Modulated Fragmentation of Proapoptotic Peptide Nanoparticles Regulates Cytotoxicity

Fast Release of Carboxylic Acid inside Cells

Delivering carboxylic acid functions into cells is challenging due to their poor permeability across lipophilic membranes at physiological pH, where they are ionized. Masking carboxylic acids as esters improves cell entry, but once inside the cell, its rapid release is essential to maintain spatiotemporal control which can be beneficial for therapeutic and diagnostic applications. This study evaluates the 2-hydroxyethyl-dithio-benzyl ester functional group which undergoes selective and rapid cleavage of the disulfide bond by thioredoxin (Trx), triggering rapid self-immolation of the thio-benzyl ester releasing the carboxylic acid. Fluorescence-based assays using the pro-fluorescent BODIPY structure have demonstrated the rapid intracellular release of carboxylic acids within minutes in both eukaryotic and prokaryotic cells. The approach was tested on antibiotics, and among them, levofloxacin ester prodrug, having the 2-hydroxyethyl-dithio-benzyl ester functional group, showed significantly enhanced antimicrobial activity against resistant and intracellular bacteria compared to its methyl ester analogue.

Rational design of peptides to overcome drug resistance by metabolic regulation

Chemotherapy is widely used clinically, however, its efficacy is often compromised by the development of drug resistance, which arises from prolonged administration of drugs or other stimuli. One of the driven causes of drug resistance in tumors or bacterial infections is metabolic reprogramming, which alters mitochondrial metabolism, disrupts metabolic pathways and causes ion imbalance. Bioactive peptide materials, due to their biocompatibility, diverse bioactivities, customizable sequences, and ease of modification, have shown promise in overcoming drug resistance. This review provides an in-depth analysis of metabolic reprogramming and associated microenvironmental changes that contribute to drug resistance in common tumors and bacterial infections, suggesting potential therapeutic targets. Additionally, we explore peptide-based materials for regulating metabolism and their potential synergic effect with other therapies, highlighting the mechanisms by which these peptides reverse drug resistance. Finally, we discuss future perspectives and the clinical challenges in peptide-based treatments, aiming to offer insights for overcoming drug-resistant diseases.

Advancing Cancer Immunotherapy through Engineering New PD-L1 Degraders: A Comprehensive Study from Small Molecules to PD-L1-Specific Peptide-Drug Conjugates

Despite the considerable achievements of antibodies targeting PD-1/PD-L1 in cancer immunotherapy, limitations in antitumor immune response and pharmacokinetics hinder their clinical adoption. Small molecules toward PD-L1 degradation signifies an innovative avenue to modulate PD-1/PD-L1 axis. Herein, we unveil a comprehensive engineering involving the development of new PD-L1 degraders based on the berberine (BBR) and palmatine (PMT) bioactive frameworks and explore their translational potential for cancer immunotherapy using a peptide-drug conjugate strategy. Chemical modifications at the O-9 position of PMT dramatically enhance the PD-L1 degradation capacity. Further conjugation of PMT degraders with an anti-PD-L1 peptide featuring disulfide linkers enables efficient GSH-specific prodrug activation, yielding synergistic immunotherapeutic benefits through both external PD-L1 blockade and internal PD-L1 degradation mechanisms. This work elucidates the compelling charm of the discovery and application of PD-L1 degraders, offering solutions to the challenges in advancing cancer immunotherapy in widespread clinics.

Polymeric Nanoparticles for Drug Delivery

The recent emergence of nanomedicine has revolutionized the therapeutic landscape and necessitated the creation of more sophisticated drug delivery systems. Polymeric nanoparticles sit at the forefront of numerous promising drug delivery designs, due to their unmatched control over physiochemical properties such as size, shape, architecture, charge, and surface functionality. Furthermore, polymeric nanoparticles have the ability to navigate various biological barriers to precisely target specific sites within the body, encapsulate a diverse range of therapeutic cargo and efficiently release this cargo in response to internal and external stimuli. However, despite these remarkable advantages, the presence of polymeric nanoparticles in wider clinical application is minimal. This review will provide a comprehensive understanding of polymeric nanoparticles as drug delivery vehicles. The biological barriers affecting drug delivery will be outlined first, followed by a comprehensive description of the various nanoparticle designs and preparation methods, beginning with the polymers on which they are based. The review will meticulously explore the current performance of polymeric nanoparticles against a myriad of diseases including cancer, viral and bacterial infections, before finally evaluating the advantages and crucial challenges that will determine their wider clinical potential in the decades to come.

Glutathione-triggered prodrugs: Design strategies, potential applications, and perspectives

The burgeoning prodrug strategy offers a promising avenue toward improving the efficacy and specificity of cytotoxic drugs. Elevated intracellular levels of glutathione (GSH) have been regarded as a hallmark of tumor cells and characteristic feature of the tumor microenvironment. Considering the pivotal involvement of elevated GSH in the tumorigenic process, a diverse repertoire of GSH-triggered prodrugs has been developed for cancer therapy, facilitating the attenuation of deleterious side effects associated with conventional chemotherapeutic agents and/or the attainment of more efficacious therapeutic outcomes. These prodrug formulations encompass a spectrum of architectures, spanning from small molecules to polymer-based and organic-inorganic nanomaterial constructs. Although the GSH-triggered prodrugs have been gaining increasing interests, a comprehensive review of the advancements made in the field is still lacking. To fill the existing lacuna, this review undertakes a retrospective analysis of noteworthy research endeavors, based on a categorization of these molecules by their diverse recognition units (i.e., disulfides, diselenides, Michael acceptors, and sulfonamides/sulfonates). This review also focuses on explaining the distinct benefits of employing various chemical architecture strategies in the design of these prodrug agents. Furthermore, we highlight the potential for synergistic functionality by incorporating multiple-targeting conjugates, theranostic entities, and combinational treatment modalities, all of which rely on the GSH-triggering. Overall, an extensive overview of the emerging field is presented in this review, highlighting the obstacles and opportunities that lie ahead. Our overarching goal is to furnish methodological guidance for the development of more efficacious GSH-triggered prodrugs in the future. By assessing the pros and cons of current GSH-triggered prodrugs, we expect that this review will be a handful reference for prodrug design, and would provide a guidance for improving the properties of prodrugs and discovering novel trigger scaffolds for constructing GSH-triggered prodrugs.

Versatile Click Linker Enabling Native Peptide Release from Nanocarriers upon Redox Trigger

Nanocarriers have shown their ability to extend the circulation time of drugs, enhance tumor uptake, and tune drug release. Therapeutic peptides are a class of drug compounds in which nanocarrier-mediated delivery can potentially improve their therapeutic index. To this end, there is an urgent need for orthogonal covalent linker chemistry facilitating the straightforward on-the-resin peptide generation, nanocarrier conjugation, as well as the triggered release of the peptide in its native state. Here, we present a copper-free clickable ring-strained alkyne linker conjugated to the N-terminus of oncolytic peptide LTX-315 via standard solid-phase peptide synthesis (SPPS). The linker contains (1) a recently developed seven-membered ring-strained alkyne, 3,3,6,6-tetramethylthiacycloheptyne sulfoximine (TMTHSI), (2) a disulfide bond, which is sensitive to the reducing cytosolic and tumor environment, and (3) a thiobenzyl carbamate spacer enabling release of the native peptide upon cleavage of the disulfide via 1,6-elimination. We demonstrate convenient "clicking" of the hydrophilic linker-peptide conjugate to preformed pegylated core-cross-linked polymeric micelles (CCPMs) of 50 nm containing azides in the hydrophobic core under aqueous conditions at room temperature resulting in a loading capacity of 8 mass % of peptide to polymer (56% loading efficiency). This entrapment of hydrophilic cargo into/to a cross-linked hydrophobic core is a new and counterintuitive approach for this class of nanocarriers. The release of LTX-315 from the CCPMs was investigated in vitro and rapid release upon exposure to glutathione (within minutes) followed by slower 1,6-elimination (within an hour) resulted in the formation of the native peptide. Finally, cytotoxicity of LTX CCPMs as well as uptake of sulfocyanine 5-loaded CCPMs was investigated by cell culture, demonstrating successful tumor cell killing at concentrations similar to that of the free peptide treatment.

OpiCa1-PEG-PLGA nanomicelles antagonize acute heart failure induced by the cocktail of epinephrine and caffeine

Background

Reducing Ca2+ content in the sarcoplasmic reticulum (SR) through ryanodine receptors (RyRs) by calcin is a potential intervention strategy for the SR Ca2+ overload triggered by β-adrenergic stress in acute heart diseases.

Methods

OpiCal-PEG-PLGA nanomicelles were prepared by thin film dispersion, of which the antagonistic effects were observed using an acute heart failure model induced by epinephrine and caffeine in mice. In addition, cardiac targeting, self-stability as well as biotoxicity were determined.

Results

The synthesized OpiCa1-PEG-PLGA nanomicelles were elliptical with a particle size of 72.26 nm, a PDI value of 0.3, and a molecular weight of 10.39 kDa. The nanomicelles showed a significant antagonistic effect with 100 % survival rate to the death induced by epinephrine and caffeine, which was supported by echocardiography with significantly recovered heart rate, ejection fraction and left ventricular fractional shortening rate. The FITC labeled nanomicelles had a strong membrance penetrating capacity within 2 h and cardiac targeting within 12 h that was further confirmed by immunohistochemistry with a self-prepared OpiCa1 polyclonal antibody. Meanwhile, the nanomicelles can keep better stability and dispersibility in vitro at 4 °C rather than 20 °C or 37 °C, while maintain a low but stable plasma OpiCa1 concentration in vivo within 72 h. Finally, no obvious biotoxicities were observed by CCK-8, flow cytometry, H&E staining and blood biochemical examinations.

Conclusion

Our study also provide a novel nanodelivery pathway for targeting RyRs and antagonizing the SR Ca2+ disordered heart diseases by actively releasing SR Ca2+ through RyRs with calcin.

Integrin-targeting disulfide-crosslinked micellar docetaxel eradicates lung and prostate cancer patient-derived xenografts

Actively targeted nanomedicines though conceptually attractive for tumor therapy are extremely hard to realize due to problems of premature drug leakage, excessive liver accretion, inadequate tumor uptake, and/or retarded drug release inside tumor cells. Here, we systemically studied the influence of disulfide crosslinking on the in vitro and in vivo performance of integrin-targeting micellar docetaxel (t-MDTX). Of note, t-M5DTX with a high disulfide content was clearly advantageous in terms of stability, intracellular drug release, anti-tumor activity toward αVβ3-overexpressing A549 cells, blood circulation and therapeutic efficacy in orthotopic A549-luc lung tumor-bearing mice. t-MDTX induced extraordinary tumor targetability with tumor-to-normal tissue ratios of 1.7-8.3. Further studies indicated that t-M5DTX could effectively eradicate αVβ3-overexpressing lung and prostate cancer patient-derived xenografts (PDX), in which ca. 80% mice became tumor-free. This integrin-targeting disulfide-crosslinked micellar docetaxel emerges as a promising actively targeted nanoformulation for tumor therapy. STATEMENT OF SIGNIFICANCE: Nanomedicines have a great potential in treating advanced tumor patients; however, their tumor-targeting ability and therapeutic efficacy remain unsatisfactory. In addition to PEGylation and ligand selection, particle size, stability and drug release behavior are also critical to their performance in vivo. In this paper, we find that small and cRGD-guided disulfide-crosslinked micellar docetaxel (t-MDTX) induces superior tumor uptake and retention but without increasing liver burden, leading to extraordinary selectivity and inhibition of αvβ3 overexpressing lung tumors. t-MDTX is further shown to effectively treat αvβ3-positive patient-derived tumor models, lending it a high potential for clinical translation.

Engineering nanoparticle toolkits for mRNA delivery

The concept of using mRNA to produce its own medicine in situ in the body makes it an ideal drug candidate, holding great potential to revolutionize the way we approach medicine. The unique characteristics of mRNA, as well as its customizable biomedical functions, call for the rational design of delivery systems to protect and transport mRNA molecules. In this review, a nanoparticle toolkit is presented for the development of mRNA-based therapeutics from a drug delivery perspective. Nano-delivery systems derived from either natural systems or chemical synthesis, in the nature of organic or inorganic materials, are summarised. Delivery strategies in controlling the tissue targeting and mRNA release, as well as the role of nanoparticles in building and boosting the activity of mRNA drugs, have also been introduced. In the end, our insights into the clinical and translational development of mRNA nano-drugs are presented.

Iron-Gallic Acid Peptide Nanoparticles as a Versatile Platform for Cellular Delivery with Synergistic ROS Enhancement Effect

Cytosolic delivery of peptides is of great interest owing to their biological functions, which could be utilized for therapeutic applications. However, their susceptibility to enzymatic degradation and multiple cellular barriers generally hinders their clinical application. Integration into nanoparticles, which can enhance the stability and membrane permeability of bioactive peptides, is a promising strategy to overcome extracellular and intracellular obstacles. Herein, we present a versatile platform for the cellular delivery of various cargo peptides by integration into metallo-peptidic coordination nanoparticles. Both termini of cargo peptides were conjugated with gallic acid (GA) to assemble GA-modified peptides into nanostructures upon coordination of Fe(III). Initial pre-complexation of Fe(III) by poly-(vinylpolypyrrolidon) (PVP) as a template favored the formation of nanoparticles, which are able to deliver the peptides into cells efficiently. Iron-gallic acid peptide nanoparticles (IGPNs) are stable in water and are supposed to generate reactive oxygen species (ROS) from endogenous H₂O₂ in cells via the Fenton reaction. The strategy was successfully applied to an exemplary set of peptide sequences varying in length (1-7 amino acids) and charge (negative, neutral, positive). To confirm the capability of transporting bioactive cargos into cells, pro-apoptotic peptides were integrated into IGPNs, which demonstrated potent killing of human cervix carcinoma HeLa and murine neuroblastoma N2a cells at a 10 µM peptide concentration via the complementary mechanisms of peptide-triggered apoptosis and Fe(III)-mediated ROS generation. This study demonstrates the establishment of IGPNs as a novel and versatile platform for the assembly of peptides into nanoparticles, which can be used for cellular delivery of bioactive peptides combined with intrinsic ROS generation.

Molecular polymer bottlebrushes in nanomedicine: therapeutic and diagnostic applications

Molecular polymer bottlebrushes are densely grafted, individual macromolecules with nanoscale proportions. The last decade has seen an increased focus on this material class, especially in nanomedicine and for biomedical applications. This Feature Article provides an overview of major developments in this area to highlight the many opportunities that these polymer architectures bring to nano-bio research. The article covers aspects of bottlebrush synthesis and summarises their use in drug and gene delivery, imaging, as theranostics and as prototype materials to correlate nanoparticle structure and composition to biological function and behaviour. Areas for future research in this area are discussed.

Fabrication of self-assembled peptide nanoparticles for in vitro assessment of cell apoptosis pathway and in vivo therapeutic efficacy

Near-infrared fluorescent (NIRF) dye-coupled self-assembled RGD-linked proapoptotic peptide nanoparticles have been synthesized with spherical shape and size ~ 30-40 nm diameters. The peptide sequence was coupled with cyanine 5.5 probe as NIRF-dye to introduce optical imaging properties and pH-dependent method was used to design Cy5.5 coupled self-assembled peptide nanoparticles (f-SAPNs). This nanoprobe has the ability to target α_vβ₃-integrin receptor overexpressed on cancer cell's surface with improved internalization capabilities into the mitochondria. The in situ study showed that this peptide sequence has potential to disrupt the mitochondrial membrane efficiently, activating the Caspase-3 enzyme, and ultimately induces cell apoptosis. It has been observed from in vitro study that the degree of apoptosis for f-SAPNs was increased from 25.6% to 96.3%, while decreased degree of necrosis from 51.7% to 0.2% compared with its parent peptide analog (Cy5.5-c[RGDKLAK]; f-CP) occurs. Further investigations revealed that these f-SAPNs showed high uptake in U87MG glioblastoma cells in comparison with PC-3 prostate cancer cells. Moreover, in vivo therapeutic studies represented the prominent decrease in the size of tumor tissue treated with f-CP and f-SAPNs (201 ± 13 mm³ and 104 ± 6 mm³, respectively) compared with untreated tumor tissues (366 ± 18 mm³). These outcomes highlighted the specificity, and efficacy of f-SAPNs toward α_vβ₃-integrin expressing tumor tissue in vivo and suggested that these novel designed f-SAPNs may serve as a potential theranostic drug for brain tumor glioblastoma multiforme. The pH-sensitive method gives NIRF dye-coupled self-assembled peptide nanoparticle (f-SAPNs), enables the tunable synthesis of spherical nanoparticles with high stability towards proteolysis, improved biocompatibility, and promising therapeutic efficacy.

Conformational Transition-Triggered Disassembly of Therapeutic Peptide Nanomedicine for Tumor Therapy

Cationic therapeutic peptides have received widespread attention due to their excellent antibacterial and antitumor properties. However, most of these peptides have undesirable delivery efficiency and high hemolytic toxicity due to the positively charged α-helix structure containing many lysine and arginine, which may restrict its in vivo applications. Herein, a conformationally transformed therapeutic peptide Pep-HCO₃ modified with bicarbonates on guanidine groups is designed. Such a design allows Pep-HCO₃ ((nap-RAGLQFPVGRLLRRLLRRLLR) nHCO₃ ) to self-assemble into nanoparticles (NP-Pep) due to disrupting helix folding and the formation of intermolecular hydrogen bonding between bicarbonates and guanidine groups. When pH is from 7.4 to 6.5 at the tumor sites, guanidine bicarbonate can be hydrolyzed to form CO₂ and guanidine groups, resulting in the disassembling of the NP-Pep into monomers α-Pep with a positively charged α-helix structure. In vivo, NP-Pep not only inhibits the tumor growth of xenografted mice with a twofold enhanced inhibition rate compared with α-Pep treatment group, but also significantly reduces the hemolytic toxicity by responding to the pH of tumor microenvironment. Therefore, the strategy of conformational transition-triggered disassembly of nanoparticles allows efficient delivery of cationic therapeutic peptides and lowering the hemolytic toxicity, which may provide an avenue for developing high-performance cationic peptide in vivo applications.

A manganese (II)-based coordinative dendrimer with robust efficiency in intracellular peptide delivery

Peptides have gained increasing interests as drug candidates in modern pharmaceutical industry, however, the development of peptide drugs acting on intracellular targets is limited due to their membrane impermeability. Here, we reported the use of metal-terpyridine based coordinative dendrimer for cytosolic peptide delivery. Among the investigated transition metal ions, Mn²⁺-coordinated polymer showed the highest delivery efficiency due to balanced peptide binding and release. It showed robust efficiency in the delivery of peptides with different charge property and hydrophobicity into various primary cells. The efficiency of Mn²⁺-terpyridine based polymer is superior to cell penetrating peptides such as oligoarginines. The material also delivered an autophagy-inducing peptide derived from Beclin-1 into cells and efficiently induced autophagy in the cells. This study provides a promising alternative to cell penetrating peptides for cytosolic peptide delivery.

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A Mn²⁺/terpyridine based polymer is rationally designed for cytosolic peptide delivery.

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The polymer shows robust efficiency in the delivery of 22 peptides with different properties into various primary cells.

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The polymer delivers an autophagy-inducing peptide derived from Beclin-1 into cells and efficiently induces autophagy.

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This study provides a promising alternative to cell penetrating peptides for cytosolic peptide delivery.

RETRACTED: Liposomal valinomycin mediated cellular K+ leak promoting apoptosis of liver cancer cells

This article has been retracted: please see Elsevier Policy on Article Withdrawal (https://www.elsevier.com/about/our-business/policies/article-withdrawal). This article has been retracted at the request of the corresponding author. It has been found that Fig 2B contains manipulated components, and Fig 5A partially overlaps with Fig 6 of a published paper authored by Mirza Muhammad Faran Ashraf Baig, et, al., The effective transfection of a low dose of negatively charged drug-loaded DNA-nanocarriers into cancer cells via scavenger receptors, J. Pharm. Anal. 11 (2021) 174-182, https://doi.org/10.1016/j.jpha.2020.10.003. The corresponding author indicated that they cannot guarantee the integrity of the images in the manuscript, as well as the conclusions of the paper. As a result, the Editor-in-Chief has decided to retract the paper. The corresponding author deeply regrets the circumstances and apologizes to the scientific community for not having detected this prior to publication.

Effective Antitumor of Orally Intestinal Targeting Penetrating Peptide-Loaded Tyroserleutide/PLGA Nanoparticles in Hepatocellular Carcinoma

Purpose

Hepatocellular carcinoma (HCC) is a common malignant tumor that seriously threatens human life and health. Currently, the majority of antitumor drugs are administered in an injectable manner, which can cause pain and side effects to patients. Objective of this study is to establish an effective oral drug delivery system for anti hepatoma drugs.

Methods

In this study, intestinal targeting cell penetrating peptide (R6LRVG) was obtained by binding cell penetrating peptide (R6) with the polypeptide of LRVG (targeting intestinal epithelial cells). Next, R6LRVG-modified tyroserleutide-poly(lactic-co-glycolic acid) (PLGA) nanoparticles (YSL-PLGA/R6LRVG NPs) were prepared. After that, the nanoparticles were characterized and their stability was evaluated. The cellular uptake, in vitro bioactivity and in vivo antitumor activity of the nanoparticles were investigated. In addition, the mechanism, including the endocytic pathway and respiratory rate detection of mitochondria, was further investigated.

Results

YSL-PLGA/R6LRVG NPs were successfully prepared. Characterization revealed YSL-PLGA/R6LRVG NPs to be globular particles with smooth surfaces and an average diameter of 222.6 nm. The entrapment efficiency and drug loading of tyroserleutide were 70.27% and 19.69%, respectively. Furthermore, the YSL-PLGA/R6LRVG NPs group exhibited the largest amount of YSL uptake. We also found that cell uptake of YSL-PLGA/R6LRVG NPs could be related to the endocytosis pathways mediated by reticulin and caveolae/lipid rafts. Additionally, the YSL-PLGA/R6LRVG NPs could interfere with mitochondrial function. In vivo experiments revealed that orally administered YSL-PLGA/R6LRVG NPs exerted excellent anticancer effects in tumor-bearing mice. Hematoxylin-eosin staining did not show any histological changes in the major organs.

Conclusion

To summarize, YSL-PLGA/R6LRVG NPs could be a useful oral delivery system of YSL and may provide a new platform for the oral delivery of anticancer drugs.

Tandem molecular self-assembly for selective lung cancer therapy with an increase in efficiency by two orders of magnitude

In situ self-assembly of prodrug molecules into nanomedicine can elevate the therapeutic efficacy of anticancer medications by enhancing the targeting and enrichment of anticancer drugs at tumor sites. However, the disassembly and biodegradation of nanomedicine after enrichment prevents the further improvement of the efficiency, and avoiding such disassembly and biodegradation remains a challenge. Herein, we rationally designed a tandem molecular self-assembling prodrug that could selectively improve the therapeutic efficacy of HCPT against lung cancer by two orders of magnitude. The tandem molecular self-assembly utilized an elevated level of alkaline phosphatase and reductase in lung cancer cells. The prodrug first self-assembled into nanofibers by alkaline phosphatase catalysis and was internalized more efficiently by lung cancer cells than free HCPT. The resulting nanofiber was next catalyzed by intracellular reductase to form a more hydrophobic nanofiber that prevented the disassembly and biodegradation, which further significantly improved the efficacy of HCPT against lung cancer both in vitro and in vivo.

Polyphenol-Containing Nanoparticles: Synthesis, Properties, and Therapeutic Delivery

Polyphenols, the phenolic hydroxyl group-containing organic molecules, are widely found in natural plants and have shown beneficial effects on human health. Recently, polyphenol-containing nanoparticles have attracted extensive research attention due to their antioxidation property, anticancer activity, and universal adherent affinity, and thus have shown great promise in the preparation, stabilization, and modification of multifunctional nanoassemblies for bioimaging, therapeutic delivery, and other biomedical applications. Additionally, the metal-polyphenol networks, formed by the coordination interactions between polyphenols and metal ions, have been used to prepare an important class of polyphenol-containing nanoparticles for surface modification, bioimaging, drug delivery, and disease treatments. By focusing on the interactions between polyphenols and different materials (e.g., metal ions, inorganic materials, polymers, proteins, and nucleic acids), a comprehensive review on the synthesis and properties of the polyphenol-containing nanoparticles is provided. Moreover, the remarkable versatility of polyphenol-containing nanoparticles in different biomedical applications, including biodetection, multimodal bioimaging, protein and gene delivery, bone repair, antibiosis, and cancer theranostics is also demonstrated. Finally, the challenges faced by future research regarding the polyphenol-containing nanoparticles are discussed.

Using Fluorescence On/Off to Trace Tandem Nanofiber Assembly/Disassembly in Living Cells

To track an intact biological process inside cells, continuous showing of the assembly/disassembly process is needed and fluorescence is advantageous in characterizing these processes. However, using fluorescence "on/off" to observe a sequential assembly/disassembly process in living cells has not been reported. Herein, we rationally designed a probe PEA-NBD-Yp and employed its fluorescence "on/off" to trace tandem assembly/disassembly of nanofibers in living HeLa cells. In vitro experiments validated that PEA-NBD-Yp could be efficiently dephosphorylated by ALP to yield PEA-NBD-Y, which self-assembled into nanofibers with the NBD fluorescence "on". Also, the PEA-NBD-Y nanofiber was disassembled by GSH, accompanied by fluorescence "off". Living cell imaging (together with ALP-inhibition or GSH-blocking) experiments sequentially showed the self-assembling nanofibers on the cell outer membrane with fluorescence "on" (On₁), translocated inside cells (On₂), and disassembled by GSH with fluorescence "off" (Off₂). We anticipate that our strategy of one probe conferring temporal "on/off" fluorescence signals might provide people with a new tool to deeply understand a biological event in living cells in the near future.

Kinetically-stable small-molecule prodrug nanoassemblies for cancer chemotherapy

Self-delivering nanocarrier based on the small-molecule prodrug nanoassemblies (NAs) have been widely used for the efficient delivery of chemotherapeutics, but the effect of kinetic stability of NAs on their delivery performance has not been illuminated. In this study, two camptothecin (CPT)-oleic acid (OA) prodrugs were used to fabricate self-assembling nanorods with similar size distribution, zeta potential and morphology but having sharply different kinetic stability, which provided an ideal platform to investigate the effects of kinetic stability. It is found that the nanorods with high kinetic stability showed a lower in vitro cytotoxicity, but were more effective to inhibit the tumor growth probably by decreasing the premature CPT release and subsequent generation of the inactive carboxylate CPT. However, such kinetically stable nanorods also resulted in the increased toxicity, probably due to the high prodrug accumulation in tissues after multiple injections. These results outlined the pivotal role of kinetic stability in determining antitumor efficacy of prodrug NAs, which provided a new insight into the delivery mechanism for the small-molecule prodrug self-delivering nanosystems.

Fabrication of stimuli-responsive nanogels for protein encapsulation and traceless release without introducing organic solvents, surfactants, or small-molecule cross-linkers

Stimuli-responsive nanogels were fabricated by reaction of proteins and polymers without using small-organic-molecules. Once the nanogels dissociated, the proteins were released with functional groups, secondary structures, and activities maintained.

Polypeptide Nanoparticles with pH-Sheddable PEGylation for Improved Drug Delivery

The variation of tumor microenvironments provides a tool for the construction of stimulus-responsive nanomedicines to enhance drug delivery efficacy. Herein, the assembly of drug-loaded polypeptide nanoparticles (NPs) with pH-sheddable modification of poly(ethylene glycol) (PEG) is prepared to enhance therapeutic efficiency. Poly(l-lysine) and poly(l-glutamic acid) were self-assembled to fabricate polypeptide NPs by electrostatic interactions, followed by PEGylation based on amidation reaction. The NP sizes can be controlled by tuning the molecular weight or the ratio of polypeptides. The PEG coating is cleavable at the tumor acid microenvironment to reverse the surface charge and reduce the NP size, which effectively enhances cell uptake. In addition, the presence of reducing reagent (e.g., glutathione) in cancer cells induces the drug (i.e., cisplatin) release from the polypeptide NPs and subsequently results in the cell toxicity. This reported method highlights the engineering of transformable polypeptide drug carriers, which provides a promising way for enhanced drug delivery efficacy.

Proapoptotic Peptide Brush Polymer Nanoparticles via Photoinitiated Polymerization-Induced Self-Assembly

Herein, we report the photoinitiated polymerization-induced self-assembly (photo-PISA) of spherical micelles consisting of proapoptotic peptide-polymer amphiphiles. The one-pot synthetic approach yielded micellar nanoparticles at high concentrations and at scale (150 mg mL-1 ) with tunable peptide loadings up to 48 wt. %. The size of the micellar nanoparticles was tuned by varying the lengths of hydrophobic and hydrophilic building blocks. Critically, the peptide-functionalized nanoparticles imbued the proapoptotic "KLA" peptides (amino acid sequence: KLAKLAKKLAKLAK) with two key properties otherwise not inherent to the sequence: 1) proteolytic resistance compared to the oligopeptide alone; 2) significantly enhanced cell uptake by multivalent display of KLA peptide brushes. The result was demonstrated improved apoptosis efficiency in HeLa cells. These results highlight the potential of photo-PISA in the large-scale synthesis of functional, proteolytically resistant peptide-polymer conjugates for intracellular delivery.

Self-assembly of mitochondria-specific peptide amphiphiles amplifying lung cancer cell death through targeting the VDAC1-hexokinase-II complex

Mitochondria-targeting peptides represent an emergent tool for cancer inhibition. Here supramolecular assemblies of novel amphiphilic cell-penetrating peptides for targeting cancer cell mitochondria are reported. The employed strategy aims at amplifying the apoptotic stimuli by weakening the mitochondrial VDAC1 (voltage-dependent anion channel-1)-hexokinase-II (HK-II) interaction. Peptide engineering is performed with the N-terminus of the HK-II protein, which binds to VDAC1. First, a designed positively charged segment (pKV) is anchored to the specific 15 amino acid sequence (MIASHLLAYFFTELN) to yield a cell-penetrating peptide (pHK-pKV). Second, a lipid chain (Pal) is conjugated to the N-terminus of pHK-pKV in order to enhance the intracellular delivery of the HK-II scaffold. The self-assembly properties of these two synthetic peptides are investigated by synchrotron small-angle X-ray scattering (BioSAXS) and cryogenic transmission electron (cryo-TEM) imaging, which evidence the formation of nanoassemblies of ellipsoid-like shapes. Circular dichroism (CD) spectroscopy demonstrates the induction of partial α-helical structures in the amphiphilic peptides. Confocal microscopy reveals the specific mitochondrial location of Pal-pHK-pKV assemblies in human non-small cell lung cancer (NSCLC) A549 cells. The cytotoxicity and apoptotic studies indicate the enhanced bioactivity of Pal-pHK-pKV self-assembled reservoirs, which cause massive A549 cell death with regard to pHK-pKV. Of significance, Pal-pHK-pKV treatment of non-cancerous NCM460 cells resulted in substantially lower cytotoxicity. The results demonstrate the potential of self-assembled lipo-peptide (HK-II-derived) conjugates as a promising strategy in cancer therapy.

Fluoroalkylation promotes cytosolic peptide delivery

Cytosolic delivery of peptides remains a challenging task owing to their susceptibility to enzymatic degradation and the existence of multiple intracellular barriers. Here, we report a new strategy to address these issues by decoration of a fluorous tag on the terminal of cargo peptides. The fluorous-tagged peptides were assembled into nanostructures, efficiently internalized by cells via several endocytic pathways and released into the cytosol after endosomal escape. They were relatively stable against enzymatic degradation and showed much higher efficiency than nonfluorinated analogs and cell penetrant peptide-conjugated ones. The proposed strategy also efficiently delivered a proapoptotic peptide into specific sites in the cells and restored the function of cargo peptide after cytosolic delivery. The fluorous-tagged proapoptotic peptide efficiently inhibited tumor growth in vivo. This study provides an efficient fluorination strategy to promote the cytosolic delivery of peptides.

Polypeptide-Based Theranostics with Tumor-Microenvironment-Activatable Cascade Reaction for Chemo-ferroptosis Combination Therapy

Nanoengineering of polymer-based therapeutic carriers is promising for precise cancer treatment. Herein, we report the fabrication of polypeptide vehicles encapsulated with anticancer drug of cisplatin (Pt drug) and Fe₃O₄ nanoparticles (denoted as Pt&Fe₃O₄@PP) as theranostics for T₂-weighted magnetic resonance imaging (MRI)-guided chemo-ferroptosis combination therapy. The number of Fe₃O₄ nanoparticles per polypeptide vehicle is well controlled by adjusting the added amount of Fe₃O₄ nanoparticles. The tumor microenvironment can trigger the release of Pt drug and Fe^2/3+, which could induce the intracellular cascade reaction to generate sufficient ^•OH for ferroptosis therapy. Moreover, the released Pt drug can cause the apoptosis of tumor cells. Meanwhile, the encapsulated Fe₃O₄ nanoparticles can also be used for T₂-weighted MRI of tumor. Both in vitro and in vivo results indicate that the reported Pt&Fe₃O₄@PP can efficiently inhibit cancer cell growth without causing significant systemic toxicity. Importantly, polypeptide vehicles could significantly reduce the side effect of free Pt drug in vivo and therefore improve the drug delivery efficacy. Our findings suggest that polypeptide-based theranostics with tumor-microenvironment-activatable cascade reaction have great potential in biomedical applications.

Thiol-responsive pro-fluorophore labeling: Synthesis of a pro-fluorescent labeled oligonucleotide for monitoring cellular uptake

Pro-fluorescent labeled oligonucleotides are potential alternative tools to classical fluorescently labeled oligonucleotides for monitoring cellular uptake. Here, we report the design and synthesis of a thiol-responsive pro-fluorophore labeled oligonucleotide, and its fluorescence responsivity to glutathione in the test tube and live cells.

Regulating vesicle bilayer permeability and selectivity via stimuli-triggered polymersome-to-PICsome transition

Compared to liposomes, polymersomes of block copolymers (BCPs) possess enhanced stability, along with compromised bilayer permeability. Though polyion complex vesicles (PICsomes) from oppositely charged block polyelectrolytes possess semipermeable bilayers, they are unstable towards physiologically relevant ionic strength and temperature; moreover, permselectivity tuning of PICsomes has remained a challenge. Starting from a single component diblock or triblock precursor, we solve this dilemma by stimuli-triggered chemical reactions within pre-organized BCP vesicles, actuating in situ polymersome-to-PICsome transition and achieving molecular size-selective cargo release at tunable rates. UV light and reductive milieu were utilized to trigger carboxyl decaging and generate ion pairs within hydrophobic polymersome bilayers containing tertiary amines. Contrary to conventional PICsomes, in situ generated ones are highly stable towards extreme pH range (pH 2-12), ionic strength (~3 M NaCl), and elevated temperature (70 °C) due to multivalent ion-pair interactions at high local concentration and cooperative hydrogen bonding interactions of pre-organized carbamate linkages.

A bi-adjuvant nanovaccine that potentiates immunogenicity of neoantigen for combination immunotherapy of colorectal cancer

Neoantigen vaccines have been enthusiastically pursued for personalized cancer immunotherapy while vast majority of neoantigens have no or low immunogenicity. Here, a bi-adjuvant neoantigen nanovaccine (banNV) that codelivered a peptide neoantigen (Adpgk) with two adjuvants [Toll-like receptor (TLR) 7/8 agonist R848 and TLR9 agonist CpG] was developed for potent cancer immunotherapy. Specifically, banNVs were prepared by a nanotemplated synthesis of concatemer CpG, nanocondensation with cationic polypeptides, and then physical loading with hydrophobic R848 and Adpgk. The immunogenicity of the neoantigen was profoundly potentiated by efficient codelivery of neoantigen and dual synergistic adjuvants, which is accompanied by reduced acute systemic toxicity. BanNVs sensitized immune checkpoint programmed death receptor 1 (PD-1) on T cells, therefore, a combination of banNVs with aPD-1 conspicuously induced the therapy response and led to complete regression of 70% neoantigen-specific tumors without recurrence. We conclude that banNVs are promising to optimize personalized therapeutic neoantigen vaccines for cancer immunotherapy.

Conjugating Aptamer and Mitomycin C with Reductant-Responsive Linker Leading to Synergistically Enhanced Anticancer Effect

Mitomycin C (MMC) has been using for the treatment of a variety of digestive tract cancers. However, its nonspecific DNA-alkylating ability usually causes severe side effects, thus largely limiting its clinical applications. The utilization of an efficient active targeted drug delivery technique would address this issue. Accordingly, we report the design and development of aptamer-mitomycin C conjugates that use different cross-linking chemistry. The targeted delivery ability and cytotoxicity of these conjugates were carefully studied. It is worth noting that a linker-dependent cytotoxicity effect was observed for these conjugates. The use of a reductant-sensitive disulfide bond cross-linking strategy resulted in significantly enhanced cytotoxicity of MMC against the target cancer cell lines. Importantly, this cytotoxicity enhancement was suited to different types of aptamers, demonstrating the success of our design. Mechanistic studies of the enhanced cytotoxicity effect indicated that the target recognition, specific binding, and receptor-mediated internalization of aptamer were also critical for the observed effect.

Disulfide-Based Self-Immolative Linkers and Functional Bioconjugates for Biological Applications

It is of vital importance to reversibly mask and selectively activate bioactive agents for advanced therapeutic and diagnostic purposes, aiming to efficiently suppress background interferences and attenuate systemic toxicity. This strategy has been involved in diverse applications spanning from chemical/biological sensors and diagnostics to drug delivery nanocarriers. Among these, redox-responsive disulfide linkages have been extensively utilized by taking advantage of extracellular and intracellular glutathione (GSH) gradients. However, direct conjugation of cleavable triggers to bioactive agents through disulfide bonds suffers from bulky steric hindrance and limited choice of trigger-drug combinations. Fortunately, the emergence of disulfide self-immolative linkers (DSILs) provides a general and robust strategy to not only mask various bioactive agents through the formation of dynamic disulfide linkages but also make it possible to be selectively activated upon disulfide cleavage in the reductive cytoplasmic milieu. In this review, recent developments in DSILs are focused with special attention on emerging chemical design strategies and functional applications in the biomedical field.

Responsive peptide-based supramolecular hydrogels constructed by self-immolative chemistry

Peptide-based supramolecular hydrogels that are stimuli-responsive under aqueous conditions have many potential biological applications, including drug delivery and sensing. Herein, we reported a series of responsive peptide-based supramolecular hydrogels that respond to glutathione (GSH), nitric oxide (NO) and hydrogen sulfide (H₂S), which are biologically important signaling molecules. The responsive hydrogelators were designed by "self-immolative" chemistry and constructed by using self-immolative groups to modify short peptides. The self-immolative capping group could be removed in the presence of a corresponding trigger, thus causing gel-sol phase transitions. The potential of our responsive hydrogels for drug release was also demonstrated in this study. Our study offered several candidates of responsive hydrogels for sensing and drug delivery.

Dual responsive micelles capable of modulating miRNA-34a to combat taxane resistance in prostate cancer

There is a direct correlation between increase in the number of cancer stem cells CSCs and chemoresistance that impedes successful chemotherapy. Synergistic therapy by targeting both bulk tumor cells and CSCs has shown promise in reversing chemoresistance and treating resistant prostate cancer. Herein, we demonstrated the fabrication of a pH and glutathione (GSH) sensitive nanocarrier for co-delivery of docetaxel (DTX) and rubone (RUB), a miR-34 activator for targeting CSCs, for the treatment of taxane resistant (TXR) prostate cancer. DTX loaded P-RUB (DTX/P-RUB) micelles were prepared by encapsulating DTX into pH responsive diisopropylaminoethanol (DIPAE) and GSH responsive RUB prodrug conjugated polycarbonate based micelles. The self-assembled DTX/P-RUB micelles displayed good stability in vitro and could efficiently target to tumors by enhanced permeability and retention (EPR) effect. After endocytosis by tumor cells, the micelles underwent expansion and disassembly due to the protonation of DIPAE and GSH induced cleavage of disulfide bond in acidic endocytic vesicles, resulting in fast release of DTX and RUB. The released RUB then upregulated the intracellular miR-34a, which then affected the expression of proteins involved in chemoresistance, thus sensitizing the tumor cells towards DTX and further leading to significant inhibition of TXR tumor progression. Thus, DTX/P-RUB micelles have the potential to treat TXR prostate cancer. By taking advantage of this dual responsive strategy, the successful delivery of many other hydrophobic drugs can be achieved for cancer treatment.

Self-Assembled Metal-Phenolic Networks on Emulsions as Low-Fouling and pH-Responsive Particles

Interfacial self-assembly is a powerful organizational force for fabricating functional nanomaterials, including nanocarriers, for imaging and drug delivery. Herein, the interfacial self-assembly of pH-responsive metal-phenolic networks (MPNs) on the liquid-liquid interface of oil-in-water emulsions is reported. Oleic acid emulsions of 100-250 nm in diameter are generated by ultrasonication, to which poly(ethylene glycol) (PEG)-based polyphenolic ligands are assembled with simultaneous crosslinking by metal ions, thus forming an interfacial MPN. PEG provides a protective barrier on the emulsion phase and renders the emulsion low fouling. The MPN-coated emulsions have a similar size and dispersity, but an enhanced stability when compared with the uncoated emulsions, and exhibit a low cell association in vitro, a blood circulation half-life of ≈50 min in vivo, and are nontoxic to healthy mice. Furthermore, a model anticancer drug, doxorubicin, can be encapsulated within the emulsion phase at a high loading capacity (≈5 fg of doxorubicin per emulsion particle). The MPN coating imparts pH-responsiveness to the drug-loaded emulsions, leading to drug release at cell internalization pH and a potent cell cytotoxicity. The results highlight a straightforward strategy for the interfacial nanofabrication of pH-responsive emulsion-MPN systems with potential use in biomedical applications.

Pre-drug Self-assembled Nanoparticles: Recovering activity and overcoming glutathione-associated cell antioxidant resistance against photodynamic therapy

In photodynamic therapy (PDT), the elevated glutathione (GSH) of cancer cells have two sides for treatment efficacy, activation pre-drug by removing activity suppressor part (advantages) and consumption reactive oxygen species (ROS) to confer PDT resistance (disadvantages). Preparation all-in-one system by simple method to make best use of the advantages and bypass the disadvantages still were remains a technical challenge. Herein, we report a robust PDT nanoparticle with above function based on a self-assembled pyridine modified Zinc phthalocyanine (ZnPc-DTP). The activity suppressor and active part of ZnPc-DTP were linked by disulfide bond. After targeting cancer cells, GSH can react with ZnPc-DTP nanoparticles by cutting disulfide bond to release its active part (ZnPc-SH) and oxidize GSH. In vitro and in vivo results indicated that ZnPc-SH can effective suppress tumor growth under the low antioxidant tumor microenvironment (TME).

Emerging Applications of Fluorogenic and Non-fluorogenic Bifunctional Linkers

Homo- and hetero-bifunctional linkers play vital roles in constructing a variety of functional systems, ranging from protein bioconjugates with drugs and functional agents, to surface modification of nanoparticles and living cells, and to the cyclization/dimerization of synthetic polymers and biomolecules. Conventional approaches for assaying conjugation extents typically rely on ex situ techniques, such as mass spectrometry, gel electrophoresis, and size-exclusion chromatography. If the conjugation process involving bifunctional linkers was rendered fluorogenic, then in situ monitoring, quantification, and optical tracking/visualization of relevant processes would be achieved. In this review, conventional non-fluorogenic linkers are first discussed. Then the focus is on the evolution and emerging applications of fluorogenic bifunctional linkers, which are categorized into hetero-bifunctional single-caging fluorogenic linkers, homo-bifunctional double-caging fluorogenic linkers, and hetero-bifunctional double-caging fluorogenic linkers. In addition, stimuli-cleavable bifunctional linkers designed for both conjugation and subsequent site-specific triggered release are also summarized.

Low-Fouling and Biodegradable Protein-Based Particles for Thrombus Imaging

Nanomedicine holds great promise for vascular disease diagnosis and specific therapy, yet rapid sequestration by the mononuclear phagocytic system limits the efficacy of particle-based agents. The use of low-fouling polymers, such as poly(ethylene glycol), efficiently reduces this immune recognition, but these nondegradable polymers can accumulate in the human body and may cause adverse effects after prolonged use. Thus, new particle formulations combining stealth, low immunogenicity and biocompatible features are required to enable clinical use. Here, a low-fouling particle platform is described using exclusively protein material. A recombinant protein with superior hydrophilic characteristics provided by the amino acid repeat proline, alanine, and serine (PAS) is designed and cross-linked into particles with lysine (K) and polyglutamic acid (E) using mesoporous silica templating. The obtained PASKE particles have low-fouling behavior, have a prolonged circulation time compared to albumin-based particles, and are rapidly degraded in the cell's lysosomal compartment. When labeled with near-infrared fluorescent molecules and functionalized with an anti-glycoprotein IIb/IIIa single-chain antibody targeting activated platelets, the particles show potential as a noninvasive molecular imaging tool in a mouse model of carotid artery thrombosis. The PASKE particles constitute a promising biodegradable and versatile platform for molecular imaging of vascular diseases.

B12-Dependent Protein Oligomerization Facilitates Layer-by-Layer Growth of Photo/Thermal Responsive Nanofilms

We report the robust growth of an entirely protein-based, photo- and thermoresponsive Layer-by-Layer nanofilm using genetically encoded SpyTag/SpyCatcher chemistry. The process was facilitated by AdoB₁₂-induced tetramerization of photoreceptor proteins. Protein cargos can be released from the film in a light-dependent manner, showing its potential for therapeutic protein delivery.

Anti-inflammatory polymersomes of redox-responsive polyprodrug amphiphiles with inflammation-triggered indomethacin release characteristics

Inflammation serves as a natural defense mechanism to protect living organisms from infectious diseases. Nonsteroidal anti-inflammatory drugs (NSAIDs) can help relieve inflammatory reactions and are clinically used to treat pain, fever, and inflammation, whereas long-term use of NSAIDs may lead to severe side effects including gastrointestinal damage and cardiovascular toxicity. Therefore, it is of increasing importance to configure new dosing strategies and alleviate the side effects of NSAIDs. Towards this goal, glutathione (GSH)-responsive disulfide bonds and hydrogen peroxide (H₂O₂)-reactive phenylboronic ester linkages were utilized as triggering moieties in this work to design redox-responsive prodrug monomers and polyprodrug amphiphiles based on indomethacin (IND) drug. Note that IND is a widely prescribed NSAID in the clinic. Starting from three types of redox-reactive IND prodrug monomers, redox-responsive polyprodrug amphiphiles were synthesized through reversible addition-fragmentation chain transfer (RAFT) polymerizations of prodrug monomers using poly(ethylene oxide) (PEO)-based macroRAFT agent. The resultant polyprodrug amphiphiles with high IND loading contents (>33 wt%) could self-assemble into polymersomes with PEO shielding coronas and redox-responsive bilayer membranes composed of IND prodrugs. Upon incubation with GSH or H₂O₂, controlled release of intact IND in the active form from polyprodrug polymersomes was actuated by GSH-mediated disulfide cleavage reaction and H₂O₂-mediated oxidation of phenylboronic ester moieties, respectively, followed by self-immolative degradation events. Furthermore, in vitro studies at the cellular level revealed that redox-responsive polymersomes could efficiently relieve inflammatory responses induced by lipopolysaccharide (LPS) in RAW264.7 macrophage cells.

Metal-Organic Frameworks for Cell and Virus Biology: A Perspective

Metal-organic frameworks (MOFs) are a class of coordination polymers, consisting of metal ions or clusters linked together by chemically mutable organic groups. In contrast to zeolites and porous carbons, MOFs are constructed from a building block strategy that enables molecular level control of pore size/shape and functionality. An area of growing interest in MOF chemistry is the synthesis of MOF-based composite materials. Recent studies have shown that MOFs can be combined with biomacromolecules to generate novel biocomposites. In such materials, the MOF acts as a porous matrix that can encapsulate enzymes, oligonucleotides, or even more complex structures that are capable of replication/reproduction (i.e., viruses, bacteria, and eukaryotic cells). The synthetic approach for the preparation of these materials has been termed "biomimetic mineralization", as it mimics natural biomineralization processes that afford protective shells around living systems. In this Perspective, we focus on the preparation of MOF biocomposites that are composed of complex biological moieties such as viruses and cells and canvass the potential applications of this encapsulation strategy to cell biology and biotechnology.

Conjugation Chemistry-Dependent T-Cell Activation with Spherical Nucleic Acids

Spherical nucleic acids (SNAs) can be potent sequence-specific stimulators of antigen presenting cells (APCs). When loaded with peptide antigens, they can be used to activate the immune system to train T-cells to specifically kill cancer cells. Herein, the role of peptide chemical conjugation to the DNA, which is used to load SNAs with antigens via hybridization, is explored in the context of APC activation. Importantly, though the antigen chemistry does not impede TLR-9 regulated APC activation, it significantly augments the downstream T-cell response in terms of both activation and proliferation. A comparison of three linker types, (1) noncleavable, (2) cleavable but nontraceless, and (3) traceless, reveals up to an 8-fold improvement in T-cell proliferation when the traceless linker is used. This work underscores the critical importance of the choice of conjugation chemistry in vaccine development.

A simple, modular synthesis of bifunctional peptide-polynorbornenes for apoptosis induction and fluorescence imaging of cancer cells

Bifunctional peptide-polynorbornenes were designed and fabricated via modular ROMP for mitochondrial-dependent apoptosis induction and fluorescence imaging of cancer cells.

Templated Polymer Replica Nanoparticles to Facilitate Assessment of Material-Dependent Pharmacokinetics and Biodistribution

Surface modification is frequently used to tailor the interactions of nanoparticles with biological systems. In many cases, the chemical nature of the treatments employed to modify the biological interface (for example attachment of hydrophilic polymers or targeting groups) is the focus of attention. However, isolation of the fundamental effects of the materials employed to modify the interface are often confounded by secondary effects imparted by the underlying substrate. Herein, we demonstrate that polymer replica particles templated from degradable mesoporous silica provide a facile means to evaluate the impact of surface modification on the biological interactions of nanomaterials, independent of the substrate. Poly(ethylene glycol) (PEG), poly(N-(2 hydroxypropyl)methacrylamide) (PHPMA), and poly(methacrylic acid) (PMA) were templated onto mesoporous silica and cross-linked and the residual particles were removed. The resulting nanoparticles, comprising interfacial polymer alone, were then investigated using a range of in vitro and in vivo tests. As expected, the PEG particles showed the best stealth properties, and these trends were consistent in both in vitro and in vivo studies. PMA particles showed the highest cell association in cell lines in vitro and were rapidly taken up by monocytes in ex vivo whole blood, properties consistent with the very high in vivo clearance subsequently seen in rats. In contrast, PHPMA particles showed rapid association with both granulocytes and monocytes in ex vivo whole blood, even though in vivo clearance was less rapid than the PMA particles. Rat studies confirmed better systemic exposure for PEG and PHPMA particles when compared to PMA particles. This study provides a new avenue for investigating material-dependent biological behaviors of polymer particles, irrespective of the properties of the underlying core, and provides insights for the selection of polymer particles for future biological applications.

An in-tether chiral center modulates the proapoptotic activity of the KLA peptide

The helical peptide KLA (KLAKLAKKLAKLAK) is a well-known inducer of cellular apoptosis, acting to disrupt the mitochondrial membrane. However, its weak cellular uptake impedes development of any further applications. Here, we have utilized a novel in-tether chiral center induced helicity strategy (CIH) to develop a potent apoptosis inducer based on this KLA sequence. Notably, for the two resulting epimers of the CIH-KLA peptide, the CIH-KLA-(R) epimer exhibited superior cellular uptakes and special mitochondrial targeting when compared with its S counterpart. This work provides a promising and versatile method to modify the KLA peptide and a proof-of-concept application for the CIH strategy in modifying bioactive peptides.