Endocytosis Pathway Self-Regulation for Precise Image-Guided Therapy through an Enzyme-Responsive Modular Peptide Probe.

Before arriving at the intracellular destinations, probes might be trapped in the lysosomes, reducing the amount of cargos, which compromises the therapeutic outcomes. The current methods are based on the fact that probes enter the lysosomes and then escape from them, which do not fundamentally solve the degradation by lysosomal hydrolases. Here, an enzyme-responsive modular peptide probe named PKP that can be divided into two parts, Pal-part and KP-part, by matrix metalloproteinase-2 (MMP-2) overexpressed in tumor microenvironments is designed. Pal-part quickly enters the cells and forms nanofibers in the lysosomes, decreasing protein phosphatase 2A (PP2A), which transforms the endocytic pathway of KP-part from clathrin-mediated endocytosis (CME) into caveolae-mediated endocytosis (CvME) and allows KP-part to directly reach the mitochondria sites without passing through the lysosomes. Finally, through self-regulating intracellular delivery pathways, the mitochondrial delivery efficiency of KP-part is greatly improved, leading to an optimized image-guided therapeutic efficiency. Furthermore, this system also shows great potential for the delivery of siRNA and doxorubicin to achieve precise cancer image-guided therapy, which is expected to significantly expand its application and facilitate the development of personalized therapy.

AIEgen-Based Lifetime-Probes for Precise Furin Quantification and Identification of Cell Subtypes.

Biochemical sensing probes based on aggregation-induced-emission luminogens (AIEgens) are widely used in biological imaging and therapy, chemical sensing, and material sciences. However, it is still a great challenge to quantify the targets through fluorescence intensity of AIEgen probes due to their undesirable aggregations. Here, a PyTPA-ZGO probe with three lifetime signals for precise quantification of furin is constructed: the lifetime signal 1 and signal 2 comes from AIEgen PyTPA-P (τPn ) and inorganic nanoparticles Zn2 GeO4 :Mn2+ -NH2 (τZn ), respectively, while the lifetime signal 3 is marked as the composite dual-lifetime signal (CDLSn , C D L S n = τ Z n τ P n ). In contrast, the fluorescence intensity signal of PyTPA-P shows defectively quantitative performance. Furthermore, it is found that the CDLSn exhibits higher significant differences than the two other lifetime signals (τPn and τZn ) thanks to its wide range between the maximum and minimum signal values and small standard deviation. Therefore, CDLSn is further used to accurately identify cell subtypes based on the specific concentration of furin in each subtype. The lifetime criterion can realize precise quantification, and it should be a promising direction of AIEgen-based quantitative analysis in the future.

Biocompatible AIEgen/p-glycoprotein siRNA@reduction-sensitive paclitaxel polymeric prodrug nanoparticles for overcoming chemotherapy resistance in ovarian cancer.

Nanoparticle drug delivery system (NDDS) is quite different from the widely studied traditional chemotherapy which suffers from drug resistance and side effect. NDDS offers the straightforward solution to the chemotherapy problem and provides an opportunity to monitor the drug delivery process in real time. In this vein, we developed one NDDS, namely Py-TPE/siRNA@PMP, to relieve resistance and side effects during chemotherapy against ovarian cancer. The Py-TPE/siRNA@PMP is a multifunctional polymeric nanoparticle contained several parts as follows: (1) a nanoparticle (NP) self-assembled by reduction-sensitive paclitaxel polymeric prodrug (PMP); (2) the glutathione (GSH)-responsive release of paclitaxel (PTX) for the suppression of ovarian cancer cells; (3) the P-glycoprotein (P-gp) siRNA for restoring the sensitivity of chemo-resistant tumor cells to chemotherapy; (4) the positively charged aggregation-induced emission fluorogen (AIEgen) Py-TPE for tumor imaging and promoting encapsulation of siRNA into the nanoparticle. Methods: The Py-TPE/siRNA@PMP nanoparticles were prepared by self-assembly method and characterized by the UV-Vis absorption spectra, zeta potentials, TEM image, stability assay and hydrodynamic size distributions. The combinational therapeutic effects of Py-TPE/siRNA@PMP on overcoming chemotherapy resistance were explored both in vitro and in vivo.Result: The Py-TPE/siRNA@PMP exhibited an average hydrodynamic size with a good stability. Meanwhile they gave rise to the remarkable chemotoxicity performances in vitro and suppressed the tumors growth in both SKOV-3/PTX (PTX resistance) subcutaneous and intraperitoneal metastasis tumor models. The investigations on ovarian cancer patient-derived xenografts (PDX) model revealed that Py-TPE/siRNA@PMP was able to effectively overcome their chemo-resistance with minimal side effects. Conclusion: Our findings demonstrated the Py-TPE/siRNA@PMP as a promising agent for the highly efficient treatment of PTX-resistant cells and overcoming the shortage of chemotherapy in ovarian cancer.

Modular Peptide Probe for Pre/Intra/Postoperative Therapeutic to Reduce Recurrence in Ovarian Cancer.

Even with optimal surgery, 80% of patients with ovarian cancer will have recurrence. Adjuvant therapy can reduce the recurrence of tumors; however, the therapeutic effect is still not prominent. Herein, we designed a modular peptide probe (TCDTMP), which can be self-assembled into nanoparticles (NPs) by loading in miR-145-5p or VEGF-siRNA. In vivo, (1) preoperative administration of TCDTMP/miR-145-5p ensured that NPs were adequately accumulated in tumors through active targeting and increased the expression of miR-145-5p in tumors, thereby inducing tumor cell apoptosis. (2) Intraoperatively, most of the tumors were removed, while the microscopic residual tumors were largely eliminated by TCDTMP/miR-145-5p-mediated photodynamic therapy (PDT). (3) Postoperatively, TCDTMP/VEGF-siRNA were given for antiangiogenesis therapy, thus delaying the recurrence of tumors. This treatment was named a preoperative (TCDTMP/miR-145-5p)||intraoperative (surgery and PDT)||postoperative (TCDTMP/VEGF-siRNA) therapeutic system and abbreviated as the PIP therapeutic system, which reduced the recurrence of ovarian cancer in subcutaneous tumor models, intraperitoneal metastasis models, and patient-derived tumor xenograft models. Our findings provide a therapeutic system based on modular peptide probes to reduce the recurrence of ovarian cancer after surgery, which provides a perspective for the surgical management of ovarian cancer.

Enzyme-Responsive Peptide-Based AIE Bioprobes.

Enzyme, which exists widely in organisms, has high specificity and high catalytic efficiency for its substrates. The absence, the reduced activity, or the overexpression of enzyme are closely related to the occurrence and development of diseases. Therefore, enzyme is often used as markers for disease detection and treatment. To detect enzyme activity and track drug release, aggregation-induced emission (AIE) bioprobes have been developed because of their excellent photostability and high signal-to-noise ratio (SNR). Among them, peptide-based AIE bioprobes with great biocompatibility and specificity are favored by an increasing number of researchers. Enzymatic hydrolysis of peptide can cause aggregation of AIE molecules and drug release. In this review, enzyme-responsive peptide-based AIE bioprobes used for biomedical application are summarized according to the three aggregation strategies triggered by various reaction between peptide and enzyme, including enzyme-triggered precipitate, enzyme-catalyzed coupling, and enzyme-instructed self-assembly. By giving some representative examples, we discuss how each aggregation strategy detects enzyme activity and treats the diseases under imaging guidance. Finally, we comment on the current problems and future prospects of enzyme-responsive peptide-based AIE bioprobes.

Tumor-Triggered Disassembly of a Multiple-Agent-Therapy Probe for Efficient Cellular Internalization.

Integration of multiple agent therapy (MAT) into one probe is promising for improving therapeutic efficiency for cancer treatment. However, MAT probe, if entering the cell as a whole, may not be optimal for each therapeutic agent (with different physicochemical properties), to achieve their best performance, hindering strategy optimization. A peptide-conjugated-AIEgen (FC-PyTPA) is presented: upon loading with siRNA, it self-assembles into FCsiRNA -PyTPA. When approaching the region near tumor cells, FCsiRNA -PyTPA responds to extracellular MMP-2 and is cleaved into FCsiRNA and PyTPA. The former enters cells mainly by macropinocytosis and the latter is internalized into cells mainly through caveolae-mediated endocytosis. This two-part strategy greatly improves the internalization efficiency of each individual therapeutic agent. Inside the cell, self-assembly of nanofiber precursor F, gene interference of CsiRNA , and ROS production of PyTPA are activated to inhibit tumor growth.

Cooperation therapy between anti-growth by photodynamic-AIEgens and anti-metastasis by small molecule inhibitors in ovarian cancer.

Metastasis is one of the main causes of death and treatment failure in ovarian cancer. Some small molecule inhibitors can effectively inhibit the metastasis of primary tumors. However, they do not kill the primary tumor cells, which may lead to continuous proliferation. Herein, we have prepared a multifunctional nanoparticles named TPD@TB/KBU2046, which consisted of three functional moieties: (1) KBU2046 (small molecule inhibitor) that can inhibit the metastasis of the primary tumors, (2) TB (photodynamic-AIEgens) that may suppress the growth of the primary tumors, and (3) TPD, which contains TMTP1 (a targeting peptide, which specifically binds to highly metastatic tumor cells) that can enhance the TB/KBU2046 dosage in the tumor site. Methods: The TPD@TB/KBU2046 was prepared by nano-precipitation method. We linked the targeting peptide (TMTP1) to the nanoparticles via amidation reaction. TPD@TB/KBU2046 nanoparticles were characterized for encapsulation efficiency, particle size, absorption spectra, emission spectra and ROS production. The combinational efficacy in image-guided anti-metastasis and photodynamic therapy of TPD@TB/KBU2046 was explored both in vitro and in vivo. Results: The TPD@TB/KBU2046 showed an average hydrodynamic size of approximately 50 nm with good stability. In vitro, TPD@TB/KBU2046 not only inhibited the metastasis of the tumors, but also suppressed the growth of the tumors under AIEgens-mediated photodynamic therapy. In vivo, we confirmed that TPD@TB/KBU2046 has the therapeutic effects of anti-tumor growth and anti-metastasis through subcutaneous and orthotopic ovarian tumor models. Conclusion: Our findings provided an effective strategy to compensate for the congenital defects of some small molecule inhibitors and thus enhanced the therapeutic efficacy of ovarian cancer.

A Multifunctional Peptide-Conjugated AIEgen for Efficient and Sequential Targeted Gene Delivery into the Nucleus.

Gene therapy has immense potential as a therapeutic approach to serious diseases. However, efficient delivery and real-time tracking of gene therapeutic agents have not been solved well for successful gene-based therapeutics. Herein we present a versatile gene-delivery strategy for efficient and visualized delivery of therapeutic genes into the targeted nucleus. We developed an integrin-targeted, cell-permeable, and nucleocytoplasmic trafficking peptide-conjugated AIEgen named TD NCP for the efficient and sequential targeted delivery of an antisense single-stranded DNA oligonucleotide (ASO) and tracking of the delivery process into the nucleus. As compared with TD NCP/siRNA-NPs (siRNA functions mainly in the cytoplasm), TD NCP/ASO-NPs (ASO functions mainly in the nucleus) exhibited a better interference effect, which further indicates that TD NCP is a nucleus-targeting vector. Moreover, TD NCP/ASO-NPs showed a favorable tumor-suppressive effect in vivo.

Efficient polymerase chain reaction assisted by metal-organic frameworks.

As a powerful tool for obtaining sufficient DNA from rare DNA resources, polymerase chain reaction (PCR) has been widely used in various fields, and the optimization of PCR is still in progress due to the dissatisfactory specificity, sensitivity and efficiency. Although many nanomaterials have been proven to be capable of optimizing PCR, their underlying mechanisms are still unclear. So far, the scientifically compelling and functionally evolving metal-organic framework (MOF) materials with high specific surface area, tunable pore sizes, alterable surface charges and favourable thermal conductivity have not been used for PCR optimization. In this study, UiO-66 and ZIF-8 were used to optimize error-prone two round PCR. The results demonstrated that UiO-66 and ZIF-8 not only enhanced the sensitivity and efficiency of the first round PCR, but also increased the specificity and efficiency of the second round PCR. Moreover, they could widen the annealing temperature range of the second round PCR. The interaction of DNA and Taq polymerase with MOFs may be the main reason. This work provided a candidate enhancer for PCR, deepened our understanding on the enhancement mechanisms of nano-PCR, and explored a new application field for MOFs.

Prewetting dichloromethane induced aqueous solution adhered on Cassie superhydrophobic substrates to fabricate efficient fog-harvesting materials inspired by Namib Desert beetles and mussels.

Namib Desert beetles harvest water from harsh environments by using their hydrophilic-hydrophobic dorsal surfaces. Generally, Cassie-state superhydrophobic materials are chosen as substrates to prepare bioinspired (super)hydrophilic/(super)hydrophobic patterned surfaces. However, due to the low adhesion and strong repellency, aqueous solution cannot be directly set on Cassie superhydrophobic materials until the dropping volume is larger than 6.5 µL. Therefore, arranging a (super)hydrophilic substance on Cassie superhydrophobic substrates to construct (super)hydrophilic/superhydrophobic patterned surfaces still remains a challenge. In this work, by prewetting with dichloromethane (DCM), the mussel-inspired hydrophilic and bio-adhesive dopamine solution (DA) could be dripped onto a Cassie superhydrophobic Cu surface with an ultralow volume of 0.1 µL, whereby low surface tension DCM would "cloak" the high surface tension DA. Along with DCM volatility, DA was adhered on the Cassie superhydrophobic surface and would then self-polymerize into hydrophilic polydopamine domains, thus hydrophilic/superhydrophobic patterned surfaces with efficient water collection could be successfully developed inspired by Namib Desert beetles and mussels. The bioinspired materials show the potential for real-world industrialization in a large scale, which is of great significance for providing living security for those living in areas with no access to fresh water.

DNA-Conjugated Amphiphilic Aggregation-Induced Emission Probe for Cancer Tissue Imaging and Prognosis Analysis.

Detection of an ultralow concentration of mRNA is important in the prognosis of gene-related diseases. In this study, a DNA-conjugated amphiphilic aggregation-induced emission probe (TPE-R-DNA) was synthesized for cancer tissue imaging and prognosis analysis based on an exonuclease III-aided target recycling technique. TPE-R-DNA comprise two components: a hydrophobic component that serves as the "turn-on" long wavelength fluorescence imaging agent (TPE-R-N3); and a hydrophilic single DNA strand (Alk-DNA) which acts as specific recognition part for target mRNA. In the absence of target mRNA, TPE-R-DNA had almost no fluorescence because of its high water solubility. Conversely, the TPE-R-DNA was digested by exonuclease III (Exo III) in the presence of MnSOD mRNA to release the hydrophobic fluorogens (TPE-R-AT). Subsequently, TPE-R-AT formed aggregates, and therefore, fluorescence signal was distinctly observed. For the first time, the structure of the hydrolysis product (TPE-R-AT), containing two bases A and T, was proved by the mass spectrum (MS) and high-performance liquid chromatography (HPLC). Moreover, the detection limit toward mRNA could be achieved in as low as 0.6 pM. Furthermore, the fluorescent signal can be used to confirm the MnSOD mRNA expression level in cancer tissue. The MnSOD mRNA expression in renal cancer was lower than in renal cancer adjacent tissue. In particular, the expression level was analyzed to predict prognosis of cancer patients. Our results demonstrate that a shorter survival time was evident among patients in lower MnSOD mRNA expression. Thereby, it indicates great potential for the development of an ultrasensitive biosensing platform for the application in disease prognosis.

A low background D-A-D type fluorescent probe for imaging of biothiols in living cells.

Two probes, structurally symmetric CBFB and asymmetric CBFM, constructed by a D-A-D (donor-acceptor-donor) type curcuminoid as the fluorophore and the DNBS (2,4-dinitrobenzenesulfonyl) group as the biothiol recognition site were designed and synthesized here. The DNBS group can quench the emission of the fluorophore by the PET (photoinduced electron transfer) process, and in the presence of biothiols, the emission of the probe was switched on as a result of the cleavage of the quencher by a nucleophilic aromatic substitution reaction. Experimental analyses and theoretical calculations revealed that two recognition moieties in the molecule can quench the fluorescence more efficiently, therefore, CBFB showed a much higher SNR (signal to noise ratio) than CBFM in biothiol detection with an emission maximum at 610 nm. This "low background" and "turn-on" fluorescent probe, CBFB, was successfully utilized to map endogenous biothiols in living cells.