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Social media has provided promotion and communication channels for organizations to reach their target audience efficiently and cost-effectively. Despite wide social media analytics applications in different areas, scant studies focus on NGOs. This research analyzes the use of social media by a well-known NGO, the Hong Kong Generation Next Arts Limited (HKGNA), on its presence and user sentiment on Twitter and Facebook to evaluate the brand image, engagement conditions, and promotion effectiveness. These findings showed a low usage frequency of their Twitter channel. Despite the overall positive sentiment, there are some deviations from their charity mission. Yet, their Facebook channel serves well for publicity, and the interaction is relatively active. Thus, more measures are necessary to improve the digital relationship between HKGNA and its targeted audience. Moreover, this methodology for data analysis serves as an example for other NGOs to improve their communication.

As a promising drug nanocarrier, carbon dots (CDs) have exhibited many excellent properties. However, some properties such as bone targeting and crossing the blood–brain barrier (BBB) only apply to a certain CD preparation with limited drug loading capacity. Therefore, it is significant to conjugate distinct CDs to centralize many unique properties on the novel drug nanocarrier. Considering that CDs have abundant and tunable surface functionalities, in this study, a direct conjugation was initiated between two distinct CD models, black CDs (B-CDs) and gel-like CDs (G-CDs) via an amidation reaction. As a result of conjugation at a mass ratio of 5:3 (B-CDs to G-CDs) and a two-step purification process, the conjugate, black-gel CDs (B-G CDs) (5:3) inherited functionalities from both CDs and obtained an enhanced thermostability, aqueous stability, red-shifted photoluminescence (PL) emission, and a figure-eight shape with a width and length of 3 and 6 nm, respectively. In addition, the necessity of high surface primary amine ( NH2) content in the CD conjugation was highlighted by replacing G-CDs with other CDs with lower surface NH2 content. Meanwhile, the carboxyl groups ( COOH) on G-CDs were not enough to trigger self-conjugation between G-CDs. Moreover, the drug loading capacity was enhanced by 54.5% from B-CDs to B-G CDs (5:3). Furthermore, when the mass ratio of B-CDs to G-CDs was decreased from 5:30, 5:100 to 5:300, the obtained nanostructures revealed a great potential of CDs as Lego-like building blocks. Also, bioimaging of zebrafish demonstrated that various B-G CDs exhibited properties of both bone targeting and crossing the BBB, which are specific properties of B-CDs and G-CDs, respectively.

In this study, top-down syntheses of carbon dots (CDs) from four different carbon precursors, namely, carbon nano powders, graphite, graphene, and carbon nanotubes, were carried out. Systematic study demonstrated that the optical properties and surface functionalities of the CDs were quite similar and mainly influenced by the synthesis method, while the sizes, morphologies, chemical compositions, and core structures of the CDs were heavily influenced by the carbon precursors. On the basis of these studies, the formation processes and structural models of these four top-down CDs were proposed. The cell cytotoxicity and photothermal conversion efficiency of these CDs were also carefully evaluated, demonstrating their potential applications in photothermal therapy.

As the scale of integrated circuits continues to expand, electronic design automation (EDA) and intellectual property (IP) reuse play an increasingly important role in the integrated circuit design process. Although many Web-EDA platforms have begun to provide online EDA software to reduce the threshold for the use of EDA tools, IP protection on the Web- EDA platform is an issue. This article uses blockchain technology to design an IP trading system for the Web-EDA platform to achieve mutual trust and transactions between IP owners and users. The structure of the IP trading system is described in detail, and a blockchain wallet for the Web-EDA platform is developed.

Symmetry constraints in the analog circuit layout have significant impacts on analog system performance. In this paper, an efficient framework is proposed to detect symmetry pairs of analog devices from the circuit netlist. Firstly, we extract the specialized feature vectors of a MOSFET device from an analog circuit netlist, and then obtain the coded vector for the device connection relationship between two MOSFET devices. According to the coded vectors, the basic building blocks of the analog circuits can be classified and the basic symmetry constraints of the circuit is recognized. Furthermore, more symmetry constraints of devices are detected through the combination of the basic building block recognition and feature representation. We executed the experiments on the open-source analog dataset of MAGICAL and our tape-out analog circuit. The experimental results showed that the proposed framework with the vector coding method achieved the promising performance in terms of the accuracy on symmetry constraint detection and building block recognition.

Individual specialization and high plasticity in feeding activity are common in natural populations. However, the role of these two in intraspecific competition is unclear. In this study, the rhythm of feeding activity, dietary composition, niche width, niche overlap, and individual specialization was explored in four different size groups of black amur bream (Megalobrama terminalis), using microscopic identification of foregut contents and stable isotope analysis (δ13C and δ15N) of dorsal muscle. Both methods observed ontogenetic shifts in dietary preference and individual specializations, and revealed that the total niche width of large individuals was greater than small individuals. Mixed linear models indicated that feeding activity was significantly influenced by time (p p = 0.244). Niche overlaps revealed that there was intensive diet competition between different size groups of black amur bream. Individual specialization in small juveniles was likely to be stronger than sub-adult and adult groups. Pearson’s correlation analysis revealed that the individual specialization was positively correlated with mean diet similarity within a group. The results indicated that intraspecific competition is reduced mainly by individual dietary specialization, rather than shift in feeding activity.

This paper studies the plan recognition problem of multi-agent systems with temporal logic tasks. The high-level temporal tasks are represented as linear temporal logic (LTL). We present a probabilistic plan recognition algorithm to predict the future goals and identify the temporal logic tasks of the agent based on the observations of their states and actions. We subsequently build a plan library composed of Nondeterministic Bu¨chi Automation to model the temporal logic tasks. We also propose a Boolean matrix generation algorithm to map the plan library to multi-agent trajectories and a task recognition algorithm to parse the Boolean matrix. Then, the probability calculation formula is proposed to calculate the posterior goal probability distribution, and the cold start situation of the plan recognition is solved using the Bayes formula. Finally, we validate the proposed algorithm via extensive comparative simulations.

The interface of nucleic acids and nanomaterials is among the most promising fields in recent years. Considerable efforts have been devoted to the development of novel systems based on the two components for various promising applications such as sensing, bioimaging, drug delivery, and theranostics. However, the determination of nucleic acid concentration in these systems remains as a challenge due to the interference of nanoparticles. To this end, we developed a simple, yet reliable, method to quantify the nucleic acid concentration in their nanoparticle or polymer conjugates based on circular dichroism (CD) spectroscopy. In this paper, three nucleic acids, namely, DNA sodium salt from calf thymus (NaDNA), DNA from herring sperm (hsDNA), and ribonucleic acid from torula yeast (tyRNA), were noncovalently conjugated to three nanoparticles. The concentrations of the three nucleic acids in their nanoparticle conjugates were successfully determined on the basis of CD spectra calibration curves.

Carbon dots have received great attention as a result of the favorable optical properties these nanoparticles possess. While much work has been done toward enhancing the optical properties, little investigation has been done on the materialistic properties of these nontoxic nanoparticles. Herein, a simple one-pot procedure for producing a highly viscous, thixotropic carbon dot gel material is presented. The carbon dots possess tunable emissions that are excitation-wavelength dependent and are an ideally viscous material.

Biofilm is an extracellular matrix of bacteria and serves as a protective shield of bacterial communities. It is crucial for microbial growth and one of the leading causes of human chronic infections as well. However, the structures and molecular mechanism of biofilm formation remain largely unknown. Here, we examined a protein, BslA, expressed in the biofilms of Bacillus subtilis. We characterized the Langmuir monolayers of BslA at the air/water interface. Using techniques in surface chemistry and spectroscopy, we found that BslA forms a stable and robust Langmuir monolayer at the air/water interface. Our results show that the BslA Langmuir monolayer underwent two-stage elasticity in the solid state phase upon mechanical compression: one is possibly due to the intermolecular interaction and the other is likely due to both the intermolecular compulsion and the intramolecular distortion. The Langmuir monolayer of BslA shows abrupt changes in rigidities and elasticities at ∼25 mN/m. This surface pressure is close to the one at which BlsA saturates the air/water interface as a self-assembled film without mechanical compression, corresponding to a mean molecular area of ∼700 Å

Carbon dots, a recent member of the renowned carbon-based nanomaterials family, have attracted significant interest from various fields. The extraordinary properties, including excellent photoluminescence, high biocompatibility, and tunable surface functionalities as well as the abundant and inexpensive nature, have led to remarkable bioapplications in bioimaging, drug delivery, and theranostics development. In this article, studies on the interaction of C-dots with biomacromolecules are reviewed first, and recent developments of C-dots for target-specific bioimaging, drug delivery as well as theranostics development are highlighted and discussed.

Highly photoluminescent gel-like carbon dots (G-CDs) were successfully synthesized for the first time by a rapid one-step solvothermal synthesis approach with citric acid and 1,2-ethylenediamine as the precursors. Their gel-like nature was revealed by the Tyndall and coagulation effects, which were elucidated by a negative ζ potential value. The influences of temperature on the properties and sizes of these G-CDs were analyzed, and the best method for a maximum quantum yield was identified. The resulting products emitted blue photoluminescence under UV light (λ=365 nm) and a gradient of color under regular light. In addition, the UV/Vis absorption and fluorescence emission spectra of the G-CDs indicated that those synthesized at 160 °C exhibited the highest fluorescence quantum yield (33 %). Atomic force microscopy and transmission electron microscopy measurements were performed, and a higher temperature of formation resulted in smaller G-CDs. Furthermore, band shifts in the UV/Vis and fluorescence spectra and sequential changes in the quantum yield values and ζ potentials in addition to elemental compositional changes as determined by X-ray photoelectron spectroscopy were monitored throughout the formation process of the G-CDs. As to applications, G-CDs were prepared as an invisible ink for printers, which exhibited the applicability of G-CDs in daily life and military activities.

Bone tissue engineering (BTE) has received significant attention due to its enormous potential in treating critical-sized bone defects and related diseases. Traditional materials such as metals, ceramics, and polymers have been widely applied as BTE scaffolds; however, their clinical applications have been rather limited due to various considerations. Recently, carbon-based nanomaterials attract significant interests for their applications as BTE scaffolds due to their superior properties, including excellent mechanical strength, large surface area, tunable surface functionalities, high biocompatibility as well as abundant and inexpensive nature. In this article, recent studies and advancements on the use of carbon-based nanomaterials with different dimensions such as graphene and its derivatives, carbon nanotubes, and carbon dots, for BTE are reviewed. Current challenges of carbon-based nanomaterials for BTE and future trends in BTE scaffolds development are also highlighted and discussed.

Nanoparticles have been conjugated to biological systems for numerous applications such as self-assembly, sensing, imaging, and therapy. Development of more reliable and robust biosensors that exhibit high response rate, increased detection limit, and enhanced useful lifetime is in high demand. We have developed a sensing platform by the conjugation of &beta, galactosidase, a crucial enzyme, with lab-synthesized gel-like carbon dots (CDs) which have high luminescence, photostability, and easy surface functionalization. We found that the conjugated enzyme exhibited higher stability towards temperature and pH changes in comparison to the native enzyme. This enriched property of the enzyme was distinctly used to develop a stable, reliable, robust biosensor. The detection limit of the biosensor was found to be 2.9 &times, 10&minus, 4 M, whereas its sensitivity was 0.81 &micro, A&middot, mmol&minus, 1&middot, cm&minus, 2. Further, we used the Langmuir monolayer technique to understand the surface properties of the conjugated enzyme. It was found that the conjugate was highly stable at the air/subphase interface which additionally reinforces the suitability of the use of the conjugated enzyme for the biosensing applications.

Bone-related diseases and dysfunctions are heavy burdens on our increasingly aged society. One important strategy to relieve this problem is through early detection and treatment of bone-related diseases. Towards this goal, there has been constant interest in developing novel bone-specific materials for imaging and drug delivery. Currently, however, materials that have high affinity and specificity towards bone are very limited. Carbon dots (C-dots) synthesized from carbon nanopowder bind to calcified bones in vivo with high affinity and specificity. In this study we show that bone binding is highly unique to a specific type of C-dot, and that this binding is non-toxic. Significantly, C-dots derived from other raw materials did not show any bone binding properties. These differences are attributed to the differences in surface chemistry of C-dot preparations, highlighting the heterogeneous nature of C-dots. Importantly, bone-binding by carbon nanopowder derived C-dots is not significantly altered by chemical functionalization of their surface. These unique properties indicate the potential applications of carbon nanopowder-derived C-dots as highly bone-specific bioimaging agents and drug carriers.

Cardiovascular disease (CVD) has threatened human lives for decades, and a technique for estimating and healing is still needed. There has been increasing interest in finding CVD diagnostic biomarkers to predict risk. Cardiac troponin I (cTnI) has proven to be a significant biomarker for acute myocardial infarction detection. An immunoassay based biosensor for cTnI can play an important role in diagnosis of CVD. Over the past decades, various methodologies regarding cTnI detection have been studied, including colorimetric, fluorescence, paramagnetic, electrochemical, and surface plasmon resonance. This review will focus more on recent strategies about surface immobilized cTnI detection.

Among various cancers, pediatric brain tumors represent the most common cancer type in children and the second most common cause of cancer related deaths. Anticancer drugs and therapies, such as doxorubicin (Dox), have severe side effects on patients during chemotherapy, especially for children as their bodies are still under development. These side effects are believed to be due to the lack of a delivery system with high efficacy and targeting selectivity, resulting in serious damages of normal cells. To improve the efficacy and selectivity, the transferrin (Trans) receptor mediated endocytosis can be utilized for drug delivery system design, as transferrin receptors are expressed on the blood brain barrier (BBB) and often over expressed in brain tumor cells. Carbon dots (C-Dots) have recently emerged as benign nanoparticles in biomedical applications owing to their good water solubility, tunable surface functionalities and excellent biocompatibility. The unique characteristics of C-Dots make them promising candidates for drug delivery development. In this study, carbon dots-transferrin-doxorubicin covalent conjugate (C-Dots-Trans-Dox) was synthesized, characterized by different spectroscopic techniques and investigated for the potential application as a drug delivery system for anticancer drug doxorubicin to treat pediatric brain tumors. Our in vitro results demonstrate greater uptake of the C-Dots-Trans-Dox conjugate compared to Dox alone presumably owing to the high levels of transferrin receptors on these tumor cells. Experiment showed that C-Dots-Trans-Dox at 10 nM was significantly more cytotoxic than Dox alone, reducing viability by 14-45%, across multiple pediatric brain tumor cell lines.

We characterized BslA, a bacterial biofilm protein, at the air/water interface using vibrational sum frequency generation spectroscopy and observed one of the sharpest amide I bands ever reported. Combining methods of surface pressure measurements, thin film X-ray reflectivity, and atomic force microscopy, we showed extremely ordered BslA at the interface.

Because accidents, disease and aging compromise the structural and physiological functions of bones, the development of an in vivo bone imaging test is critical to identify, detect and diagnose bone related development and dysfunctions. Recent advances in fluorescence instrumentation offer a new alternative for traditional bone imaging methods. However, the development of new in vivo bone imaging fluorescence materials has significantly lagged behind. Here we show that carbon dot nanoparticles (C-dots) with low quantum yield ("dark") bind to calcified bone structures of live zebrafish larvae with high affinity and selectivity. Binding resulted in a strong enhancement of luminescence that was not observed in other tissues, including non-calcified endochondral elements. Retention of C-dots by bones was very stable, long lasting, and with no detectable toxicity. Furthermore, we found C-dots to be a suitable carrier to deliver fluorescein to bones. These observations support a novel and revolutionary use of C-dots as highly specific bioagents for bone imaging and diagnosis, and as bone-specific drug delivery vehicles.

In this article, we explored the surface chemistry properties of a cholera toxin B (CTB) monolayer at the air-subphase interface and investigated the change in interfacial properties through in situ spectroscopy. The study showed that the impact of the blue shift was negligible, suggesting that the CTB molecules were minimally affected by the subphase molecules. The stability of the CTB monolayer was studied by maintaining the constant surface pressure for a long time and also by using the compression-decompression cycle experiments. The high stability of the Langmuir monolayer of CTB clearly showed that the driving force of CTB going to the amphiphilic membrane was its amphiphilic nature. In addition, no major change was detected in the various in situ spectroscopy results (such as UV-vis, fluorescence, and IR ER) of the CTB Langmuir monolayer with the increase in surface pressure. This indicates that no aggregation occurs in the Langmuir monolayer of CTB.

The host-guest properties of acetylated aryl pyrogallol[4]arene (AcPy) were studied as a Langmuir monolayer at the air-water interface. The self-assembled Langmuir monolayer properties and interactions with monovalent and divalent metal cations were investigated using surface pressure- and surface potential-area isotherms, compression-decompression cycles, stability, and infrared reflection-absorption spectroscopy (IRRAS). A favorable interaction is observed for complexation between acetylated aryl pyrogallol[4]arene with divalent calcium and cadmium cations, while no interaction is observed for monovalent sodium and potassium cations. Spectroscopic techniques allow for discrimination between cadmium and calcium complexation.

Biosensing methods and devices using graphene oxide (GO) have recently been explored for detection and quantification of specific biomolecules from body fluid samples, such as saliva, milk, urine, and serum. For a practical diagnostics application, any sensing system must show an absence of nonselective detection of abundant proteins in the fluid matrix. Because lysozyme is an abundant protein in these body fluids (e.g., around 21.4 and 7 μg/mL of lysozyme is found in human milk and saliva from healthy individuals, and more than 15 or even 100 μg/mL in patients suffering from leukemia, renal disease, and sarcoidosis), it may interfere with detections and quantification if it has strong interaction with GO. Therefore, one fundamental question that needs to be addressed before any development of GO based diagnostics method is how GO interacts with lysozyme. In this study, GO has demonstrated a strong interaction with lysozyme. This interaction is so strong that we are able to subsequently eliminate and separate lysozyme from aqueous solution onto the surface of GO. Furthermore, the strong electrostatic interaction also renders the selective adsorption of lysozyme on GO from a mixture of binary and ternary proteins. This selectivity is confirmed by sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE), fluorescence spectroscopy, and UV-vis absorption spectroscopy.

Graphene oxide (GO) has demonstrated various promising applications in biomedical field. But information on how GO interacts with cell membrane or model system is still extremely limited. It is also unknown how GO orientates itself when interacting with lipids. In this study, the Langmuir monolayer technique is applied at the air–water/aqueous interface to study the nature and orientation of interaction between GO and lipid models. Five lipids (DODAB, DSEPC, DSPC, DSPA, and SA) with the same 18-carbon alkyl chain but different head groups of charges are purposely chosen to rationalize the possible interactions. Experimental results show that the interaction is governed by electrostatic interaction between the polar head groups and GO. GO can incorporate into the monolayer of positively charged lipids DODAB and DSEPC, but not the neutrally or negatively charged lipids (DSPC, DSPA, and SA). When GO is injected to the subphase underneath the monolayer of positively charged lipid DODAB and DSEPC, different be...

Reaction of formaldehyde with amino acids followed by oxidation with hydrogen peroxide to produce a fluorophore Norharman product is well known and was used for the spectrofluorimetric determination of l -tryptophan (Trp). This study aimed to use graphene oxide (GO) to enhance the selectivity and sensitivity of Trp in presence of other amino acids and possible interfering compounds. Different parameters such as pH, temperature, incubation time, and concentrations of formaldehyde, H 2 O 2 and GO were studied to optimize the condition of determination. Experimental data showed that the maximum fluorescence intensity was achieved in pH 7.0–9.0 phosphate buffer mixed with 7–10% (v/v) formaldehyde and 1–2% (v/v) H 2 O 2 as oxidizing agent at 60 C for 1 h. On the basis of calibration curve of various concentrations of Trp in the presence of 20 μg mL −1 GO, the lower limit of detection (LOD) of Trp was determined as 0.092 nmol mL −1 and the lower limit of quantification (LOQ) was 0.3 nmol mL −1 . The selectivity of Trp in presence of other amino acids and possible interfering compounds were studied with and without GO. The data obtained after inner filter effect corrections revealed that the selectivity of Trp in presence of amino acids and other possible interfering agents was improved in the range of 76–96%, compared with that in absence of GO. The enhancement of selectivity in the presence of GO indicates that the Trp and other amino acid and possible interfering compounds were adsorbed by GO, and the selective uptaking of Trp-by the reaction with formaldehyde followed by oxidation with H 2 O 2 at 60 C with high selectivity and sensitivity was achieved successfully.

Triblock copolymer Pluronic F127 (PF127) has previously been demonstrated to disperse graphene oxide (GO) in electrolyte solution and block the hydrophobic interaction between GO and l-tryptophan and l-tyrosine. However, the nature of this interaction between PF127 and GO remains to be characterized and elucidated. In the present study, we aimed to characterize and understand the interaction between GO and PF127 using a 2-dimensional Langmuir monolayer methodology at the air-water interface by surface pressure-area isotherm measurement, stability, adsorption, and atomic force microscopy (AFM) imaging. Based on the observation of surface pressure-area isotherms, adsorption, and stability of PF127 and PF127/GO mixture at the air-water interface, GO is suggested to change the conformation of PF127 at the air-water interface and also drag PF127 from the interface to the bulk subphase. Atomic force microscopy (AFM) image supports this assumption, as GO and PF127 can be observed by spreading the subphase solution outside the compressing barriers, as shown in the TOC graphic.

The application of nanoparticles (NPs) for biomedical use is one of the fastest growing fields in science. The great potential has attracted attention from many fields, including chemistry, biology, medicine, and engineering. However, with relatively little understanding of biomacromolecule–NP interactions, there are increasing safety concerns about the use of nanomaterials in biomedical fields. To determine the biocompatibility of NPs and evaluate their nanosafety, great efforts are currently being made on investigating biomacromolecule–NP interactions. Spectroscopic methods and strategies play an important role in these investigations to help us understand the mechanistic basis for the biological activity of NPs, which is essential for the safe application of nanotechnology. Herein, in this chapter, we summarize the recent progress in the study of protein–NP, DNA–NP, and lipid–NP interactions based on various spectroscopic techniques.

This article investigates the surface chemistry properties of the β-galactosidase monolayer at the air-subphase interface at the vicinity of its substrate, X-gal. We have demonstrated that the β-galactosidase in the monolayer form remained active and performed hydrolysis of the X-gal in the subphase. We investigated the β-galactosidase Langmuir monolayer in absence and presence of X-gal in the subphase of varying concentration of X-gal with the sodium chloride solution. It was found that the limiting molecular area as well as the collapse surface pressure kept on decreasing with the increasing concentration of X-gal. In accordance to the data obtained from the isotherm it was also found that β-galactosidase forms a stable monolayer that does not aggregate at the air-subphase interface. The stability of the monolayer at the air-subphase interface was studied by using compression-decompression cycles with and without X-gal at varying concentration and different surface pressures. The infrared reflection-absorption spectroscopy (IRRAS) and Brewster angle microscopy (BAM) of β-galactosidase Langmuir monolayer was also investigated for pure and mixed β-galactosidase at the air-subphase.

Peptides and proteins have become very promising drug candidates in recent decades due to their unique properties. However, the application of these drugs has been limited by their high enzymatic susceptibility, low membrane permeability and poor bioavailability when administered orally. Considerable efforts have been made to design and develop drug delivery systems that could transport peptides and proteins to targeted area. Although it is of great importance to determine the composition after loading a drug to the carrier, the ability to do so is significantly limited by current analytical methods. In this letter, five important proteins, α1-antitrypsin, hemoglobin human, human serum albumin, human transferrin and r-globulin were chemically conjugated to two model drug carriers, namely carbon dots and polymer O-(2-carboxyethyl) polyethylene glycol. A simple yet convenient method based on circular dichroism spectroscopy was developed to determine the compositions of the various protein-carrier conjugates.

Drug delivery to the central nervous system (CNS) in biological systems remains a major medical challenge due to the tight junctions between endothelial cells known as the blood-brain-barrier (BBB). Here we use a zebrafish model to explore the possibility of using transferrin-conjugated carbon dots (C-Dots) to ferry compounds across the BBB. C-Dots have previously been reported to inhibit protein fibrillation, and they are also used to deliver drugs for disease treatment. In terms of the potential medical application of C-Dots for the treatment of CNS diseases, one of the most formidable challenges is how to deliver them inside the CNS. To achieve this in this study, human transferrin was covalently conjugated to C-Dots. The conjugates were then injected into the vasculature of zebrafish to examine the possibility of crossing the BBB in vivo via transferrin receptor-mediated endocytosis. The experimental observations suggest that the transferrin-C-Dots can enter the CNS while C-Dots alone cannot.

Understanding the interaction between graphene oxide (GO) and the biomolecules is fundamentally essential, especially for disease- and drug-related peptides and proteins. In this study, GO was found to strongly interact with amino acids (tryptophan and tyrosine), peptides (Alzheimer's disease related amyloid beta 1-40 and type 2 diabetes related human islet amyloid polypeptide), and proteins (drug-related bovine and human serum albumin) by fluorescence quenching, indicating GO was a universal quencher for tryptophan or tyrosine related peptides and proteins. The quenching mechanism between GO and tryptophan (Trp) or tyrosine (Tyr) was determined as mainly static quenching, combined with dynamic quenching (Förster resonance energy transfer). Different quenching efficiency between GO and Trp or Tyr at different pHs indicated the importance of electrostatic interaction during quenching. Hydrophobic interaction also participated in quenching, which was proved by the presence of nonionic amphiphilic copolymer Pluronic F127 (PF127) in GO dispersion. The strong hydrophobic interaction between GO and PF127 efficiently blocked the hydrophobic interaction between GO and Trp or Tyr, lowering the quenching efficiency.

Human islet amyloid polypeptide (hIAPP) is the source of the major component of the amyloid deposits found in the islets of Langerhans of around 95 per cent type 2 diabetic patients. The formation of aggregates and mature fibrils is thought to be responsible for the dysfunction and death of the insulin-producing pancreatic β-cells. Investigation on the conformation, orientation and self-assembly of the hIAPP at time zero could be beneficial for our understanding of its stability and aggregation process. To obtain these insights, the hIAPP at time zero was studied at the air–aqueous interface using the Langmuir monolayer technique. The properties of the hIAPP Langmuir monolayer at the air–aqueous interface on a NaCl subphase with pH 2.0, 5.6 and 9.0 were examined by surface pressure- and potential-area isotherms, UV–Vis absorption, fluorescence spectroscopy and Brewster angle microscopy. The conformational and orientational changes of the hIAPP Langmuir monolayer under different surface pressures were characterized by p-polarized infrared-reflection absorption spectroscopy, and the results did not show any prominent changes of conformation or orientation. The predominant secondary structure of the hIAPP at the air–aqueous interface was α-helix conformation, with a parallel orientation to the interface during compression. These results showed that the hIAPP Langmuir monolayer at the air–aqueous interface was stable, and no aggregate or domain of the hIAPP at the air–aqueous interface was observed during the time of experiments.

New trinuclear complexes [Cu(NiL1)2(C2H5OH)2](ClO4)2 (1) and [Co(NiL2)2(H2O)2](ClO4)2 ·2(H2O) (2) were prepared using macrocyclic complex ligands with excess Cu(ClO4)2 · 6(H2O) and Co(ClO4)2 · 6(H2O), respectively, and characterized by X-ray crystallography. L1 and L2 denote the dianions of diethyl 5,6,7,8,15,16-hexahydro-6,7-dioxodibenzo[1,4,8,11]tetraazacyclotetradecine-13,18-dicarboxylate and diethyl 5,6,7,8,15,16-hexahydro-15-methyl-6,7-dioxodibenzo[1,4,8,11]tetraazacyclotetradecine-13,18-dicarboxylate, respectively. In each complex, Ni(II) has the same distorted N4 square planar coordination. In 1, Cu(II) resides in a distorted octahedral O6 coordination environment, and the trinuclear cations are linked by oxamido–carbonyl interactions and π ··· π interactions involving unclosed π-systems to form 1-D supramolecular chains. In 2, Co(II) also resides in a distorted octahedral O6 coordination environment, while the trinuclear cations are linked by O–H ··· O hydrogen bonds and π ··· π interactions invol...

Interactions between carbon nanomaterials, including carbon dots, fullerene, carbon nanotube, graphene, and graphene oxide, and biomolecules play an important role in the field of nanobiotechnology. Due to the unique properties of carbon nanomaterials and the magnificent features of their colloids, it shows high potential in fibrillation inhibition, high sensitivity sensor fabrication, bioimaging, drug delivery, and other areas. Hereby, we will go over different families of carbon nanomaterials regarding to the interaction between carbon nanomaterials and biomolecules at the interface, and their applications will be reviewed as well.

The attenuated total reflection technique was utilized to obtain FTIR spectra of (13)C-labeled peptides with a sequence of (AAAAK)4AAAAY in H2O. The regular amide I band was not at the typical position as reported in globular proteins, whereas the (13)C amide I band was still sensitive to conformation change.

Considerable efforts have been made to synthesize and characterize protein–nanoparticle conjugates (protein–NPs) for their promising applications in bionanotechnology. However, protein concentration determination in the protein–NPs has so far not been reported. In this Letter, we present a simple and nondestructive approach to quantify the protein concentration in the protein–NPs aqueous solution using circular dichroism (CD) spectroscopy. Carbon dots (∼4 nm), gold nanoparticles (∼10 nm), and polyethylene glycol (PEG, molecular weight ∼3000) were either physically mixed or covalently conjugated (not in the case of gold nanoparticles) with proteins (human transferrin, human serum albumin, and ovalbumin). We were able to quantify the protein concentration in the protein–nanoparticle conjugates using a calibration curve from the CD spectra.

Protein fibrillization is associated with many devastating neurodegenerative diseases. This process has been studied using spectroscopic and microscopic methods. In this study, epi-fluorescence at the air–water interface was developed as an innovative technique for observing fibrillization of bovine serum albumin and human insulin.

Isotope-edited FTIR spectroscopy has been shown to be able to determine peptide's structure in the residue level in D2O, which is not a physiological solvent. Here, attenuated total reflection technique was utilized to successfully apply isotope-edited FTIR spectroscopy in H2O to determine the conformation of specific residues in a model peptide.