| The microbial growth generally refers to the increasing of the groups. It is very meaningful to monitor the situation of microorganism either in theory or in practice. The traditional research is mainly on judging whether the microorganism grows well is mainly by the assay the quantity of the microorganism, microbial count or physiological indicators. However, it is still blank in the detection dramatic changes of energy in the cells. As one of the important products in the process of energy metabolism, the amount of intracellular AMP directly reflects the situation of the energy metabolism in the cells. What is more, cAMP, another space conformation of AMP, is also a very important internal indicator in signal transaction. It means that AMP can show the level of luxuriantly in living cells and its level should be important index on the monitoring the microbial growth. Here, an AMP aptasensor was designed and constructed successfully, which can be used as a tool in the analysis of the low-molecular-weight substrate AMP in vivo. The concrete steps are bellowing:1. Synthesis of streptavidin-coated magnetic beads. Biomagnetic separation technique is one of the most cost-effective resorts in areas of separation biotechnology and is becoming increasingly important as it widely be used in possible applications in the biosciences. Magnetic beads (MB) can be separated easily and quickly by magnetic fields. When MBs are coated with different chemical groups, they can be efficiently used together with some bioaffine ligands, e.g. proteins or antibodies which modified MBs could bind to high affinity target. The targets were usually, DNA, RNA, bacteria or even be cells. In this study, we had synthesized many streptavidin coated magnetic beads by chemical reaction. When magnetic fields were exerted on the tube, MBs were collected quickly. X-diffract experiment reflected that MBs are 19 nm diameterγ-Fe2O3 crystal particles. Hydrolyzing reaction take place between MBs and TEOS in alkaline solutions and then treated with AEAPS, streptavidin could be ligand with the MBs and be used in the system.2. The construction of aptasensor. In this experiment, we developed a new method for the detection of AMP by a biosensor. The aptasensor includes two different oligonucleotides:one is a 5'-biotin modified DNA with a length of sequence of aptamer for AMP. It could bind together with streptavidin-coated magnetic beads (SMB). The other is a 5'-cy3 labeled DNA, which is partially complementary with the former strand. These two labeled DNA strands, firstly hybridize to a certain proportion, and then incubate with SMB. By this process, the aptasensor is finally assembled and could be used as a tool to detect AMP. It could well provide a readout fluorescence intensity changes in the supernatant, when the special structure of the aptamer-analyte complex was formed. The detection limit of AMP in this work had been reached 6.25×10-8mol/L, which was better than the result of previous works.3. To explore the possible application of this newly established aptabiosensor, three microorganisms were chose to cultivate. Their logarithm phases are chose as the detection target in the experiments. After cell walls of the organism were treated with the help of Lysozyme, intracellular AMP were released quickly into solution. As soon as this supernatant mixed with the assembled aptabiosensor, it can active the detection process of AMP. All data implied that these biosensors could be used in vivo.In order to improve greatly their detection sensitivity, reduce well the cost and broaden largely application of the biosensors, we further work on choosing different signal groups with higher cost-effective ratio in detection and try the best to decrease the background signal;All in all, these aptasensor can be well used in monitoring the energy changes in vivo. The construction of sensor also provide a platform in environment protection, food, clinic et. al scopes...
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