A peptide probe for the detection of neurokinin-1 receptor by disaggregation enhanced fluorescence and magnetic resonance signals

Research progress of organic fluorescent probes for lung cancer related biomarker detection and bioimaging application

As one of the major public health problems, cancers seriously threaten the human health. Among them, lung cancer is considered to be one of the most life-threatening malignancies. Therefore, developing early diagnosis technology and timely treatment for lung cancer is urgent. Recent research has witnessed that measuring changes of biomarkers expressed in lung cancer has practical significance. Meanwhile, we note that bioimaging with organic fluorescent probes plays an important role for its high sensitivity, real-time analysis and simplicity of operation. In the past years, kinds of organic fluorescent probes targeting lung cancer related biomarker have been developed. Herein, we summarize the research progress of organic fluorescent probes for the detection of lung cancer related biomarkers in this review, along with their design principle, luminescence mechanism and bioimaging application. Additionally, we put forward some challenges and future prospects from our perspective.

High-density lipoprotein-mimicking nanodiscs carrying peptide for enhanced therapeutic angiogenesis in diabetic hindlimb ischemia

Therapeutic strategies using endogenous stem cell mobilizer can provide effective cell-free therapy for addressing various ischemic diseases. In particular, substance P (SP) exhibited therapeutic regeneration by facilitating mobilization of endogenous stem cells from bone marrow to the injured sites. However, its therapeutic effect has been limited due to short half-life and rapid degradation of administered SP peptides in vivo. Here we sought to develop high-density lipoprotein (HDL)-mimicking nanodiscs conjugated with SP (HDL-SP) in order to increase the in vivo half-life, bone marrow targeting, and therapeutic efficacy of SP for the treatment of diabetic peripheral ischemia. Conjugation of SP onto HDL nanodisc led to remarkable ∼3215- and ∼1060-fold increase in the ex vivo and in vivo half-lives of SP, respectively. Accordingly, HDL-SP nanodiscs improved retention of SP in bone marrow after systemic administration, leading to efficient mobilization of stem cells from bone marrow into blood circulation and reduction of systemic inflammation. Consequently, nanodisc based SP peptide delivery promoted blood vessel formation, blood perfusion recovery and markedly improved limb salvage in diabetic hindlimb ischemia model relative to administration of free SP without nanodisc modification. Therefore, HDL-SP nanodisc can provide a novel strategy for the treatment of diabetic ischemia and HDL nanodisc modification could be potentially useful for the extension of plasma circulation of other labile peptides.

Amplified fluorescence emission of bolaamphiphilic perylene-azacrown ether derivatives directed towards molecular recognition events

Long-term creative approaches have been considered in the design of molecular probes to overcome the quenching effect of important dyes in an aqueous medium. Using the rational donor-acceptor based design principle, we demonstrate herein the different fluorescence states of a non-conjugated symmetrical perylene-azacrown ether system in a solution, from the molecular to the aggregated states. The ethylene-spacer is exceptionally capable of fluorescence enhancement, even in the aggregated state (organic nanoparticle, ONPs, 44 nm), overcoming the quenching effect on changing the solvent from tetrahydrofuran to water. The ONPs with crown ether receptors at the surface show colloidal stability in an aqueous solution. Furthermore, an improved fluorescent state is developed via ONPs-polymer (protamine, Pro) hybridization. Supramolecular interactions between the crown ring and the guanidinium group in Pro play an important role in the ONPs-Pro hybrid formation. The decorated fluorescent hybrid state is finally used as a nano-probe for sensing heparin via the turn-OFF mechanism. The decoration method is further generalized by recognition of the nucleotides. Herein, we detail the bottom-up approach to the molecular design and development of the different fluorescent states of a useful probe. Most excitingly, this new approach is very general and adaptive to facile detection.

Self-assembling peptide-based building blocks in medical applications

Peptides and peptide-conjugates, comprising natural and synthetic building blocks, are an increasingly popular class of biomaterials. Self-assembled nanostructures based on peptides and peptide-conjugates offer advantages such as precise selectivity and multifunctionality that can address challenges and limitations in the clinic. In this review article, we discuss recent developments in the design and self-assembly of various nanomaterials based on peptides and peptide-conjugates for medical applications, and categorize them into two themes based on the driving forces of molecular self-assembly. First, we present the self-assembled nanostructures driven by the supramolecular interactions between the peptides, with or without the presence of conjugates. The studies where nanoassembly is driven by the interactions between the conjugates of peptide-conjugates are then presented. Particular emphasis is given to in vivo studies focusing on therapeutics, diagnostics, immune modulation and regenerative medicine. Finally, challenges and future perspectives are presented.

Near-Infrared Fluorogenic Probes with Polarity-Sensitive Emission for in Vivo Imaging of an Ovarian Cancer Biomarker

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.

Photoluminescence Architectures for Disease Diagnosis: From Graphene to Thin-Layer Transition Metal Dichalcogenides and Oxides

Ever since the discovery of graphene, increasing efforts have been devoted to the use of this stellar material as well as the development of other graphene-like materials such as thin-layer transition metal dichalcogenides and oxides (TMD/Os) for a variety of applications. Because of their large surface area and unique optical properties, these two-dimensional materials with a size ranging from the micro- to the nanoscale have been employed as the substrate to construct photoluminescence architectures for disease diagnosis as well as theranostics. These architectures are built through the simple self-assembly of labeled biomolecular probes with the substrate material, leading to signal quenching. Upon the specific interaction of the architecture with a target biomarker, the signal can be spontaneously restored in a reversible manner. Meanwhile, by co-loading therapeutic agents and employing the inherent photo-thermal properties of the material substrates, a combined disease imaging and therapy (theranostics) can be achieved. This review highlights the latest advances in the construction and application of graphene and TMD/O based thin-layer material composites for single-target and multiplexed detection of a variety of biomarkers and theranostics. These versatile material architectures, owing to their ease in preparation, low cost and flexibility in functionalization, provide promising tools for both basic biochemical research and clinical applications.

G-quadruplex induced chirality of methylazacalix[6]pyridine via unprecedented binding stoichiometry: en route to multiplex controlled molecular switch

Nucleic acid based molecular device is a developing research field which attracts great interests in material for building machinelike nanodevices. G-quadruplex, as a new type of DNA secondary structures, can be harnessed to construct molecular device owing to its rich structural polymorphism. Herein, we developed a switching system based on G-quadruplexes and methylazacalix[6]pyridine (MACP6). The induced circular dichroism (CD) signal of MACP6 was used to monitor the switch controlled by temperature or pH value. Furthermore, the CD titration, Job-plot, variable temperature CD and ¹H-NMR experiments not only confirmed the binding mode between MACP6 and G-quadruplex, but also explained the difference switching effect of MACP6 and various G-quadruplexes. The established strategy has the potential to be used as the chiral probe for specific G-quadruplex recognition.