•This simple peptide system containing a pyrene fluorogen and arginine-glycine-aspartic acid (RGD) sequence could be utilized to release DDP in situ.•The peptide cargo carrier efficiently penetrated tumour cells for enhancing therapeutic efficacy.The self-assembled peptide cargo carrier with the ability of probe offered an effective strategy to deliver and track the anticancer drug, cisplatin (DDP) in ovarian cancer cells. This simple peptide system containing a pyrene fluorogen and arginine-glycine-aspartic acid (RGD) sequence could be utilized to release DDP in situ by the specific recognition between an RGD motif and αvβ3 integrin that was over-expressed on ovarian cancer cells. Importantly, we found that the disassembly-triggered peptide nanofibers, PA1, could effectively combine with DDP and release DDP in the cytoplasm with the pyrene fluorescence restoring. Moreover, the peptide cargo carrier efficiently penetrated tumour cells for enhancing therapeutic efficacy. Our system could open the door for the delivery of anticancer drug in cancer-related therapy.The self-assembled peptide cargo carrier with the ability of probe offered an effective strategy to deliver and track the anticancer drug, cisplatin (DDP) in ovarian cancer cells.Download high-res image (248KB)Download full-size image

Peptide functionalized polydiacetylene (PDA) micelles encapsulated with camptothecin (CPT) kill ovarian cancer cells by the lysosome release of anticancer drug CPT. Moreover, the sub-30 nm PDA micelles penetrate efficiently into a tumor for enhanced therapeutic efficacy.

Abundant lipopolysaccharide (LPS) can result in sepsis and septic shock, indicating a serious Gram-negative bacterial contamination. We have developed a novel strategy based on dendritic antimicrobial peptides that can detoxify LPS. The dendritic antimicrobial peptides bind to LPS at the surface of Gram-negative bacteria, killing the bacteria but removing the LPS from the cell wall of dead Gram-negative bacteria, hence detoxifying pathogenic bacteria in its host cells and effectively improving survival of animals infected with Pseudomonas aeruginosa. Our findings provide a way to detoxify bacterial contamination.

Lysophosphatidic acid (LPA, cutoff values ≥ 1.5 μM) is an effective biomarker for early stage ovarian cancer. The development of selective probes for LPA detection is therefore critical for early clinical diagnosis. Although current methods have been developed for the detection of LPA in solution, they cannot be used for tracking LPA in vivo. Here, we report a near-infrared (NIR) fluorescent probe that can selectively respond to LPA based on polarity-sensitive emission at a very low detection limit of 0.5 μM in situ. This probe exhibits a marked increase of fluorescence at 720 nm upon binding to LPA, allowing the direct visualization of LPA in vitro and in vivo without interference from other biomolecules. Moreover, the probe containing two arginine-glycine-aspartic acid units can be efficiently taken up by cancer cells based on an αvβ3 integrin receptor targeting mechanism. It also exhibits excellent biocompatibility and high pH stability in live cells and in vivo. Confocal laser scanning microscopy and flow cytometric imaging of SKOV-3 cells have confirmed that our probe can be used to image LPA in live cells. In particular, its NIR turn-on fluorescence can be used to effectively monitor LPA imaging in a SKOV-3 tumor-bearing mouse model. Our probe may pave the way for the detection of cancer-related biomarkers and even for early stage cancer diagnosis.Keywords: biomarker; lysophosphatidic acid; near-infrared; polarity-sensitive; probe

Through their unique and specific interactions with various metal ions, naturally occurring proteins control structures and functions of many biological processes and functions in organisms. Inspired by natural metallopeptides, chemists have developed artificial peptides which coordinate with metal ions through their functional groups either for introducing a special reactivity or for constructing nanostructures. However, the design of new coordination peptides requires a deep understanding of the structures, assembly properties, and dynamic behaviours of such peptides. This review briefly discusses strategies of peptide self-assembly induced by metal coordination to different natural and non-natural binding sites in the peptide. The structures and functions of the obtained aggregates are described as well. We also highlight some examples of a metal-induced peptide self-assembly with relevance to biotechnology applications.

In the present study, three new luminogens ATT-(1–3) based on 1,3,5-triazine and end-capped with multi-branched triphenylamine-containing alkyl chains have been synthesized and characterized. All the three dyes are nonemissive in solution but have a strong red fluorescent emission in the aggregate state. The two-photon absorption (2PA) cross sections measured by the open aperture Z-scan technique are determined to be as large as 2756, 4750 and 10003 GM for ATT-1, ATT-2 and ATT-3 in chloroform, respectively, showing a dramatic enhancement with an increasing number of donor branches. The relationship between their structures and properties on one- and two-photon absorption and aggregation-induced emission (AIE) is discussed, which can serve as a guideline for the development of a series of solid materials with larger two-photon cross sections and high fluorescence quantum yield. In addition, one- and two-photon fluorescence (2PF) microscopy images of HeLa cells incubated with these three dyes were obtained to demonstrate the potential applications of these fluorophores in biosensing and bioimaging.

Polydiacetylene (PDA) micelles have been widely used to deliver anticancer drugs in the treatment of a variety of tumours and for imaging living cells. In this study, we developed an effective strategy to directly conjugate magainin II (MGN-II) to the surface of PDA micelles using a fluorescent dye. These stable and well-defined PDA micelles had high cytotoxicity in cancer cell lines, and were able to reduce the tumour size in mice. The modified PDA micelles improved the anticancer effects of MGN-II in the A549 cell line only at a concentration of 16.0 μg mL−1 (IC50). In addition, following irradiation with UV light at 254 nm, the PDA micelles gave rise to an energy transfer from the fluorescent dye to the backbone of PDA micelles to enhance the imaging of living cells. Our results demonstrate that modified PDA micelles can not only be used in the treatment of tumors in vitro and in vivo in a simple and directed way, but also offer a new platform for designing functional liposomes to act as anticancer agents.

A bis-spiropyran functionalized peptide 1, which exhibits good cell-permeability, excellent biocompatibility and low cytotoxicity, has been developed for reversible and real-time lysosomal tracking.

A pyrene-functionalized peptidic inhibitor 1 binds to and inhibits β-tryptase in a non-competitive and reversible manner even in cells. Upon protein binding a fluorescence increase of the two pyrene fluorophores is observed which allows using 1 as a fluorescent light-up probe for this enzyme.

A triphenylamine-based fluorescent probe 1 with larger Stokes shift (∼141 nm) has been synthesized, which can make an efficient nucleophilic addition by reacting with CN− in water. Upon addition of CN−, the red fluorescence of 1 was distinctly quenched. Importantly, 1 exhibits a highly selective response toward CN− over other anions in water and a high sensitivity (detection limit ⩽ 11 nM). Moreover, it has potential application to track CN− levels in living cells by confocal laser scanning microscopy (CLSM).A new fluorescent triphenylamine-based sensor 1 with larger Stokes shift (∼141 nm) was developed, showing red-emitting fluorescence with high selectivity to cyanide anion in pure water and in living HeLa cells.

Peptide functionalized polydiacetylene (PDA) micelles encapsulated with camptothecin (CPT) kill ovarian cancer cells by the lysosome release of anticancer drug CPT. Moreover, the sub-30 nm PDA micelles penetrate efficiently into a tumor for enhanced therapeutic efficacy.

Through their unique and specific interactions with various metal ions, naturally occurring proteins control structures and functions of many biological processes and functions in organisms. Inspired by natural metallopeptides, chemists have developed artificial peptides which coordinate with metal ions through their functional groups either for introducing a special reactivity or for constructing nanostructures. However, the design of new coordination peptides requires a deep understanding of the structures, assembly properties, and dynamic behaviours of such peptides. This review briefly discusses strategies of peptide self-assembly induced by metal coordination to different natural and non-natural binding sites in the peptide. The structures and functions of the obtained aggregates are described as well. We also highlight some examples of a metal-induced peptide self-assembly with relevance to biotechnology applications.

A pyrene-functionalized peptidic inhibitor 1 binds to and inhibits β-tryptase in a non-competitive and reversible manner even in cells. Upon protein binding a fluorescence increase of the two pyrene fluorophores is observed which allows using 1 as a fluorescent light-up probe for this enzyme.

A bis-spiropyran functionalized peptide 1, which exhibits good cell-permeability, excellent biocompatibility and low cytotoxicity, has been developed for reversible and real-time lysosomal tracking.

In the present study, three new luminogens ATT-(1–3) based on 1,3,5-triazine and end-capped with multi-branched triphenylamine-containing alkyl chains have been synthesized and characterized. All the three dyes are nonemissive in solution but have a strong red fluorescent emission in the aggregate state. The two-photon absorption (2PA) cross sections measured by the open aperture Z-scan technique are determined to be as large as 2756, 4750 and 10003 GM for ATT-1, ATT-2 and ATT-3 in chloroform, respectively, showing a dramatic enhancement with an increasing number of donor branches. The relationship between their structures and properties on one- and two-photon absorption and aggregation-induced emission (AIE) is discussed, which can serve as a guideline for the development of a series of solid materials with larger two-photon cross sections and high fluorescence quantum yield. In addition, one- and two-photon fluorescence (2PF) microscopy images of HeLa cells incubated with these three dyes were obtained to demonstrate the potential applications of these fluorophores in biosensing and bioimaging.