| Based on the application of nano-materials in high-sensitive detection and drug delivery,this article designed a kind of beacon-Au nanoparticles for rapid detection of uropathogens with high sensitivity and specificity;We also prepared hexagonal mesoporous silica(HMS)loaded with RGD-hylina 1 to acquire lower toxicity and better efficiency.This study includes three aspects:1 Highly sensitive and rapid bacteria detection using beacon-Au nanoparticlesThis article designed a kind of beacon-Au nanoparticles to improve the efficiency and sensitivity of uropathogens detection.In order to detect uropathogens rapidly and sensitively,this study designed beacons according to conservative and universal 16S rRNA.The underlying mechanism is,in the absence of target sequence,the probe forms a stem-loop structure through its complementary ends,thus the fluorescent molecular FAM modified to the probe's end is quenched by the BHQ1 nearby,which is modified to the other end;Once the target is present,the stem-loop structure is opened,at the same time,FAM is apart from the quencher and became fluorescent,so the concentration can be inferred by the fluorescence intensity.Firstly,we prepared gold nanoparticles and characterized them through ultraviolet spectrophotometer and TEM.Then,the DNA probes were enriched on the 13 nm AuNPs' surface,and DLS was used to test whether they are successfully connected.After that,we compared the sensitivity of beacons and beacon-Au nanoparticles for E.coli detection.To test the specificity of beacon and beacon-Au nanoparticles,a target sequence,a 4-base-mismatch sequence,a completely irrelevant sequence and an irrelevant 3008 bp plasmid were used.Patients' urine samples were used to test the sensitivity of beacons and beacon-Au nanoparticles to uropathogens.In the end,we studied the ability of beacon-Au nanoparticles to detect E.coli in serum and resist interference.The results show:The Au nanoparticles prepared in our study were in uniform sizes and were successfully connected with beacons.By monitoring the fluorescence intensity,we verified that beacon-Au nanoparticlcs can detect 102 cfu/ml E.coli in 1 h,which means the sensitivity is 103 times than that of beacons alone.Meanwhile,beacon-Au nanoparticles are all highly specific and resistant to interference(P<0.04).The results indicate:our study for the first time utilized beacon-Au nanoparticles to dectect E.coli rapidly with high sensitivity and specificity,solving the defects of conventional methods such as tedious procedures,high cost and long duration.Besides,this detection method is easy to be tuned by changing the beacon's sequence for high-sensitivity detection of animal bacteria and virus,early pregnancy of livestock and food safety.2 A study on antimicrobial peptides sequences of nanomaterials mesoporous silica(HMS-COOH)carrying drug system As undesirable toxic and side effects being tumor drug therapies' problem,this study designed a delivery system where HMS-carried antibacterial peptides releases at targeted tumor tissues as the pH changes.We first chose two antibacterial peptides,melittin from bee venom and hylin al from skin of South American tree frogs,and then modified their sequences to connect tumor-cell-targeting peptides,SP94 and RGD,with different specificity.Anti-tumor activities and hemolytic characteristics before and after connection were compared to select the most suitable antibacterial peptide for HMS to carry.Influence of structure and length of targeting peptides on bioactivity of antibacterial peptides was also studied.The results show:As for the property of promoting apoptosis of tumor cells,RGD-melittin has the strongest effect,followed by melittin,while SP94-melittin has the weakest effect.Comparing the hemolysis of the three compounds,we saw that RGD-melittin is less hemolytic at 0.2 ?M,?M and 2 ?M than melittin and SP94-melittin with highly significant difference(P<0.01)or significant difference(P<0.05).The results indicate:Melittin itself has a long sequence,and is influenced by SP94 which also has a relatively long sequence,so that the bioactivity of SP94-melittin is lower than that of melittin.As RGD has a short sequence,it doesn't affect melittin much,on the contrary,the targeting property contributes to RGD-melittin's bioactivity.Based on these results,we infer that the length,spatial structure and specificity of the targeting peptide may influence the activity and function of the whole peptide.Therefore,we should take into account the interactions of length,spatial structure and bioactivity of peptides when designing multifunctional hybrid peptides.3 Mesoporous silica(HMS-COOH)binded with targeting hybrid antibacterial polypeptides blocks tumor cells growthAs undesirable toxic and side effects being tumor drug therapies' problem,this study designed a delivery system where HMS-carried antibacterial peptides releases at targeted tumor tissues as the pH changes.Based on the assays above,RGD-hylin-al was chosen as the carried drug to be loaded on HMS via electrostatic interaction.Nano-materials can target and gather at tumor tissues,where pH is relatively lower than normal tissues,which contributes to the smart release of RGD-hylin-al-HMS,lowering the toxic to normal cells and hemolysis of RGD-hylin-al.The results show:The other two antibacterial peptides,hylin al and RGD-hylin-al,do not have significant difference in promoting apoptosis of tumor cells(P>0.05),and with respect to hemolysis,they have significant difference only at 7?M(P<0.05,38.7%vs 19.7%).HMS-COOH we chose itself promotes apoptosis of tumor cells and the apoptotic rate rises with the concentration,but it doesn't have hemolytic characteristics.At low concentrations of 6?g/ml and 12.5?g/ml,the tumor cell apoptotic rate promoted by RGD-hylin-al-HMS when pH=7 is lower than that when pH=5.5 with highly significant difference(P<0.01).Compared with RGD-hylin-al,RGD-hylin-a1-HMS is less hemolytic(P<0.05).Removal of unbinded RGD-hylin-al from RGD-hylin-al-HMS by centrifugation does not affect its apoptosis and hemolysis outcome.The results indicate:Considering the comparisons of several kinds of antibacterial peptides above,RGD-hylin-al was chosen to be loaded on HMS targeting tumor cells.The experiments verified that this delivery system achieve the desired effects of lowering toxicity and enhancing efficiency. |
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