The influence of α and α' subunits on SPI Pickering emulsions based on natural hybrid breeding varieties.

In this study, food-grade protein nanoparticles (Wild-NPs, α-lack-NPs, α'-lack-NPs, and (α + α')-lack-NPs) were organized as emulsion stabilizers via thermal induction. The effects of α and α' subunits in soybean protein isolate (SPI) on Wild nanoparticle Pickering emulsion (Wild-NPPEs), α-lack nanoparticle Pickering emulsion (α-lack-NPPEs), α'-lack nanoparticle Pickering emulsion (α'-lack-NPPEs) and (α + α')-lack nanoparticle Pickering emulsion ((α + α')-lack-NPPEs) were investigated. The Pickering emulsion stabilization mechanism indicated that the α'-lack-NPs particle size, surface hydrophobicity, and contact angle were mostly comparatively large. Therefore, the absence of the α' subunit made the desorption of protein nanoparticles at the oil and water interface require higher energy. Through the hydrophobic interaction between molecules, the structure and properties of the emulsion were improved, showing good stability. The existence of α'-lack-NPPEs leads to the formation of a gel-like network in the emulsion, which increases the viscosity of the emulsion and makes the network structure of the emulsion more uniform and denser.

Discovering covalent inhibitors of protein-protein interactions from trillions of sulfur(VI) fluoride exchange-modified oligonucleotides.

Molecules that covalently engage target proteins are widely used as activity-based probes and covalent drugs. The performance of these covalent inhibitors is, however, often compromised by the paradox of efficacy and risk, which demands a balance between reactivity and selectivity. The challenge is more evident when targeting protein-protein interactions owing to their low ligandability and undefined reactivity. Here we report sulfur(VI) fluoride exchange (SuFEx) in vitro selection, a general platform for high-throughput discovery of covalent inhibitors from trillions of SuFEx-modified oligonucleotides. With SuFEx in vitro selection, we identified covalent inhibitors that cross-link distinct residues of the SARS-CoV-2 spike protein at its protein-protein interaction interface with the human angiotensin-converting enzyme 2. A separate suite of covalent inhibitors was isolated for the human complement C5 protein. In both cases, we observed a clear disconnection between binding affinity and cross-linking reactivity, indicating that direct search for the aimed reactivity-as enabled by SuFEx in vitro selection-is vital for discovering covalent inhibitors of high selectivity and potency.

Effects of Exogenous Lanthanum Nitrate on the Active Substance Content and Antioxidant Activity of Caterpillar Medicinal Mushroom Cordyceps militaris (Ascomycetes).

Cordyceps militaris is a medicinal and edible mushroom. Researchers often add exogenous substances to the culture medium to increase the active substance content in C. militaris. However, the effect of earth elements on the active substance content in C. militaris and its antioxidant effects have not been reported. In this study, the active substance content in C. militaris treated with lanthanum nitrate was determined using high-performance liquid chromatography and ultraviolet spectrophotometry, and the effect on the antioxidant capacity of C. militaris after lanthanum nitrate spraying was further explored. The results showed that, in the experimental concentration range, the two concentrations of 10 mg/L and 50 mg/L had a significant influence on the active substance content of C. militaris. When the concentration of lanthanum nitrate was 10 mg/L, the synthesis of pentostatin and cordycepin was promoted. When the concentration of lanthanum nitrate was 50 mg/L, it significantly promoted the synthesis of cordycepin, and the ferric-reducing power and DPPH· scavenging rate of C. militaris treated at this concentration were significantly higher than those of the control group. However, lanthanum nitrate had no significant effect on ergosterol synthesis (P > 0.05). Finally, considering that the residual amount of lanthanum in C. militaris and the residual amount of lanthanum in 50 mg/L lanthanum nitrate-treated C. militaris is within the allowable daily intake of 4.2 mg for humans, the optimal concentration of lanthanum nitrate-treated C. militaris is 50 mg/L.

Effects of Soybean Trypsin Inhibitor on Pancreatic Oxidative Damage of Mice at Different Growth Periods.

The bioactive components in soybeans have significant physiological functions. However, the intake of soybean trypsin inhibitor (STI) may cause metabolic disorders. To investigate the effect of STI intake on pancreatic injury and its mechanism of action, a five-week animal experiment was conducted, meanwhile, a weekly monitor on the degree of oxidation and antioxidant indexes in the serum and pancreas of the animals was carried out. The results showed that the intake of STI had irreversible damage to the pancreas, according to the analysis of the histological section. Malondialdehyde (MDA) in the pancreatic mitochondria of Group STI increased significantly and reached a maximum (15.7 nmol/mg prot) in the third week. Meanwhile, the antioxidant enzymes superoxide dismutase (SOD), glutathione peroxidase (GSH-Px), trypsin (TPS), and somatostatin (SST) were decreased and reached minimum values (10 U/mg prot, 87 U/mg prot, 2.1 U/mg prot, 10 pg/mg prot) compared with the Group Control. The RT-PCR results of the expression of SOD, GSH-Px, TPS, and SST genes were consistent with the above. This study demonstrates that STI causes oxidative structural damage and pancreatic dysfunction by inducing oxidative stress in the pancreas, which could increase with time.

Clinical Efficacy of Minocycline Hydrochloride for the Treatment of Peri-Implant Disease: A Systematic Review With Meta-Analysis of Randomized Controlled Trials.

This systematic review aimed to assess the clinical efficacy of the local application of minocycline hydrochloride for treating peri-implantitis. Four databases-PubMed, EMBASE, Cochrane Library, and China National Knowledge Infrastructure-were searched from their inception through December 2020. English and Chinese randomized controlled trials (RCTs) that compared minocycline hydrochloride with control regimes, including negative control, iodine solution or glycerin, and chlorhexidine, for patients with peri-implant diseases were retrieved. Three outcomes-plaque index (PLI), probing depth (PD), and sulcus bleeding index (SBI)-were assessed using meta-analysis based on the random-effects model. Fifteen RCTs were included in the present meta-analysis, and results suggested that minocycline hydrochloride significantly affected PLI, PD, or SBI reduction regardless of the type of comparator regime. However, subgroup analyses suggested that minocycline hydrochloride was not superior to chlorhexidine in terms of reduction of PLI (1 week: MD = -0.18, 95% CI = -0.55 to 0.20, P = .36; 4 weeks: MD = -0.08, 95% CI = -0.23 to 0.07, P = .28; 8 weeks: MD = -0.01, 95% CI = -0.18 to 0.16, P = .91) and PD (1 week: MD = 0.07, 95% CI = -0.27 to 0.41, P = .68; 4 weeks: MD = -0.10, 95% CI = -0.43 to 0.24, P = .58; 8 weeks: MD = -0.30, 95% CI = -0.68 to 0.08, P = .12), and minocycline hydrochloride was also not better than chlorhexidine regarding reduction of SBI at 1 week after treatment (MD = -0.10; 95% CI = -0.21 to 0.01; P = .08). This study concludes that minocycline hydrochloride as adjuvant therapy of nonsurgical treatment enhances the clinical results when compared to control regimes. However, the difference between minocycline hydrochloride and chlorhexidine should be further investigated by designing additional high-quality studies with large sample sizes.

Characterization of the physicochemical, thermal and rheological properties of cashew kernel starch.

The study aimed to characterize physicochemical, thermal, and rheological properties of cashew nut starch (CNS) and then compare the obtained results with the properties of potato and corn starches. CNS showed higher gelatinization temperatures (112.29 °C) than those noted for potato and maize starches (78.44-94.65 °C). In addition, CNS had higher peak viscosity (19.03 mPa·s) than high amylose corn starch. The static shear rheological test indicated that the CNS followed a pseudoplastic behavior. In addition, CNS sample showed a thixotropic patter, which was less pronounced than that observed for potato starch, but higher than the value reported for high amylose corn starch. These results demonstrated that the shear resistance of CNS was lower than high amylose corn starch, but higher than potato starch. The storage and loss modulus (G' and G", respectively) of the CNS were higher than those reported for the rest of samples. In this line, elastic properties were predominant in CNS sample. In conclusion, results from this study provided insight into physicochemical and structural properties of cashew nut starch, which could represent a preliminary step for its future application in food processing.

Selection and identification of high-affinity aptamer of Kunitz trypsin inhibitor and their application in rapid and specific detection.

Kunitz trypsin inhibitor (KTI), a harmful protein, seriously affects food hygiene and safety. Therefore, a sensitive, efficient, and rapid method for KTI detection is urgently needed. Aptamers are short and single-stranded (ss) DNA that recognize target molecules with high affinity. This work used graphene oxide-SELEX (GO-SELEX) to screen KTI aptamers. The positive and reverse screening was designed to ensure the high specificity and affinity of the selected aptamers. After 10 rounds of screening, multiple nucleic acid chains were obtained, and the chains were sequenced. Three aptamers with better affinity were obtained, and the values of the dissociation constant (K d) were calculated to be 52.6 nM, 22.7 nM, and 67.9 nM, respectively. Finally, a colorimetric aptamer biosensor based on gold nanoparticles (AuNPs) was constructed. The biosensor exhibited a broader linear range of 30-750 ng/ml, with a lower detection limit of 18 ng/ml, and the spiked recovery rate was between 98.2% and 103.3%. This experiment preliminary demonstrated the potential of the application of KTI aptamer in the real sample tests.

How Do Anchors' Characteristics Influence Consumers' Behavioural Intention in Livestream Shopping? A Moderated Chain-Mediation Explanatory Model.

Livestream shopping has become the focus of current marketing practises, while theoretical research on it is still in initial stages. Thus, from the para-social interaction (PSI) theory perspective, this study draws on cognitive-affective system theory as an analytical framework to explore internal mechanisms of how anchors' characteristics influence consumer behavioural intentions in livestream shopping while considering the characteristics of consumer online interaction propensity. We conducted a survey questionnaire with a sample of 355 consumers who experienced livestream shopping and used structural equation modelling to assess their behavioural intentions. Our results reveal that anchors' physical attractiveness, social attractiveness, and professional ability influence consumers' intentions to follow the authors' suggestions and recommend anchors to others during live streams. PSI and affective trust in anchors are the chain-mediation mechanisms. Furthermore, consumers' online interaction propensity positively moderates the influence of anchors' characteristics on PSI and plays a moderating role on the whole chain mediation. However, this only affects anchors' physical attractiveness and social attractiveness while exert no effect on anchors' professional ability. This study advances the theoretical research on livestream shopping and provides practical inspiration for managers to develop more targeted livestream marketing strategies.

Chemical synthesis of stimuli-responsive guide RNA for conditional control of CRISPR-Cas9 gene editing.

CRISPR-Cas9 promotes changes in identity or abundance of nucleic acids in live cells and is a programmable modality of broad biotechnological and therapeutic interest. To reduce off-target effects, tools for conditional control of CRISPR-Cas9 functions are under active research, such as stimuli-responsive guide RNA (gRNA). However, the types of physiologically relevant stimuli that can trigger gRNA are largely limited due to the lack of a versatile synthetic approach in chemistry to introduce diverse labile modifications into gRNA. In this work, we developed such a general method to prepare stimuli-responsive gRNA based on site-specific derivatization of 2'-O-methylribonucleotide phosphorothioate (PS-2'-OMe). We demonstrated CRISPR-Cas9-mediated gene editing in human cells triggered by oxidative stress and visible light, respectively. Our study tackles the synthetic challenge and paves the way for chemically modified RNA to play more active roles in gene therapy.

Wavelength-Selective Activation of Photocaged DNAzymes for Metal Ion Sensing in Live Cells.

RNA-cleaving DNAzymes are widely applied as sensors for detecting metal ions in environmental samples owing to their high sensitivity and selectivity, but their use for sensing biological metal ions in live cells is challenging because constitutive sensors fail to report the spatiotemporal heterogeneity of biological processes. Photocaged DNAzymes can be activated by light for sensing purposes that need spatial and temporal resolution. Studying complex biological processes requires logic photocontrol, but unfortunately all the literature-reported photocaged DNAzymes working in live cells cannot be selectively controlled by light irradiation at different wavelengths. In this work, we developed photocaged DNAzymes responsive to UV and visible light using a general synthetic method based on phosphorothioate chemistry. Taking the Zn2+-dependent DNAzyme sensor as a model, we achieved wavelength-selective activation of photocaged DNAzymes in live human cells by UV and visible light, laying the groundwork for the logic activation of DNAzyme-based sensors in biological systems.

Hepatocyte Growth Factor Inhibits Renal Angiotensin II Expression in 5/6 Nephrectomized Rats.

Angiotensin II (Ang II) contributes to renal dysfunction, while hepatocyte growth factor (HGF) protects against renal dysfunction. However, the relationship between Ang II and HGF in chronic kidney disease (CKD) remains unknown. This study aimed to investigate the effect of HGF on Ang II expression in CKD. A rat model of CKD was established using female Wistar rats subjected to 5/6 nephrectomy (5/6 Nx). HGF was overexpressed in rat renal tissues using PCI-neo-HGF. Immunohistochemical staining and western blot analysis of renal Ang II expression were performed in 5/6 Nx rats treated with vehicle (negative control), Lotensin (positive control), or HGF for different periods of time (before 5/6 Nx, 5 and 9 weeks after 5/6 Nx). Compared with the 0-week group (before 5/6 Nx group), the protein expression of Ang II was significantly induced in rat renal tissues at 5 and 9 weeks after 5/6 Nx (p<0.05), suggesting the possible involvement of Ang II in 5/6 Nx-induced CKD. Importantly, HGF treatment for 5 or 9 weeks markedly inhibited renal Ang II expression and greatly improved the renal morphology in 5/6 Nx rats, compared with the vehicle-treated group (p<0.05). The effects of HGF on renal Ang II expression and renal morphology were similar to those of Lotensin, suggesting that HGF may protect against 5/6 Nx-induced CKD through downregulating Ang II. HGF is a novel regulator of Ang II expression and plays a protective role in 5/6 Nx-induced CKD.

Orthogonal Activation of RNA-Cleaving DNAzymes in Live Cells by Reactive Oxygen Species.

RNA-cleaving DNAzymes are useful tools for intracellular metal-ion sensing and gene regulation. Incorporating stimuli-responsive modifications into these DNAzymes enables their activities to be spatiotemporally and chemically controlled for more precise applications. Despite the successful development of many caged DNAzymes for light-induced activation, DNAzymes that can be intracellularly activated by chemical inputs of biological importance, such as reactive oxygen species (ROS), are still scarce. ROS like hydrogen peroxide (H2 O2 ) and hypochlorite (HClO) are critical mediators of oxidative stress-related cell signaling and dysregulation including activation of immune system as well as progression of diseases and aging. Herein, we report ROS-activable DNAzymes by introducing phenylboronate and phosphorothioate modifications to the Zn2+ -dependent 8-17 DNAzyme. These ROS-activable DNAzymes were orthogonally activated by H2 O2 and HClO inside live human and mouse cells.

Catechin attenuates TNF-α induced inflammatory response via AMPK-SIRT1 pathway in 3T3-L1 adipocytes.

Chronic inflammation is a fundamental symptom of many diseases. Catechin possesses anti-oxidant and anti-inflammatory properties. However, the mechanism of catechin to prevent inflammation in 3T3-L1 adipocytes caused by TNF-α remains unknown. Therefore, the effects of catechin on the gene expression of cytokines and the activation of cell signals in TNF-α induced 3T3-L1 adipocytes were investigated. The effects of catechin on adipogenesis and cell viability were detected by Oil Red O staining and CCK-8 assay, respectively. The genes expression of cytokines was determined by real-time RT-PCR. The expression of NF-κB, AMPK, FOXO3a and SIRT1 on translation level was determined by western blotting analysis. The results demonstrated that catechin significantly enhanced adipogenesis and cell viability. catechin inhibited the gene expression of pro-inflammatory cytokines including IL-1α, IL-1ß, IL-6, IL-12p35, and inflammatory enzymes including iNOS and COX-2, but enhanced the gene expression of anti-inflammatory cytokines including IL-4 and IL-10. Catechin also inhibited the activation of NF-κB, AMPK, FOXO3a and SIRT1, but increased the phosphorylation level of the above factors. All these results indicated that as a potential therapeutic strategy catechin has the ability of attenuating inflammatory response triggered by TNF-α through signaling cascades involved in inflammation and cytokines.

Enhancing Catalytic Activity of Uranyl-Dependent DNAzyme by Flexible Linker Insertion for More Sensitive Detection of Uranyl Ion.

The uranyl-dependent DNAzyme 39E cleaves its nucleic acid substrate in the presence of uranyl ion (UO22+). It has been widely utilized in many sensor designs for selective and sensitive detection of UO22+ in the environment and inside live cells. In this work, by inserting a flexible linker (C3 Spacer) into one critical site (A20) of the 39E catalytic core, we successfully enhanced the original catalytic activity of 39E up to 8.1-fold at low UO22+ concentrations. Applying such a modified DNAzyme (39E-A20-C3) in a label-free fluorescent sensor for UO22+ detection achieved more than 1 order of magnitude sensitivity enhancement over using native 39E, with the UO22+ detection limit improved from 2.6 nM (0.63 ppb) to 0.19 nM (0.047 ppb), while the high selectivity to UO22+ over other metal ions was fully preserved. The method was also successfully applied for the detection of UO22+-spiked environmental water samples to demonstrate its practical usefulness.

Role of the thioredoxin interacting protein in diabetic nephropathy and the mechanism of regulating NOD­like receptor protein 3 inflammatory corpuscle.

Inflammatory response serves an important role in diabetic nephropathy (DN); however, the mechanism of inflammatory response results in renal damage is not yet clear. The aim of the present study was to investigate the role of the thioredoxin interacting protein (TXNIP)/NOD­like receptor protein 3 (NLRP3) axis­mediated activation of NLRP3 inflammasome in DN. A diabetic rat model was induced by streptozotocin injection. Hematoxylin and eosin (H&E) staining and streptavidin­peroxidase staining were then used to examine the kidney tissue morphology, and TXNIP and NLRP3 protein expression levels, respectively. Furthermore, RNA interference technology was applied to silence the TXNIP gene. TXNIP and NLRP3 inflammasome activation­associated proteins and mRNAs were detected by western blot analysis and RT­qPCR, respectively. Enzyme­linked immunosorbent assay was also used to examine interleukin (IL)­1 and IL­18 expression, while flow cytometry was performed to detect reactive oxygen species production. The data revealed that TXNIP and NLRP3 were overexpressed in kidney tissue of DN rats, and the level of antioxidant genes was downregulated. It was also observed that glucose promoted TXNIP expression and activation of NLRP3 inflammasome in a time­dependent and dose­dependent manner, therefore promoting inflammatory responses. Silencing of TXNIP gene resulted in the downregulation of NLRP3 inflammasome activation, and inhibited the expression levels of IL­1 and IL­18 in a high­glucose environment. Furthermore, low expression of TXNIP promoted the levels of antioxidant genes and reduced the ROS levels. Taken together, the high­glucose environment was able to upregulated the level of inflammatory factors by promoting the expression of TXNIP and the activation of NLRP3 inflammasome, consequently participating in DN.

Evanescent wave aptasensor for continuous and online aminoglycoside antibiotics detection based on target binding facilitated fluorescence quenching.

The biosensors capable for on-site continuous and online monitoring of pollutants in environment are highly desired due to their practical importance and convenience. The group specific detection of pollutants is especially attractive due to the diversity of environmental pollutants. Here we devise an evanescent wave aptasensor based on target binding facilitated fluorescence quenching (FQ-EWA) for the online continuous and group-specific detection of aminoglycoside antibiotics (AMGAs). In FQ-EWA, a fluorophore labeled DNA aptamer selected against kanamycin was used for both the target recognition in solution and signal transduction on optical fiber of EWA. The aptamers form multiple-strand complex (M-Apt) in the absence of AMGAs. The binding between AMGA and the aptamer disrupts M-Apt and leads to the formation of AMGA -aptamer complex (AMGA-Apt). The photo-induced electron transfer between the fluorophore and AMGA partially quenches the fluorescence of AMGA-Apt. The structure-selective absorption of AMGA-Apt over M-Apt on the graphene oxide further quenches the fluorescence of AMGA-Apt. Meanwhile, the unbound aptamers in solution assemble with the unlabeled aptamers immobilized on the fiber to form M-Apt. The amount of M-Apt on the fiber is inversely proportional to the concentration of AMGAs, enabling the signal-off detection of AMGAs from 200nM to 200µM with a detection limit of 26nM. The whole detection process is carried out in an online mode without any offline operation, providing a great benefit for system automation and miniaturization. FQ-EWA also shows great surface regeneration capability and enables the continuous detection more than 60 times.

Hepatocyte growth factor inhibits tubular epithelial­myofibroblast transdifferentiation by suppression of angiotensin II via the JAK2/STAT3 signaling pathway.

Tubular epithelial­myofibroblast transdifferentiation (TEMT) is important in the development of chronic renal failure. The present study investigated whether hepatocyte growth factor (HGF) inhibits TEMT, and whether this function may be associated with the inhibition of angiotensin II (AngII) and the Janus kinase 2/signal transducer and activator of transcription 3 (JAK2/STAT3) signaling pathway. Human HK­2 kidney proximal tubular cells were divided into 4 groups and treated with AngII (1x10­6 M), HGF (8x10­3 M), AngII plus HGF or control conditions, followed by an assessment of apoptosis induction and the expression levels of α­smooth muscle actin (α­SMA), which is a marker of TEMT. as well as the activation level of JAK2, phosphorylated (p)­JAK2, STAT3 and p­STAT3 signaling pathways. In HK­2 cells, α­SMA mRNA and protein expression levels increased following treatment with AngII, however, decreased expression was observed following exposure to HGF. HGF counteracted the AngII­induced increase in the expression of α­SMA in HK­2 cells. Similar expression profiles were observed for the phosphorylated forms of JAK2 and STAT3, indicating the possible involvement of this signaling pathway. The results demonstrated that treatment of cells with AngII was associated with the induction of apoptosis when compared with the control. By contrast, treatment with HGF attenuated AngII­induced apoptosis. The results suggested that HGF may inhibit TEMT by inhibiting AngII through the JAK2/STAT3 signaling pathway in HK­2 cells and HGF may prevent apoptosis induced by AngII. The present study provides a basis for understanding the mechanisms involved in the inhibition of TEMT by HGF, which requires further investigation.

Reusable split-aptamer-based biosensor for rapid detection of cocaine in serum by using an all-fiber evanescent wave optical biosensing platform.

A rapid, facile, and sensitive assay of cocaine in biological fluids is important to prevent illegal abuse of drugs. A two-step structure-switching aptasensor has been developed for cocaine detection based on evanescent wave optical biosensing platform. In the proposed biosensing platform, two tailored aptamer probes were used to construct the molecular structure switching. In the existence of cocaine, two fragments of cocaine aptamer formed a three-way junction quickly, and the fluorophore group of one fragment was effectively quenched by the quencher group of the other one. The tail of the three-way junction hybridized with the cDNA sequences immobilized on the optical fiber biosensor. Fluorescence was excited by evanescent wave, and the fluorescence signal was proportional to cocaine concentration. Cocaine was detected in 450 s (300 s for incubation and 150 s for detection and regeneration) with a limit of detection (LOD) of 165.2 nM. The proposed aptasensor was evaluated in human serum samples, and it exhibited good recovery, precision, and accuracy without complicated sample pretreatments.

Label-free fluorescence detection of melamine with a truncated aptamer.

The 2008 Chinese milk scandal caused by the adulteration of melamine encouraged the public to pay attention to melamine detection in milk products and other food stuffs. To allow simple and rapid detection of melamine, we previously isolated an 88 nt melamine aptamer (called Rd29C33) using the structure-switching SELEX. However, this 88 nt oligonucleotide is costly to synthesize, and may also complicate the rational design of biosensors for melamine detection. To overcome this obstacle, we truncated Rd29C33 at several sites, and a 34 nt Rd29C33-T7 melamine aptamer was finally found to show comparable binding affinity and better selectivity to melamine compared to the original 88 nt Rd29C33. Furthermore, a label-free bioassay method for melamine detection was designed by using Rd29C33-T7 and thiazole orange (TO). The addition of melamine to a mixture of Rd29C33-T7 and TO caused the release of TO from Rd29C33-T7, resulting in a decrease of the fluorescence intensity of the solution. A detection limit of 0.12 µM for melamine was achieved using this label-free method. Good recovery ranging from 82.6% to 97.2% for melamine detection in whole milk samples suggested the promise of this bioassay method for application in monitoring melamine in real food stuffs.

Portable Detection of Melamine in Milk Using a Personal Glucose Meter Based on an in Vitro Selected Structure-Switching Aptamer.

Melamine detection in milk and other foods has attracted much attention since the discovery that melamine-adulterated food causes severe kidney damage. Although many methods have been developed to detect melamine, few methods can provide quantitative results using an affordable and portable device that is suitable for home use or field application. To achieve this goal, we herein report the first in vitro selection of a melamine responsive aptamer using a structure-switching method. A personal glucose meter (PGM) based melamine sensor was designed and subsequently tested using the newly isolated aptamer. Conversion of melamine concentration to glucose amount was achieved by including an invertase-conjugated DNA that is complementary to part of the aptamer. Melamine binding triggers the release of the invertase-DNA conjugate, which hydrolyzes sucrose into glucose. The glucose produced is then measured directly using an off-the-shelf PGM. The described sensor shows high selectivity for melamine against several closely related melamine analogues, such as cyanuric acid, ammeline, and ammelide, and has low detection limits of 0.33 µM (or 41.1 ppb) in buffer and 0.53 µM (or 67.5 ppb) in 80% whole milk without any pretreatment. The detection limits meet the threshold of 2.5 ppm for non-infant-formula products and 1 ppm for melamine in infant milk products as defined by the U.S. Food and Drug Administration (FDA). In addition to the PGM sensor demonstrated here, the same aptamer can be converted into other types of sensors with different signal outputs, allowing portable detection of melamine under a variety of conditions.