SEARCH · PubMed Health

Results for “Efficiency”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 271 records · Page 15Linked to original sources

PubMed2005

Technical efficiency of peripheral health units in Pujehun district of Sierra Leone: a DEA application.

BACKGROUND: The Data Envelopment Analysis (DEA) method has been fruitfully used in many countries in Asia, Europe and North America to shed light on the efficiency of health facilities and programmes. There is, however, a dearth of such studies in countries in sub-Saharan Africa. Since hospitals and health centres are important instruments in the efforts to scale up pro-poor cost-effective interventions aimed at achieving the United Nations Millennium Development Goals, decision-makers need to ensure that these health facilities provide efficient services. The objective of this study was to measure the technical efficiency (TE) and scale efficiency (SE) of a sample of public peripheral health units (PHUs) in Sierra Leone. METHODS: This study applied the Data Envelopment Analysis approach to investigate the TE and SE among a sample of 37 PHUs in Sierra Leone. RESULTS: Twenty-two (59%) of the 37 health units analysed were found to be technically inefficient, with an average score of 63% (standard deviation = 18%). On the other hand, 24 (65%) health units were found to be scale inefficient, with an average scale efficiency score of 72% (standard deviation = 17%). CONCLUSION: It is concluded that with the existing high levels of pure technical and scale inefficiency, scaling up of interventions to achieve both global and regional targets such as the MDG and Abuja health targets becomes far-fetched. In a country with per capita expenditure on health of about USD 7, and with only 30% of its population having access to health services, it is demonstrated that efficiency savings can significantly augment the government's initiatives to cater for the unmet health care needs of the population. Therefore, we strongly recommend that Sierra Leone and all other countries in the Region should institutionalize health facility efficiency monitoring at the Ministry of Health headquarter (MoH/HQ) and at each health district headquarter.

Benchmarking↗

PubMed2006

Sphingomyelin-enriched microdomains define the efficiency of native Ca(2+)-triggered membrane fusion.

Membrane microdomains or ;rafts' are suggested to act as regulators of the exocytotic process and also appear to be the sites of Ca(2+)-triggered membrane fusion. Microdomains are postulated to maintain the localization of ;efficiency' factors, including Ca(2+) sensors and other protein and lipid components. Separation of the fundamental ability to fuse from the efficiency of the process has suggested dependence of efficiency factors on microdomain organization. Cholesterol, a key component of membrane microdomains, contributes to both the efficiency and the fundamental ability to fuse. However, testing for a selective effect of native microdomains on the efficiency of fusion, without affecting membrane cholesterol density, has not been assessed. Hydrolysis of sphingomyelin disrupts native raft domains on secretory vesicles. Disruption of microdomains enriched in sphingomyelin-cholesterol by treatment with sphingomyelinase selectively and dose dependently inhibited the Ca(2+) sensitivity and late kinetics of secretory vesicle fusion. As a native microdomain constituent, sphingomyelin is associated with Ca(2+) sensing through its interaction with other raft-bound lipid and/or protein factors, thereby supporting the physiological Ca(2+) sensitivity of membrane fusion. Furthermore, the sphingomyelinase-driven generation of ceramide, contributing to the total membrane negative curvature, preserves the ability to fuse despite extensive cholesterol removal. Membrane microdomain integrity thus underlies the efficiency of fusion but not the fundamental ability of native vesicles to undergo Ca(2+)-triggered membrane merger. The results are consistent with a fundamental fusion machine of intrinsically low Ca(2+) sensitivity that, supported by accessory ;efficiency' components, facilitates Ca(2+)-triggered bilayer merger under physiological conditions.

Animals↗

PubMed1985

Efficiency of vertebrate locomotory muscles.

We have examined the efficiency of vertebrate striated muscle at two different organizational levels: whole animals and isolated muscles. Terrestrial locomotion is used as a model of 'normal' muscular contraction; animal size and running speed are used as independent variables in order to change either the metabolic requirements of the muscles or the mechanical power production by the muscles over a wide range of values. The weight-specific metabolic power input to an animal increases nearly linearly with speed and increases with decreasing body size, while the weight-specific mechanical power output increases curvilinearly with speed and is independent of size. Consequently, the efficiency of the muscles in producing positive work increases with speed and the peak efficiency increases with increasing body size, attaining values of over 70% in large animals, but only 7% in small ones. The isolated muscle experiments were performed on frog muscle, and rat 'fast' and 'slow' muscles. We measured the work done, the oxygen consumed during recovery from the stimulation, and calculated the efficiency and the 'economy' (the cost of maintaining tension). The muscles were made to: (i) emulate the contractions seen during locomotion, i.e. shorten after a pre-stretch; or (ii) shorten at the same velocity and from the same muscle length as in (i), but without the pre-stretch. It was found that in mammalian muscles the peak efficiency with a pre-stretch attained high values, approaching the peak efficiencies in large animals. The maximum efficiency (attained at 1 length s-1 in fast muscle and at 0.5 lengths s-1 in slow muscle) did not differ much in the two muscles, whereas economy was greater in the slow muscle than in the fast muscle.

Animals↗

PubMed2005

An efficiency analysis of Veterans Health Administration hospitals.

This study evaluates the efficiency of Veterans Health Administration (VHA) hospitals using a variable-returns to scale, input-oriented, data envelopment analysis method. Hospital executives, health care policymakers, taxpayers, and ultimately the veteran patient population benefit from studies that look to improve the efficiency of the VHA. Data for 131 VHA hospitals in 1998 and 121 in 2001 were analyzed by using data envelopment analysis to measure hospital efficiency. The results indicated that efficiency in VHA hospitals improved from 85% in 1998 to 86% in 2001. Although this level of efficiency is commendable, the study documents potential savings through more efficient use of resources. From a management perspective, this study shows opportunities for improved management and the realignment of resources to better meet demand. From a policy perspective, the study highlights the political problems associated with improving efficiency and providing access to critical health care services.

Benchmarking↗

PubMed2000

Comparing the agreement among alternative models in evaluating HMO efficiency.

OBJECTIVE: To describe the efficiency of HMOs and to test the robustness of these findings across alternative models of efficiency. This study examines whether these models, when constructed in parallel to use the same information, provide researchers with the same insights and identify the same trends. DATA SOURCES: A data set containing 585 HMOs operating from 1985 through 1994. Variables include enrollment, utilization, and financial information compiled primarily from Health Care Investment Analysts, InterStudy HMO Census, and Group Health Association of America. STUDY DESIGN: We compute three estimates of efficiency for each HMO and compare the results in terms of individual performance and industry-wide trends. The estimates are then regressed against measures of case mix, quality, and other factors that may be related to the model estimates. PRINCIPAL FINDINGS: The three models identify similar trends for the HMO industry as a whole; however, they assess the relative technical efficiency of individual firms differently. Thus, these techniques are limited for either benchmarking or setting rates because the firms identified as efficient may be a consequence of model selection rather than actual performance. CONCLUSIONS: The estimation technique to evaluate efficient firms can affect the findings themselves. The implications are relevant not only for HMOs, but for efficiency analyses in general. Concurrence among techniques is no guarantee of accuracy, but it is reassuring; conversely, radically distinct inferences across models can be a warning to temper research conclusions.

Efficiency, Organizational↗

PubMed2003

Comparing the efficiency of national health systems: a sensitivity analysis of the WHO approach.

The World Health Organization (WHO) has used econometric methods to measure the efficiency of health care systems. We assess the robustness of WHO results to definitions of efficiency and statistical procedures. Originally analysed by the WHO, the data are for 1997 (50 countries) and 1993-1997 (141 countries). The efficiency of each country in promoting population health is estimated after taking into account health care expenditure, all other expenditure and education levels. Efficiency scores are compared under different definitions of efficiency and different estimation methods. The results show that the country rankings and efficiency scores are sensitive to the definition of efficiency and choice of model specification. We conclude that econometric methods can yield insights into complex socioeconomic phenomena. However, the lack of robust results to reasonable alternative specifications suggests that it is premature to use the methods adopted by the WHO to construct league tables of health systems.

Data Collection↗

PubMed1990

The mechanical efficiency of front crawl swimming.

In this study the gross efficiency of swimming was determined in a group of male (N = 6) and female (N = 4) competitive swimmers. The gross efficiency is defined as the ratio of the power output (W) to the power input (W). In a range of swimming velocities (0.95-1.6 m.s-1), the power input (rate of energy expenditure, 445-1137 W) was calculated from the oxygen uptake values (1.33-3.25 1 O2.min-1). The total power output (26-108 W) was directly measured during front crawl swimming using a system of underwater push-off pads instrumented with a force transducer (MAD-system). Using the MAD-system, the effect on total body drag due to the addition of the respiratory apparatus was evaluated to be negligible. The gross efficiency ranged from 5 to 9.5%. At equal swimming speed, the male competitive swimmers demonstrated a higher gross efficiency. However, this was due to the higher power output required by the male swimmers at a given speed. Gross efficiency was dependent on the absolute power output such that as power output increased so did the calculated gross efficiency. At the same power output, the values for the gross efficiency do not differ between the male and female competitive swimmers.

Biomechanical Phenomena↗

PubMed1993

Effects of body mass on exercise efficiency and VO2 during steady-state cycling.

Oxygen uptake (VO2) and exercise efficiency during cycle ergometer exercise are considered to be independent of body mass. To determine the validity of this assumption, 50 females ranging in body mass from 41.5-98.9 kg exercised on a cycle ergometer with no load at 60 rpm and at 25, 50, 75, and 100 W at 60 and 90 rpm. Gross VO2 and efficiency, net VO2 and efficiency, work VO2 and efficiency, and delta efficiency were computed. Gross and net VO2 were significantly and positively correlated with body mass at all work rates and pedal frequencies. Gross efficiency was significantly and negatively correlated with body mass at all work rates and pedal frequencies. Work VO2 and body mass were not significantly correlated. The correlations between work and delta efficiency and body mass were not significant. Since body mass was found to be significantly correlated with gross VO2, the following equation was developed using stepwise multiple regression to predict gross VO2: VO2 (ml.min-1) = 10.9 (work rate, W) + 8.2 (pedal rate, rpm) + 8.3 (body mass, kg) - 559.6. These data suggest that body mass should be considered when estimating the oxygen uptake during cycle ergometer exercise.

Adult↗

PubMed1999

Relative efficiency of microglia, astrocytes, dendritic cells and B cells in naive CD4+ T cell priming and Th1/Th2 cell restimulation.

We have compared the efficiency of central nervous system and peripheral antigen-presenting cells (APC) in T cell priming and restimulation. OVA peptide 323 - 339-dependent activation of DO11.10 TCR-transgenic naive CD4+ and polarized Th1 or Th2 cells was assessed in the presence of microglia and astrocytes from the neonatal mouse brain as well as dendritic cells (DC) and B cells purified from adult mouse lymph nodes. DC were the most efficient in inducing naive T cell proliferation, IL-2 secretion and differentiation into Th1 cells, followed by IFN-gamma-preactivated microglia, large and small B cells. Astrocytes failed to activate naive T cells. IFN-gamma-pretreated microglia were as efficient as DC in the restimulation of Th1 cells, whereas IFN-gamma-pretreated astrocytes, large and small B cells were much less efficient. Conversely, Th2 cells were efficiently restimulated by all the APC types examined. During T cell priming, DC secreted more IL-12 than microglia but similar amounts of IL-12 were secreted by the two cell types upon interaction with Th1 cells. The hierarchy of APC established in this study indicates that DC and microglia are the most efficient in the stimulation of naive CD4(+) T cells and in the restimulation of Th1 cells, suggesting that activated microglia may effectively contribute to Th1 responses leading to central nervous system inflammation and tissue damage. These potentially pathogenic responses could be counteracted by the high efficiency of astrocytes as well as microglia in restimulating Th2 cells.

Animals↗

PubMed1995

Spatial dependence of the optical collection efficiency in flow cytometry.

The sensitive flow cytometric detection of fluorescent species in liquid sample streams requires efficient collection of light from small [approximately 1 picoliter (pl)] sample volumes. This is often accomplished with high numerical aperture (NA) imaging collection optics used in combination with a spatial filter. A method to measure the spatial variation of the optical collection efficiency within the sample volume, using a submicrometer light source, is described. Measurements of the relative optical collection efficiency are presented for two optical collection systems used in our laboratory for single molecule detection. The measurement are in qualitative agreement with relative optical collection efficiency calculations using a simple geometrical optics model. Absolute measurements of the peak collection efficiencies for the two collection systems are also presented. These absolute collection efficiency measurements are in good quantitative agreement with ideal collection efficiencies calculated using measured transmissions and rated NAs of the collection optics. The utility of this information for the characterization and optimization of sensitive fluorescence detection apparatus is discussed.

Equipment Design↗

PubMed2002

Transfection of embryonal carcinoma cells at high efficiency using liposome-mediated transfection.

Embryonal carcinoma (EC) cells are recognized as an excellent model system for studying the early stages of mammalian development. Many studies performed with EC cells involve transient transfection with promoter/reporter gene constructs and/or mammalian expression vectors. One of the limitations of working with EC cells is their inability to be transfected at high efficiency. In most cases, EC cells are transfected using the calcium phosphate method. The objective of this study was to identify protocols and culture conditions that significantly increase the transfection efficiency of EC cells. F9 EC cells were used for this purpose, because they are the EC cell line studied most commonly. We show that the transfection efficiency of F9 EC cells using the calcium phosphate method is less than 5%; whereas, their transfection efficiency can be improved approximately 15-fold using optimized culture conditions and liposome-based transfection reagents. Specifically, we demonstrate that more than 50% of F9 EC cells can be transfected using LipofectAMINE 2000. In addition to higher levels of transfection, there is much less plate-to-plate variation with liposome-based reagents as compared to transfection with calcium phosphate. Interestingly, transfection efficiency using these reagents was found to be inversely related to cell density. This contrasts sharply with the recommendation that transfection with LipofectAMINE 2000 or LipofectAMINE in conjunction with the PLUS reagent be performed at high cell densities. Given the improvements in transfection efficiency reported here, it will now be possible to perform studies with F9 EC cells that require transfection at significantly higher levels than that achieved using the calcium phosphate method. Overall, the highest transfection efficiencies were consistently obtained using LipofectAMINE 2000.

Drug Carriers↗

PubMedDate not supplied

Effect of leader primary structure on the translational efficiency of phosphoglycerate kinase mRNA in yeast.

In order to determine the effect of the nucleotide composition of the 5'-untranslated (leader) region on the translational efficiency of mRNA in yeast, we replaced a large part of the leader region of the phosphoglycerate kinase (PGK) gene by various deoxyoligonucleotides of defined sequence. All mutations left the context of the transcription initiation site and AUG start codon intact. The mutant genes were introduced into yeast cells on a multicopy vector and the ratio of the steady-state levels of PGK mRNA and protein were determined. We found translational efficiency to be unaffected by the presence of either an 18 nucleotides (nt) long polyA or polyC tract or by sequences consisting of mixtures of A and C residues in any proportion. In contrast, a poly U tract, as well as mixtures of U and C residues, reduced translational efficiency by a factor of two to three, presumably by long-range base-pairing between the leader and sequences elsewhere in the coding or 3'-non-coding regions of the messenger. In agreement with this hypothesis, a five-fold reduction in translational efficiency was found for an mRNA carrying a polyC tract in the leader as well as a polyG tract in the trailer, neither of which had any effect on translational efficiency by itself. Therefore, we conclude that the leader and trailer regions (including the polyA tail) of PGK mRNA are sufficiently close to base-pair when containing complementary sequences. The resulting secondary structure evidently constitutes a barrier for incoming 40S subunits on their way to the AUG start codon. The presence of an 18 nt long polyG tract in the leader completely abolished translation of the PGK mRNA in accordance with earlier observations. However, we found that leaders containing up to 40% G residues interspersed with either A or U, still allow highly efficient translation. This value is about four times as high as the average G content of leader sequences in naturally occurring yeast mRNAs. Finally, neither deletion of about 40% of the trailer sequence of PGK mRNA, nor replacement of this sequence by homopolymer tracts had any effect on translational efficiency.

Amino Acid Sequence↗

PubMed2001

Experimental Investigation of the Orthokinetic Coalescence Efficiency of Droplets in Simple Shear Flow.

The coalescence efficiency of two droplets in simple shear flow was experimentally investigated. The effects of the radius of the colliding droplets, the viscosity of the continuous medium, and the radii ratio on the coalescence efficiency were studied. The coalescence efficiency was determined from the critical angle, alpha(crit), above which the droplets coalesce and below which no coalescence takes place. It was found that the coalescence efficiency decreases and then increases with the flow number. The theories of the drainage models and the trajectory analysis were unable to predict the experimental results. This was attributed to the inadequacy of the existing expression used for the critical film thickness. On the basis of the experimental data obtained a new expression for the critical film thickness was proposed. The new expression predicts a decrease followed by an increase in the critical film thickness. The increase in the critical film thickness is, perhaps, due to instabilities that take place at the interfaces. Implementing the proposed expression for the critical film thickness, the experimentally measured coalescence efficiency, the capture angle and the contact time were successfully predicted. The experimental investigation revealed that the coalescence efficiency does not depend on the radii ratio in the range 0.7 to 1. The experimental investigation also showed that the coalescence efficiency increases as the viscosity of the continuous phase decreases. Measuring the capture angle showed that coalescence can take place either in the compression or in the extensional quadrant of the shear plane. A variation in the capture angle and the contact time was observed for a given fixed set of conditions. The change of the angle alpha with time was measured. The measured values were compared to those calculated from an equation derived by R. S. Allan and S. G. Mason (J. Colloid Interface Sci. 17, pp. 383, 1962). A good agreement was obtained when the droplets were of equal radii and small in size. When the droplets were large in size and of different radii, the agreement was not satisfactory. Measuring the distance between the centers of the colliding droplets showed that the two droplets vibrated when they came close to each other. Copyright 2001 Academic Press.

Journal Article↗

PubMed2003

Brain activations during visual search: contributions of search efficiency versus feature binding.

We investigated the involvement of the parietal cortex in binding features during visual search using functional magnetic resonance imaging. We tested 10 subjects in four visual search tasks across which we independently manipulated (1) the requirement to integrate different types of features in a stimulus (feature or conjunction search) and (2) the degree of search efficiency (efficient or inefficient). We identified brain areas that were common to all conditions of visual search and areas that were sensitive to the factors of efficiency and feature binding. Visual search engaged an extensive network of parietal, frontal, and occipital areas. The factor of efficiency exerted a strong influence on parietal activations along the intraparietal sulcus and in the superior parietal lobule. These regions showed a main effect of efficiency and showed a simple effect when inefficient conditions were compared directly with efficient pop-out conditions in the absence of feature binding. Furthermore, a correlation analysis supported a tight correspondence between posterior parietal activation and the slope of reaction-time search functions. Conversely, feature binding during efficient pop-out search was not sufficient to modulate the parietal cortex. The results confirm the important role of the parietal cortex in visual search, but suggest that feature binding is not a requirement to engage its contribution.

Adolescent↗

PubMed2002

A minimal genome simian foamy virus type 1 vector system with efficient gene transfer.

Foamy viruses have several inherent features for the opportunity to develop efficient and versatile vectors for gene therapy. We have constructed a series of vectors and helper plasmids based on simian foamy virus type 1 (SFV-1) to establish the minimum vector genome required for efficient gene transduction. To characterize the efficiency of gene transduction by these vectors, the green fluorescent protein (GFP) coding sequence is linked to the human cytomegalovirus immediate gene promoter. Several deletion analyses of SFV-1 vectors revealed that the minimum genome with efficient GFP transduction contained the 5' untranslated region extending to the first 637 nucleotides of the gag gene, a 596 nucleotides of pol sequence from position 3137-3733, the 3' pol region at position 5200-5693, the 3' end polypurine tract, and the 3' LTR. An additional 1131 nucleotides can be removed from the 3' end LTR without affecting the efficiency of vector transduction. SFV-1 vector can therefore accommodate a minimum 8930 base-size heterologous DNA fragment. Furthermore, the efficiency of SFV-1 vector transduction was analyzed using different packaging plasmids. GFP transduction with packaging plasmid that contained the 5' R-U5 region of the LTR was compared with helper plasmids that had deletions in this region except for 22 nucleotides (positions 21-41), the first 61, 77, or 140 nucleotides of the R of the LTR. Transduction efficiencies were significantly reduced with the deletion mutations implicating that for optimum SFV-1 vector productions a packaging construct that includes the 5' R-U5 is required.

5' Untranslated Regions↗

PubMed1993

Metabolic cost and efficiency in two forms of squatting exercise in children and adults.

These experiments investigated the oxygen consumption and work efficiency of adults and children performing identical movement patterns. Adult men (mean age 24) and male children (mean age 12) performed squatting exercises with and without a pause at the lowest point of the squat. The former were termed no rebound squats and the latter were termed rebound squats. Subjects performed the exercises without load and with loads equal to 5%, 10% and 15% of body mass. The results showed that the children consumed 10% more oxygen per unit total body mass than the adults. The gross efficiency of the adults was significantly greater than that of the children. Net and apparent efficiencies were not significantly different between the age groups. Gross and net efficiencies declined with load. Rebound squats required 13% less oxygen than no rebound squats. The gross, net and apparent efficiency of rebound squats was significantly greater than that of no rebound squats. It is suggested that the greater gross efficiencies of adults is related to their lower basal metabolic rate and that the greater efficiency of rebound exercise is related to the storage of energy in elastic tissues.

Adult↗

PubMed2002

Differential modulation of efficiency in a food-rewarded "differential reinforcement of low-rate" 72-s schedule in rats by norepinephrine and serotonin reuptake inhibitors.

RATIONALE: The differential reinforcement of low-rate 72-s (DRL 72-s) schedule, in which rats must withhold a response for at least 72 s to obtain a reward (generally water), is an attractive procedure for the characterisation of potential antidepressant agents. Indeed, several antidepressants have been shown to improve efficiency (ratio of reinforcement rate to response rate) in this model, either by decreasing response rates and/or by increasing reinforcement rates. OBJECTIVE: Herein, we compared the actions of antidepressants known to inhibit serotonin (5-HT), norepinephrine (NE) and/or dopamine (DA) reuptake in a food-rewarded DRL 72-s schedule. METHODS: Rats trained in a food-rewarded DRL 72-s schedule and showing stable baseline performance were administered with drugs i.p. once a week. In independent experiments, the influence of drugs on food intake, spontaneous locomotor activity and extracellular levels of monoamines in the frontal cortex was evaluated. RESULTS: In confirmation of previous studies, the tricyclic agent imipramine (10.0 mg/kg) and the "atypical" agent mianserin (40.0 mg/kg) significantly increased efficiency. In analogy, the selective NE reuptake inhibitors (NARIs) desipramine (20.0 mg/kg), nortriptyline (2.5 mg/kg) and reboxetine (0.63 mg/kg) all displayed marked enhancements in efficiency. In contrast, the selective 5-HT reuptake inhibitors (SSRIs) citalopram (10.0 mg/kg), fluvoxamine (10.0 mg/kg) and paroxetine (10.0 mg/kg) all significantly decreased efficiency. The mixed 5-HT/NE reuptake inhibitors (SNRIs) venlafaxine (2.5 mg/kg, 10.0 mg/kg) and S33005 (0.16-10.0 mg/kg), likewise, did not increase efficiency. Further, the DA reuptake inhibitors (DARIs) bupropion (0.16-10.0 mg/kg) and GBR12935 (0.63-10.0 mg/kg) had no effect on DRL 72-s performance. All drug classes exerted a similar, mild inhibitory influence on food intake and locomotor behaviour. Imipramine, mianserin and NARIs markedly increased extracellular levels of NE, and SSRIs elevated levels of 5-HT, while SSRIs augmented levels of both. CONCLUSIONS: The present experimental procedure demonstrates, in analogy to imipramine and mianserin, robust and consistent increases in efficiency with NARIs. Their effects may be distinguished from a decrease in efficiency elicited by SSRIs, and a lack of activity of SNRIs and DARIs. While the reasons underlying the ineffectiveness of SSRIs (in contrast to previous studies) remain to be clarified, these data underline the importance of adrenergic mechanisms in the control of behaviour under conditions of delayed responding. Further, they support the interest of DRL 72-s procedures for the characterisation of diverse classes of antidepressant agent.

Adrenergic Uptake Inhibitors↗

PubMed2006

Development of an efficient amine-functionalized glass platform by additional silanization treatment with alkylsilane.

Aminosilane-treated molecular layers on glass surfaces are frequently used as functional platforms for biosensor preparation. All the amino groups present on the surface are not available in reactive forms, because surface amino groups interact with remaining unreacted surface silanol groups. Such nonspecific interactions might reduce the efficiency of chemical immobilization of biomolecules such as DNA, enzymes, antibodies, etc., in biosensor fabrication. To improve immobilization efficiency we have used additional surface silanization with alkylsilane (capping) to convert the remaining silanol groups into Si-O-Si linkages, thereby liberating the amino groups from nonspecific interaction with the silanol groups. We prepared different types of capped amine surface and evaluated the effect of capping on immobilization efficiency by investigating the fluorescence intensity of Cy3-NHS (N-hydroxysuccinimide) dye that reacted with amino groups. The results indicate that most of the capped amine surfaces resulted in enhanced efficiency of immobilization of Cy3-NHS compared with the untreated control amine surface. We found a trend that trialkoxysilanes had greater capping effects on immobilization efficiency than monoalkoxysilanes. It was also found that the aliphatic chain of alkylsilane, which does not participate in the capping of the silanol, had an important function in enhancing immobilization efficiency. These results would be useful for preparation of an amine-modified surface platform, with enhanced immobilization efficiency, which is essential for developing many kinds of biosensors on a silica matrix.

Alkylation↗