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We report that repeated thermal perturbation by thermal cycling (TC) accelerates the formation rate of amyloid filaments at microliter volumes (10-200 μL) and produces a new conformation of zigzag-shaped filaments. The amyloid filaments have been synthesized under different TC conditions, such as temperature variations (Δ

Pacific herring (Clupea pallasii Valenciennes, 1847) is a commercially important species that inhabits the coastal waters of the North Pacific from Korea to California, USA. This study analyzed the target strength (TS, dB re 1 m2) of Pacific herring individuals (n = 14, total length (LT) = 21.3–32.3 cm) at 38 and 120 kHz using ex-situ measurements and the Kirchhoff-ray mode (KRM) model. The least-squares regressions of the TS–LT relationship for the ex-situ measurements were TS38kHz = 20 log10(LT) − 70.10 (r = 0.17) and TS120kHz = 20 log10(LT) − 70.59 (r = 0.10). The least-squares regressions for the KRM model were TS38kHz = 20 log10(LT) − 68.39 (r = 0.40) and TS120kHz = 20 log10(LT) − 69.74 (r = 0.49). The b20 value of the KRM model was 1.71 dB higher than that of the ex-situ measurement at 38 kHz but similar at 120 kHz. These results provide basic data to evaluate the distribution and abundance of Pacific herring using fisheries’ acoustic technology.

Melanoma is visible unlike other types of cancer, but it is still challenging to diagnose correctly because of the difficulty in distinguishing between benign nevus and melanoma. We conducted a robust investigation of melanoma, identifying considerable differences in local elastic properties between nevus and melanoma tissues by using atomic force microscopy (AFM) indentation of histological specimens. Specifically, the histograms of the elasticity of melanoma displayed multimodal Gaussian distributions, exhibiting the heterogeneous mechanical properties, in contrast with the unimodal distributions of elasticity in the benign nevus. We identified this notable signature was consistent regardless of blotch incidence by sex, age, anatomical site (e.g., thigh, calf, arm, eyelid, and cheek), or cancer stage (I, IV, and V). In addition, we found that the non-linearity of the force-distance curves for melanoma is increased compared to benign nevus. We believe that AFM indentation of histological specimens may technically complement conventional histopathological analysis for earlier and more precise melanoma detection.

The detection of circulating protein (CP) is very important for the diagnosis and therapeutics of cancer. Conventional techniques based on a specific antibody–antigen interaction are still lacking ...

Acoustic surveys were used to locate coastal Pacific herring (Clupea pallasii) spawning grounds, and the spatial and temporal patterns of their spawning in Jinhae Bay, Korea were examined. We deployed mooring with a newly designed autonomous echosounder for ~70 days during the Pacific herring spawning season in Jinhae Bay, from January to April 2018. At the same time, ship-based acoustic surveys were conducted to identify the spatial distribution twice, at 38 and 120 kHz, onboard the fishing vessel in January and April 2018 in the bay. Fish school signals, including those from adult Pacific herring, are often detected through ship-based acoustic surveys in January, from outside the bay. In the spring, weak scattering signals from fish larvae and zooplankton were continuously detected inside the bay. Backscatter at the mooring in the center of Jinhae Bay was low from mid-January to early March, gradually increasing to higher levels until the end of March. The backscatter observed from the mooring correlated well with ship-based acoustic surveys in the center of the bay. This study proposes that the mooring type acoustic echosounder is a valuable tool for temporal abundance information and other aspects of fish behavior.

Here, we demonstrate a powerful method to discriminate DNA mismatches at single-nucleotide resolution from 0 to 5 mismatches (χ0 to χ5) using Kelvin probe force microscopy (KPFM). Using our previously developed method, we quantified the surface potentials (SPs) of individual DNA-capped nanoparticles (DCNPs, ∼100 nm). On each DCNP, DNA hybridization occurs between ∼2200 immobilized probe DNA (pDNA) and target DNA with mismatches (tDNA, ∼80 nM). Thus, each DCNP used in the bioassay (each pDNA-tDNA interaction) corresponds to a single ensemble in which a large number of pDNA-tDNA interactions take place. Moreover, one KPFM image can scan at least dozens of ensembles, which allows statistical analysis (i.e., an ensemble average) of many bioassay cases (ensembles) under the same conditions. We found that as the χn increased from χ0 to χ5 in the tDNA, the average SP of dozens of ensembles (DCNPs) was attenuated owing to fewer hybridization events between the pDNA and the tDNA. Remarkably, the SP attenuation vs. the χn showed an inverse-linear correlation, albeit the equilibrium constant for DNA hybridization exponentially decreased asymptotically as the χn increased. In addition, we observed a cascade reaction at a 100-fold lower concentration of tDNA (∼0.8 nM); the average SP of DCNPs exhibited no significant decrease but rather split into two separate states (no-hybridization vs. full-hybridization). Compared to complementary tDNA (i.e., χ0), the ratio of no-hybridization/full-hybridization within a given set of DCNPs became ∼1.6 times higher in the presence of tDNA with single mismatches (i.e., χ1). The results imply that our method opens new avenues not only in the research on the DNA hybridization mechanism in the presence of DNA mismatches but also in the development of a robust technology for DNA mismatch detection.

Molybdenum disulfide (MoS2) field-effect transistor (FET)-based biosensors have attracted significant attention as promising candidates for highly sensitive, label-free biomolecule detection devices. In this paper, toward practical applications of biosensors, we demonstrate reliable and quantitative detection of a prostate cancer biomarker using the MoS2 FET biosensor in a nonaqueous environment by reducing nonspecific molecular binding events and realizing uniform chemisorption of anti-PSA onto the MoS2 surface. A systematic and statistical study on the capability of the proposed device is presented, and the biological binding events are directly confirmed and characterized through intensive structural and electrical analysis. Our proposed biosensor can reliably detect various PSA concentrations with a limit of 100 fg/mL. Moreover, rigorous theoretical simulations provide a comprehensive understanding of the operating mechanism of the MoS2 FET biosensors, and further suggests the enhancement of the sensitivity through engineering device design parameters.

Biological processes related to amyloid-β (Aβ ) aggregation and deposition are associated with the onset of Alzheimer’s disease. Although these processes are attributed to electrostatic interactions between the Aβ42 sequences, the electrical properties of Aβ aggregates (i.e., oligomers and fibrils) have not yet been fully explored despite their importance. Here, we investigated the nanoelectrical properties (i.e., surface potential) of Aβ42 aggregates using Kelvin probe force microscopy (KPFM) and found that the surface potential of the Aβ42 aggregates was changed from positive to negative with pH, passing across zero surface potential at pH=5.2-5.4. The measured surface potentials were ranged from 48 to -35 mV/nm for both the oligomers and the fibrils. From our observations, we determined the isoelectric points (pIs) of both cases. Using the commercial software PyMOL, we also converted the surface potential of a single monomorphic Aβ42 fibril; in the simulation, we calculated the net charges of the monomorphic fibrils depending on pH, predicted its pI by Boltzmann curve fitting, and compared these results with our experimental KPFM data.

Red blood cell (RBC) dysfunction is often associated with a pathological intervention, and it has been proposed as a critical risk factor for certain lethal diseases. Examining the cell viability of RBCs under various physiological conditions is essential and of importance for precise diagnosis and drug discovery in the field of medicine and pharmacy. In this paper, we report a new analytical method that employs dielectrophoretic (DEP) force measurements in absolute units to assess the viability, and potentially the functionality of RBCs. We precisely quantify the frequency-dependent DEP forces of the RBCs by using a micro-electrode embedded chip combined with optical tweezers. DEP characteristics are known to be well-correlated with the viability of biological cells, and DEP forces are measured in both fresh and long-term stored RBCs to investigate the effect that the storage period has on the cell viability. Moreover, we investigate the DEP behavior of RBCs when exposed to oxidative stress and verify whether EDTA protects the RBCs from an oxidant. From the experiments, it is found that the fresh RBCs without oxidative stress display very high DEP forces over the entire frequency range, exhibiting two cutoff frequencies. However, both the RBCs stored for the long-term period and exposed to oxidative stress reveals that there exist no significant DEP forces over the frequency range. The results indicate that the DEP forces can serve as a useful parameter to verify whether the RBCs in certain blood are fresh and not exposed to oxidative stress. Therefore, it is believed that our system can be applied to a diagnostic system to monitor the cell viability of the RBCs or other types of cells.

High-temporal resolution profiles of acoustic backscatter were collected from a traditional bamboo set net along the coast of the Southern Sea, Korea, using sideward-looking multi-beam imaging sonar. These data were used to examine the impact of variations in tidal cycles and current speeds on the bamboo set net. The relatively high influx of fish during the nighttime compared to the low influx and high outflux of fish during the daytime suggests visual avoidance of the net by the fish during the daytime. The observed diel variation in the captured fish flux was significantly correlated with the current speed (day: r = 0.35, p = 0.002, night: r = 0.60, p < 0.001). The ratio of influx and outflux of fish, and current speed were correlated in a linear relationship (day: r = 0.45, p < 0.001; night: r = 0.56, p < 0.001). The fish activity of those inhabiting the bamboo set nets appears to be greatly influenced by day-night differences and current speed. The present study enhances understanding of fish behavior via utilization of a bamboo set net in the coastal zone.

Aberrant expression of microRNA (miRNA) in biological cells is crucial evidence for early diagnosis of cancer. Improvements in molecular detection techniques enabled miRNA to be detected in human blood obtained from liquid biopsies (e.g., Polymerase chain reaction, microcantilever sensor, and surface-enhanced Raman spectroscopy). Despite the advances in molecular detection technology, a simultaneous detection of single or multiple mutations of miRNAs is still a challenge. Here, we show electrostatic force microscopy (EFM) imaging of DNA-capped gold nanoparticles (DCNP) that enables discrimination between single and three-nucleotide polymorphism (SNP, TNP): 1 and 3-point mismatched nucleotides in miRNA-21 (M1_RNA, M3_RNA). Detection of the miRNA-21 and their mutant sequence is owing to sterically well-adjusted DNA–RNA interactions that take place within the confined spaces of DCNP. The average absolute EFM amplitudes of DCNP interacting with M1_RNA, and M3_RNA (− 81.0 ± 11.5, and − 65.7 ± 8.2 mV) were found to be lower than the DCNP reacting with normal (non-mutant) miRNA-21 (− 100.2 ± 13.6 mV).

The detection of circulating protein (CP) is very important for the diagnosis and therapeutics of cancer. Conventional techniques based on a specific antibody-antigen interaction are still lacking because of a shortage of cost effectiveness, complicated sandwich structure and tagging process, and inconsistent detection of CP due to the inherent instability of antibodies. Herein, we demonstrate a hybrid device consisting of two-dimensional (2D) nanoscale molybdenum disulfide (MoS

With the rapid development of nanotechnology and its associated waste stream, public concern is growing over the potential toxicity exposure to heavy metal ions poses to the human body and the environment. Herein, we report an extremely sensitive Kelvin probe force microscopy (KPFM)-based platform for detecting nanotoxic materials (e.g. Ag+) accomplished by probing the integrated surface potential differences of a single gold nanoparticle on which an interaction between probe DNA and target DNA occurs. This interaction can amplify the surface potential of the nanoparticle owing to the coordination bond mediated by Ag+ (cytosine-Ag+-cytosine base pairs). Interestingly, compared with conventional methods, this platform is capable of extremely sensitive Ag+ detection (∼1 fM) in a remarkably wide-range (1 fM to 1 μM). Furthermore, this platform enables Ag+ detection in a practical sample (general drinking water), and this KPFM-based technique may have the potential to detect other toxic heavy metal ions and single nucleotide polymorphisms by designing specific DNA sequences.

Various approaches have been proposed for point-of-care diagnostics, and in particular, optical detection is preferred because it is relatively simple and fast. At the same time, field-effect transistor (FET)-based biosensors have attracted great attention because they can provide highly sensitive and label-free detection. In this work, we present highly sensitive, epidermal skin-type point-of-care devices with system-level integration of flexible MoS2 FET biosensors, read-out circuits, and light-emitting diode (LEDs) that enable real-time detection of prostate cancer antigens (PSA). Regardless of the physical forms or mechanical stress conditions, our proposed high-performance MoS2 biosensors can detect a PSA concentration of 1 pg·mL–1 without specific surface treatment for anti-PSA immobilization on the MoS2 surface on which we characterize and confirm physisorption of anti-PSA using Kelvin probe force microscopy (KPFM) and tapping-mode atomic force microscopy (tm-AFM). Furthermore, current modulation induced by the binding process was stably maintained for longer than 2–3 min. The results indicate that flexible MoS2-based FET biosensors have great potential for point-of-care diagnostics for prostate cancer as well as other biomarkers.

Ascorbic acid, which is widely used as a therapeutic agent for various disorders (e.g. chronic diseases and cancers), has potential therapeutic roles for neurodegenerative disease such as Huntington’s, Parkinson’s and Alzheimer’s diseases. The ability to impede amyloid fibril formation has a great demand on developing clinical medicine with respect to successfully preventing neurodegenerative diseases. Here, we report that L-ascorbic acid inhibits β-lactoglobulin amyloid formation in vitro. For quantitative characterization of the inhibitory effect of L-ascorbic acid on fibrillation, we performed high-resolution atomic force microscopy and thioflavin T fluorescence assay. Fourier transform infrared spectra indicated secondary structure differences of fibrils formed with and without ascorbic acid. These results suggest great potential of ascorbic acid for use in the prevention or treatment of amyloidogenic diseases. Open image in new window

This study investigated a method for monitoring fish flux though a set net in the coastal South Sea, Korea, using sideward-looking wide angle multi-beam imaging sonar (blueview). This data set was used to examine the impact of changes in diel variation and current speed from a set net. During nighttime, the influx of fish in the set net was significantly 22 times higher than in daytime. The time when high fish flux was observed corresponded to the time of low current speed during nighttime. In contrast, the fish flux was not affecting current speed during daytime. The study provides implications for understanding fish behavior through use of a set net.

Understanding of the interactions of silver ions (Ag+) with polynucleotides is important not only to detect Ag+ over a wide range of concentrations in a simple, robust, and high-throughput manner but also to investigate the intermolecular interactions of hydrogen and coordinate interactions that are generated due to the interplay of Ag+, hydrogen ions (H+), and polynucleotides since it is critical to prevent adverse environmental effects that may cause DNA damage and develop strategies to treat this damage. Here, we demonstrate a novel approach to simultaneously detect Ag+ satisfying the above requirements and examine the combined intermolecular interactions of Ag+–polycytosine and H+–polycytosine DNA complexes using dielectrophoretic tweezers-based force spectroscopy. For this investigation, we detected Ag+ over a range of concentrations (1 nM to 100 μM) by quantifying the rupture force of the combined interactions and examined the interplay between the three factors (Ag+, H+, and polycytosine) using the...

Nemopilema nomurai jellyfish, which are believed to complete their development in the East China Sea, have started migrating into the Yellow Sea in recent years. We obtained biomass estimates of this species in the Yellow Sea using bottom trawl fishing gear and sighting surveys over a 5-year period. These methods are effective for obtaining N. nomurai jellyfish density estimates and information about the community distribution near the bottom or surface of the sea. To verify the vertical distributions of giant jellyfish between, we used hydroacoustic equipment, including an optical stereo camera system attached to a towed sledge and an echo counting method with scientific echosounder system. Acoustic and optical data were collected while the vessel moved at 3 knots, from which the distribution and density of N. nomurai jellyfish were analyzed. Subsequently, the camera system was towed from a 7 m mean depth to sea level, with the detection range of the acoustic system extending from an 8 m depth to the bottom surface. The optical and acoustic methods indicated the presence of vertical distribution of 0.113 (inds/m3) and 0.064 (inds/m3), respectively. However, the vertical distribution indicated that around 93% of individuals occurred at a depth range of 10–40 m; thus, a 2.4-fold greater density was estimated by acoustic echo counting compared to the optical method.

To study the absorption characteristics of rhodopsin, a dim-light photoreceptor, in chub mackerel (Scomber japonicus) and the relationship between light wavelengths on the photoresponse, the rod opsin gene was cloned into an expression vector, pMT4. Recombinant opsin was transiently expressed in COS-1 cells and reconstituted with 11-cis-retinal. Cells containing the regenerated rhodopsin were solubilized and subjected to UV/Vis spectroscopic analysis in the dark and upon illumination. Difference spectra from the lysates indicated an absorption maximum of mackerel rhodopsin around 500 nm. Four types of light-emitting diode (LED) modules with different wavelengths (red, peak 627 nm; cyan, 505 nm; blue, 442 nm; white, 447 + 560 nm) were constructed to examine their effects on the photoresponse in chub mackerel. Behavioral responses of the mackerels, including speed and frequencies acclimated in the dark and upon LED illumination, were analyzed using an underwater acoustic camera. Compared to an average speed of 22.25 ± 1.57 cm/s of mackerel movement in the dark, speed increased to 22.97 ± 0.29, 24.66 ± 1.06, 26.28 ± 2.28, and 25.19 ± 1.91 cm/s upon exposure to red, blue, cyan, and white LEDs, respectively. There were increases of 103.48 ± 1.58, 109.37 ± 5.29, 118.48 ± 10.82, and 109.43 ± 3.92 %, respectively, in the relative speed of the fishes upon illumination with red, blue, cyan, and white LEDs compared with that in the dark (set at 100 %). Similar rate of wavelength-dependent responses was observed in a frequency analysis. These results indicate that an LED emitting a peak wavelength close to an absorption maximum of rhodopsin is more effective at eliciting a response to light.

In recent years, Kelvin probe force microscopy (KPFM) has emerged as a versatile toolkit for exploring electrical properties on a broad range of nanobiomaterials and molecules. An analysis using KPFM can provide valuable sample information including surface potential and work function of a certain material. Accordingly, KPFM has been widely used in the areas of material science, electronics, and biomedical science. In this review, we will briefly explain the setup of KPFM and its measuring principle and then survey representative results of various KPFM applications ranging from material analysis to device analysis. Finally, we will discuss some possibilities of KPFM on whether it is applicable to various sensor systems. Our perspective shed unique light on how KPFM can be used as a biosensor as well as equipment to measure electrical properties of materials and to recognize various molecular interactions.

Volume backscattering strength (Sv in dB re 1 m−1) of ice krill (Euphausia crystallorophias) was observed at two frequencies (38 and 120 kHz) with a calibrated split-beam echosounder system in the Amundsen Sea coastal polynya. The horizontal and vertical scattering layers in the upper 200 m of the water column were known with the existence of predominant ice krill (>95%) in this region. Acoustic identification using a two-frequency dB window between Sv at 38 and Sv at 120 kHz separated echoes originating from dominant ice krill from other zooplankton species. The frequency dependence of ice krill at 38 and 120 kHz was examined and the result presented that ice krill might have different acoustic characteristics from other Southern Ocean zooplankton species including Euphausia superba. This result could be applied to improve the ability of acoustic identification and precise density estimation of ice krill in the high-latitude coastal waters of Antarctica.

This study examined the spatiotemporal distribution of demersal fish aggregations in the Northern East China Sea by conducting a trawl survey with hydroacoustic devices. A bottom trawl was used for this survey and fish density was determined from the catch data. Acoustic data were collected at frequencies of 38 and 200 kHz from November to December 2014 and converted into the nautical area scattering coefficient (NASC, ). In the catch data analysis, the range of catch per unit area by station was and for the acoustic data, that of the NASC was . The values were significantly correlated. The combined results of both surveys found that the density was highest at St. 5 ( 10.3', 23.3') and lowest at St. 8 ( 20.7', 36.3'). The application of hydroacoustic methods offers a new approach for estimating the biomass of demersal fish aggregations.

In this study, we developed a gDNA extraction method using magnetic beads (MBs) and an ultrasonic transducer. The ultrasonic wave maximizes the effective surface area of MBs and generates vigorous turbulence which were promoted the lysis of the WBCs and the gDNA capturing. In addition, it removes the impurities that may remain in the clusters of MBs due to the aggregation of MBs, thereby increasing the purity of extracted gDNA and increasing the efficiency of gDNA amplification. The vigorous dispersion of MBs by the ultrasonic wave can increase the temperature in the chamber by more than 50℃ in a short time to promote the gDNA elution reaction. From this method, gDNA was extracted successfully with 1 μl of whole blood from six different people, and the quantity of gDNA extracted from 1 μl of whole blood was in the range of 10 to 52 μg/ml. The total extraction time was less than 8 min, which was much faster than the conventional 1.5-tube based method (45 min).

The surface potential of nanoparticles plays a key role in numerous applications, such as drug delivery and cellular uptake. The estimation of the surface potential of nanoparticles as drug carriers or contrast agents is important for the design of nanoparticle-based biomedical platforms. Herein, we report the direct measurement of the surface potential of individual gold nanorods (GNRs) via Kelvin probe force microscopy (KPFM) at the nanoscale. GNRs were capped by a surfactant, cetyltrimethylammonium bromide (CTAB), which was removed by centrifugation. CTAB removal is essential for GNR-based biomedical applications because of the cytotoxicity of CTAB. Applying KPFM analysis, we found that the mean surface potential of the GNRs became more negative as the CTAB was removed from the GNR. The results indicate that the negative charge of GNRs is covered by the electrostatic charge of the CTAB molecules. Similar trends were observed in experiments with gold nanospheres (GNS) capped by citrates. Overall, KPFM-based techniques characterize the surfactant of individual nanoparticles (i.e. GNR or GNS) with high resolution by mapping the surface potential of a single nanoparticle, which aids in designing engineered nanoparticles for biomedical applications.

This study investigated the variations in the sound-scattering layer (SSL) that were reflected from the mesozooplankton communities around the Northwind Ridge in the western Arctic Ocean. A multi-frequency acoustic survey was conducted to reveal the SSL distribution dominated by Arctic copepods in the early summer of 2010. The SSL distribution was well correlated with the salinity, nutrients and chlorophyll a (chl-a) associated with the features of the Pacific Summer Water (PSW). The SSL was observed primarily in the uppermost 100 m of the PSW, which provided a desirable habitat for Arctic copepods due to high nutrients and phytoplankton biomass. The highest density SSL was observed in the eddy-like structure of the PSW, which is most likely because of the high nutrients and chl-a. High regional densities in the SSL indicated that Arctic copepods provide a large portion of the biomass and contribution to the food webs in the PSW, in the western Arctic Ocean.

The Yellow Sea, characterized by a high concentration of suspended solids, is a semi-enclosed, marginal sea and shallow water in the northwestern Pacific Ocean, located between the Korean Peninsula and China. In this paper, we describe the response of acoustically determined weighted mean depth (WMD) of the krill, Euphausia pacifica, to variations in suspended solid concentration (SSC) during the daytime in spring and summer. E. pacifica was identified from the difference in the volume backscattering strength at 38 and 200 kHz. Our results indicated a correlation between the WMD of E. pacifica and the density of SSC during the daytime in both spring and summer. E. pacifica aggregation was distributed mainly near the bottom when the SSC was relatively low, but did not descend to the bottom when the SSC was relatively high. This implies that the SSC may be an important environmental factor affecting the behavior of E. pacifica.

The worldwide abundance of various jellyfish appears to have increased in coastal ecosystems in recent years. The enormous jellyfish blooms cause a variety of problems for the local ecology, fisheries, and aquatic-sports in coastal locations. In this study, jellyfish sting protection net was installed to ensure the safety and reduction of the inflow into the Haeundae beach. In order to confirm the stability of the protection net, the tension for protection net was measured from variation of current speed. The periods for maximum tension were observed correspond to the periods of maximum current speed. The maximum tension for protection net was measured up to 4,100 kg. From field evaluations, the jellyfish sting protection net has demonstrated to stability from the current and tide in the Haeundae beach.

국내 내수면은 하천의 수위 유지 및 농업용수 공급을 위한 보 부터 수자원의 효율적인 관리 및 발전소 운영을 위한 다목적 댐 에 이르기까지 다양한 규모의 수리 구조물이 축조되어 있다. 그 중 용담호는 2001년 용담댐이 준공되어 생성된 인공호수로 서 해안 지역의 효율적인 수자원으로 사용되고 있다. 2000년 이전 용담호는 얕은 수심 및 빠른 유속의 계류성 하천이었으나, 용담 댐 완공 이후 완만한 유속 및 정체로 인한 오염 물질의 퇴적 현 상으로 생태계 큰 변화가 진행되고 있는 수역이다(Lee et al., 2009). 특히 용담댐 건설 이후 서식지의 수몰로 인한 고유 어종 의 서식지 감소와 블루길과 배스 등 외래종의 유입으로 생태계 교란이 진행되고 있다(Yang et al., 2012). 국내에서 육상 담수역 및 해양에서 어류의 시·공간적인 분포 파악을 위한 조사는 1960년 이후 현재까지 주로 어구어업으로 진행되고 있다(Choi, 1971; Huh, 1986; Cha et al., 2004). 용담 호 또한 2000년 이후 낚시, 투망, 족대, 일각망 등의 어구 조사 를 통해서 어류의 종조성 및 분포 특성에 대한 연구가 진행되고 있다(Lee et al., 2009; Yang et al., 2012). 이러한 전통적인 채집 방법은 정성적인 자료 측면에서 많은 장점이 있지만, 한정된 채 집 면적 및 수층 제한성이라는 측면에서 정량적인 자료 도출에 오차를 만들어 낼 가능성이 높다. 정성 분석이 치우친 어구 채집 방법의 문제점을 극복하기 위한 방법 중 하나인 생물 음향 기법 은 1980년대 초 제시되어 국내에서는 1990년대 이후 주로 해양 생물의 분포 및 자원량 조사에 활발히 적용되고 있다(Kang et al., 2003; Lee et al., 2014). 생물 음향조사는 국외에서 해양 생태계뿐만 아니라 호수 및 저수지와 같은 담수 환경에서 어류 분포의 정량적인 평가와 대 상 어류의 모니터링 및 생태학에 관한 연구에 적용되고 있다 (Godleska and Jelonek, 2006; Knudsen and Larsson, 2009). 생물 음향 기법의 특징은 연구자의 주관을 배제시키고 사전에 설정된 음향 조사 정선으로부터 연속적이며 전 수층에 대한 객 수중음향기법을 이용한 용담호의 어류 분포특성 연구 이형빈·이경훈*·김성훈·김인옥·강돈혁

Ice krill is the keystone species in the neritic ecosystem in the Southern Ocean, where it replaces the more oceanic Antarctic krill. It is essential to understand the variation of target strength (TS in dB re 1 m2) with the different body size to accurately estimate ice krill stocks. However, there is comparatively little knowledge of the acoustic backscatter of ice krill. The TS of individual, formalin-preserved, tethered ice krill was measured in a freshwater test tank at 38, 120, and 200 kHz with a calibrated split-beam echo sounder system. Mean TS was obtained from 21 individual ice krill with a broad range of body lengths (L: 13–36 mm). The length (L, mm) to wet weight (W; mg) relationship for ice krill was W=0.001218×103 × L3.53 (R2 =0.96). The mean TS-to-length relationship were TS38 kHz =−177.4+57log10 (L), (R2 = 0.86); TS120 kHz = −129.9+31.56log10 (L), (R2 =0.87); and TS200 kHz =−117.6+24.66log10 (L), (R2 =0.84). Empirical estimates of the relationship between the TS and body length of ice krill were established at 38, 120, and 200 kHz and compared with predictions obtained from both the linear regression model of Greene et al. (1991) and the Stochastic Distorted Wave Born Approximation (SDWBA) model. This result might be applied to improve acoustic detection and density estimation of ice krill in the Southern Ocean. Further comparative studies are needed with in situ target strength including various body lengths of ice krill.

Matrix metalloproteinase (MMP) is a key marker and target molecule for cancer diagnosis, as MMP is able to cleave peptide chains resulting in degradation of extracellular matrix (ECM), a necessary step for cancer development. In particular, MMP2 has recently been recognized as an important biomarker for lung cancer. Despite the important role of detecting MMP molecules in cancer diagnosis, it is a daunting task to quantitatively understand a correlation between the status of cancer development and the secretion level of MMP in a blood droplet. Here, we demonstrate a nanoscale cancer diagnosis by nanomechanical quantitation of MMP2 molecules under cancer progression with using a blood droplet of lung cancer patients. Specifically, we measured the frequency dynamics of nanomechanical biosensor functionalized with peptide chains mimicking ECM in response to MMP2 secreted from tumors in lung with different metastasis level. It is shown that the frequency shift of the biosensor, which exhibits the detection sensitivity below 1 nM, enables the quantitation of the secretion level of MMP2 molecules during the progression of cancer cells or tumor growth. More importantly, using a blood droplet of lung cancer patients, nanomechanical biosensor is shown to be capable of depicting the correlation between the secretion level of MMP2 molecules and the level of cancer metastasis, which highlights the cantilever-based MMP2 detection for diagnosis of lung cancer. Our finding will broaden the understanding of cancer development activated by MMP and allow for a fast and point-of-care cancer diagnostics.

우리나라 황해 내만 및 연안역은 생물의 다양성이 높은 해역 으로 어류의 산란장 및 보육장으로 이용된다(Kim et al., 1994; Lee and Hwang, 1995). 그 중 아산만은 갯벌이 넓게 발달되어 있어 갑각류와 무척추 동물이 대량으로 서식하여 다양한 연안 어류 및 회유성 어류에 좋은 서식처로 생태계에 매우 중요한 역 할을 담당하는 해역이다(Cha et al., 2013). 하지만 1970년대 이 후 방조제 건설 및 공업 단지의 조성 등의 지속적인 산업화 활 동에 의한 환경 오염의 증가로 해양 생물의 서식처가 위협받고 있는 해역이다(Kim et al., 1994). 또한 아산만 및 남양만 인근 해역은 삽교 및 아산방조제, 서해대교, 남양방조제, 화용방조 제, 석문지구방조제 등의 건설과 석문공단, 인주공단 등 시설 공사로 인한 해양 환경의 변동이 높아 어류의 분포 및 자원량 에 영향을 미칠 가능성이 높은 해역으로 알려져 있다(Lee and Hwang, 1995). 국내에서 해양 및 육상 담수역에서 수산자원의 시·공간 분포 및 자원량 파악을 위한 과학적인 조사는 1960년 이후 현재까지 주로 어구 어업을 이용하였다(Choi, 1971; Huh, 1986; Cha et al., 2004). 어구 조사시 어란 및 유생은 봉고 네트로, 어류 유생 및 성체는 중층 및 저층 트롤과 같은 대형 어구로 채집 후 종조 성 및 체장 특성을 파악하였다. 1990년 이후로는 어류 자원량 추정 모델을 이용하는 간접적인 방법으로 자원량 변동을 추정 하였다(Jang et al., 1992; Choi et al., 1999). 아산만 인근의 어 수산음향기법을 이용한 아산만 멸치(Engraulis japonicus)와 기타어군의 분포 및 현존량 추정 이형빈·강돈혁*·임양재·이경훈