Study of semi-specific BOD biosensors for biosensor-array

Abstract

Reovee reostuse taset määratakse selle biokeemilise hapnikutarbe alusel (BHT). BHT iseloomustab hapniku hulka, mis on vajalik proovis leiduva orgaanilise aine biokeemiliseks lagundamiseks. Kuigi BHT analüüs ei ole spetsiifiline ühelegi saasteainele, on see siiski väga oluline üldine indikaator aine potentsiaalsest keskkonnaohtlikkusest pinnavetele. Paraku kulub analüüsi tulemuste saamiseks 5 või 7 päeva ning seetõttu on reoveepuhastusseadmete juhtimine selliseid teste kasutades väga keeruline. Antud probleemi lahendamiseks koostati lihtsad ja usaldusväärsed pool-spetsiifilised BHT biosensorid, mis võimaldasid tulemuse saada vähem, kui 30 minutiga. Antud biosensoritega oli võimalik hinnata BHT-d, mis oli põhjustatud raskesti lagundatavatest ühenditest, mille suhtes nad olid pool-spetsiifilised. Samas kui universaalne biosensor ja biosensorid, mis on pool-spetsiifilised mõnele teisele raskesti lagundatavale ühendile, ei määranud seda ja alahindasid proovi BHT7 umbkaudu selle raskesti lagundatava ühendi poolt tekitatud BHT väärtuses, 10-25%. Kuigi biosensorid alahindasid enamike reaalsete tööstuslike reoveeproovide BHT7, võimaldasid pool-spetsiifilised biosensorid siiski saada täpsemaid tulemusi kui universaalne biosensor, mis alahindas proovi BHT7 suuremas ulatuses. Seega on pool-spetsiifilised biosensorid sobivamad BHT mõõtmiseks tööstuslikes reovetes, kui universaalne biosensor, kuid ainult juhul, kui on olemas eelinfo proovi koostise ja päritolu kohta, mis võimaldab valida sobiva pool-spetsiifilise biosensori. Antud probleem lahendati erinevate pool-spetsiifiliste biosensorite ühendamisega sensor-riviks – „bioelektrooniliseks keeleks“. Selle sensor-rivi signaali analüüsiks rakendati mitmemõõtmelise andmete analüüsi meetodeid. Antud meetodite rakendamisel võimaldas PCA eristada proove nende koostise ja BHT7 väärtuse alusel ning PLS võimaldas märgatavalt paremini hinnata proovide BHT7 väärtusi kõigis proovides.

Pollution load of wastewaters is determined on the basis of their biochemical oxygen demand (BOD) which measures the oxygen required for the biochemical degradation of organic material. Although the BOD test is not specific to any pollutant, it continues to be one of the important general indicators of the substance potential to be an environmental pollutant for surface waters. However, it takes 5 or 7 days to gain results and management of wastewater treatment facilities can be very difficult using this kind of tests. To address this limitation, simple and reliable semi-specific BOD biosensors were constructed which enabled us to gain results within less than 30 minutes. In addition, these biosensors can measure BOD derived from refractory compounds to which they are semi-specific. Therefore, better estimation of BOD is gained. On the other hand, universal biosensor and biosensors not semi-specific to that certain refractory compound cannot detect it and thus, underestimate the BOD7 of the sample to the extent made up by this compound, 10-25%. Although biosensors underestimated the BOD7 of most real industrial wastewater samples, the semi-specific biosensors still produced better correlation of sensor-BOD and BOD7 in real samples than universal biosensor which underestimated the BOD7 of samples to a greater extent. Therefore, semi–specific biosensors are more appropriate for measuring BOD in specific industrial wastewaters than universal biosensor. However, it is vital to have a prior knowledge about samples composition and origin to select the suitable sensor. This problem was overcome by using different biosensors as an array – bioelectronic tongue - and application of multivariate data analysis. Qualitative information was extracted by using PCA, which enabled us to distinguish different samples by their composition and BOD7 values. In addition, PLS was used for quantitative analysis which resulted in good correlation of sensor-BOD and BOD7 in all samples.