Multifunctional, High-Strength Electronic Skin Based on the Natural Sheepskin Fiber Network for Multifaceted Human Health Monitoring and Management.

Inspired by the animal skin fiber network, we developed an electronic skin (e-skin) utilizing natural sheepskin as the primary substrate. This innovative design addresses the limitations of conventional e-skins, including inadequate mechanical strength, overly complex artificial network construction, and limited health monitoring capabilities. This e-skin successfully retains the structure and properties of natural sheepskin while exhibiting exceptional mechanical strength (with a breaking strength of 4.01 MPa) and high elongation (with an elongation at a break of 304.8%). Moreover, it possesses various desirable attributes such as electrical conductivity, antibacterial properties, biocompatibility, and environmental stability. In addition, this e-skin has the advantage of diverse data collection (joint movement, bioelectricity, foot health detection, and speech disorder communication systems). Therefore, this e-skin breaks the traditional construction strategy and single-mode application and is expected to become an ideal material for building smart sensor devices.

[Analysis of clinical phenotype and genetic variant in a Chinese pedigree affected with cleidocranial dysplasia].

OBJECTIVE: To analyze the clinical features and pathogenic variant in a Chinese pedigree affected with cleidocranial dysplasia (CCD). METHODS: Clinical data of 8 patients from the pedigree was collected, including physical examination and X-ray images of head, face, spine, limbs, and mouth. Peripheral blood samples were collected from 6 affected members for the extraction of genomic DNA. The proband and other 3 patients were subjected to trio-whole exome sequencing. Candidate variant was verified by Sanger sequencing of the other 2 affected members from the pedigree. RESULTS: This pedigree has included 22 members (8 affected) from four generations. Genetic testing revealed that the proband has harbored a novel pathogenic variant of the RUNX2 gene [NM_001024630: c.1268_1277del (p.P425Afs*56)], which was inherited from her mother and carried by all affected members in the pedigree. The same variant was not detected among the unaffected members, suggesting co-segregation with the phenotype. CONCLUSION: The c.1268_1277del (p.P425Afs*56) variant of the RUNX2 gene probably underlay the pathogenesis of CCD in this pedigree. Genetic testing has facilitated the definite diagnosis and enabled prenatal diagnosis.

ROMP Synthesis of Side-Chain Ferrocene-Containing Polyelectrolyte and Its Redox-Responsive Hydrogels Showing Dramatically Improved Swelling with ß-Cyclodextrin.

A new side-chain ferrocene (Fc)-containing polyelectrolyte has been synthesized by controlled ring-opening metathesis polymerization of a water-soluble Fc-containing norbornene-based quaternary ammonium salt, as well as the corresponding covalently cross-linked polyelectrolyte hydrogel. In order to provide Fc-containing supramolecular polyelectrolyte hydrogels whose swelling property is largely improved by host-guest interaction, a covalently cross-linked polyelectrolyte hydrogel is soaked into the ß-CD aqueous solution to form ß-CD@Fc supramolecular polyelectrolyte hydrogel, or alternatively the quaternary ammonium salt supramolecular monomer is first formed, then copolymerized with a crosslinking agent to fabricate the supramolecular hydrogel with better water absorption ability. All the Fc-containing hydrogels exhibited good redox-responsiveness with swelling-shrinking behaviors by chemically reversibly adjusting the disassembly/assembly of ß-CD@Fc inclusion complexes. This is the first example of side-chain Fc-containing polycationic supramolecular hydrogels possessing swelling-shrinking properties based on the splitting/combining of ß-CD and Fc units, and potential applications are expected as controlled drug delivery and actuators.

Study on the correlation between adipocyte fatty-acid binding protein, glucolipid metabolism, and pre-eclampsia.

AIM: We aimed to explore the relation between the level of adipocyte fatty-acid binding protein (A-FABP) in the gestational period and related indices of glucolipid metabolism, and the possible mechanisms of occurrence and development of pre-eclampsia. METHODS: Seventy-six pre-eclampsia patients were enrolled and divided into the mild pre-eclampsia (n = 42) and severe pre-eclampsia (n = 34) groups. Forty-eight healthy pregnant women were selected as a control group. The indices of all participants were examined, including serum A-FABP, fasting insulin (FINS), fasting blood glucose, total cholesterol (TC), triglycerides (TG), low-density lipoprotein (LDL), and high-density lipoprotein (HDL), and homeostatic model assessment insulin resistance (HOMA-IR) index was calculated. After the delivery of the placenta, the level of A-FABP in the placenta was detected by immunochemistry. Then, the correlation between serum A-FABP and indices of glucolipid metabolism and placental A-FABP were analyzed. RESULTS: Serum A-FABP, FINS, TG, TC, HOMA-IR, and placental A-FABP were significantly higher in pre-eclampsia patients and the level of HDL was obviously lower than in the control group. Serum A-FABP was positively correlated with FINS, TG, TC, and HOMA-IR, and placental A-FABP was negatively correlated with HDL in pre-eclampsia patients. In the control group, serum A-FABP was positively correlated only with TG, and uncorrelated with the other indices (P > 0.05). CONCLUSION: The level of A-FABP was correlated with insulin resistance and indices of glucolipid metabolism in pre-eclampsia patients. High-levels of A-FABP might increase insulin resistance by causing glucose and lipid metabolism disorders and ultimately inducing the occurrence and development of pre-eclampsia.

Tetrablock Metallopolymer Electrochromes.

Multi-block polymers are highly desirable for their addressable functions that are both unique and complementary among the blocks. With metal-containing polymers, the goal is even more challenging insofar as the metal properties may considerably extend the materials functions to sensing, catalysis, interaction with metal nanoparticles, and electro- or photochrome switching. Ring-opening metathesis polymerization (ROMP) has become available for the formation of living polymers using highly efficient initiators such as the 3rd generation Grubbs catalyst [RuCl2 (NHC)(=CHPh)(3-Br-C5 H4 N)2 ], 1. Among the 24 possibilities to introduce 4 blocks of metallopolymers into a tetrablock metallocopolymer by ROMP using the catalyst 1, two viable pathways are disclosed. The synthesis, characterization, electrochemistry, electron-transfer chemistry, and remarkable electrochromic properties of these new nanomaterials are presented.

Electrostatic Assembly of Functional and Macromolecular Ferricinium Chloride-Stabilized Gold Nanoparticles.

Substituted ferrocenes with various stereoelectronic effects including a ferrocene-terminated dendrimer in ether reduce aqueous HAuCl4 to gold nanoparticles (AuNPs) by interfacial electron transfer. The dependence on the stirring speed plays a crucial role, and the stereoelectronic influences on the reaction rates are dramatic. With a ferrocene-containing polymer, the reaction is conducted using an homogeneous THF/water medium, also forming AuNPs. Fully stable functional, dendritic and polymeric ferricinium chloride-stabilized AuNPs are obtained with core sizes between 13 and 35 nm, an optimal size range for potential biomedical applications. Finally the ferricinium coating of the Au nanoparticles is replaced by a more electron-rich ferricinium derivative by exergonic redox reaction with the corresponding ferrocene derivative.

New ROMP Synthesis of Ferrocenyl Dendronized Polymers.

First- and second-generation Percec-type dendronized ferrocenyl norbornene macromonomers containing, respectively, three and nine ferrocenyl termini are synthesized and polymerized by ring-opening metathesis polymerization using Grubbs' third-generation olefin metathesis catalyst with several monomer/catalyst feed ratios between 10 and 50. The rate of polymerization is highly dependent on the generation of the dendronized macromonomers, but all these ring-opening metathesis polymerization reactions are controlled, and near-quantitative monomer conversions are achieved. The numbers of ferrocenyl groups obtained are in agreement with the theoretical ones according to the cyclic voltammetry studies as determined using the Bard-Anson method.

Diblock Polyelectrolytic Copolymers Containing Cationic Iron and Cobalt Sandwich Complexes: Living ROMP Synthesis and Redox Properties.

Diblock metallopolymer polyelectrolytes containing the two redox-robust cationic sandwich units [CoCp'Cp](+) and [FeCp'(η(6)-C6 Me6)](+) (Cp = η(5)-C5 H5; Cp' = η(5)-C5H4-) as hexafluorophosphate ([PF6](-)) salts are synthesized by ring-opening metathesis polymerization using Grubbs' third generation catalyst. Their electrochemical properties show full chemical and electrochemical reversibilities allowing fine determination of the copolymer molecular weight using Bard-Anson's electrochemical method by cyclic voltammetry.

Living ROMP Synthesis and Redox Properties of Diblock Ferrocene/Cobalticenium Copolymers.

Using the third-generation Grubbs catalyst, the living ring-opening metathesis polymerization of ferrocene/cobalticenium copolymers is conducted with theoretical numbers of 25 monomer units for each block, and their redox and electrochemical properties allow using the Bard-Anson electrochemical method to determine the number of metallocenyl units in each block.

Redox-Robust Pentamethylferrocene Polymers and Supramolecular Polymers, and Controlled Self-Assembly of Pentamethylferricenium Polymer-Embedded Ag, AgI, and Au Nanoparticles.

We report the first pentamethylferrocene (PMF) polymers and the redox chemistry of their robust polycationic pentamethylferricenium (PMFium) analogues. The PMF polymers were synthesized by ring-opening metathesis polymerization (ROMP) of a PMF-containing norbornene derivative by using the third-generation Grubbs ruthenium metathesis catalyst. Cyclic voltammetry studies allowed us to determine confidently the number of monomer units in the polymers through the Bard-Anson method. Stoichiometric oxidation by using ferricenium hexafluorophosphate quantitatively and instantaneously provided fully stable (even in aerobic solutions) blue d(5) Fe(III) metallopolymers. Alternatively, oxidation of the PMF-containing polymers was conducted by reactions with Ag(I) or Au(III) , to give PMFium polymer-embedded Ag and Au nanoparticles (NPs). In the presence of I2 , oxidation by using Ag(I) gave polymer-embedded Ag/AgI NPs and AgNPs at the surface of AgI NPs. Oxidation by using Au(III) also produced an Au(I) intermediate that was trapped and characterized. Engineered single-electron transfer reactions of these redox-robust nanomaterial precursors appear to be a new way to control their formation, size, and environment in a supramolecular way.

Mixed-valent click intertwined polymer units containing biferrocenium chloride side chains form nanosnakes that encapsulate gold nanoparticles.

Polymers containing triazolylbiferrocene are synthesized by ROMP or radical chain reactions and react with HAuCl4 to provide class-2 mixed-valent triazolylbiferrocenium polyelectrolyte networks (observed inter alia by TEM and AFM) that encapsulate gold nanoparticles (AuNPs). With triazolylbiferrocenium in the side polymer chain, the intertwined polymer networks form nanosnakes, unlike with triazolylbiferrocenium in the main polymer chain. By contrast, simple ferrocene-containing polymers do not form such a ferricenium network upon reaction with Au(III), but only small AuNPs, showing that the triazolyl ligand, the cationic charge, and the biferrocenium structure are coresponsible for such network formations.

CQDs-Cross-Linked Conductive Collagen/PAA-Based Nanocomposite Organohydrogel Coupling Flexibility with Multifunctionality for Dual-Modal Sensing of Human Motions.

Conductive hydrogels are ideal materials for intelligent medical devices, human-machine interfaces, and flexible bioelectrodes due to their adjustable mechanical properties and electrical responsiveness, whereas it is still a great challenge to achieve the integration of excellent flexibility and biocompatibility into one hydrogel sensor while also incorporating self-healing, self-adhesion, environmental tolerance, and antimicrobial properties. Here, a nanocomposite conductive organohydrogel was constructed by using collagen (Col), alginate-derived carbon quantum dots (OSA-CQDs), poly(acrylic acid) (PAA), ethylene glycol reduced AgNPs, and Fe3+ ions. Depending on OSA-CQDs with multiple chemical binding sites and high specific surface area as cross-linkers, while coupling highly biologically active Col chains and PAA chains are serving as an energy dissipation module, the resulting organohydrogel exhibited excellent flexibility (795% of strain, 193 kPa of strength), high cell compatibility (>95% survival rate), self-healing efficiency (HE = 79.5%), antifreezing (-20 °C), moisturizing (>120 h), repeatable adhesion (strength >20 kPa, times >10), inhibitory activity against Escherichia coli and Staphylococcus aureus (9 and 21.5 cm2), conductivity, and strain sensitivity (σ = 1.34 S/m, gauge factor (GF) = 11.63). Based on the all-in-one integration of multifunction, the organohydrogel can collaboratively adapt to the multimode of strain sensing and electrophysiological sensing to realize wireless real-time monitoring of human activities and physiological health. Therefore, this work provides a new and common platform for the design and sensing of next-generation hydrogel-based smart wearable sensors.

Collagen fiber-reinforced, tough and adaptive conductive organohydrogel e-skin for multimodal sensing applications.

Conductive hydrogels (CHs) with high sensitivity and multifunctional property are considered as excellent materials for wearable devices and flexible electronics. Surface synapses and internal multilayered structures are key factors for highly sensitive pressure sensors. Nevertheless, current CHs lack environmental adaptability, multifunctional perception, and instrument portability, which seriously hinders their application as sensors. Here, waste collagen fibers (buffing dust of leather), polyvinyl alcohol (PVA) and gelatin (Gel) were used as the basic framework of the hydrogel, loaded with a conductive material (silver nanoparticles (BD-CQDs@AgNPs)) and an anti-freezing moisturizer (glycerol (Gly)), resulting in a multifunctional conductive organohydrogel (BPGC-Gly). As a temperature and humidity sensor, it demonstrated an excellent temperature response range (-20-60 °C) and was capable of rapid response (2.4 s) and recovery (1.6 s) to human breathing. As a strain/pressure sensor, it allowed real-time monitoring of human movement and had a high low-pressure sensitivity (S = 4.26 kPa-1, 0-12.5 kPa). Interestingly, BPGC-Gly could also be used as a portable bioelectrode or the acquisition, monitoring and analysis of EMG/ECG signals. In this work, BPGC-Gly was assembled with wireless transmission to achieve multimodal heath detection, which opens new avenues for multi-responsive CHs, comprehensive human health monitoring and next-generation wearable electronic skin (e-skin).

Carbon Quantum Dot-Functionalized Dermis-Derived Transparent Electronic Skin for Multimodal Human Motion Signal Monitoring and Construction of Self-Powered Triboelectric Nanogenerator.

Electronic skin (e-skin) is considered as a highly promising interface for human-computer interaction systems and wearable electronic devices. Through elaborate design and assembly of various materials, it possesses multiple characteristics similar to human skin, including remarkable flexibility, stretchability, sensitivity to temperature and humidity, biocompatibility, and efficient interfacial ion/electron transport capabilities. Here, we innovatively integrate multifunctional carbon quantum dots (CQDs), which exhibit conductivity, antibacterial properties, ultraviolet absorption, and fluorescence emission, with poly(acrylic acid) and glycerin (Gly) into a three-dimensional network structure of natural goatskin collagen fibers. Through a top-down design strategy enhanced by hydrogen bond reconstruction, we successfully fabricated a novel transparent e-skin (PAC-eSkin). This e-skin exhibited significant tensile properties (4.94 MPa of tensile strength and 263.42% of a maximum breaking elongation), while also possessing Young's modulus similar to human skin (2.32 MPa). It is noteworthy that the functionalized CQDs used was derived from discarded goat hair, and the addition of Gly gave PAC-eSkin excellent antifreezing and moisturizing properties. Due to the presence of ultrasmall CQDs, which creates efficient ion/electron transport channels within PAC-eSkin, it could rapidly sense human motion and physiological signals (with a gauge factor (GF) of 1.88). Furthermore, PAC-eSkin had the potential to replace traditional electrode patches for real-time monitoring of electrocardiogram, electromyogram, and electrooculogram signals, with a higher SNR (signal-to-noise ratio) of 25.1 dB. Additionally, the customizable size and shape of PAC-eSkin offer vast possibilities for the construction of single-electrode triboelectric nanogenerator systems. We have reason to believe that the design and development of this transparent e-skin based on CQDs-functionalized dermal collagen matrices can pave a new way for innovations in human-computer interaction interfaces and their sensing application in diverse scenarios.

Chestnut-Tannin-Crosslinked, Antibacterial, Antifreezing, Conductive Organohydrogel as a Strain Sensor for Motion Monitoring, Flexible Keyboards, and Velocity Monitoring.

Flexible sensing devices (FSDs) fabricated using conductive hydrogels have attracted researchers' extensive enthusiasm in recent years due to their versatility. Considering the complexity of their application environments, the integration of various functional characteristics (e.g., excellent mechanical, antibacterial, and antifreezing properties) is an important guarantee for FSDs to stably perform their applications in different environments. Herein, we developed a multifunctional conductive polyvinyl alcohol (PVA) organohydrogel PVA-CT-Ag-Al-Gly (PCAAG) by using a green, natural, and cheap biomass, chestnut tannin (CT), as a crosslinking agent, nano-silver particles (AgNPs) as an antimicrobial agent, aluminum trichloride (AlCl3) as a conducting medium, and the mixed water-glycerol as the solvent system. In this organohydrogel system, CT acted not only as the reducing and stabilizing agent for the preparation of antibacterial AgNPs but also as the crosslinking agent owing to its strong multiple hydrogen bonding interactions with PVA, realizing its multifunctional application. The PCAAG organohydrogel possessed outstanding physical and mechanical properties (350.54% of the maximum fracture strain and 1.55 MPa of the maximum tensile strength), considerable bacteriostatic effects against both Escherichia coli and Staphylococcus aureus, and excellent freeze resistance (it could function normally at -20 °C). The motion-monitoring sensor based on the PCAAG organohydrogel exhibited excellent specificity recognition for both large-amplitude (e.g., elbow bending, wrist bending, finger bending, running and walking, etc.) and small-amplitude (frowning and swallowing) human movements. The flexible keyboard constructed by using the PCAAG organohydrogel could easily achieve the transformation between digital signals and electrical signals, and the signal output had both specificity and stability. The velocity-monitoring sensor fabricated by using the PCAAG organohydrogel could accurately measure the speed of the object movement (less than 3% of relative error). In short, the present PCAAG organohydrogel solves the problems of the single application environment and a few application scenarios of traditional conductive hydrogels and possesses remarkable application potential as a multifunctional FSD in many fields such as artificial intelligence, sport management, soft robots, and human-computer interface.

Self-Healable, Adhesive, Anti-Drying, Freezing-Tolerant, and Transparent Conductive Organohydrogel as Flexible Strain Sensor, Triboelectric Nanogenerator, and Skin Barrier.

Conductive hydrogels have attracted tremendous interest in the construction of flexible strain sensors and triboelectric nanogenerators (TENGs) owing to their good stretchability and adjustable properties. Nevertheless, how to simultaneously achieve high transparency, self-healing, adhesion, antibacterial, anti-freezing, anti-drying, and biocompatibility properties through a simple method remains a challenge. Herein, a transparent, freezing-tolerant, and multifunctional organohydrogel (PAOAM-PDO) as electrode for strain sensors and TENGs was constructed through a free radical polymerization in the 1,3-propanediol (PDO)/water binary solvent system, in which oxide sodium alginate, aminated gelatin, acrylic acid, and AlCl3 were used as raw materials. The obtained PAOAM-PDO exhibited good transparency (>90%), self-healing, adhesiveness, antibacterial property, good conductivity (1.13 S/m), and long-term environmental stability. The introduction of PDO endowed PAOAM-PDO with freezing resistance with a low freezing point of -60 °C, and PAOAM-PDO could serve as a protective skin barrier to prevent frostbite at low temperature. PAOAM-PDO could be assembled as strain sensors to monitor heterogeneous human movements with high strain sensitivity (gauge factor of 7.05, strain = 233%). Meanwhile, PAOAM-PDO could be further fabricated as a TENG with a "sandwich" structure in single electrode mode. Moreover, the resulting TENG achieved electrical outputs with simple hand tapping and served as a self-powered device to light light-emitting diodes. This work displays a feasible strategy to build environment-tolerant and multifunctional organohydrogels, which possess potential applications in the wearable electronics and self-powered devices.

Collagen-Based Organohydrogel Strain Sensor with Self-Healing and Adhesive Properties for Detecting Human Motion.

Conductive hydrogels are ideal for flexible sensors, but it is still a challenge to produce such hydrogels with combined toughness, self-adhesion, self-healing, anti-freezing, moisturizing, and biocompatibility properties. Herein, inspired by natural skin, a highly stretchable, strain-sensitive, and multi-environmental stable collagen-based conductive organohydrogel was constructed by using collagen (Col), acrylic acid, dialdehyde carboxymethyl cellulose, 1,3-propylene glycol, and AlCl3. The resulting organohydrogel exhibited excellent tensile (strain >800%), repeatable adhesion (>10 times), self-healing [self-healing efficiency (SHE) ≈ 100%], anti-freezing (-60 °C), moisturizing (>20 d), and biocompatible properties. This organohydrogel also possessed good electrical conductivity (σ = 3.4 S/m) and strain-sensitive properties [GF (gauge factor) = 13.65 with the maximal strain of 400%]. Notably, the organohydrogel had a considerable low-temperature self-healing performance (SHE = 88% at -24 °C) and rapid underwater self-healing property (SHE = 92%, self-healing time <20 min). This type of strain sensor could not only accurately and continuously monitor the large-scale motions of the human body but also provide an accurate response to the human tiny motions. This work not only proposes a development strategy for a multifunctional conductive organohydrogel with multiple environmental stability but also provides potential research value for the construction of biomimetic electronic skin.

Radiocarbon dating of charcoal and bone collagen associated with early pottery at Yuchanyan Cave, Hunan Province, China.

Yuchanyan Cave in Daoxian County, Hunan Province (People's Republic of China), yielded fragmentary remains of 2 or more ceramic vessels, in addition to large amounts of ash, a rich animal bone assemblage, cobble and flake artifacts, bone tools, and shell tools. The artifacts indicate that the cave was a Late Paleolithic foragers' camp. Here we report on the radiocarbon ages of the sediments based on analyses of charcoal and bone collagen. The best-preserved charcoal and bone samples were identified by prescreening in the field and laboratory. The dates range from around 21,000 to 13,800 cal BP. We show that the age of the ancient pottery ranges between 18,300 and 15,430 cal BP. Charcoal and bone collagen samples located above and below one of the fragments produced dates of around 18,000. These ceramic potsherds therefore provide some of the earliest evidence for pottery making in China.

Highly Sensitive and Robust Polysaccharide-Based Composite Hydrogel Sensor Integrated with Underwater Repeatable Self-Adhesion and Rapid Self-Healing for Human Motion Detection.

Tough, biocompatible, and conductive hydrogel-based strain sensors are attractive in the fields of human motion detection and wearable electronics, whereas it is still a great challenge to simultaneously integrate underwater adhesion and self-healing properties into one hydrogel sensor. Here, a highly stretchable, sensitive, and multifunctional polysaccharide-based dual-network hydrogel sensor was constructed using dialdehyde carboxymethyl cellulose (DCMC), chitosan (CS), poly(acrylic acid) (PAA), and aluminum ions (Al3+). The obtained DCMC/CS/PAA (DCP) composite hydrogels exhibit robust mechanical strength and good adhesive and self-healing properties, due to the reversible dynamic chemical bonds and physical interactions such as Schiff base bonds and metal coordination. The conductivity of hydrogel is 2.6 S/m, and the sensitivity (gauge factor (GF)) is up to 15.56. Notably, the DCP hydrogel shows excellent underwater repeatable adhesion to animal tissues and good self-healing properties in water (self-healing rate > 90%, self-healing time < 10 min). The DCP hydrogel strain sensor can sensitively monitor human motion including finger bending, smiling, and wrist pulse, and it can steadily detect human movement underwater. This work is expected to provide a new strategy for the design of high-performance intelligent sensors, particularly for applications in wet and underwater environments.

PRIN: a predicted rice interactome network.

BACKGROUND: Protein-protein interactions play a fundamental role in elucidating the molecular mechanisms of biomolecular function, signal transductions and metabolic pathways of living organisms. Although high-throughput technologies such as yeast two-hybrid system and affinity purification followed by mass spectrometry are widely used in model organisms, the progress of protein-protein interactions detection in plants is rather slow. With this motivation, our work presents a computational approach to predict protein-protein interactions in Oryza sativa. RESULTS: To better understand the interactions of proteins in Oryza sativa, we have developed PRIN, a Predicted Rice Interactome Network. Protein-protein interaction data of PRIN are based on the interologs of six model organisms where large-scale protein-protein interaction experiments have been applied: yeast (Saccharomyces cerevisiae), worm (Caenorhabditis elegans), fruit fly (Drosophila melanogaster), human (Homo sapiens), Escherichia coli K12 and Arabidopsis thaliana. With certain quality controls, altogether we obtained 76,585 non-redundant rice protein interaction pairs among 5,049 rice proteins. Further analysis showed that the topology properties of predicted rice protein interaction network are more similar to yeast than to the other 5 organisms. This may not be surprising as the interologs based on yeast contribute nearly 74% of total interactions. In addition, GO annotation, subcellular localization information and gene expression data are also mapped to our network for validation. Finally, a user-friendly web interface was developed to offer convenient database search and network visualization. CONCLUSIONS: PRIN is the first well annotated protein interaction database for the important model plant Oryza sativa. It has greatly extended the current available protein-protein interaction data of rice with a computational approach, which will certainly provide further insights into rice functional genomics and systems biology. PRIN is available online at http://bis.zju.edu.cn/prin/.