cancer Therapy

Epidermal growth factor receptor (EGFR) plays a key role in signal transduction pathways associated with cell proliferation, growth, and survival. Its overexpression and aberrant activation in malignancy correlate with poor prognosis and short survival. Targeting inhibition of EGFR by small-molecular tyrosine kinase inhibitors (TKIs) is emerging as an important treatment model besides of chemotherapy, greatly reshaping the landscape of cancer therapy. However, they are still challenged by the off-targeted toxicity, relatively limited cancer types, and drug resistance after long-term therapy. In this review, we summarize the recent progress of oral, pulmonary, and injectable drug delivery systems for enhanced and targeting TKI delivery to tumors and reduced side effects. Importantly, EGFR-TKI-based combination therapies not only greatly broaden the applicable cancer types of EGFR-TKI but also significantly improve the anticancer effect. The mechanisms of TKI resistance are summarized, and current strategies to overcome TKI resistance as well as the application of TKI in reversing chemotherapy resistance are discussed. Finally, we provide a perspective on the future research of EGFR-TKI-based cancer therapy.

Tuning Peptide-Based Hydrogels: Co-Assembly with Composites Driving the Highway to Technological Applications

Self-assembled peptide-based gels provide several advantages for technological applications. Recently, the co-assembly of gelators has been a strategy to modulate and tune gel properties and even implement stimuli-responsiveness. However, it still comprises limitations regarding the required library of compounds and outcoming properties. Hence, efforts have been made to combine peptide-based gels and (in)organic composites (e.g., magnetic nanoparticles, metal nanoparticles, liposomes, graphene, silica, clay, titanium dioxide, cadmium sulfide) to endow stimuli-responsive materials and achieve suitable properties in several fields ranging from optoelectronics to biomedical. Herein, we discuss the recent developments with composite peptide-based gels including the fabrication, tunability of gels' properties, and challenges on (bio)technological applications.

Enzymatic Noncovalent Synthesis for Targeting Subcellular Organelles

Enzymatic noncovalent synthesis (ENS) exploits enzymatic reactions to produce spatially organized higher-order supramolecular assemblies that modulate cellular processes. While ENS is a general mechanism to create higher-order assemblies of proteins for diverse cellular functions, the exploration of ENS of other bioactive molecules, such as peptides or small organic molecules, is rather limited. Since ENS generates non-diffusive supramolecular assemblies locally, it provides a unique approach to targeting subcellular organelles. In this Review, we highlight the recent progress of the application of ENS of peptide assemblies for targeting subcellular organelles. After a brief introduction of the concept of ENS, we introduce the case of generating artificial filaments by ENS in cell cytosol, then discuss the use of ENS for targeting endoplasmic reticulum, mitochondria, Golgi apparatus, and lysosomes, and finally we describe the targeting of nucleus by ENS. We hope to illustrate the promise of ENS, as a localized molecular process in an open system, for understanding diseases, controlling cell behaviors, and developing new therapeutics.

Structure-Based Programming of Supramolecular Assemblies in Living Cells for Selective Cancer Cell Inhibition

Here we report on the design, synthesis, and assembly of an enzymatic programmable peptide system inspired by endocytic processes to induce molecular assemblies formation spatiotemporally in living cancer cells, resulting in glioblastoma cell death mainly in necroptosis. Our results indicate the stability and glycosylation of molecules play an essential role in determining the final bioactivity. Detailed mechanistic studies by CLSM, Flow cytometry, western blot, and Bio-EM suggest the site-specific formation of assemblies, which could induce the LMP and activate the downstream cell death pathway. Moreover, we also demonstrate that our strategy can boost the activity of commercial chemotherapy drug by escaping lysosome sequestration. We expected this work would be expanded towards artificial intelligent biomaterials for cancer therapy and imaging precisely.

Defining the Landscape of the Pauling-Corey Rippled Sheet: An Orphaned Motif Finding New Homes

When peptides are mixed with their mirror images in an equimolar ratio, two-dimensional periodic structural folds can form, in which extended peptide strands are arrayed with alternating chirality. The resultant topography class, termed the rippled β-sheet, was introduced as a theoretical concept by Pauling and Corey in 1953. Unlike other fundamental protein structural motifs identified around that time, including the α-helix and the pleated β-sheet, it took several decades before conclusive experimental data supporting the proposed rippled β-sheet motif were gained. Much of the key experimental evidence was provided over the course of the past decade through the concurrent efforts of our three laboratories. Studies that focused on developing new self-assembling hydrogel materials have shown that certain amphiphilic peptides form fibrils and hydrogel networks that are more rigid and have a higher thermodynamic stability when made from racemic peptide mixtures as opposed to pure enantiomers. Related interrogation of assemblies composed of mixtures of l- and d-amphiphilic peptides confirmed that the resulting fibrils were composed of alternating l/d peptides consistent with rippled β-sheets. It was also demonstrated that mirror-image amyloid beta (Aβ) could act as a molecular chaperone to promote oligomer-to-fibril conversion of the natural Aβ enantiomer, which was found to reduce Aβ neurotoxicity against different neuronal cell models. With a cross-disciplinary approach that combines experiment and theory, our three laboratories have demonstrated the unique biophysical, biochemical, and biological properties that arise upon mixing of peptide enantiomers, in consequence of rippled β-sheet formation. In this Account, we give an overview of the early history of the rippled β-sheet and provide a detailed structural description/definition of this motif relative to the pleated β-sheet. We then summarize the key findings, obtained on three unique sets of aggregating mirror-image peptide pairs through independent efforts of our three laboratories, and use these results to delineate the landscape of the rippled β-sheet structural motif to inspire future studies. Peptide sequence parameters that favor rippled β-sheet assembly are described, along with the accompanying kinetic and thermodynamic properties, as well as the resulting emergent physical properties of the assemblies. The Account then concludes with a brief overview of some key unresolved challenges in this nascent field. There is much potential for future applications of this unique supramolecular motif in the realm of materials design and biomedical research. We hope this Account will stimulate much-needed discussion of this fascinating structural class to eventually produce a fully quantitative, rational framework for the molecular engineering of rippled β-sheets in the future.

Poly(ester-thioether) microspheres co-loaded with erlotinib and α-tocopheryl succinate for combinational therapy of non-small cell lung cancer

Polymer microspheres are attracting wide attention in localized cancer therapy owing to the excellent biocompatibility and drug loading capacity, controllable biodegradation speeds, and minimized systemic toxicity. Herein, we presented poly(ester-thioether) microspheres, porous and nonporous, as drug depots for localized therapy of non-small cell lung cancer (NSCLC). Specifically, erlotinib and α-tocopheryl succinate (α-TOS), which are respectively an epidermal growth factor receptor (EGFR) inhibitor and mitochondria destabilizer, were efficiently loaded into porous and nonporous poly(ester-thioether) microspheres for the treatment of EGFR-overexpressing NSCLC (A549 cells). The poly(ester-thioether) microspheres significantly improved the bioavailability of both erlotinib and α-TOS in comparison to the free drug combination, realizing synergistic inhibition of A549 cells both in vitro and in vivo. The porous microspheres displayed faster degradation and drug release than the nonporous counterpart, thereby showing better anticancer efficacy. Overall, our study reported a new anticancer strategy of erlotinib and α-TOS combination for therapy of NSCLC, and established that poly(ester-thioether) microspheres could be a robust and biodegradable reservoir for drug delivery and localized cancer therapy.

Synergistic Interplay of Covalent and Non-Covalent Interactions in Reactive Polymer Nanoassembly Facilitates Intracellular Delivery of Antibodies

The primary impediments in developing large antibodies as drugs against intracellular targets involve their low transfection efficiency and suitable reversible encapsulation strategies for intracellular delivery with retention of biological activity. To address this, we outline an electrostatics-enhanced covalent self-assembly strategy to generate polymer-protein/antibody nanoassemblies. Through structure-activity studies, we down-select the best performing self-immolative pentafluorophenyl containing activated carbonate polymer for bioconjugation. With the help of an electrostatics-aided covalent self-assembly approach, we demonstrate efficient encapsulation of medium to large proteins (HRP, 44 kDa and β-gal, 465 kDa) and antibodies (ca. 150 kDa). The designed polymeric nanoassemblies are shown to successfully traffic functional antibodies (anti-NPC and anti-pAkt) to cytosol to elicit their bioactivity towards binding intracellular protein epitopes and inducing apoptosis.

Design of a Peptide-Based Electronegative Hydrogel for the Direct Encapsulation, 3D Culturing, in Vivo Syringe-Based Delivery, and Long-Term Tissue Engraftment of Cells

Soft materials that facilitate the three-dimensional (3D) encapsulation, proliferation, and facile local delivery of cells to targeted tissues will aid cell-based therapies, especially those that depend on the local engraftment of implanted cells. Herein, we develop a negatively charged fibrillar hydrogel based on the de novo-designed self-assembling peptide AcVES3-RGDV. Cells are easily encapsulated during the triggered self-assembly of the peptide leading to gel formation. Self-assembly is induced by adjusting the ionic strength and/or temperature of the solution, while avoiding large changes in pH. The AcVES3-RGDV gel allows cell-material attachment enabling both two-dimensional and 3D cell culture of adherent cells. Gel-cell constructs display shear-thin/recovery rheological properties enabling their syringe-based delivery. In vivo cellular fluorescence as well as tissue resection experiments show that the gel supports the long-term engraftment of cells delivered subcutaneously into mice.

Hollow gold nanoshells-incorporated injectable genetically engineered hydrogel for sustained chemo-photothermal therapy of tumor

BACKGROUND

Combined therapy has demonstrated to be an effective strategy for cancer therapy. Herein, an injectable hydrogel based on the genetically engineered polypeptide and hollow gold nanoshells (HAuNS) has been developed for chemo-photothermal therapy of HepG2 tumor.

METHODS

PC₁₀A/DOX/HAuNS nanogel was prepared with layer-by-layer through the adsorption of DOX and PC₁₀A successively. DOX with positive charge and PC₁₀A with negative charge were coated step by step onto the surface of negatively charged HAuNS. The multifunctional hydrogel PC₁₀A/DOX/HAuNS were prepared via dissolving hybrid PC₁₀A/DOX/HAuNS nanogel in polypeptide PC₁₀A. Chemotherapy drug DOX in the PC₁₀A/DOX/HAuNS hydrogel was absorbed on the HAuNS and directly embedded in the PC₁₀A hydrogel, which contributes to sequentially release of the drug. Specifically, DOX adsorbed on the HAuNS could be released slowly for sustainable chemotherapy.

RESULTS

The PC₁₀A/DOX/HAuNS hydrogel could pass 26-gauge needle without clogging, indicating that it is injectable. In addition, the PC₁₀A/DOX/HAuNS hydrogel possessed outstanding photothermal effect and photothermal stability. In both in vitro cell and in vivo tumor-bearing mice experiments, a remarkably enhance tumor inhibition was observed by the combined therapy of chemo-photothermal therapy compared with photothermal therapy or chemotherapy alone.

CONCLUSIONS

The combined chemotherapy and photothermal therapy of PC₁₀A/DOX/HAuNS hydrogels could significantly improve the therapeutic effect. Therefore, the multifunctional hydrogel PC₁₀A/DOX/HAuNS is promising to provide a new strategy for sustained chemo-photothermal therapy.

Hierarchically Compartmentalized Supramolecular Gels through Multilevel Self-Sorting

Hierarchical compartmentalization through the bottom-up approach is ubiquitous in living cells but remains a formidable task in synthetic systems. Here we report on hierarchically compartmentalized supramolecular gels that are spontaneously formed by multilevel self-sorting. Two types of molecular gelators are formed in situ from nonassembling building blocks and self-assemble into distinct gel fibers through a kinetic self-sorting process; interestingly, these distinct fibers further self-sort into separated microdomains, leading to microscale compartmentalized gel networks. Such spontaneously multilevel self-sorting systems provide a "bottom-up" approach toward hierarchically structured functional materials and may play a role in intracellular organization.