A Guanidinobenzol-Rich Polymer Overcoming Cascade Delivery Barriers for CRISPR-Cas9 Genome Editing.

The efficient cytosolic delivery of the CRISPR-Cas9 machinery remains a challenge for genome editing. Herein, we performed ligand screening and identified a guanidinobenzol-rich polymer to overcome the cascade delivery barriers of CRISPR-Cas9 ribonucleoproteins (RNPs) for genome editing. RNPs were stably loaded into the polymeric nanoparticles (PGBA NPs) by their inherent affinity. The polymer facilitated rapid endosomal escape of RNPs via a dynamic multiple-step cascade process. Importantly, the incorporation of fluorescence in the polymer helps to identify the correlation between cellular uptake and editing efficiency, increasing the efficiency up to 70% from the initial 30% for the enrichment of edited cells. The PGBA NPs efficiently deliver RNPs for in vivo gene editing via both local and systemic injections and dramatically reduce PCSK9 level. These results indicate that PGBA NPs enable the cascade delivery of RNPs for genome editing, showing great promise in broadening the therapeutic potential of the CRISPR-Cas9 technique.

Chemotaxis-guided Self-propelled Macrophage Motor for Targeted Treatment of Acute Pneumonia.

Immune cells exhibit great potential as carriers of nanomedicine, attributed to their high tolerance to internalized nanomaterials and targeted accumulation in inflammatory tissues. However, the premature efflux of internalized nanomedicine during systemic delivery and slow infiltration into inflammatory tissues have limited their translational applications. Herein, a motorized cell platform as a nanomedicine carrier for highly efficient accumulation and infiltration in the inflammatory lungs and effective treatment of acute pneumonia are reported. ß-Cyclodextrin and adamantane respectively modified manganese dioxide nanoparticles are intracellularly self-assembled into large aggregates mediated via host-guest interactions, to effectively inhibit the efflux of nanoparticles, catalytically consume/deplete H2 O2 to alleviate inflammation, and generate O2 to propel macrophage movement for rapid tissue infiltration. With curcumin loaded into MnO2 nanoparticles, macrophages carry the intracellular nano-assemblies rapidly into the inflammatory lungs via chemotaxis-guided, self-propelled movement, for effective treatment of acute pneumonia via immunoregulation induced by curcumin and the aggregates.

Microfluidics-Assisted Fluorescence Mapping of DNA Phosphorothioation.

As the key player of a new restriction modification system, DNA phosphorothioate (PT) modification, which swaps oxygen for sulfur on the DNA backbone, protects the bacterial host from foreign DNA invasion. The identification of PT sites helps us understand its physiological defense mechanisms, but accurately quantifying this dynamic modification remains a challenge. Herein, we report a simple quantitative analysis method for optical mapping of PT sites in the single bacterial genome. DNA molecules are fully stretched and immobilized in a microfluidic chip by capillary flow and electrostatic interactions, improving the labeling efficiency by maximizing exposure of PT sites on DNA while avoiding DNA loss and damage. After screening 116 candidates, we identified a bifunctional chemical compound, iodoacetyl-polyethylene glycol-biotin, that can noninvasively and selectively biotinylate PT sites, enabling further labeling with streptavidin fluorescent nanoprobes. With this method, PT sites in PT+ DNA can be easily detected by fluorescence, while almost no detectable ones were found in PT- DNA, achieving real-time visualization of PT sites on a single DNA molecule. Collectively, this facile genome-wide PT site detection method directly characterizes the distribution and frequency of DNA modification, facilitating a better understanding of its modification mechanism that can be potentially extended to label DNAs in different species.

Targeted delivery and enhanced uptake of chemo-photodynamic nanomedicine for melanoma treatment.

Nanoparticles (NPs) modified with targeting ligands have often shown great potential in targeted drug delivery for tumor therapy. However, the clearance of NPs by the monocyte-phagocyte system (MPS) and the relatively low cellular uptake by tumor cells have significantly limited the antitumor efficacy of a variety of nanomedicines. Tumor microenvironment-mediated multidrug resistance also reduces the antitumor efficacy of internalized nanomedicines. Herein, we developed an innovative nanomedicine for combined chemo-photodynamic therapy of melanoma through targeted drug delivery and significantly improved the cellular uptake of the nanomedicine through the charge-reversal phenomenon. An amphiphilic platinum (IV)-polyethylenimine-chlorin e6 (Pt(IV)-PEI-Ce6) polymer was designed, prepared, and self-assembled into NPs (PPC) in an aqueous solution, and these NPs were subsequently coated with hyaluronic acid (HA) to afford PPC@HA. The surface-coated HA provided PPC with a negatively charged surface potential to reduce the clearance by the MPS during systemic circulation and enhanced the targeted delivery of PPC to CD44-overexpressing melanoma cells. Upon accumulation in the tumor site, hyaluronidase overexpressed in the tumor induced HA degradation to release the positively charged PPC, resulting in an increased internalization of PPC into tumor cells. Bioactive Pt(II) was released in response to high glutathione level in the tumor cells for effective tumor chemotherapy. Under 650 nm laser irradiation, Ce6 produced reactive oxygen species (ROS), thus driving photodynamic therapy. Finally, PPC@HA exhibited combined photodynamic-chemotherapeutic antitumor efficacy against the melanoma cells in mice. STATEMENT OF SIGNIFICANCE: Tumors are one of the greatest threats to human health, and chemotherapy has been one of the most common therapeutic modalities for treating tumors; however, many challenges related to chemotherapy remain, such as low delivery efficiency, side effects, and unsatisfactory therapeutic efficacy. Nanomedicines modified with targeting ligands have often shown great potential in improving targeted drug delivery for tumor therapy; however, the clearance of nanomaterials by the monocyte-phagocyte system and the relatively low cellular uptake by tumor cells have significantly limited the antitumor efficacy of a variety of nanomedicines. Herein, we developed a novel charge-reversal-based, hyaluronic acid-coated, Pt(IV) prodrug and chlorin e6-based nanomedicine to improve systemic circulation and targeted accumulation of the nanomedicine in the tumor tissue and to enhance its intracellular uptake. This nanomedicine may provide a potential new platform to improve the drug content inside tumor cells and to effectively inhibit tumor growth through combined chemotherapy and photodynamic therapy.

Cyclodextrin-Derived ROS-Generating Nanomedicine with pH-Modulated Degradability to Enhance Tumor Ferroptosis Therapy and Chemotherapy.

Nowadays, destruction of redox homeostasis to induce cancer cell death is an emerging anti-cancer strategy. Here, the authors utilized pH-sensitive acetalated ß-cyclodextrin (Ac-ß-CD) to efficiently deliver dihydroartemisinin (DHA) for tumor ferroptosis therapy and chemodynamic therapy in a synergistic manner. The Ac-ß-CD-DHA based nanoparticles are coated by an iron-containing polyphenol network. In response to the tumor microenvironment, Fe2+ /Fe3+ can consume glutathione (GSH) and trigger the Fenton reaction in the presence of hydrogen peroxide (H2 O2 ), leading to the generation of lethal reactive oxygen species (ROS). Meanwhile, the OO bridge bonds of DHA are also disintegrated to enable ferroptosis of cancer cells. Their results demonstrate that these nanoparticles acted as a ROS generator to break the redox balance of cancer cells, showing an effective anticancer efficacy, which is different from traditional approaches.

Supramolecular biomaterials for bio-imaging and imaging-guided therapy.

Benefiting from their unique advantages, including reversibly switchable structures, good biocompatibility, facile functionalization, and sensitive response to biological stimuli, supramolecular biomaterials have been widely applied in biomedicine. In this review, the representative achievements and trends in the design of supramolecular biomaterials (mainly those derived from biomacromolecules) with specific macromolecules including peptides, deoxyribonucleic acid, and polysaccharides, as well as their applications in bio-imaging and imaging-guided therapy are summarized. This review will serve as an important summary and "go for" reference for explorations of the applications of supramolecular biomaterials in bio-imaging and image-guided therapy, and will promote the development of supramolecular chemistry as an emerging interdisciplinary research area.

Macrophage-hitchhiking supramolecular aggregates of CuS nanoparticles for enhanced tumor deposition and photothermal therapy.

In this design, small CuS nanoparticles (NPs) were intracellularly self-assembled into large supramolecular aggregates via host-guest interactions between sequentially internalized ß-cyclodextrin-capped CuS NPs and ferrocene-capped CuS NPs inside macrophages, thus the efflux of CuS NPs was significantly inhibited during the macrophage-hitchhiking delivery. Biodistribution studies in mice confirmed the dramatically enhanced deposition of CuS NPs in the tumor tissue of mice injected with macrophages carrying intracellular CuS aggregates, in comparison to that of mice treated with macrophages carrying CuS NPs. In response to the inflammatory tumor microenvironment, the oxidation of ferrocene would dissociate the ß-cyclodextrin-ferrocene host-guest pair, driving disassembly of the CuS aggregates and release of small CuS NPs for deep tissue penetration and enhanced photothermal therapy. This precisely controlled intracellular self-assembly and disassembly of the nanomedicine inside macrophages provides a novel cell-hitchhiking delivery strategy that not only minimizes premature leakage of the nanomedicine but also greatly improves the delivery efficiency and tumor penetration for safe, effective tumor therapy.

Supramolecular Tropism Driven Aggregation of Nanoparticles In Situ for Tumor-Specific Bioimaging and Photothermal Therapy.

Inorganic nanomedicine has attracted increasing attentions in biomedical sciences due to their excellent biocompatibility and tunable, versatile functionality. However, the relatively poor accumulation and retention of these nanomedicines in targeted tissues have often hindered their clinical translation. Herein, highly efficient, targeted delivery, and in situ aggregation of ferrocene (Fc)-capped Au nanoparticles (NPs) are reported to cucurbit[7]uril (CB[7])-capped Fe3 O4 NPs (as an artificial target) that are magnetically deposited into the tumor, driven by strong, multipoint CB[7]-Fc host-guest interactions (here defined as "supramolecular tropism" for the first time), leading to high tumor accumulation and retention of these NPs. The in vitro and in vivo studies demonstrate the precisely controlled, specific accumulation, and retention of Au NPs in the tumor cells and tissue via supramolecular tropism and in situ aggregation, which afford locally enhanced CT imaging of cancer and enable tumor-specific photothermal therapy attributed to the plasmonic coupling effects between adjacent Au NPs within the supramolecular aggregations. This work provides a novel concept of supramolecular tropism, which may drive targeted delivery and enable specific accumulation, retention, and activation of nanomedicine for improved bioimaging and therapy of cancer.

Supramolecular micelles as multifunctional theranostic agents for synergistic photodynamic therapy and hypoxia-activated chemotherapy.

Photodynamic therapy (PDT), where a photosensitizer (under light irradiation) converts molecular oxygen to singlet oxygen to elicit programmed cell death, is a promising cancer treatment modality with a high temporal and spatial resolution. However, only limited cancer treatment efficacy has been achieved in clinical PDT due to the hypoxic conditions of solid tumor microenvironment that limits the generation of singlet oxygen, and PDT process often leads to even more hypoxic microenvironment due to the consumption of oxygens during therapy. Herein, we designed novel supramolecular micelles to co-deliver photosensitizer and hypoxia-responsive prodrug to improve the overall therapeutic efficacy. The supramolecular micelles (CPC) were derived from a polyethylene glycol (PEG) system dually tagged with hydrophilic cucurbit[7]uril (CB[7]) and hydrophobic Chlorin e6 (Ce6), respectively on each end, for synergistic antitumor therapy via PDT of Ce6 and chemotherapy of a hypoxia-responsive prodrug, banoxantrone (AQ4N), loaded into the cavity of CB[7]. In addition, CPC was further modularly functionalized by folate (FA) via strong host-guest interaction between folate-amantadine (FA-ADA) and CB[7] to produce a novel nanoplatform, AQ4N@CPC-FA, for targeted delivery. AQ4N@CPC-FA exhibited enhanced cellular uptake, negligible cytotoxicity and good biocompatibility, and improved intracellular reactive oxygen species (ROS) generation efficiency. More importantly, in vivo evaluation of AQ4N@CPC-FA revealed a synergistic antitumor efficacy between PDT of Ce6 and hypoxia-activated chemotherapy of AQ4N (that can be converted to chemotherapeutic AQ4 for tumor chemotherapy in response to the strengthened hypoxic tumor microenvironment during PDT treatment). This study not only provides a new nanoplatform for synergistic photodynamic-chemotherapeutic treatment, but also offers important new insights to design and development of multifunctional supramolecular drug delivery system. STATEMENT OF SIGNIFICANCE: Photodynamic therapy (PDT) has exhibited a variety of advantages for cancer phototherapy as compared to traditional chemotherapy. However, the unsatisfactory therapeutic efficacy by PDT alone as a result of the enhanced tumor hypoxia during PDT has limited its clinical application. Herein, we designed multifunctional supramolecular micelles to co-deliver photosensitizer and hypoxia-responsive prodrug to improve the overall therapeutic efficacy. The supramolecular micelles are biocompatible and possess strong red absorption, controlled drug release profile, and ultimately enhanced therapeutic outcome via PDT-chemotherapy. This study not only provides a new nanoplatform for synergistic photodynamic-chemotherapeutic treatment of cancer, but also offers important new insights to design and development of multifunctional supramolecular drug delivery tool for multi-modality cancer therapy.

Self-Propelled Asymmetrical Nanomotor for Self-Reported Gas Therapy.

Gas therapy has emerged as a new therapeutic strategy in combating cancer owing to its high therapeutic efficacy and biosafety. However, the clinical translation of gas therapy remains challenging due to the rapid diffusion and limited tissue penetration of therapeutic gases. Herein, a self-propelled, asymmetrical Au@MnO2 nanomotor for efficient delivery of therapeutic gas to deep-seated cancer tissue for enhanced efficacy of gas therapy, is reported. The Au@MnO2 nanoparticles (NPs) catalyze endogenous H2 O2 into O2 that propels NPs into deep solid tumors, where SO2 prodrug is released from the hollow NPs owing to the degradation of MnO2 shells. Fluorescein isothiocyanate (FITC) is conjugated onto the surface of Au via caspase-3 responsive peptide (DEVD) and the therapeutic process of gas therapy can be optically self-reported by the fluorescence of FITC that is turned on in the presence of overexpressed caspase-3 as an apoptosis indicator. Au@MnO2 nanomotors show self-reported therapeutic efficacy and high biocompatibility both in vitro and in vivo, offering important new insights to the design and development of novel nanomotors for efficient payload delivery into deep tumor tissue and in situ monitoring of the therapeutic process.

Polyamine-Responsive Morphological Transformation of a Supramolecular Peptide for Specific Drug Accumulation and Retention in Cancer Cells.

The precise accumulation and extended retention of nanomedicines in the tumor tissue has been highly desired for cancer therapy. Here a novel supramolecular-peptide derived nanodrug (SPN) that can be transformed to microfibers in response to intracellular polyamine in cancer cells for significantly enhanced tumor specific accumulation and retention is developed. The supramolecular-peptide is constructed via the non-covalent interactions between cucurbit[7]uril (CB[7]) and Phe on Phe-Phe-Val-Leu-Lys-camptothecin conjugates (FFVLK-CPT, PC). The resultant amphiphilic supramolecular complex subsequently self-assembles into nanoparticles with a hydrodynamic diameter of 164.2 ± 3.7 nm. Upon internalization into spermine-overexpressed cancer cells, the CB[7]-Phe host-guest pairs can be competitively dissociated by spermine and can release free PC, which immediately form ß-sheet structures and subsequently reorganize into microfibers, leading to dramatically improved accumulation, retention, and sustained release of CPT in tumor cells for highly effective cancer therapy. Accordingly, this SPN exhibit rather low toxicity against non-cancerous cells due to the morphological stability and fast exocytosis of the nanodrugs in those cells without abundant spermine. This study reports the first supramolecular peptide capable of polyamine-responsive "nanoparticle-to-microfiber" transformation for specific tumor therapy with minimal side effects. This work also offers novel insights to the design and development of stimuli-responsive nanomaterials as precision medicine.

A hypoxia responsive nanoassembly for tumor specific oxygenation and enhanced sonodynamic therapy.

The hypoxic tumor microenvironment (TME) and non-specific distribution of sonosensitizers are two major obstacles that limit practical applications of sonodynamic therapy (SDT) in combating tumors. Here we report a hypoxia-responsive nanovesicle (hMVs) as delivery vehicles of a sonosensitizer to enhance the efficacy of SDT via specific payload release and local oxygenation in the tumor. The nanovesicles are composed of densely packed manganese ferrite nanoparticles (MFNs) embedded in hypoxia-responsive amphiphilic polymer membranes. With δ-aminolevulinic acid (ALA) loaded in the hollow cavities, the hMVs could rapidly dissociate into discrete nanoparticles in the hypoxic TME to release the payload and induce the generation of reactive oxygen species (ROS) under ultrasound (US) radiation. Meanwhile, the released MFNs could catalytically generate O2 to overcome the hypoxic TME and thus enhance the efficacy of SDT. After treatment, the dissociated MFNs could be readily excreted from the body via renal clearance to reduce long term toxicity. In vitro and in vivo experiments displayed effective tumor inhibition via hMVs-mediated SDT, indicating the great potential of this unique nanoplatform in effective SDT by generating sufficient ROS in deep-seated hypoxic tumors that are not readily accessible by conventional photodynamic therapy.

Supramolecular Polymerization-Induced Nanoassemblies for Self-Augmented Cascade Chemotherapy and Chemodynamic Therapy of Tumor.

The clinical application of chemodynamic therapy is impeded by the insufficient intracellular H2 O2 level in tumor tissues. Herein, we developed a supramolecular nanoparticle via a simple one-step supramolecular polymerization-induced self-assembly process using platinum (IV) complex-modified ß-cyclodextrin-ferrocene conjugates as supramolecular monomers. The supramolecular nanoparticles could dissociate rapidly upon exposure to endogenous H2 O2 in the tumor and release hydroxyl radicals as well as platinum (IV) prodrugs in situ, which is reduced into cisplatin to significantly promote the generation of H2 O2 in the tumor tissue. Thus, the supramolecular nanomedicine overcomes the limitation of conventional chemodynamic therapy via the self-augmented cascade radical generation and drug release. In addition, dissociated supramolecular nanoparticles could be readily excreted from the body via renal clearance to effectively avoid systemic toxicity and ensure long term biocompatibility of the nanomedicine. This work may provide new insights on the design and development of novel supramolecular nanoassemblies for cascade chemo/chemodynamic therapy.

Supramolecular nanovesicles for synergistic glucose starvation and hypoxia-activated gene therapy of cancer.

Glucose starvation has emerged as a therapeutic strategy to inhibit tumor growth by regulating glucose metabolism. However, the rapid proliferation of cancer cells could induce the hypoxic tumor microenvironment (TME) which limits the therapeutic efficacy of glucose starvation by vascular isomerization. Herein, we developed a "dual-lock" supramolecular nanomedicine system for synergistic cancer therapy by integrating glucose oxidase (GOx) induced starvation and hypoxia-activated gene therapy. The host-guest interactions (that mediate nano-assembly formation) and hypoxia-activatable promoters act as two locks to keep glucose oxidase (GOx) and a therapeutic plasmid (RTP801::p53) inside supramolecular gold nanovesicles (Au NVs). Upon initial dissociation of the host-guest interactions and hence Au NVs by cancer-specific reactive oxygen species (ROS), GOx is released to consume glucose and oxygen, generate H2O2 and induce the hypoxic TME, which act as the two keys for triggering burst payload release and promoter activation, thus allowing synergistic starvation and gene therapy of cancer. This "dual-lock" supramolecular nanomedicine exhibited integrated therapeutic effects in vitro and in vivo for tumor suppression.

Supramolecular nanomedicine for selective cancer therapy via sequential responsiveness to reactive oxygen species and glutathione.

Cancer cells are generally immersed in an oxidative stress environment with a high intracellular reduction level. Thus, nanocarriers with sequential responsiveness to oxidative and reductive species, matching the traits of high oxidation in the tumor tissue microenvironment and high reduction potential inside cancer cells, are highly desired for specific cancer therapy. Herein, we report a supramolecular nanomedicine comprised of a reduction-responsive nanoparticle (NP) core whose surface was modified by an oxidation-responsive polyethylene glycol (PEG) derivative via strong host-guest interactions. In this delicate design, the PEGylation of NPs not only reduced their immunogenicity and extended systemic circulation, but also enabled oxidation-responsive de-PEGylation in the tumor tissues and subsequent intracellular payload release in response to glutathione (GSH) inside tumor cells. As a proof of concept, this supramolecular nanomedicine exhibited specific chemotherapeutic effects against cancer in vitro and in vivo with a decent safety profile.

ROS-initiated chemiluminescence-driven payload release from macrocycle-based Azo-containing polymer nanocapsules.

Reactive oxygen species (ROS) overproduction is involved in many pathological processes, particularly in inflammatory diseases. Therefore, ROS-responsive nanocarriers for specific drug release have been highly sought after. Herein we developed a ROS-responsive drug delivery system based on covalently self-assembled polymer nanocapsules (Azo-NCs) formed via crosslinking macrocyclic cucurbit[6]urils by a photo-sensitive azobenzene derivative (Azo). Luminol, a chemiluminescent molecule activatable by ROS, was co-loaded into Azo-NCs together with a therapeutic payload. When exposed to high ROS concentration that is typically encountered in inflammatory cells or tissues, the ROS-initiated blue chemiluminescence of luminol drives photoisomerization of the Azo groups within Azo-NCs, leading to Azo-NCs' surface transformation and distortion of the nanostructure, and subsequent payload release. As a proof-of-concept, ROS-responsive payload release from luminol-loaded Azo-NCs in inflammatory cells and zebrafish was demonstrated, showing promising anti-inflammatory effects in vitro and in vivo.

Amelioration of ulcerative colitis via inflammatory regulation by macrophage-biomimetic nanomedicine.

Ulcerative colitis (UC) is featured with relapsing inflammation in the colon, where macrophages are recruited and polarized locally into M1 type to drive further inflammation. Pharmacotherapy of UC has exhibited limited efficacy, mostly due to the poor specificity. Methods: A macrophage-biomimetic nanomedicine was developed for targeted treatment of UC, which was derived from reactive oxygen species (ROS)-sensitive ß-cyclodextrin, loaded with rosiglitazone, and coated with macrophage membrane. The ability of the nanomedicine in regulating macrophage polarization was examined at cellular level, and the macrophage-tropism driven targeted delivery into the inflammatory colon was investigated by ex vivo bio-imaging distribution assay. Furthermore, the nanomedicine's therapeutic efficacy was systemically examined in dextran sulfate sodium (DSS)-induced colitis model in mice. Results: The nanomedicine effectively polarized macrophages to M2 and protected epithelial cells from oxidative stress in vitro. In addition, macrophage-membrane led the nanomedicine to the inflammatory colon with a high targeting efficiency. In response to the elevated ROS in the inflammatory tissue, the nanomedicine released rosiglitazone specifically and regulated macrophage polarization in vivo. Macrophage membrane also assisted inflammation suppression by sequestering proinflammatory cytokines. Working in such a synergy, the nanomedicine exhibited significant therapeutic effects against UC in mice. Conclusions: This macrophage-biomimetic nanomedicine leverages the inflammatory tropism and inflammatory cytokine sequestration effects of macrophage membrane for targeted delivery and local inflammation suppression, the ROS-responsiveness of ß-cyclodextrin-based matrix for specific payload release, and the macrophage-polarizing effect of rosiglitazone for inflammatory regulation, thereby exhibiting considerable therapeutic efficacy against UC in mice. This study offers important new insights on the design and development of biomimetic nanomaterials for inflammation regulations.

Supramolecular Induction of Mitochondrial Aggregation and Fusion.

Mitochondrial fission is often associated with the development of oxidative stress related diseases, as the fragmentation of mitochondria undermines their membranes, advances production of reactive oxygen species, and promotes apoptosis. Therefore, induction of mitochondrial aggregation and fusion could potentially reverse such medical conditions. Herein, a supramolecular strategy to induce mitochondrial aggregation and fusion is developed for the first time. A polyethylene glycol (PEG) system that was dually tagged with triphenylphosphonium (TPP) and adamantane (ADA), namely TPP-PEG-ADA, was designed to target mitochondria and functionalize their surfaces with ADA. Thereafter, the addition of cucurbit[7]uril (CB[7]) grafted hyaluronic acid (HA) induced supramolecular aggregation and fusion of mitochondria, via strong host-guest interactions between the CB[7] moiety of CB[7]-HA and ADA residing on the surface of mitochondria. As a proof-of-principle, chemically stressed SH-SY5Y cells and zebrafish neurons were effectively protected via this supramolecular mitochondrial fusion strategy in vitro and in vivo, respectively. This study may open up new venues in not only fundamentally controlling mitochondrial dynamics but also addressing the medical needs to treat diseases associated with mitochondrial fission and fragmentation.

Host-Guest Protein Assembly for Affinity Purification of Methyllysine Proteomes.

Protein-protein interactions drive self-assembly of biomacromolecules and thus enable important physiological functions at a cellular level. Supramolecular chemists have developed artificial host-guest interactions that are similar with, yet distinct from and orthogonal to, the natural protein-protein interactions. For instance, cucurbit[n]urils are synthetic receptors that can specifically recognize proteins with N-terminal aromatic residues with high affinities, yet this interaction can be reversed by the competition of small molecules such as amantadine. Herein, we develop a site-specific, oriented protein-display method by combining the host-guest interaction based on cucurbit[7]uril and a covalent protein-peptide reaction. A methyllysine-binding protein HP1ß chromodomain (CD) is immobilized via host-guest interactions and used as the "bait" to capture methyllysine proteomes from cancer cells. The captured "fish"-methyllysine-containing proteins-can be released via competitive displacement by amantadine in a nondenaturing and traceless manner. This affinity purification method found 73 novel methyllysine sites from 101 identified sites among 66 methylated proteins from 255 HP1ß CD-binding proteins in cancer cells via subsequent mass spectrometric analysis. This work thereby presents a new strategy of artificial host-guest protein assembly in affinity purification of methyllysine proteins in coupling to mass spectrometry.