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The effect of the U-shaped cavity of conformationally flexible chiral Lewis acidic boron-based catalysts in multiselective Diels-Alder reactions was investigated. The U-shaped catalysts can recognize substituents at the terminal acetylene moiety of propynal based on steric factors and can also recognize alkyne and alkene substrates based on the match/mismatch between the catalysts and substrates. Moreover, even in a mixture of different catalysts and substrates, the desired competitive reactions can proceed multiselectively. This proof-of-concept study should contribute to the development of artificial enzyme-like catalysis in vitro.

Thermoelectric (TE) modules are exposed to temperature gradients and repeated thermal cycles during their operation; therefore, mechanically robust n- and p-type legs are required to ensure their structural integrity. The difference in the coefficients of thermal expansion (CTEs) of the two legs of a TE module can cause stress buildup and the deterioration of performance with frequent thermal cycles. Recently, n-type Mg 3 Sb 2 and p-type MgAgSb have become two promising components of low-temperature TE modules because of to their high TE performance, nontoxicity, and abundance. However, the CTEs of n-Mg 3 Sb 2 and p-MgAgSb differ by approximately 10%. Furthermore, the oxidation resistances of these materials at increased temperatures are unclear. This work manipulates the thermal expansion of Mg 3 Sb 2 by alloying it with Mg 3 Bi 2 . The addition of Bi to Mg 3 Sb 2 reduces the coefficient of linear thermal expansion from 22.6 × 10 -6 to 21.2 × 10 -6 K -1 for Mg 3 Sb 1.5 Bi 0.5 , which is in excellent agreement with that of MgAgSb (21 × 10 -6 K -1 ). Furthermore, thermogravimetric data indicate that both Mg 3 Sb 1.5 Bi 0.5 and MgAgSb are stable in air and Ar at temperatures below ∼570 K. The results suggest the compatibility and robustness of Mg 3 Sb 1.5 Bi 0.5 and MgAgSb as a pair of thermoelectric legs for low-temperature TE modules.

Visible light, particularly in the blue region of the spectrum, can cause cell dysfunction through the generation of singlet oxygen, contributing to cellular aging and age-related pathologies. Although photooxidation of nucleic acids, lipids, and amino acids has been extensively studied, the magnitude and span of blue-light-induced protein damages within proteome remain largely unknown. Herein we present a chemoproteomic approach to mapping blue-light-damaged proteins in live mammalian cells by exploiting a nucleophilic alkyne chemical probe. A gene ontology enrichment analysis revealed that cell surface proteins are more readily oxidized than other susceptible sets of proteins, including mitochondrial proteins. In particular, the integrin family of cell surface receptors (ITGs) was highly ranked in the mammalian cells tested, including human corneal endothelial cells. The blue-light-oxidized ITGB1 protein was functionally inactive in promoting cell adhesion and proliferation, suggesting that the photodamage of integrins contributes to the blue-light-induced cell dysfunction. Further application of our method to various cells and tissues should lead to a comprehensive analysis of light-sensitive proteins.

Melanin is an organic material biosynthesized from tyrosine in pigment-producing cells. The present study reports a simple method to generate tailored functional materials in mammalian cells by chemically fabricating intracellular melanin. Our approach exploits synthetic tyrosine derivatives to hijack the melanin biosynthesis pathway in pigment-producing cells. Its application was exemplified by synthesizing and using a paramagnetic tyrosine derivative, m-YR, which endowed melanoma cells with responsiveness to external magnetic fields. The mechanical force generated by the magnet-responsive melanin forced the cells to elongate and align parallel to the magnetic power lines. Critically, even non-pigment cells were similarly remote-controlled by external magnetic fields once engineered to express tyrosinase and treated with m-YR, suggesting the versatility of the approach. The present methodology may potentially provide a new avenue for mechanobiology and magnetogenetic studies and a framework for magnetic control of specific cells.

A multiselective Diels-Alder (DA) reaction of α-arylacroleins with cyclopentadiene using BBr 3 -assisted chiral BINOL-derived phosphoric acid catalysts has been developed. This unusual exo - and enantioselective DA reaction can be multicontrolled by the chiral cavity of the in situ -formed acid-base cooperative catalysts, in particular, suppressing the competitive hetero Diels-Alder (HDA) reaction effectively.

Covalent inhibitors of enzymes are increasingly appreciated as pharmaceutical seeds, yet discovering non-cysteine-targeting inhibitors remains challenging. Herein, we report an intriguing experience during our activity-based proteomic screening of 1601 reactive small molecules, in which we monitored the ability of library molecules to compete with a cysteine-reactive iodoacetamide probe. One epoxide molecule, F8, exhibited unexpected enhancement of the probe reactivity for glyceraldehyde-3-phosphate dehydrogenase (GAPDH), a rate-limiting glycolysis enzyme. In-depth mechanistic analysis suggests that F8 forms a covalent adduct with an aspartic acid in the active site to displace NAD + , a cofactor of the enzyme, with concomitant enhancement of the probe reaction with the catalytic cysteine. The mechanistic underpinning permitted the identification of an optimized aspartate-reactive GAPDH inhibitor. Our findings exemplify that activity-based proteomic screening with a cysteine-reactive probe can be used for discovering covalent inhibitors that react with non-cysteine residues.

To stabilize small interfering RNA (siRNA) in the bloodstream for systemic RNAi therapeutics, we previously fabricated ultrasmall siRNA nanocarriers that were sub-20 nm in hydrodynamic diameter, named as unit polyion complexes (uPICs), using two-branched poly(ethylene glycol)- b -poly(l-lysine) (bPEG-PLys). The blood retention time of uPICs is dramatically increased in the presence of free bPEG-PLys, suggesting dynamic stabilization of uPICs by free bPEG-PLys based on their equilibrium. Herein, we examined how the degree of polymerization of PLys (DP PLys ) affected the dynamic stability of uPICs in the bloodstream during prolonged circulation. We prepared a series of bPEG-PLys with DP PLys values of 10, 13, 20, 40, and 80 for the uPIC formation and siRNA with 40 negative charges. These bPEG-PLys were then evaluated in physicochemical characterization and pharmacokinetic analyses. Structural analyses revealed that the uPIC size and association numbers were mainly determined by the molecular weights of PEG and DP PLys , respectively. Under bPEG-PLys-rich conditions, the hydrodynamic diameters of uPICs were 15-20 nm, which were comparable to that of the bPEG block (i.e., ∼18 nm). Importantly, DP PLys significantly affected the association constant of bPEG-PLys to siRNA ( K a ) and blood retention of free bPEG-PLys. A smaller DP PLys resulted in a lower K a and a longer blood retention time of free bPEG-PLys. Thus, DP PLys can control the dynamic stability of uPICs, i.e., the balance between K a and blood concentration of free bPEG-PLys. Ultimately, the bPEG-PLys with DP PLys values of 14 and 19 prolonged the blood circulation of siRNA-loaded uPICs with relatively small amounts of free bPEG-PLys. This study revealed that the uPIC formation between siRNA and bPEG-PLys can be controlled by their charges, which may be helpful for designing PIC-based delivery systems.

Effective inhibition of the protein derived from cellular myelocytomatosis oncogene (c-Myc) is one of the most sought-after goals in cancer therapy. While several c-Myc inhibitors have demonstrated therapeutic potential, inhibiting c-Myc has proven challenging, since c-Myc is essential for normal tissues and tumors may present heterogeneous c-Myc levels demanding contrasting therapeutic strategies. Herein, we developed tumor-targeted nanomedicines capable of treating both tumors with high and low c-Myc levels by adjusting their ability to spatiotemporally control drug action. These nanomedicines loaded homologues of the bromodomain and extraterminal (BET) motif inhibitor JQ1 as epigenetic c-Myc inhibitors through pH-cleavable bonds engineered for fast or slow drug release at intratumoral pH. In tumors with high c-Myc expression, the fast-releasing (FR) nanomedicines suppressed tumor growth more effectively than the slow-releasing (SR) ones, whereas, in the low c-Myc tumors, the efficacy of the nanomedicines was the opposite. By studying the tumor distribution and intratumoral activation of the nanomedicines, we found that, despite SR nanomedicines achieved higher accumulation than the FR counterparts in both c-Myc high and low tumors, the antitumor activity profiles corresponded with the availability of activated drugs inside the tumors. These results indicate the potential of engineered nanomedicines for c-Myc inhibition and spur the idea of precision pH-sensitive nanomedicine based on cancer biomarker levels.

A hydrogen bonding network in chiral Brønsted acid catalysts is important for the construction of a chiral cavity and the enhancement of catalytic activity. In this regard, we developed a highly enantioselective aza-Friedel-Crafts reaction of indoles and pyrroles with acyclic α-ketimino esters in the presence of a chiral C 1 -symmetric BINOL-derived bis(phosphoric acid) catalyst. The desired alkylation products with chiral quaternary carbon centers were obtained in high yields with high enantioselectivities on up to a 1.2-g scale with 0.2 mol % catalyst loading. Interestingly, the absolute configurations of the products from indoles and pyrroles were opposite even with the use of the same chiral catalyst. Moreover, preliminary mechanistic considerations disclosed that a unique hydrogen bonding network with or without π-π interactions among the catalyst and substrates might partially play a pivotal role.

Delivering therapeutic antibodies into the brain across the blood-brain barrier at a therapeutic level is a promising while challenging approach in the treatment of neurological disorders. Here, we present a polymeric nanomicelle (PM) system capable of delivering therapeutically effective levels of 3D6 antibody fragments (3D6-Fab) into the brain parenchyma for inhibiting Aβ aggregation. PM assembly was achieved by charge-converting 3D6-Fab through pH-sensitive citraconylation to allow complexation with reductive-sensitive cationic polymers. Brain targeting was achieved by functionalizing the PM surface with glucose molecules to allow interaction with recycling glucose transporter (Glut)-1 proteins. Consequently, 41-fold enhanced 3D6-Fab accumulation in the brain was achieved by using the PM system compared to free 3D6-Fab. Furthermore, therapeutic benefits were obtained by successfully inhibiting Aβ 1-42 aggregation in Alzheimer's disease mice systemically treated with 3D6-Fab-loaded glucosylated PM. Hence, this nanocarrier system represents a promising method for effectively delivering functional antibody agents into the brain and treating neurological diseases.

For intravenous delivery of antisense oligonucleotides (ASOs) to solid tumors, a triblock copolymer was synthesized from poly(2-ethyl-2-oxazoline) (PEtOx), poly(2- n -propyl-2-oxazoline) (PnPrOx), and poly(l-lysine) (PLL) segments. The triblock copolymer, PEtOx-PnPrOx-PLL, was utilized to fabricate a compartmentalized polymeric micelle featuring a hydrophilic PEtOx shell, thermoresponsive PnPrOx interlayer, and ASO/PLL polyion complex (PIC) core. In this formulation, the PnPrOx-derived interlayer underwent the phase transition from hydrophilic elongated state to hydrophobic collapsed state at a lower critical solution temperature (LCST) to enhance the micelle stability. Three triblock copolymers comprising varying lengths of PEtOx segment (2k, 7k, and 12 kDa) were compared to investigate the effect of hydrophilic chain length on the micelle properties. The triblock copolymer micelles (TCMs) were prepared in a two-step manner: mixing between triblock copolymer and ASO in a buffer solution at 4 °C and then increasing the temperature of the solution up to 37 °C. This protocol was crucial for the fabrication of TCMs with both smaller size and narrower size distribution, probably due to the formation of the well-compartmentalized hydrophobic interlayer in the micelle structure. The presence of the PnPrOx segment dramatically enhanced the stability of TCMs in serum-containing media and elicited more efficient cellular uptake of ASO payloads, resulting in higher gene silencing efficiency in cultured prostate cancer (PC-3) cells, compared with a control diblock copolymer micelle (DCM). The blood circulation property of TCMs was prolonged with an increase in the length of PEtOx segment, permitting the efficient accumulation of ASO payloads in a subcutaneous PC-3 tumor model. Ultimately, the systemic delivery of ASO targeting a long noncoding RNA (lncRNA) by the TCMs significantly reduced the expression level of lncRNA in the subcutaneous PC-3 tumor in a sequence-specific manner. These results demonstrate the superiority of TCMs equipped with the hydrophilic shell and hydrophobic interlayer to the cancer-targeted systemic ASO delivery.

Dexamethasone is a glucocorticoid steroid with anti-inflammatory properties used to treat many diseases, including cancer, in which it helps manage various side effects of chemo-, radio-, and immunotherapies. Here, we investigate the tumor microenvironment (TME)-normalizing effects of dexamethasone in metastatic murine breast cancer (BC). Dexamethasone normalizes vessels and the extracellular matrix, thereby reducing interstitial fluid pressure, tissue stiffness, and solid stress. In turn, the penetration of 13 and 32 nm dextrans, which represent nanocarriers (NCs), is increased. A mechanistic model of fluid and macromolecule transport in tumors predicts that dexamethasone increases NC penetration by increasing interstitial hydraulic conductivity without significantly reducing the effective pore diameter of the vessel wall. Also, dexamethasone increases the tumor accumulation and efficacy of ∼30 nm polymeric micelles containing cisplatin (CDDP/m) against murine models of primary BC and spontaneous BC lung metastasis, which also feature a TME with abnormal mechanical properties. These results suggest that pretreatment with dexamethasone before NC administration could increase efficacy against primary tumors and metastases.

Polyion complex vesicles (PICsomes) formed from a self-assembly of an oppositely charged pair of block- and homo-polyelectrolytes have shown exceptional features for functional loading of bioactive agents. Nevertheless, the stability of PICsomes is often jeopardized in a physiological environment, and only PICsomes having chemically cross-linked membranes have endured in harsh in vivo conditions, such as in the bloodstream. Herein, we developed versatile PICsomes aimed to last in in vivo settings by stabilizing their membrane through a combination of ionic and hydrogen bonding, which is widely found in natural proteins as a salt bridge, by controlled introduction of guanidinium groups in the polycation fraction toward concurrent polyion complexation and hydrogen bonding. The guanidinylated PICsomes were successfully assembled under physiological salt conditions, with precise control of their morphology by tuning the guanidinium content, and the ratio of anionic and cationic components. Guanidinylated PICsomes with 100 nm diameter, which are relevant to nanocarrier development, were stable in high urea concentration, at physiological temperature, and under serum incubation, persisting in blood circulation in vivo.

Antibody fragment (Fab')-installed polyion complex (PIC) micelles were constructed to improve targetability of small interfering RNA (siRNA) delivery to pancreatic cancer cells. To this end, we synthesized a block copolymer of azide-functionalized poly(ethylene glycol) and poly(l-lysine) and prepared PIC micelles with siRNA. Then, a dibenzylcyclooctyne (DBCO)-modified antihuman tissue factor (TF) Fab' was conjugated to azido groups on the micellar surface. A fluorescence correlation spectroscopic analysis revealed that 1, 2, or 3 molecule(s) of Fab'(s) were installed onto one micellar nanoparticle according to the feeding ratio of Fab' (or DBCO) to micelle (or azide). The resulting micelles exhibited ∼40 nm in hydrodynamic diameter, similar to that of the parent micelles before Fab' conjugation. Flow cytometric analysis showed that three molecules of Fab'-installed PIC micelles (3(Fab')-micelles) had the highest binding affinity to cultured pancreatic cancer BxPC3 cells, which are known to overexpress TF on their surface. The 3(Fab')-micelles also exhibited the most efficient gene silencing activity against polo-like kinase 1 mRNA in the cultured cancer cells. Furthermore, the 3(Fab')-micelles exhibited high penetrability and the highest cellular internalization amounts in BxPC3 spheroids compared with one or two molecule(s) of Fab'-installed PIC micelles. These results demonstrate the potential of anti-TF Fab'-installed PIC micelles for active targeting of stroma-rich pancreatic tumors.

Occult nodal metastases increase the risk of cancer recurrence, demoting prognosis and quality of life of patients. While targeted drug delivery by using systemically administered nanocarriers can potentially control metastatic disease, lymph node metastases have been mainly dealt by locally injecting nanocarriers, which may not always be applicable. Herein, we demonstrated that sub-50 nm polymeric micelles incorporating platinum anticancer drugs could target lymph node metastases in a syngeneic melanoma model after systemic injection, even after removing the primary tumors, limiting the growth of the metastases. By comparing these micelles with clinically used doxorubicin-loaded liposomes (Doxil) having 80 nm, as well as a 70 nm version of the micelles, we found that the targeting efficiency of the nanocarriers against lymph node metastases was associated with their size-regulated abilities to extravasate from the blood vasculature in metastases and to penetrate within the metastatic mass. These findings indicate the potential of sub-50 nm polymeric micelles for developing effective conservative treatments against lymph node metastasis capable of reducing relapse and improving survival.

Nanomedicines capable of smart operation at the targeted site have the potential to achieve the utmost therapeutic benefits. Providing nanomedicines that respond to endogenous stimuli with an additional external trigger may improve the spatiotemporal control of their functions, while avoiding drawbacks from their inherent tissue distribution. Herein, by exploiting the permeabilization of endosomes induced by photosensitizer agents upon light irradiation, we complemented the intracellular action of polymeric micelles incorporating camptothecin (CPT), which can sharply release the loaded drug in response to the reductive conditions of the cytosol, as an effective strategy for precisely controlling the function of these nanomedicines in vivo, while advancing toward a light-activated chemotherapy. These camptothecin-loaded micelles (CPT/m) were stable in the bloodstream, with minimal drug release in extracellular conditions, leading to prolonged blood circulation and high accumulation in xenografts of rat urothelial carcinoma. With the induction of endosomal permeabilization with the clinically approved photosensitizer, Photofrin, the CPT/m escaped from the endocytic vesicles of cancer cells into the cytosol, as confirmed both in vitro and in vivo by real-time confocal laser microscopies, accelerating the drug release from the micelles only in the irradiated tissues. This spatiotemporal switch significantly enhanced the in vivo antitumor efficacy of CPT/m without eliciting any toxicity, even at a dose 10-fold higher than the maximum tolerated dose of free CPT. Our results indicate the potential of reduction-sensitive drug-loaded polymeric micelles for developing safe chemotherapies after activation by remote triggers, such as light, which are capable of permeabilizing endosomal compartments.

For systemic delivery of siRNA to solid tumors, a size-regulated and reversibly stabilized nanoarchitecture was constructed by using a 20 kDa siRNA-loaded unimer polyion complex (uPIC) and 20 nm gold nanoparticle (AuNP). The uPIC was selectively prepared by charge-matched polyionic complexation of a poly(ethylene glycol)-b-poly(L-lysine) (PEG-PLL) copolymer bearing ∼40 positive charges (and thiol group at the ω-end) with a single siRNA bearing 40 negative charges. The thiol group at the ω-end of PEG-PLL further enabled successful conjugation of the uPICs onto the single AuNP through coordinate bonding, generating a nanoarchitecture (uPIC-AuNP) with a size of 38 nm and a narrow size distribution. In contrast, mixing thiolated PEG-PLLs and AuNPs produced a large aggregate in the absence of siRNA, suggesting the essential role of the preformed uPIC in the formation of nanoarchitecture. The smart uPIC-AuNPs were stable in serum-containing media and more resistant against heparin-induced counter polyanion exchange, compared to uPICs alone. On the other hand, the treatment of uPIC-AuNPs with an intracellular concentration of glutathione substantially compromised their stability and triggered the release of siRNA, demonstrating the reversible stability of these nanoarchitectures relative to thiol exchange and negatively charged AuNP surface. The uPIC-AuNPs efficiently delivered siRNA into cultured cancer cells, facilitating significant sequence-specific gene silencing without cytotoxicity. Systemically administered uPIC-AuNPs showed appreciably longer blood circulation time compared to controls, i.e., bare AuNPs and uPICs, indicating that the conjugation of uPICs onto AuNP was crucial for enhancing blood circulation time. Finally, the uPIC-AuNPs efficiently accumulated in a subcutaneously inoculated luciferase-expressing cervical cancer (HeLa-Luc) model and achieved significant luciferase gene silencing in the tumor tissue. These results demonstrate the strong potential of uPIC-AuNP nanoarchitectures for systemic siRNA delivery to solid tumors.

For systemic siRNA delivery applications, well-defined drug carriers are required that guarantee stability for both carrier and cargo. Among various concepts progressing in market or final development, cationic nanohydrogel particles may serve as novel transport media especially designed for siRNA-in vivo experiments. In this work, the interaction of nanohydrogel particles with proteins and serum components was studied via dynamic light scattering in human blood serum as novel screening method prior to applications in vivo. The formation of larger aggregates mostly caused by charge interaction with albumin could be suppressed by nanogel loading with siRNA affording a neutral zeta potential for the complex. Preliminary in vivo studies confirmed the results inside the light-scattering cuvette. Although both carrier and cargo may have limited stability on their own under physiological relevant conditions, they can form safe and stable complexes at a charge neutralized ratio and thus making them applicable to systemic siRNA delivery.

We describe the preparation of well-defined multicompartment micelles from polybutadiene-block-poly(1-methyl-2-vinyl pyridinium methyl sulfate)-block-poly(methacrylic acid) (BVqMAA) triblock terpolymers and their use as advanced drug delivery systems for photodynamic therapy (PDT). A porphyrazine derivative was incorporated into the hydrophobic core during self-assembly and served as a model drug and fluorescent probe at the same time. The initial micellar corona is formed by negatively charged PMAA and could be gradually changed to poly(ethylene glycol) (PEG) in a controlled fashion through interpolyelectrolyte complex formation of PMAA with positively charged poly(ethylene glycol)-block-poly(L-lysine) (PLL-b-PEG) diblock copolymers. At high degrees of PEGylation, a compartmentalized micellar corona was observed, with a stable bottlebrush-on-sphere morphology as demonstrated by cryo-TEM measurements. By in vitro cellular experiments, we confirmed that the porphyrazine-loaded micelles were PDT-active against A549 cells. The corona composition strongly influenced their in vitro PDT activity, which decreased with increasing PEGylation, correlating with the cellular uptake of the micelles. Also, a PEGylation-dependent influence on the in vivo blood circulation and tumor accumulation was found. Fully PEGylated micelles were detected for up to 24 h in the bloodstream and accumulated in solid subcutaneous A549 tumors, while non- or only partially PEGylated micelles were rapidly cleared and did not accumulate in tumor tissue. Efficient tumor growth suppression was shown for fully PEGylated micelles up to 20 days, demonstrating PDT efficacy in vivo.

Ligand-mediated drug delivery systems have enormous potential for improving the efficacy of cancer treatment. In particular, Arg-Gly-Asp peptides are promising ligand molecules for targeting αvβ3/αvβ5 integrins, which are overexpressed in angiogenic sites and tumors, such as intractable human glioblastoma (U87MG). We here achieved highly efficient drug delivery to U87MG tumors by using a platinum anticancer drug-incorporating polymeric micelle (PM) with cyclic Arg-Gly-Asp (cRGD) ligand molecules. Intravital confocal laser scanning microscopy revealed that the cRGD-linked polymeric micelles (cRGD/m) accumulated rapidly and had high permeability from vessels into the tumor parenchyma compared with the PM having nontargeted ligand, "cyclic-Arg-Ala-Asp" (cRAD). As both cRGD/m- and cRAD-linked polymeric micelles have similar characteristics, including their size, surface charge, and the amount of incorporated drugs, it is likely that the selective and accelerated accumulation of cRGD/m into tumors occurred via an active internalization pathway, possibly transcytosis, thereby producing significant antitumor effects in an orthotopic mouse model of U87MG human glioblastoma.

There are few reports on the physiological effects of metal nanoparticles (nps), especially with respect to their functions as scavengers for superoxide anion radical (O2(.-)) and hydroxyl radical (.OH). We tried to detect the scavenging activity of Pt nps using a hypoxanthine-xanthine oxidase system for O2(.-) and using a Fenton and a UV/H2O2 system for .OH. Electron spin resonance analysis revealed that 2 nm particle size Pt nps have the ability to scavenge O2(.-) and .OH. The calculated rate constant for the O2(.-)-scavenging reaction was 5.03 +/- 0.03 x 10(7) M (-1) s (-1). However, the analysis of the Fenton and UV/H 2O 2 system in the presence of Pt nps suggested that the .OH-scavenging reaction cannot be determined in both systems. Among particle sizes tested from 1 to 5 nm, 1 nm Pt nps showed the highest O2(.-)-scavenging ability. Almost no cytotoxicity was observed even after adherent cells (TIG-1, HeLa, HepG2, WI-38, and MRC-5) were exposed to Pt nps at concentrations as high as 50 mg/L. Pt nps scavenged intrinsically generated reactive oxygen species (ROS) in HeLa cells. Additionally, Pt nps significantly reduced the levels of intracellular O2(.-) generated by UVA irradiation and subsequently protected HeLa cells from ROS damage-induced cell death. These findings suggest that Pt nps may be a new type of antioxidant capable of circumventing the paradoxical effects of conventional antioxidants.