Background and Objectives: Endemic plants are integral part of the ecosystem that provide innumerable benefits. Thus, emerging studies and applications using these endemic plants continue to increase globally. In this study, the preparation of gold nanoparticles (AuNPs) has been carried out by using the aqueous leaves extract of Dillenia philippinensis Rolfe. (Katmon) as the bioreductants. Methodology: After the synthesis of AuNPs, the process was further subjected to optimization to assure the production of AuNPs with the best parameters. Synthesized and optimized AuNPs were characterized using FTIR, XRD, DLS, Zeta Potential, and TEM. Results: Optimization results that provide the desired properties for AuNPs were a volume ratio of 1:2 (HAuCl₄: leaves extract), no significant difference (p>0.05) with the sequence of addition and reaction time, and acidic pH. The synthesized AuNPs' particles were found to contain hydroxyl and amine groups, had broad, amorphous, and spherical particles that have a mean diameter of 60.6nm, a PDI of 0.563, and a repulsion force of -13.720mV. The optimized and characterized AuNPs were then further used as a colorimetric sensing material, showing the potential applicability of AuNPs in the heavy metal analysis. Conclusion Gold nanoparticles were able to be synthesized with the use of bioreductants that are present in the aqueous leaves extract of Katmon. This concludes that endemic plants in the Philippines can be used for the synthesis of AuNPs and can be applied in the field of phytonanotechnology and other applied sciences.
Surface Plasmon Resonance

OBJECTIVEIn situ, real timely and dynamically monitoring the processes of theaflavin (TF), curcumin (Cur) and cyanidin (Cy) binding to human whole saliva (WS) surface has been investigated by surface plasmon resonance (SPR) technique at the molecular level.

METHODSThe affinity between pigments and WS, association rate constant (k(a)), dissociation rate constant (k(d)), association equilibrium constant (K(A)) and dissociation equilibrium constant (K(D)) of pigments binding on WS surface had been determined by SPR and the Langmuir model as well as the Freundlich model. The data were analyzed by one-way ANOVA and SNK-q test.

RESULTSThere were significant differences among TF, Cur and Cy in k(a), k(d), K(A) and K(D) (P<0.05). Our results showed that the adsorption isotherm of pigments on WS surface could be better described by the Freundlich model than the Langmuir model. The pigments adsorption on WS surface was dominant by specific interactions, such as hydrogen bonding. The affinity of pigments to WS were TF> Cur>Cy (P<0.05), as evidenced by the rate constants and equilibrium constants.

CONCLUSIONCompared with Cur and Cy, TF shows much higher adsorption capacity on WS surface, suggesting the importance of the hydroxyl group in pigment/protein interactions.

OBJECTIVE: To establish quantitative surface plasmon resonance (SPR) assay for antibodies against human platelet antigen-1a (HPA-1a). METHODS: Recombinant protein was fixed on the chip surface by amino coupling method. SPR assay was used to detect the standard antibodies against HPA-1a at different conceatration. The optimal experimental parameters were determined, and standard curves were constructed with linear regression. Moreover, the sensitivity, specificity, accuracy and precision of the assay were evaluated. RESULTS: The quantitative SPR assay for HPA-1a antibodies was established. The determination ranges were 0-20 IU, with accuracy (recovery rate) was 97.75%-103.08%. The intra-assay precision [coefficients of variation (CV)] was 3.53%-4.29%, and the inter-assay precision (CV) was 2.08%-4.40%. For specificity test, several kinds of monoclonal and human antibodies against platelet membrane protein were tested and no positive result was observed. CONCLUSION The established quantitative SPR assay for HPA-1a antibodies shows good sensitivity, specificity, accuracy and precision, and this rapid and simple method provides a new reference method for scientific research and clinical antibody detection.
Antigens, Human Platelet ; Blood Platelets ; Humans ; Isoantibodies ; Surface Plasmon Resonance

Surface plasmon resonance (SPR) biosensors have become an advanced method for measuring biological molecular interaction. This article is focused on the principle and advantages of SPR biosensor chip technology, and its new applications in biomedical research fields. Its application prospects are also discussed.
Clinical Laboratory Techniques ; Drug Evaluation, Preclinical ; methods ; Surface Plasmon Resonance ; instrumentation

Gene expression exhibits temporal and spatial patterns to response environmental changes and growth cycle. Gene expression is under strict control at different levels among which control at transcription level is the predominant mode, especially in prokaryotes. In this review, we summarized the new developments of methods used in transcriptional studies, including modifications and improvements of the classic methods, such as gel-shift assay, DNA foot printing, and in vivo reporter system. In addition, we introduced examples to apply new methods, such as surface plasmon resonance (SPR) and isothermal titration calorimetry (ITC) to characterize protein-DNA, ligand-protein, and ligand-protein-DNA interactions. The collection of these methods and their application could guide and accelerate relevant studies.
Calorimetry ; DNA Footprinting ; Gene Expression ; Ligands ; Proteins ; Surface Plasmon Resonance ; Transcription, Genetic

OBJECTIVETo prepare a zinc porphyrinated polyimide nanofibrous membrane for rapid detection of trace amount of ammonia.

METHODSZinc porphyrin chromophore was copolymerized into polyimide backbones and the according nanofibrous membrane was prepared by electrospinning technique. Ammonia detection was achieved by recording the color and spectral changes of the membrane before and after exposing to the target gas. The sensitivity, selectivity and detection limit of prepared membrane were further studied.

RESULTSThe obtained nanofibrous membrane preserved typical photophysical properties of zinc porphyrin chromophores. When exposed to ammonia, a dual chromo and spectrum responses of the nanofibrous membrane were observed. The binding affinity constant and the detection limit of zinc porphyrinated polyimide nanofibrous membrane calculated from surface plasmon resonance (SPR) analysis and UV-vis were 3.33 X10³ L/mol and 3.13 mg/m³, respectively.

CONCLUSIONThe membrane prepared in this study exhibits good sensitivity, selectivity and reproducibility towards ammonia detection.

Imported malaria has become a major risk factor for malaria prevention and control in China. How to screen malaria quickly for people entering China is an urgent problem to be solved. Protein microarrays are widely used in high-throughput screening and diagnosis. In this study, surface plasmon resonance (SPR) technique for malaria detection was established by using the specific adsorption surface treated by polyethylene glycol polymer, and the malaria specific antigen HRP2 was used as capture probe. The optimal concentration of antigen, sensitivity and specificity of detection, as well as anti-interference ability of the chip were analyzed. The SPR protein chip was applied to detect specific antibodies of malignant malaria in serum with the advantage of label-free, instant and fast. Compared with fluorescence quantitative PCR, there were no significant difference in sensitivity and specificity between the two methods. This study lays a foundation for further development of protein microarray for malaria typing identification, and it is conducive to the rapid screening of malaria for people entering.
Antibodies ; China ; Humans ; Malaria/diagnosis* ; Protein Array Analysis ; Surface Plasmon Resonance

OBJECTIVE: To investigate the feasibilily of screening and identifying the red blood cell type alloantibodies by means of surface plasman resonance(SPR) technique so as to provide a new method for detecting the transfusion compatibility of red blood cells. METHODS: The RBC antigens for screening the alloantibody were fixed on the SPR chip surface by means of amino coupling method; the analysis conditions of SPR chip were optimized and then the control serum with RBC blood group antibody positive was detected; the performance of SPR chip for detection of serum was analysed; the consistance of rusults detected by SPR technique and microcolum agglutination for clinieal samples of 129 thalasstmia patients with history of lone-term blood transfusion were compared; at the same time, the blood group amtibodies in 7 patients with blood group antibody positive were identified before blood transfusion by using SPR chip so as to select the RBC antigen compatible blood for transfusion; and the efficacy of RBC transfusion was followed up and evaluated. RESULTS: The repeatability, sensitivity and specificity of SPR chip technique for detecting the blood group alloantibodies all were better. The SPR technique and microcolumn agglutination method were not significant different for screening blood group alloantibodies (χ2 = 0.333, P＞0.05), and the overall consistency was 97.2%; the results of SPR technique in 7 patients with positive blood group antibodies were as follows: 3 cases with anti-E, 1 case anti-M, 1 case anti-C, 1 case anti-Jka and 1 case autoantibody, which were consistent with the results of microcolumn agglutination tests, and the compatible red blood cells were selected for transfusion, of which the infusion of 6 cases was effective. In only 1 case the infusion was ineffective because of autoantibody. CONCLUSION For screening and identification of blood group alloantibodies, the performance of SPR chip technique is equivalent to the micro-column agglutination, but the procedure of SPR technique is simpler, faster and high-throughput and label-free, which can meet the basic requirements for rapid screening and identification of blood group alloantibodies before transfusion of red blood cells.
Blood Group Antigens ; Blood Transfusion ; Erythrocytes ; Humans ; Isoantibodies ; Surface Plasmon Resonance

The detection method of gene chip based on SPR principle is a potential high-throughput microanalysis method without labelling. With the use of Self-assembled monolayer (SAM) technology, the gene chip of Neisseria gonorrhoeae probe lattice has been prepared, detected and analyzed using the Surface plasmon resonance (SPR) and SPR imaging (SPRI) gene chip detection system here-in provided for research in the hybridizatin reaction on the probe lattice of gene chip. The result indicates that there is an obvious resonance assimilate peak on the SPR resonance curve. And after hybridization, the refractive index and resonance as well as molecular weight of the probe have increased. So whether a hybridization takes place or whether the wanted ingredient is in the sample under examination can be determined by using SPR to watch the detecting interface or the resonance curve. The SPRI detection system is available for observing the happening of a hybridization on the probe of gene chip in real-time and straighforwardly. The SPR and SPRI system can do analysis qualitatively and quantitatively.
DNA Probes ; genetics ; Neisseria gonorrhoeae ; genetics ; Oligonucleotide Array Sequence Analysis ; instrumentation ; methods ; Surface Plasmon Resonance ; methods ; Surface Properties

The optical neural recording techniques are promising tools in recent years. Compared to the traditional electrophysiological recording, the optical means offer several advantages including no inclusion of electrical noise, simultaneous imaging of a large number of neurons, or selective recording from genetically-targeted neurons. Overall the optical neural recording technique comprises the intrinsic and the extrinsic optical recordings. The methods for intrinsic neural recording employ the change of optical properties in brains such as blood flow/oxygenation, cellular volume change, or refractive index change without addition of external indicators. Those properties can be detected using various optical techniques including laser Doppler flowmetry (LDF), near-infrared (NIR) spectrometer, functional optical coherence tomography (fOCT), and surface plasmon resonance (SPR). The extrinsic monitoring techniques use fluorescence signals reflecting neuronal activity via chemical or genetic modification of the neuronal cells. Two most popular activity-dependent fluorescent probes, calcium indicators and voltage-sensitive fluorescent proteins will be examined in this review. The principles, the instrumentations and in vivo applications of those optical signal measurements are described.
Brain ; Calcium ; Fluorescence ; Fluorescent Dyes ; Laser-Doppler Flowmetry ; Neurons ; Noise ; Proteins ; Refractometry ; Surface Plasmon Resonance ; Tomography, Optical Coherence