Micro-abrasion mechanisms of cast CoCrMo in simulated body fluids

The abrasion seen on some of the retrieved CoCrMo hip joints has been reported to be caused by entrained hard particles in vivo. However, little work has been reported on the abrasion mechanisms of CoCrMo alloy in simulated body environments. Therefore. this study covers the mapping of micro-abrasion wear mechanisms of cast CoCrMo induced by third body hard particles under a wide range of abrasive test conditions. This study has a specific focus on covering the possible in vivo wear modes seen on metal-on-metal (MoM) surfaces. Nano-indentation and nano-scratch tests were also employed to further investigate the secondary wear mechanisms-nano-scale material deformation that involved in micro-abrasion processes. This work addresses the potential detrimental effects of third body hard particles in vivo such as increased wear rates (debris generation) and corrosion (metal-ion release). The abrasive wear mechanisms of cast CoCrMo have been investigated under various wear-corrosion conditions employing two abrasives, SiC (similar to 4 mu m) and Al(2)O(3) (similar to 1 mu m), in two test solutions, 0.9% NaCl and 25% bovine serum. The specific wear rates, wear mechanisms and transitions between mechanisms are discussed in terms of the abrasive size, volume fraction and the test solutions deployed. The work shows that at high abrasive volume fractions, the presence of protein enhanced the wear loss due to the enhanced particle entrainment, whereas at much lower abrasive volume fractions, protein reduced the wear loss by acting as a boundary lubricant or rolling elements which reduced the abrasivity (load per particle) of the abrasive particles. The abrasive wear rate and wear mechanisms of the CoCrMo are dependent on the nature of the third body abrasives, their entrainment into the contact and the presence of the proteins. (C) 2009 Elsevier B.V. All rights reserved.

Comparison of functionally orientated tooth replacement and removable partial dentures on the nutritional status of partially dentate older patients: a randomised controlled clinical trial

OBJECTIVES: The aims of this study were to conduct a randomised controlled clinical trial (RCT) of partially dentate older adults comparing functionally orientated treatment based on the SDA concept with conventional treatment using RPDs to replace missing natural teeth. The two treatment strategies were evaluated according to their impact on nutritional status measured using haematological biomarkers.

METHODS: A randomised controlled clinical trial (RCT) was conducted of partially dentate patients aged 65 years and older (Trial Registration no. ISRCTN26302774). Each patient provided haematological samples which were screened for biochemical markers of nutritional status. Each sample was tested in Cork University Hospital for serum Albumin, serum Cholesterol, Ferritin, Folate, Vitamin B12 and 25-hydroxycholecalciferol (Vitamin D).

RESULTS: A mixed model analysis of covariance (ANCOVA) indicated that for Vitamin B12 (p=0.9392), serum Folate (p=0.5827), Ferritin (p=0.6964), Albumin (p=0.8179), Serum Total Cholesterol (p=0.3670) and Vitamin D (p=0.7666) there were no statistically significant differences recorded between the two treatment groups. According to the mixed model analysis of covariance (ANCOVA) for Vitamin D there was a significant difference between levels recorded at post-operative time points after treatment intervention (p=0.0470). There was an increase of 7% in 25-hydroxycholecalciferol levels recorded at 6 months compared to baseline (p=0.0172). There was no further change in recorded levels at 12 months (p=0.6482) and these increases were similar within the two treatment groups (p>0.05).

CONCLUSIONS: The only measure which illustrated consistent significant improvements in nutritional status for either group were Vitamin D levels. However no significant difference was recorded between the two treatment groups.

CLINICAL SIGNIFICANCE: Functionally orientated prosthodontic rehabilitation for partially dentate older patients was no worse than conventional removable partial dentures in terms of impact on nutritional status.

Impact of tooth replacement strategies on the nutritional status of partially-dentate elders

OBJECTIVE: To investigate the impact of tooth replacement on the nutritional status of partially dentate older patients, and, to compare two different tooth replacement strategies; conventional treatment using removable partial dentures and functionally orientated treatment based on the shortened dental arch.

BACKGROUND: Amongst older patients, diet plays a key role in disease prevention, as poor diets have been linked to numerous illnesses. Poor oral health and loss of teeth can have very significant negative effects on dietary intake and nutritional status for elderly patients. There is evidence that good oral health generally, has positive effects on the nutritional intake of older adults.

MATERIALS AND METHODS: A randomised, controlled clinical trial was designed to investigate the impact of tooth replacement on the nutritional status of partially dentate elders. Forty-four patients aged over 65 years completed the trial, with 21 allocated to conventional treatment and 23 allocated to functionally orientated treatment. Nutritional status was accessed at baseline and after treatment using the Mini Nutritional Assessment (MNA) and a range of haematological markers.

RESULTS: At baseline, relationships were observed between the number of occluding tooth contacts and some measures of nutritional status. As the number of contacts increased, MNA scores (R = 0.16), in addition to vitamin B12 (R = 0.21), serum folate (R = 0.32) and total lymphocyte count (R = 0.35), also increased. After treatment intervention, the only measure of nutritional status that showed a statistically significant improvement for both treatment groups was MNA score (p = 0.03). No significant between group differences were observed from analysis of the haematological data.

CONCLUSION: In this study, prosthodontic rehabilitation with both conventional treatment and functionally orientated treatment resulted in an improvement in MNA score. Haematological markers did not illustrate a clear picture of improvement in nutritional status for either treatment group.

FoodCAP: acid-labile protein adducts of heterocyclic amines in human blood are not viable biomarkers of HCA dietary exposure

Intake of heterocyclic amines (HCAs, carcinogens produced during cooking of meat/fish, the most abundant being PhIP, DiMeIQx and MeIQx) is influenced by many factors including type/thickness of meat and cooking method/temperature/duration. Thus, assessment of HCA dietary exposure is difficult. Protein adducts of HCAs have been proposed as potential medium-term biomarkers of exposure, e.g. PhIP adducted to serum albumin or haemoglobin. However, evidence is still lacking that HCA adducts are viable biomarkers in humans consuming normal diets. The FoodCAP project, supported by World Cancer Research Fund, developed a highly sensitive mass spectrometric method for hydrolysis, extraction and detection of acid-labile HCAs in blood and assessed their validity as biomarkers of exposure. Multiple acid/alkaline hydrolysis conditions were assessed, followed by liquid-liquid extraction, clean-up by cation-exchange SPE and quantification by UPLC-ESI-MS/ MS. Blood was analysed from volunteers who completed food diaries to estimate HCA intake based on the US National Cancer Institute’s CHARRED database. Standard HCAs were recovered quantitatively from fortified blood. In addition, PhIP/MeIQx adducts bound to albumin and haemoglobin prepared in vitro using a human liver microsome system were also detectable in blood fortified at low ppt concentrations. However, except for one sample (5pg/ml PhIP), acid-labile PhIP, 7,8-DiMeIQx, 4,8-DiMeIQx and MeIQx were not observed above the 2pg/ml limit of detection in plasma (n=35), or in serum, whole blood or purified albumin, even in volunteers with high meat consumption (nominal HCA intake >2µg/day). It is concluded that HCA blood protein adducts are not viable biomarkers of exposure. Untargeted metabolomic analyses may facilitate discovery of suitable markers.

Evidence supporting a role for N-epsilon-(3-formyl-3,4-dehydropiperidino)lysine accumulation in Muller glia dysfunction and death in diabetic retinopathy

Purpose: Recent evidence suggests that neuroglial dysfunction and degeneration contributes to the etiology and progression of diabetic retinopathy. Advanced lipoxidation end products (ALEs) have been implicated in the pathology of various diseases, including diabetes and several neurodegenerative disorders. The purpose of the present study was to investigate the possible link between the accumulation of ALEs and neuroretinal changes in diabetic retinopathy.

Methods: Retinal sections obtained from diabetic rats and age-matched controls were processed for immunohistochemistry using antibodies against several well defined ALEs. In vitro experiments were also performed using a human Muller (Moorfields/Institute of Ophthalmology-Muller 1 [ MIO-M1]) glia cell line. Western blot analysis was used to measure the accumulation of the acrolein-derived ALE adduct N epsilon-(3-formyl-3,4-dehydropiperidino)lysine (FDP-lysine) in Muller cells preincubated with FDP-lysine-modified human serum albumin (FDP-lysine-HSA). Responses of Muller cells to FDP-lysine accumulation were investigated by analyzing changes in the protein expression of heme oxygenase-1 (HO-1), glial fibrillary acidic protein (GFAP), and the inwardly rectifying potassium channel Kir4.1. In addition, mRNA expression levels of vascular endothelial growth factor (VEGF), interleukin-6 (IL-6), and tumor necrosis factor-alpha (TNF alpha) were determined by reverse transcriptase PCR (RT-PCR). Apoptotic cell death was evaluated by fluorescence-activated cell sorting (FACS) analysis after staining with fluorescein isothiocyanate (FITC)-labeled annexin V and propidium iodide.

Results: No significant differences in the levels of malondialdehyde-, 4-hydroxy-2-nonenal-, and 4-hydroxyhexenal-derived ALEs were evident between control and diabetic retinas after 4 months of diabetes. By contrast, FDP-lysine immunoreactivity was markedly increased in the Muller glia of diabetic rats. Time-course studies revealed that FDP-lysine initially accumulated within Muller glial end feet after only a few months of diabetes and thereafter spread distally throughout their inner radial processes. Exposure of human Muller glia to FDP-lysine-HSA led to a concentration-dependent accumulation of FDP-lysine-modified proteins across a broad molecular mass range. FDP-lysine accumulation was associated with the induction of HO-1, no change in GFAP, a decrease in protein levels of the potassium channel subunit Kir4.1, and upregulation of transcripts for VEGF, IL-6, and TNF-alpha. Incubation of Muller glia with FDP-lysine-HSA also caused apoptosis at high concentrations.

Conclusions: Collectively, these data strongly suggest that FDP-lysine accumulation could be a major factor contributing to the Muller glial abnormalities occurring in the early stages of diabetic retinopathy.

A differential protein solubility approach for the depletion of highly abundant proteins in plasma using ammonium sulfate

Depletion of highly abundant proteins is an approved step in blood plasma analysis by mass spectrometry (MS). In this study, we explored a precipitation and differential protein solubility approach as a fractionation strategy for abundant protein removal from plasma. Total proteins from plasma were precipitated with 90% saturated ammonium sulfate, followed by differential solubilization in 55% and 35% saturated ammonium sulfate solutions. Using a four hour liquid chromatography (LC) gradient and an LTQ-Orbitrap XL mass spectrometer, a total of 167 and 224 proteins were identified from the 55% and 35% ammonium sulfate fractions, whereas 235 proteins were found in the remaining protein fractions with at least two unique peptides. SDS-PAGE and exclusive total spectrum counts from LC-MS/MS analyses clearly showed that majority of the abundant plasma proteins were solubilized in 55% and 35% ammonium sulfate solutions, indicating that the remaining protein fraction is of potential interest for identification of less abundant plasma proteins. Serum albumin, serotransferrin, alpha-1-antitrypsin and transthyretin were the abundant proteins that were highly enriched in 55% ammonium sulfate fractions. Immunoglobulins, complement system proteins, and apolipoproteins were among other abundant plasma proteins that were enriched in 35% ammonium sulfate fractions. In the remaining protein fractions a total of 40 unique proteins were identified of which, 32 proteins were identified with at least 10 exclusive spectrum counts. According to PeptideAtlas, 9 of these 32 proteins were estimated to be present at low μg ml(-1) (0.12-1.9 μg ml(-1)) concentrations in the plasma, and 17 at low ng ml(-1) (0.1-55 ng ml(-1)) range.

Reference gene selection in human periodontal ligament cells

Background: Real-time quantitative PCR (qPCR) is a highly sensitive and specific method which is used extensively for determining gene expression profiles in a variety of cell and tissue types. In order to obtain accurate and reliable gene expression quantification, qPCR data are generally normalised against so-called reference or housekeeping genes. Ideally, reference genes should have abundant and stable RNA transcriptomes under the experimental conditions employed. However, reference genes are often selected rather arbitrarily and indeed some have been shown to have variable expression in a variety of in vitro experimental conditions.
Objective: The objective of the current study was to investigate reference gene expression in human periodontal ligament (PDL) cells in response to treatment with lipopolysaccharide (LPS).
Method: Primary human PDL cells were grown in Dulbecco’s Modified Eagle Medium with L-glutamine supplemented with 10% fetal bovine serum, 100UI/ml penicillin and 100µg/ml streptomycin. RNA was isolated using the RNeasy Mini Kit (Qiagen) and reverse transcribed using the QuantiTect Reverse Transcription Kit (Qiagen). The expression of a total of 19 reference genes was studied in the presence and absence of LPS treatment using the Roche Reference Gene Panel. Data were analysed using NormFinder and Bestkeeper validation programs.
Results: Treatment of human PDL cells with LPS resulted in changes in expression of several commonly used reference genes, including GAPDH. On the other hand the reference genes β-actin, G6PDH and 18S were identified as stable genes following LPS treatment.
Conclusion: Many of the reference genes studied were robust to LPS treatment (up to 100 ng/ml). However several commonly employed reference genes, including GAPDH varied with LPS treatment, suggesting they would not be ideal candidates for normalisation in qPCR gene expression studies.

Functional expression of TRPV4 in human periodontal ligament cells

Background: Periodontal ligament (PDL) cells are exposed to physical forces in vivo in response to mastication, parafunction, speech and orthodontic tooth movement. Although it has been shown that PDL cells perceive and respond directly to mechanical stimulation, the nature of the ion channels that mediate this mechanotransduction remain to be fully elucidated. The transient receptor potential (TRP) superfamily of ion channels is believed to play a critical role in sensory physiology, where they act as transducers for thermal, chemical and mechanical stimuli. Recent studies have shown that members of the vanilloid (TRPV) and ankyrin (TRPA) subfamilies encode mechanosensitive TRPs. The vanilloid family member TRPV4 is one such non selective calcium permeable cationic channel which has been shown to be activated by chemical ligands, hypotonicity, and mechanical stimuli. Objectives: The objective of the current study was to investigate functional expression of TRPV4 in cultured human PDL cells. Methods: Human PDL cells were grown in Dulbecco's Modified Eagle Medium with L-glutamine supplemented with 10% fetal bovine serum (FBS), 100UI/ml penicillin and 100μg/ml streptomycin. Cells in passage 4-6 were used in all experiments. TRPV4 functional expression was determined using ratiometric calcium imaging. Cultured cells were loaded with intracellular Ca2+ probe fura-2 and cells were then stimulated with the TRPV4 agonists, 4alpha-phorbol 12,13-didecanoate (4alpha-PDD), GSK1016790A or hypotonic solution. The TRPV4 antagonist RN 1734 was used to block the corresponding agonist responses. Results: PDL fibroblasts responded to application of TRPV4 agonists and hypotonic stimuli by an increase in intracellular calcium which was attenuated in the presence of the TRPV4 antagonist. Conclusions: We have shown for the first time the functional expression of the mechanosensitive TRPV4 channel in human PDL cells. The molecular identity and mechanisms of activation of mechanosensitive TRP channels in PDL cells merit further investigation.

Engineering new strategies to improve pharmacokinetics of therapeutic proteins

Tese de doutoramento, Farmácia (Biotecnologia Farmacêutica), Universidade de Lisboa, Faculdade de Farmácia, 2014

Gestão integrada da doença renal crónica em Portugal : o panorama atual e o papel do profissional de nutrição na obtenção de melhores resultados em saúde

RESUMO - A doença renal crónica (DRC) resulta da perda de função renal, sendo necessário a terapêutica de substituição, no estádio terminal. Em Portugal está atualmente em vigor o modelo de Gestão Integrada da Doença, que tem inerente o cumprimento de objetivos e metas pelas unidades de diálise. Uma alimentação adequada é um pilar fundamental ao sucesso do tratamento desta doença, o que torna o profissional de nutrição indispensável. Este trabalho pretendeu avaliar o cumprimento das metas e objetivos estabelecidos no modelo referido, e relacionar os resultados obtidos com a existência de contacto entre o profissional de nutrição e os pacientes. Para a persecução dos objetivos, foram analisadas duas bases de dados disponibilizadas pela Direção Geral da Saúde: a base de dados da Plataforma de Gestão Integrada da Doença Renal Crónica em 2012 e a do Questionário de Avaliação da Satisfação dos Doentes em Hemodiálise em 2013. Verificou-se uma melhoria contínua ao longo dos anos do cumprimento das metas e objetivos preconizados em Portugal para o tratamento da DRC, com um cumprimento da maioria no ano de 2012. No entanto, os parâmetros ferritina e albumina sérica ficaram aquém da recomendação. Observou-se um nível elevado de satisfação do paciente quanto ao trabalho do profissional de nutrição, apesar de ser frequente a inexistência de contacto entre ambas as partes. Os resultados obtidos demonstram também que o profissional de nutrição tem um papel importante para a obtenção de melhores resultados de saúde nos pacientes em tratamento por hemodiálise, pelo que se sugere um acompanhamento da totalidade deste tipo de população por este profissional.

Impact of preoperative risk factors on morbidity after esophagectomy: is there room for improvement?

BACKGROUND: Despite progress in multidisciplinary treatment of esophageal cancer, oncologic esophagectomy is still the cornerstone of therapeutic strategies. Several scoring systems are used to predict postoperative morbidity, but in most cases they identify nonmodifiable parameters. The aim of this study was to identify potentially modifiable risk factors associated with complications after oncologic esophagectomy. METHODS: All consecutive patients with complete data sets undergoing oncologic esophagectomy in our department during 2001-2011 were included in this study. As potentially modifiable risk factors we assessed nutritional status depicted by body mass index (BMI) and preoperative serum albumin levels, excessive alcohol consumption, and active smoking. Postoperative complications were graded according to a validated 5-grade system. Univariate and multivariate analyses were used to identify preoperative risk factors associated with the occurrence and severity of complications. RESULTS: Our series included 93 patients. Overall morbidity rate was 81 % (n = 75), with 56 % (n = 52) minor complications and 18 % (n = 17) major complications. Active smoking and excessive alcohol consumption were associated with the occurrence of severe complications, whereas BMI and low preoperative albumin levels were not. The simultaneous presence of two or more of these risk factors significantly increased the risk of postoperative complications. CONCLUSIONS: A combination of malnutrition, active smoking and alcohol consumption were found to have a negative impact on postoperative morbidity rates. Therefore, preoperative smoking and alcohol cessation counseling and monitoring and improving the nutritional status are strongly recommended.

Use of limitations of radiolabeled anti-CEA antibodies and their fragments for photoscanning detection of human colorectal carcinomas.

Fifty-three patients with histologically proven carcinoma were injected with highly purified [131I]-labeled goat antibodies or fragments of antibodies against carcinoembryonic antigen (CEA). Each patient was tested by external photoscanning 4, 24, 36 and 48 h after injection. In 22 patients (16 of 38 injected with intact antibodies, 5 of 13 with F(ab')2 fragments and 1 of 2 with Fab' fragments), an increased concentration of 131I radioactivity corresponding to the previously known tumor location was detected by photoscanning 36-48 h after injection. Blood pool and secreted radioactivity was determined in all patients by injecting 15 min before scanning, [99mTc]-labeled normal serum albumin and free 99mTc04-. The computerized subtraction of 99mTc from 131I radioactivity enhanced the definition of tumor localization in the 22 positive patients. However, in spite of the computerized subtraction, interpretation of the scans remained doubtful for 12 patients and was entirely negative for 19 additional patients. In order to provide a more objective evaluation for the specificity of the tumor localization of antibodies, 14 patients scheduled for tumor resection were injected simultaneously with [131I]-labeled antibodies or fragments and with [125I]-labeled normal goat IgG or fragments. After surgery, the radioactivity of the two isotopes present either in tumor or adjacent normal tissues was measured in a dual channel scintillation counter. The results showed that the antibodies or their fragments were 2-4 times more concentrated in the tumor than in the normal tissues. In addition, it was shown that the injected antibodies formed immune complexes with circulating CEA and that the amount of immune complexes detectable in serum was roughly proportional to the level of circulating CEA.

Fluorometric monitoring of the properties of proteins entrapped in sol-gel derived matrices

The successful development of stable biosensors incorporating entrapped proteins suffers from poor understanding of the properties of the entrapped biomolecules. This thesis reports on the use of fluorescence spectroscopy to investigate the properties of proteins entrapped in sol-gel processed silicate materials. Two different single tryptophan (Trp) proteins were investigated in this thesis, the Ca2 + binding protein cod III parvalbumin (C3P) and the salicylate binding protein human serum albumin (HSA). Furthermore, the reactive single cysteine (Cys) residue within C3P and HSA were labelled with the probes iodoacetoxynitrobenzoxadiazole (C3P) and acrylodan (C3P and HSA) to further examine the structure, stability and function of the free and entrapped proteins. The results show that both C3P and HSA can be successfully entrapped into sol-gelderived matrices with retention of function and conformational flexibility.

The isolation, partial purification and preliminary characterization of a growth factor from chick embryo brains

Chicl( brain growth factor (CBGF) is a mitogen isolated from embryonic chick brains thought to have a potential role as a trophic factor involved in nerve dependent amphibian limb regeneration. In addition, CBGF stimulates 3H-thymidine incorporation in chick embryo brain astrocytes in vitro. In this study, cultured chick embryo brain non-neuronal cells were employed in a bioassay to monitor CBGF activity throughout various stages of its pllrification. Cell culture and assay conditions were optimized. Nonneuronal cells grew best on collagen-coated culture dishes in complete medium, were most responsive to a growth stimulus [10% fetal bovine serum (FBS)] at the second and third subcultures, and were healthiest when rendered "quiescent" in medium supplemented with 1% FBS. The most effective bioassay conditions consisted of a minimum 14.5 hour "quiescence" time (24 hours was used), a 6 hour "prestimulation" time, and a 24 hour 3H-thymidine labeling time. Four-day subconfluent primary non-neuronal cells consisted of 6.63% GFAP positive cells; as a result cultures were thought to be mainly composed of astroblasts. CBGF was purified from 18-day chick embryo brains by ultrafiltration through Amicon PM-30 and YM-2 membranes, size exclusion chromatography through a Biogel P6 column, and analytical reverse-phase high-performance liquid chromatography (rp-HPLC). The greatest activity resided in rp-HPLC fraction #7 (10 ng/ml) which was as effective as 10% FBS at stimulating 3H-thymidine incorporation in chick embryo brain nonneuronal cells. Although other researchers report the isolation of a mitogenic fraction consisting of 5'-GMP from the embryonic chick brain, UV absorbance spectra, rp-HPLC elution profiles, and fast atom bombardment (FAB) mass spectra indicated that CBGF is neither 5'-GMP nor 51-AMP. 2 Moreover, commercially available 5t-GMP was inhibitory to 3H-thymidine incorporation in the chick non-neuronal cells, while Sf-AMP had no effect. Upon treatment with pronase, the biological activity of fraction P6-3 increased; this increase was nearly 30% greater than what would be expected from a simple additive effect of any mitogenic activity of pronase alone together with P6-3 alone. This may suggest the presence of an inhibitor protein. The bioactive component may be a protein protected by a nucleoside/nucleotide or simply a nucleoside/nucleotide acting alone. While the FAB mass spectrum of rp-HPLC fraction #7 did not reveal molecular weight or sequence information, the ion of highest molecular weight was observed at m/z 1610; this is consistent with previous estimations of CBGF's size. 3

Monocouches peptidiques auto-assemblées et applications dans le domaine des biocapteurs de résonance de plasmon de surfaces

Ces travaux visent à étendre les applications de la résonance de plasmons de surface (SPR) L’objectif est d’offrir des outils diagnostics plus rapides, efficaces et simple d’utilisation pour diagnostiquer ou effectuer le suivi de conditions cliniques. Pour se faire, un nouveau type d’instrumentation SPR basé sur l’utilisation d’un prisme d’inversion (dove) a permis d’atteindre une limite de détection (LOD) de 10-6 unité d’indice de réfraction (RIU), une valeur comparable aux instruments commerciaux complexes tout en demeurant peu dispendieux, robuste et simple d’utilisation. Les travaux présentés dans cet ouvrage visent, dans un second temps, à réduire les interactions nonspécifiques (NSB) entre la surface des biocapteurs SPR et les composants de la matrice biologique complexe telles que: l’urine, le lysat cellulaire, le sérum et le sang. Ces dernières induisent des réponses empêchant l’utilisation de biocapteurs SPR en milieux complexes. Les acides aminés (AA) offrent une grande variété de propriétés physico-chimiques permettant la mise au point de monocouches auto-assemblées (SAM) aux propriétés diverses. Initialement, 19 des 20 acides aminés naturels ont été attachés à l’acide 3-mercaptopropionique (3-MPA) formant des SAMs peptidomimétiques. La quantité d’interactions nonspécifiques engendrées par ces différentes surfaces a été mesurée en exposant ces surfaces au sérum sanguin bovin complet variant de 400 ng/cm² jusqu’à 800 ng/cm². La détection à l’aide de ces surfaces de la β-lactamase (une enzyme responsable de la résistance aux antibiotiques au niveau μM) a démontré la possibilité d’employer ces surfaces pour bâtir des biocapteurs SPR. Des peptides de longueur allant de 2 à 5 résidus attachés à 3-MPA ont été synthétisés sur support solide. Cette étude a démontré que l’augmentation de la longueur des peptides formés d’AA résistants aux NBS accroit leur résistance jusqu’à 5 résidus. Le composé le plus performant de ce type (3-MPA-(Ser)5-OH) a permis d’atteindre 180 ng/cm². Cette valeur est similaire à celle des meilleures surfaces disponibles commercialement, notamment les surfaces de polyethylène glycol (PEG) à 100 ng/cm². Des surfaces de 3-MPA-(Ser)5-OH ont permis l’étalonnage de la β-lactamase et sa quantification directe dans un lysat cellulaire. La LOD pour ces biocapteurs est de 10 nM. Une troisième génération de surfaces peptidiques binaires a permis la réduction de la NSB jusqu’à un niveau de 23±10 ng/cm² une valeur comparable aux meilleures surfaces disponibles. Ces surfaces ont permis l’étalonnage d’un indicateur potentiel du cancer la metalloprotéinase-3 de matrice (MMP-3). Les surfaces formées de peptides binaires (3-MPA-H3D2-OH) ont permis la quantification directe de la MMP-3 dans le sérum sanguin complet. Une quatrième génération de surfaces peptidiques a permis de réduire davantage le niveau de NSB jusqu’à une valeur de 12 ± 11 ng/cm². Ces surfaces ont été modifiées en y attachant une terminaison de type acide nitriloacétique (NTA) afin d’y attacher des biomolécules marquées par six résidus histidines terminaux. Ces surfaces ont permis le développement d’une méthode rapide de balayage des ligands ciblant le « cluster of differenciation-36 » (CD36). L’étude d’électroformation des monocouches de peptide a permis de déterminer les conditions de formation optimales d’une couche de 3-MPA-HHHDD-OH permettant ainsi la formation de monocouches résistantes au NSB en moins de 6 minutes en appliquant un potentiel de formation de 200mV vs Ag/AgCl.