Applications Of CBT-Cys Click Condensation Reaction And Enzyme-instructed Self-assembly In Immunology

Supramolecular nanomaterials,derived from the click condensation reaction between 2-cyano-benzothiazole(CBT)and 1,2-aminothiol group of cysteine(Cys)which could be controlled by pH,reduction,or enzyme in physiological condition,have been applied in many fields including molecular imaging(e.g.,optical imaging and magnetic resonance imaging(MRI)),materials chemistry(e.g.,nanoparticles and hydrogels),and protein labeling.Although there have been amount of researchers focusing on employing nanomaterials to modulate immune system for intervening immune diseases as tumor or infectious diseases,studies,using CBT-Cys click condensation reaction or enzyme-instructed self assembly(EISA)to design supramolecular materials to intentionally influence immune system,and sequentially change diseases progression,or to explore the probable effects induced by these materials in immune system,still should be deepen and widen.Depending on the excellent biocompatibility of peptides from their natural properties,we designed a series of small molecule precursors that could be transformed into various supermolecular nanomaterials induced by CBT-Cys and EISA mechanisms to realize goals including drug delivery or molecular imaging in different immunological conditions.Using the above systems,the following enhanced anti-tumor capacity of paclitaxel,enzyme activity imaging,and enhanced anti-inflammation/liver fibrosis effects of dexamethasone have been achieved,which should be supportive for the development of the interdiscipline between supramolecular nanotechnology and immunology:1.In chemotherapy,high concentration of paclitaxel(PTX)is used for anti-tumor treatment but toxic to immune cells.At lower concentration,PTX was found able to stimulate the anti-tumor potentials of immune cells.Thus,lowering down the cytotoxicity of PTX at high concentration but maintaining its anti-tumor stimulation to immune cells remains challenging.Herein,employing a click condensation reaction,we rationally designed a PTX derivative,Cys(StBu)-Arg-Arg-Arg-Lys(PTX)-CBT(1),for the facile preparation of its nanoparticle 1-NP.In vitro assays indicated that,at high PTX concentration,1-NP showed significantly lower cytotoxicity to macrophages than PTX,could be efficiently phagocytosed by macrophages and consequently polarize the cells into an anti-tumor state in a dose-dependent manner.In vivo experiments further confirmed that 1-NP possessed higher anti-tumor efficacy than free PTX but lower cytotoxicity to immune cells in both immune organs and tumor sites.Our results suggest that,by using different dose of 1-NP,patients can precisely regulate the activation of immune system for an effective anti-tumor and balanced autoimmune responses.We also envision that our strategy could be a combined immunotherapy and chemotherapy for a more efficient anti-tumor treatment in the future.2.As to extracellular enzymes associtated with immune diseases,there are still short of reports on enzyme-controlled disassembly of self-quenched near-infrared(NIR)fluorescent nanoparticles turning fluorescence on for specific detection/imaging of their activity in vitro and in vivo.Herein,we reported the rational design of a new NIR probe 1 whose fluorescence signal was self-quenched upon reduction-controlled condensation and subsequent assembly of its nanoparticles(i.e.,1-NP).Subsequently disassembly of 1-NP by matrix metalloproteinase 2(MMP-2)turned the fluorescence on.Employing this enzymatic strategy,we successfully applied 1-NP for NIR detection of MMP-2 in vitro and NIR imaging of MMP-2 activity in living cells.Moreover,we also applied 1-NP for discriminative NIR imaging for MMP-2 activity of MC38 tumors in nude mice.We envision that this NIR probe 1 might be further developed for tumor-targeted imaging in routine preclinical studies or even in patients in the future.3.Dexamethasone(Dex)is one of the essential medicines to treat inflammation diseases but an overdose of Dex will lead to severe adverse effects.Therefore.development of new strategy to boost the anti-inflammation efficacy of Dex is important but remains challenging.Herein,employing an enzyme-instructed self-assembly system,we developed an intracellular coassembly strategy to boost the anti-inflammation efficacy of Dex.Under the catalysis of alkaline phosphatase(ALP),the hydrogelator precursor Nap-Phe-Phe-Tyr(H2PO3)-OH(1p)self-assembled to form Gel 1 but Dexamethasone sodium phosphate(Dp)only yielded Dex precipitates.However,equivalent 1p and Dp subjected to ALP-triggered coassembly to form Gel 2.Cell experiments indicated that intracellular ALP-triggered coassembly of Dp with 1p extensively boosted the anti-inflammation efficacy of Dex on two types inflammatory cell models.We envision that,in near future,our strategy of intracellular coassembly could be widely employed to boost the therapeutic effects of more drugs while in the meantime alleviate their undesired adverse effects.4.Many chronic liver diseases will advance to hepatic fibrosis and,if without timely intervention,liver cirrhosis or even hepatocellular carcinoma.Anti-inflammation could be a standard therapeutic strategy for hepatic fibrosis treatment but a "smart" strategy of hepatic fibrosis-targeted,either self-assembly or slow release of an anti-inflammation drug(e.g.,Dex),has not been reported.Herein,we rationally designed a hydrogelator precursor Nap-Phe-Phe-Lys(Dex)-Tyr(H2PO3)-OH(1-Dex-P)and proposed a tandem enzymatic strategy of self-assembly and slow release,with which the precursor exhibited much stronger anti-hepatic fibrosis effect than Dex both in vitro and in vivo.Enzymatic experiments validated that 1-Dex-P was firstly subjected to alkaline phosphatase(ALP)-dephosphorylation to yield Nap-Phe-Phe-Lys(Dex)-Tyr-OH(1-Dex)which self-assembled into Nanofiber 1-Dex while the nanofiber was then hydrolyzed by esterase to transform into Nanofiber 1,accompanied by slow release of Dex.We anticipate that our "smart" tandem enzymatic strategy could be widely em-ployed to design more sophisticated drug delivery systems to achieve enhanced therapeutic efficacy than free drugs in the future.