Recent advances in dietary polysaccharides from Allium species: Preparation, characterization, and bioactivity.

Allium plants, including garlic, onions, shallots, and leeks, belong to the Alliaceae family and are utilized as vegetable, medicinal, and ornamental plants. These plants are consumed both raw and cooked and are noted in traditional medicine for their antibacterial, antitumor, and diuretic properties. Allium plants are a rich source of polyphenols, organosulfur compounds, flavonoids, alkaloids, and polysaccharides, which contribute to their health benefits. As consumer interest in the association between diet and health grows, there is an increasing market demand for foods that promote health, particularly those rich in dietary fiber or non-starch polysaccharides. Allium polysaccharides (APS) have molecular weights of 1 × 103-1 × 106 Da containing small amounts of pectin, glucofructan, or glycoproteins and large amounts of fructans. APS, despite its complex structure, is one of the principal active components of Allium plants but is often overlooked, which restricts its practical application. This paper provides a comprehensive overview of the extraction and purification, structural and functional characteristics, bioactivities, structure-function relationships, and chemical modifications of APS, as well as the effects of APS processing and storage. Additionally, this paper outlines future research directions for APS, which will inform its development and application in the food, pharmaceutical, and cosmetic industries.

Polysaccharide extracted from cultivated Sanghuangporous vaninii spores using three-phase partitioning with enzyme/ultrasound pretreatment: Physicochemical characteristics and its biological activity in vitro.

Sanghuangporous vaninii, as a valuable dietary supplement and medicinal ingredient, contains abundant bioactive polysaccharides that have health-promoting effects. In the present study, four polysaccharides (SVSPs-C, SVSPs-E, SVSPs-U, and SVSPs-E/U) were extracted for the first time from S. vaninii spores by three-phase partitioning (TPP), enzyme pretreatment before TPP (E-TPP), ultrasonic pretreatment before TPP (U-TPP), and enzyme pretreatment followed by ultrasonic before TPP (E/U-TPP) methods, respectively. Their physicochemical characteristics and in vitro pharmacological functions were determined and compared. Results showed that four TPP-based extraction methods had remarkable impacts on the extraction yield, chemical properties, monosaccharide compositions, and molecular weights (Mw) of SVSPs. Specifically, SVSPs-E/U obtained by E/U-TPP showed the highest extraction yield (25.40 %), carbohydrate content (88.50 %), and the lowest protein content (0.86 %). The four SVSPs had high-Mw (183.8-329.1 kDa) and low-Mw (23.0-156.4 kDa) fractions and mainly consisted of galactose, glucose, and mannose with different contents. In vitro bioactivities assays indicated that SVSPs-E/U possessed stronger antioxidant, hypoglycemic, hypouricemic, immunostimulatory, and antitumor activities than those of SVSPs-C, SVSPs-E, and SVSPs-U. Therefore, our results provide an efficient and promising extraction technique for bioactive polysaccharides from S. vaninii spores, as well as SVSPs had the potential to be applied in functional food, pharmaceutical, and cosmetics fields.

Recent advances in research on Allium plants: functional ingredients, physiological activities, and applications in agricultural and food sciences.

Fruits and vegetables (FVs) have long been a major source of nutrients and dietary phytochemicals with outstanding physiological properties that are essential for protecting humans from chronic diseases. Moreover, the growing demand of consumers for nutritious and healthy foods is greatly promoting the increased intake of FVs. Allium (Alliaceae) is a perennial bulb plant genus of the Liliaceae family. They are customarily utilized as vegetable, medicinal, and ornamental plants and have an important role in agriculture, aquaculture, and the pharmaceutical industry. Allium plants produce abundant secondary metabolites, such as organosulfur compounds, flavonoids, phenols, saponins, alkaloids, and polysaccharides. Accordingly, Allium plants possess a variety of nutritional, biological, and health-promoting properties, including antimicrobial, antioxidant, antitumor, immunoregulatory, antidiabetic, and anti-inflammatory effects. This review aims to highlight the advances in the research on the bioactive components, physiological activities and clinical trials, toxicological assessment for safety, and applications of different Allium plants. It also aims to cover the direction of future research on the Allium genus. This review is expected to provide theoretical reference for the comprehensive development and utilization of Allium plants in the fields of functional foods, medicine, and cosmetics.

Recent advances in the bioactive polysaccharides and other key components from Phellinus spp. and their pharmacological effects: A review.

Phellinus spp. is one of the largest genera of Hymenochaetaceae with approximately 220 species, such as P. vaninii, P. buamii, P. linteus, and P. igniarius, these species are considered as precious food supplements and medicinal ingredients in China, Korea, Japan, and other Asian countries for over 2000 years. Phellinus spp. contains abundant bioactive polysaccharides and other key components (e.g., phenolics, terpenes, steroids, etc.). Pharmacological investigations have confirmed that bioactive polysaccharides and other important secondary metabolites from Phellinus spp. possess multiple health-promoting benefits, including antitumor, immunomodulatory, anti-inflammatory, antidiabetic, antioxidant, and antimicrobial effects. However, comprehensive evaluations on the preparation and structural characteristics, bioactivities, and toxicology of these functional components (e.g., polysaccharides, phenolics, terpenes, steroids) from various Phellinus spp. species are very limited, which may restrict the practical application of Phellinus spp. This review summarizes the physicochemical characteristics, pharmacological activities, and possible mechanisms of bioactive components from Phellinus spp. according to published studies from 2017 to 2022. It also surveyed the toxicological assessment for safety and applications of different Phellinus spp. species. This review aims to provide useful references and promising directions for the comprehensive development and utilization of Phellinus spp. in functional foods, pharmaceuticals, and cosmetics.

Physicochemical and functional characteristics of polysaccharides from okra extracted by using ultrasound at different frequencies.

In this study, single- (SFU) and dual-frequency (DFU) ultrasounds were used to extract polysaccharides from okra (Abelmoschus esculentus (L.) Moench) pods (OPSs), and the physicochemical characteristics, functional properties, and in vitro biological activities of the OPSs were comparatively evaluated. Results showed that ultrasonic extractions at different frequencies led to remarkable variations in extraction yields, chemical components, monosaccharide compositions, molecular weights (MWs), surface morphologies, and rheological properties of the OPSs but hardly affected their preliminary structural features and thermal stabilities. The OPS obtained through DFU at 40/60 kHz with the lowest MWs (0.85-14.93 × 105 Da) and highest polyphenol content (7.38%) as well as loosest network structures showed superior antioxidant, cholesterol absorption and nitrite ion absorption capacities than the other OPSs, and the OPS extracted through SFU at 20 kHz with the highest carboxylate content (76.08%), MWs (7.28-32.83 × 105 Da) and degree of esterification (30.7%) exhibited higher bile acid-binding capacity than the other OPSs.

Emulsifying properties of a ferulic acid-grafted curdlan conjugate and its contribution to the chemical stability of ß-carotene.

A biopolymer-polyphenol conjugate-stabilized oil-in-water emulsion system was established to improve the chemical stability and bioaccessibility of ß-carotene (BC). In this study, the emulsifying properties and contribution of a ferulic acid-grafted curdlan conjugate (Cur-D-g-FA) to the chemical stability of BC were investigated. Results showed that the emulsification ability of emulsions stabilized by Cur-D-g-FA remarkably increased with an increasing concentration from 0.05% to 0.8% (w/v) along with decreasing average droplet sizes, negatively charged zeta potentials, and uniform size distributions. The emulsions stabilized by 0.8% Cur-D-g-FA exhibited pronounced shear thinning and solid-like elastic properties as well as satisfactory oxidation stability. The emulsions stabilized by 0.8% Cur-D-g-FA had excellent ability to improve the chemical stability of BC when exposed to different environmental stresses and resulted in the favorable bioaccessibility of BC in vitro. The results prove that Cur-D-g-FA as a promising stabilizer has great potential to protect liposoluble nutrients in food-grade emulsion-delivery systems.

Conjugation of ferulic acid onto pectin affected the physicochemical, functional and antioxidant properties.

BACKGROUND: Pectin, as a functional ingredient, is best known as a gelling and thickening agent, stabilizer, and fat substitute in processed foods. The synthesis of pectin graft copolymers is considered one of the most fascinating ways to improve its physicochemical and functional properties. In this study, therefore, water-soluble pectin or ultrasound-treated pectins (UP30 and UP60) grafted with ferulic acid (FA) conjugates, pectin-g-FA, UP30-g-FA and UP60-g-FA, were synthesized via a free radical-mediated grafting procedure, and their physicochemical, structural, and functional characteristics were investigated. Moreover, 2,2-diphenyl-1-picryl-hydrazyl (DPPH)-radical scavenging activity, Trolox equivalent antioxidant capacity (TEAC) assay and ferric-reducing ability of plasma (FRAP) assay were used to evaluate their antioxidant activities in vitro. RESULTS: Results showed that FA was covalently grafted onto pectin or ultrasound-treated pectins, and the grafting ratios of pectin-g-FA, UP30-g-FA and UP60-g-FA were 65.43 ± 1.30, 82.55 ± 1.71 and 75.82 ± 0.89 mg FA/g, respectively. Although the molecular weights, apparent viscosities, and thermal stabilities of the three FA-grafted pectin conjugates decreased and their surface morphologies were different from those of native pectin and ultrasound-treated pectins, they possessed prominent DPPH-radical scavenging ability [half maximal inhibitory concentration (IC50 ) of 0.32 to 0.89 mg mL-1 ) and antioxidant capacity (TEAC of 100.02 to 153.42 µmol Trolox/g sample; FRAP: 166.41 to 270.27 µmol FeSO4 /g sample). Their antioxidant potentials were positively correlated with the grafting ratio. CONCLUSION: This study provided a promising strategy for the functionalization of pectin, and the prepared FA-grafted pectin conjugates could be explored as functional ingredients that showed potential for applications in food and agriculture systems. © 2020 Society of Chemical Industry.

Proteoglycan isolated from Corbicula fluminea exerts hepato-protective effects against alcohol-induced liver injury in mice.

Corbicula fluminea (Asian clam), a freshwater bivalve mollusk, has been consumed in China for centuries as a health food and traditional Chinese medicine for treating liver diseases and alcoholism. This study aimed to evaluate the hepato-protective effects and potential mechanisms of a proteoglycan (PSP) from C. fluminea on alcohol-induced liver injury in mice. Results showed that PSP pretreatment significantly antagonized the increases in serum alanine aminotransferase, aspartate aminotransferase, triacylglycerides, and hepatic malondialdehyde levels; elevated the antioxidant enzyme activities and hepatic glutathione levels; and suppressed the levels of hepatic inflammatory cytokines in alcohol-induced liver injury in mice (P < 0.05). Histopathological observation further revealed the potential hepato-protective effect of PSP against alcohol damage. Particularly, PSP pretreatment resulted in significantly decreased expression of cytochrome P450 2e1 (CYP2E1) while significantly upregulating the expression of hemeoxygenase-1 (HO-1) (P < 0.05). These results suggested that PSP could protect the liver from hepatocyte injury induced by alcohol possibly by alleviating hepatic lipid metabolism, elevating antioxidant-enzyme activity, suppressing the immune inflammatory response, and reversing the expression levels of CYP2E1 and HO-1. Therefore, PSP may be developed as a food supplement that can be used to prevent liver diseases.

Pectin-decorated selenium nanoparticles as a nanocarrier of curcumin to achieve enhanced physicochemical and biological properties.

In this study, the authors developed pectin-stabilised selenium nanoparticles (pectin-SeNPs) for curcumin (Cur) encapsulation and evaluated their physicochemical properties and biological activities. Results showed that pectin-SeNPs and Cur-loaded pectin-SeNPs (pectin-SeNPs@Cur) exhibited monodisperse and homogeneous spherical structures in aqueous solutions with mean particle sizes of ∼61 and ∼119 nm, respectively. Cur was successfully encapsulated into pectin-SeNPs through hydrogen bonding interactions with an encapsulation efficiency of ∼60.6%, a loading content of ∼7.4%, and a pH-dependent and controlled drug release in vitro. After encapsulation was completed, pectin-SeNPs@Cur showed enhanced water solubility (∼500-fold), dispersibility, and storage stability compared with those of free Cur. Moreover, pectin-SeNPs@Cur possessed significant free radical scavenging ability and antioxidant capacity in vitro, which were stronger than those of pectin-SeNPs. Antitumour activity assay in vitro demonstrated that pectin-SeNPs@Cur could inhibit the growth of HepG2 cells in a concentration-dependent manner, and the nanocarrier pectin-SeNPs exhibited a low cytotoxic activity against HepG2 cells. Therefore, the results suggested that pectin-SeNPs could function as effective nanovectors for the enhancement of the water solubility, stability, and in vitro bioactivities of hydrophobic Cur.

Antidiabetic activity of a polysaccharide-protein complex from Asian Clam (Corbicula fluminea) in streptozotoxin-induced diabetic rats and its underlying mechanism.

The antidiabetic activity and potential underlying mechanism of a polysaccharide-protein (PSP) complex from Corbicula fluminea were determined in streptozotoxin (STZ)-induced diabetic rats. PSP exhibited inhibitory activity (in vitro) against α-glucosidase and α-amylase via a reversible competitive inhibition pattern with a stronger inhibition for α-glucosidase. Dietary administration of PSP had potential antidiabetic activities in vivo, which was evidenced by the fact that PSP alleviates body weight loss and organ injuries, reduced fasting blood glucose levels, elevated glucose tolerance, and ameliorated lipid metabolism and hepatic functions, as well as attenuated oxidative stress in STZ-treated diabetic rats. Furthermore, our results demonstrated that the antidiabetic activities of PSP were associated with the activation of the phosphoinositide 3-kinase/protein kinase B signaling pathway in STZ-treated rats. These findings supported the potential of PSP to be used as a functional ingredient in the preparation of functional and medicinal foods to inhibit diabetes mellitus and its complications.

Preparation, characterization, rheological and antioxidant properties of ferulic acid-grafted curdlan conjugates.

In this study, water-soluble curdlan products (Cur and Cur-D) were prepared by an alkali-neutralization treatment process, after which ferulic acid (FA)-grafted Cur conjugates (Cur-g-FA and Cur-D-g-FA) were fabricated in the presence and absence of salt by adopting an approach involving free-radicals generated by the ascorbic acid/hydrogen peroxide redox pair under an inert atmosphere. Results showed that FA was successfully grafted onto the C-6 and C-4 positions of the Cur chains through covalent linkages and that the presence of salt exerted minor influences on the grafting ratios and structural characterizations of the products. Cur-g-FA and Cur-D-g-FA showed decreased crystallinity, thermal stability, and rheological properties, as well as a distinct surface morphology, when compared with those of native Cur. However, Cur-g-FA and Cur-D-g-FA also exhibited remarkably enhanced free-radical scavenging ability and antioxidant capacity in vitro. These results indicate that FA-grafted Cur conjugates have great potential application in the field of functional foods.

Three-phase partitioning for the direct extraction and separation of bioactive exopolysaccharides from the cultured broth of Phellinus baumii.

In this study, three-phase partitioning (TPP) was used to directly extract and separate bioactive exopolysaccharides (EPSs) from a cultured broth of Phellinus baumii. The maximum extraction yield of EPS was 52.09% under the following optimal conditions: 20% (w/v) ammonium sulfate concentration, 1.0:1.5 (v/v) ratio of cultured broth to t­butanol, 30 min, and 35 °C. A multifrequency power ultrasound in a sequential mode coupled with TPP resulted in ~9.12% increment in extraction yield and ~80% reduction in extraction time compared with those of traditional TPP. The carbohydrate (88.21%) and uronic acid (3.37%) contents of partially purified EPS were higher than those of EPS-C obtained through conventional ethanol precipitation and separation methods. EPS and EPS-C exhibited similar preliminary structural characteristics and different monosaccharide compositions and molecular weights. The radical-scavenging abilities, antioxidant capacities, α­amylase and α­glycosidase inhibitory activities, and macrophage stimulation activities of EPS were also higher than those of EPS-C. Therefore, it could be concluded that TPP as a simple and green separation technique could be used to directly extract and separate bioactive EPS from the fermentation broths of mushrooms and other fungi.

Polysaccharide isolated from Phellinus linteus mycelia exerts anti-inflammatory effects via MAPK and PPAR signaling pathways.

In the present study, the anti-inflammatory function of Phellinus linteus polysaccharide (PLP) was investigated in animal and cell inflammation models, and the anti-inflammatory mechanism of PLP was also explored. Sixty 8-week ICR mice were randomly divided into 3 groups, and DSS group and DSS + PLP group mice received 2.0% DSS and PLP was orally administered at 500 mg/kg/day. Our data showed that PLP administration obviously improved the health status of mice and inhibited DSS-induced pathological alterations and significantly reduced inflammatory cytokine expressions in the colonic tissues. In lipopolysaccharide-induced inflammation cell model, PLP supplement also significantly reduced inflammatory cytokine expressions and inhibited MAPK pathway as well as the translocations of NF-κB and AP-1. Meanwhile, PLP supplement regulated PPARα and PPARγ phosphorylation and blocked MAPK activation. Taken together, PLP exhibits anti-inflammatory function and its molecular mechanism may be involved in MAPK and PPAR signal pathways, which reduce the expressions of inflammatory cytokines.

Construction, stability, and enhanced antioxidant activity of pectin-decorated selenium nanoparticles.

Selenium nanoparticles (SeNPs) as a new replacement source of other Se forms applied in nutritional supplements have been associated with health-related issues. Pectin (PEC) as a well-known food-grade polysaccharide has been considered as a potential soft template for the preparation and stabilization of SeNPs in aqueous medium. In this study, therefore, PEC was used as a stabilizer and dispersing agent to form well-dispersed and stable SeNPs under a simple redox system of selenite and ascorbic acid. Se/PEC ratios significantly affected the color of the suspension, particle size, and surface morphology of the as-prepared SeNPs in the presence of PEC. PEC-SeNPs with a Se/PEC ratio of 1:2 appeared amorphous and exhibited a well-dispersed and stable spherical structure with an average size of ∼41 nm, which corresponds to the strong hydrogen bonding between the hydroxyl groups of PEC and SeNPs. The PEC-SeNPs (Se/PEC = 1:2) remained highly stable in different acidic solutions for at least 1 month. Small and highly stable PEC-SeNPs (Se/PEC = 1:2) possessed the strongest DPPH radical scavenging ability and antioxidant capacity among the evaluated PEC-SeNPs. They also possessed a low cytotoxic activity against cancer cells (SPCA-1 and HeLa) and normal cells (RWPE-1) in vitro. These findings suggested that pectin as a surface decorator could be effectively used to improve the stability and antioxidant capacity of SeNPs remarkably.

Formation and characterization of polyelectrolyte complex synthesized by chitosan and carboxylic curdlan for 5-fluorouracil delivery.

In this study, negatively charged carboxylic curdlan (Cc) bearing a ß-1,3-polyglucuronic acid structure was employed to fabricate nanosized polyelectrolyte complexes (PECs) with positively charged chitosan (CS) in aqueous solution as potential carriers for 5-fluorouracil (5Fu) delivery. Nanosized CS/Cc PECs were formed by the addition of 0.5mg/mL solutions of CS and Cc with a mixing ratio of 1:1 (w/w) at pH 3.0. Under optimized conditions, the prepared CS/Cc PECs showed spherical morphology with an average size of about 180nm and a zeta potential of around 41mV. The 5Fu drug was incorporated into the nanosized CS/Cc PECs and showed excellent encapsulation efficiency (86.47%) and loading content (10.81%). The drug release data in vitro indicated that the nanosized CS/Cc PECs are promising carriers for the sustained release of 5Fu with an anomalous transport mechanism following the Ritger-Peppas model. Besides, the CS/Cc PECs exhibited low cytotoxic activity against SPCA-1 and HeLa cell lines in vitro. This finding suggested that the development of the nanosized CS/Cc PECs offered great promise as an antitumor drug platform.

Advances in antitumor polysaccharides from phellinus sensu lato: Production, isolation, structure, antitumor activity, and mechanisms.

Edible and medicinal fungi (mushrooms) are widely applied to functional foods and nutraceutical products because of their proven nutritive and medicinal properties. Phellinus sensu lato is a well-known medicinal mushroom that has long been used in preventing ailments, including gastroenteric dysfunction, diarrhea, hemorrhage, and cancers, in oriental countries, particularly in China, Japan, and Korea. Polysaccharides represent a major class of bioactive molecules in Phellinus s. l., which have notable antitumor, immunomodulatory, and medicinal properties. Polysaccharides that were isolated from fruiting bodies, cultured mycelia, and filtrates of Phellinus s. l. have not only activated different immune responses of the host organism but have also directly suppressed tumor growth and metastasis. Studies suggest that polysaccharides from Phellinus s. l. are promising alternative anticancer agents or synergizers for existing antitumor drugs. This review summarizes the recent development of polysaccharides from Phellinus s. l., including polysaccharide production, extraction and isolation methods, chemical structure, antitumor activities, and mechanisms of action.

Purification, characterization and antitumor activity of polysaccharides extracted from Phellinus igniarius mycelia.

Water-soluble intracellular polysaccharides (IPS) were extracted from cultured mycelia of Phellinus igniarius. The IPS were purified by ethanol fractional precipitation, ion-exchange and size exclusion chromatography in that order. Homogeneous polysaccharide IPSW-1, IPSW-2, IPSW-3, and IPSW-4 were obtained, which molecular characteristics were examined using multiangle laser-light scattering and refractive index detector system. The average molecular weights of them were 34.1, 17.7, 15.1, 21.7kDa, respectively. GC analysis indicated that IPSW-1, IPSW-2 and IPSW-3 all only contained glucose, while IPSW-4 was composed of rhamnose, xylose, mannose, glucose and galactose in a molar ratio of 1.29:1.21:1:43.86:1.86. UV and IR analysis suggested they belonged to α-type of the pyran group and didn't contain protein. These homogeneous polysaccharides could inhibit the growth of SW480 and HepG2 cells to a certain extent in a dose-dependent manner. So they could be beneficial for the further development of a natural carcinoma preventive agent and functional food.

Self-aggregated nanoparticles of carboxylic curdlan-deoxycholic acid conjugates as a carrier of doxorubicin.

In this study, a new non-toxic, biodegradable, biocompatible and water-soluble carboxylic curdlan bearing the dissociable COOH group in 100% purity, which was prepared by 4-acetamido-TEMPO-mediated oxidation, was hydrophobically modified by deoxycholic acid (DOCA) to attain novel amphiphilic curdlan derivatives (CCDs) for the preparation of nano-carriers for antitumor drug doxorubicin (DOX). Under the effect of ultrasonication, the carboxylic curdlan derivatives in water were self-aggregated into spherical nanoparticles with diameters ranging from 214 nm to 380 nm. The critical aggregation concentrations decreased from 0.047 mg/mL to 0.016 mg/mL with increasing DS of DOCA. DOX-loaded CCD nanoparticles were prepared in an aqueous medium with dialysis method. The DOX-CCD nanoparticles exhibited pH- and dose-dependent drug release profiles during in vitro release experiments. Moreover, the drug transport mechanism was Fickian diffusion according to the Ritger-Peppas model. The CCD nanoparticles might be explored as potential carriers for hydrophobic drugs with controlled release and delivery functions.

Structural features and antitumor activity of a novel polysaccharide from alkaline extract of Phellinus linteus mycelia.

A novel high molecular weight polysaccharide (PL-N1) was isolated from alkaline extract of the cultured Phellinus linteus mycelia. The weight average molecular weight (Mw) of PL-N1 was estimated at 343,000kDa. PL-N1 comprised arabinose, xylose, glucose, and galactose in the molar ratio of 4.0:6.7:1.3:1.0. The chemical structure of PL-N1 was investigated by FTIR and NMR spectroscopies and methylation analysis. The results showed that the backbone of PL-N1 comprised (1→4)-linked ß-D-xylopyranosyl residues, (1→2)-linked α-D-xylopyranosyl residues, (1→4)-linked α-D-glucopyranosyl residues, (1→5)-linked ß-D-arabinofuranosyl residues, (1→4)-linked ß-D-xylopyranosyl residues which branched at O-2, and (1→4)-linked ß-D-galactopyranosyl residues which branched at O-6. The branches consisted of (1→)-linked α-D-arabinofuranosyl residues. Antitumor activity assay in vitro showed that PL-N1 could inhibit the growth of HepG2 cells to a certain extent in a dose-dependent manner. Thus, PL-N1 may be developed as a potential, natural antitumor agent and functional food.

Highly selective and sensitive nucleic acid detection based on polysaccharide-functionalized silver nanoparticles.

Polysaccharide-functionalized silver nanoparticles (Oc-AgNPs) with a mean diameter of 15 nm were utilized as a novel and effective fluorescence-sensing platform for nucleic acid detection. Tests on the oligonucleotide sequences associated with the human immunodeficiency virus as a model system showed that the Oc-AgNPs effectively absorbed and quenched dye-labeled single-stranded DNA through strong hydrogen bonding interactions and slight electrostatic attractive interactions. The proposed system efficiently differentiated between complementary and mismatched nucleic acid sequences with high selectivity and good reproducibility at room temperature.