Catecholamine Detection Using a Functionalized Poly(L-dopa)-Coated Gate Field-Effect Transistor

A highly sensitive catecholamine (CA) sensor was created using a biointerface layer composed of a biopolymer and a potentiometric detection device. For the detection of CAs, 3-aminophenylboronic acid (3-NH2-PBA) was reacted with the carboxyl side chain of L-3,4-dihydroxyphenylalanine (L-dopa, LD) and the PBA-modified L-dopa was directly copolymerized with LD on an Au electrode, resulting in a 3.5 nm thick PBA-modified poly(PBA–LD/LD) layer-coated Au electrode. By connecting the PBA–LD-coated Au electrode to a field-effect transistor (FET), the molecular charge changes at the biointerface of the Au electrode, which was caused by di-ester binding of the PBA–CA complex, were transduced into gate surface potential changes. Effective CAs included LD, dopamine (DA), norepinephrine (NE), and epinephrine (EP). The surface potential of the PBA–LD-coated Au changed after the addition of 40 nM of each CA solution; notably, the PBA–LD-coated Au showed a higher sensitivity to LD because the surface potential change could already be observed after 1 nM of LD was added. The fundamental parameter analyses of the PBA–LD to CA affinity from the surface potential shift against each CA concentration indicated the highest affinity to LD (binding constant (Ks): 1.68 × 106 M–1, maximum surface potential shift (Vmax): 182 mV). Moreover, the limit of detection for each CA was 3.5 nM in LD, 12.0 nM in DA, 7.5 nM in NE, and 12.6 nM in EP. From these results, it is concluded that the poly(PBA–LD/LD)-coated gate FET could become a useful biosensor for neurotransmitters, hormones, and early detection of Parkinson’s disease

Well-designed dopamine-imprinted polymer interface for selective and quantitative dopamine detection among catecholamines using a potentiometric biosensor

We report a well-designed biointerface enabling the selective and quantitative detection of dopamine (DA) using a potentiometric biosensor. To enhance the detection selectivity of DA, a DA-templated molecularly imprinted polymer (DA–MIP) was synthesized on the extended Au gate electrode of a field-effect transistor (FET) biosensor. For a quantitative DA analysis, the thickness of the DA–MIP was controlled to ca. 60 nm by surface-initiated atom transfer radical polymerization (SI-ATRP). In this process, the DA–MIP was copolymerized with vinylphenylboronic acid (vinyl-PBA), inducing molecular charges at the biointerface of the FET gate electrode. These charges were generated by the diol-binding between PBA and dopamine (a catecholamine), and were directly detected as a change in surface potential. In fact, the surface potential at the gate of the DA–MIP-coated FET responded significantly to DA added at concentrations ranging from 40 nM to μM, whereas that of a non-imprinted polymer (NIP)-coated FET hardly changed over this range. Moreover, by measuring the kinetic parameters and electrochemical properties of well-designed devices with various added catecholamines, we confirmed that the DA–MIP-coated FET biosensor selectively and quantitatively detects DA

Catecholamine Detection Using a Functionalized Poly(l‑dopa)-Coated Gate Field-Effect Transistor

A highly sensitive catecholamine (CA) sensor was created using a biointerface layer composed of a biopolymer and a potentiometric detection device. For the detection of CAs, 3-aminophenylboronic acid (3-NH₂-PBA) was reacted with the carboxyl side chain of l-3,4-dihydroxyphenylalanine (l-dopa, LD) and the PBA-modified l-dopa was directly copolymerized with LD on an Au electrode, resulting in a 3.5 nm thick PBA-modified poly­(PBA–LD/LD) layer-coated Au electrode. By connecting the PBA–LD-coated Au electrode to a field-effect transistor (FET), the molecular charge changes at the biointerface of the Au electrode, which was caused by di-ester binding of the PBA–CA complex, were transduced into gate surface potential changes. Effective CAs included LD, dopamine (DA), norepinephrine (NE), and epinephrine (EP). The surface potential of the PBA–LD-coated Au changed after the addition of 40 nM of each CA solution; notably, the PBA–LD-coated Au showed a higher sensitivity to LD because the surface potential change could already be observed after 1 nM of LD was added. The fundamental parameter analyses of the PBA–LD to CA affinity from the surface potential shift against each CA concentration indicated the highest affinity to LD (binding constant (<i>K</i>_s): 1.68 × 10⁶ M^–1, maximum surface potential shift (<i>V</i>_max): 182 mV). Moreover, the limit of detection for each CA was 3.5 nM in LD, 12.0 nM in DA, 7.5 nM in NE, and 12.6 nM in EP. From these results, it is concluded that the poly­(PBA–LD/LD)-coated gate FET could become a useful biosensor for neurotransmitters, hormones, and early detection of Parkinson’s disease

Consumption Rates and Use Patterns of Firewood and Charcoal in Urban and Rural Communities in Yedashe Township, Myanmar

There is concern over the environmental impact of charcoal use for cooking in urban areas; however, studies have mainly been limited to Africa and South Asia. This investigation aimed to evaluate woodfuel consumption rates and patterns in an urban area in Yedashe Township, Myanmar and compared them with results from a rural area in the same township. From interviews with 66 urban households, it was evident that firewood and charcoal consumption rates in the urban area were about one-third and one-fourth, respectively, of those in the rural area. These low consumption rates were because of multiple-fuel use (mainly woodfuel and electricity) in the urban area in contrast to single-fuel use in the rural area. We estimated the forest area required to meet woodfuel demand of the whole township to be 3738 ha; that could decrease by almost 40% (1592 ha) if the single-fuel use in the rural area switched to the multiple-fuel methods used in the urban area. This study confirms that urbanization with an &ldquo;energy stack&rdquo; in multiple-fuel use, rather than an &ldquo;energy ladder&rdquo; from firewood to charcoal, could largely reduce the environmental impact on forests

Condition of Illegally Logged Stands Following High Frequency Legal Logging in Bago Yoma, Myanmar

The restoration of degraded forests is the focus of global attention. Effective restoration requires information on the condition of degraded forests. This study aimed to understand the conditions of illegally logged stands that had also experienced inappropriately short rotations between legal logging cycles in natural production forests in Myanmar. Four rectangular plots (each 0.64 ha) were established in 2013. The plots included illegally logged stumps in three compartments where the latest legal logging was conducted in 2011 after very short rotations between legal logging cycles (up to five harvests between 1995 and 2011, compared with a recommended 30-year logging cycle). Using data from the field measurements in 2013 on the legal and illegal stumps and living trees, we reconstructed stand structure just before and after legal logging in 2011. Before the legal logging in 2011, there were variations in stand structure and the composition of commercial species among four plots. Illegal logging (14&ndash;31 trees ha&minus;1) was much higher than legal logging (0&ndash;11 trees ha&minus;1). Illegal logging targeted six to nine species that were suitable for high-quality charcoal from various sized trees, while legal logging targeted one or two timber species with a diameter at breast height (DBH) larger than 58 cm. The number of remaining trees in 2013 ranged from 33 to 181 trees ha&minus;1. There was a negative relationship with the number of bamboo clumps, which varied from 6 to 145 clumps ha&minus;1. Bamboo-dominated stands with a low remaining stock of commercial trees may need active restoration such as bamboo cutting and replanting of commercial species. Bamboo cutting could generate income for the local community

Condition of Illegally Logged Stands Following High Frequency Legal Logging in Bago Yoma, Myanmar

The restoration of degraded forests is the focus of global attention. Effective restoration requires information on the condition of degraded forests. This study aimed to understand the conditions of illegally logged stands that had also experienced inappropriately short rotations between legal logging cycles in natural production forests in Myanmar. Four rectangular plots (each 0.64 ha) were established in 2013. The plots included illegally logged stumps in three compartments where the latest legal logging was conducted in 2011 after very short rotations between legal logging cycles (up to five harvests between 1995 and 2011, compared with a recommended 30-year logging cycle). Using data from the field measurements in 2013 on the legal and illegal stumps and living trees, we reconstructed stand structure just before and after legal logging in 2011. Before the legal logging in 2011, there were variations in stand structure and the composition of commercial species among four plots. Illegal logging (14–31 trees ha−1) was much higher than legal logging (0–11 trees ha−1). Illegal logging targeted six to nine species that were suitable for high-quality charcoal from various sized trees, while legal logging targeted one or two timber species with a diameter at breast height (DBH) larger than 58 cm. The number of remaining trees in 2013 ranged from 33 to 181 trees ha−1. There was a negative relationship with the number of bamboo clumps, which varied from 6 to 145 clumps ha−1. Bamboo-dominated stands with a low remaining stock of commercial trees may need active restoration such as bamboo cutting and replanting of commercial species. Bamboo cutting could generate income for the local community