Assessment of the imprinting efficiency of an imide with a "stoichiometric" pyridine-based functional monomer in precipitation polymerisation.

The efficiency of the stoichiometric non-covalent imprinting of the imide 2,3,5-tri-O-acetyluridine (TAU) with 2,6-bis(acrylamido)pyridine (BAAPy) as functional monomer due to their strong donor-acceptor-donor/acceptor-donor-acceptor (DAD/ADA) hydrogen bond array interaction has been evaluated by bulk imprinting. This study is the first to investigate the imprinting and template rebinding efficiencies of the TAU/BAAPy molecularly imprinted polymeric (MIP) system prepared by precipitation polymerisation. We found that the stoichiometric 1:1 T:FM ratio has not been maintained in precipitation polymerisation and an optimal TAU:BAAPy ratio of 1:2.5 was obtained in acetonitrile without agitation affording an affinity constant (1.7 × 104 M-1 ) and a binding capacity (3.69 µmol/g) higher than its bulk counterpart. Molecular modelling, NMR studies, and selectivity assays against analogues uridine and 2,3,5-tri-O-acetyl cytidine (TAC) indicate that, aside from the DAD/ADA hydrogen bond interaction, BAAPy also interacts with the acetyl groups of TAU. Template incorporation and rebinding in precipitation MIPs are favoured by a moderate initiator concentration, ie, initiator:total monomer (I:TM) ratio of 1:131, while low I:TM ratio (ie, 1:200) drastically reduced template incorporation and binding capacity. Vigorous agitation by stirring showed higher template incorporation but significantly lower template rebinding compared to that prepared without agitation. While the imprinting efficiencies for the best performing bulk and precipitation TAU MIPs generated in this study were moderate, 41% and 60%, respectively, their rebinding capacities were only between 3 and 4% of the incorporated template. We also present quantitative nuclear magnetic resonance spectroscopy as an efficient method for MIP characterisation.

Water-compatible silica sol-gel molecularly imprinted polymer as a potential delivery system for the controlled release of salicylic acid.

Molecularly imprinted polymers (MIPs) for salicylic acid were synthesized and evaluated in aqueous environments in the aim to apply them as drug delivery carriers. One organic MIP and one inorganic MIP based on the sol-gel process were synthesized. The organic MIP was prepared by radical polymerization using the stoichiometric functional monomer, 1-(4-vinylphenyl)-3-(3,5-bis(trifluoromethyl)phenyl)urea, which can establish strong electrostatic interactions with the -COOH of salicylic acid. The sol-gel MIP was prepared with 3-(aminopropyl)triethoxysilane and trimethoxyphenylsilane, as functional monomers and tetraethyl orthosilicate as the crosslinker. While the organic MIPs bound the target specifically in acetonitrile, they exhibited lower binding in the presence of water, although the imprinting factor increased under these conditions, due to reduced non-specific binding. The sol-gel MIP has a high specificity and capacity for the drug in ethanol, a solvent compatible with drug formulation and biomedical applications. In vitro release profiles of the polymers in water were evaluated, and the results were modelled by Fick's law of diffusion and the power law. Analysis shows that the release mechanism was predominantly diffusion-controlled.

Evaluation of molecularly imprinted polymers using 2',3',5'-tri-O-acyluridines as templates for pyrimidine nucleoside recognition.

In this paper, we describe the synthesis and evaluation of molecularly imprinted polymers (MIPs), prepared using 2',3',5'-tri-O-acyluridines as 'dummy' templates, for the selective recognition of uridine nucleosides. The MIPs were synthesised using a non-covalent approach with 2,6-bis-acrylamidopyridine (BAAPy) acting as the binding monomer and ethylene glycol dimethacrylate (EGDMA) as the cross-linking agent. The MIPs were evaluated in terms of capacity, selectivity and specificity by analytical and frontal liquid chromatography measurements. The results obtained in organic mobile phases suggest that the nucleosides are specifically bound to the polymer by the complementary hydrogen bonding motifs of the binding monomer and the nucleoside bases. The MIPs exhibited relatively high imprinting factors for 2',3',5'-tri-O-acyluridines, while they did not show any binding capacity for other nucleosides lacking the imide moiety on their base. Moreover, the presence of ester-COO groups in the EGDMA cross-linker may lead to the formation of additional hydrogen bonds with the 2',3' and/or 5'-OH of sugar part, allowing enhancement of the recognition of the uridine nucleosides. In aqueous media, results show that the binding is driven by hydrophobic interactions.

Total knee arthroplasty using a cemented single-radius, condylar-stabilized design performed without posterior cruciate ligament sacrifice.

Aims: Total knee arthroplasty (TKA) with a highly congruent condylar-stabilized (CS) articulation may be advantageous due to increased stability versus cruciate-retaining (CR) designs, while mitigating the limitations of a posterior-stabilized construct. The aim was to assess ten-year implant survival and functional outcomes of a cemented single-radius TKA with a CS insert, performed without posterior cruciate ligament sacrifice. Methods: This retrospective cohort study included consecutive patients undergoing TKA at a specialist centre in the UK between November 2010 and December 2012. Data were collected using a bespoke electronic database and cross-referenced with national arthroplasty audit data, with variables including: preoperative characteristics, intraoperative factors, complications, and mortality status. Patient-reported outcome measures (PROMs) were collected by a specialist research team at ten years post-surgery. There were 536 TKAs, of which 308/536 (57.5%) were in female patients. The mean age was 69.0 years (95% CI 45.0 to 88.0), the mean BMI was 32.2 kg/m2 (95% CI 18.9 to 50.2), and 387/536 (72.2%) survived to ten years. There were four revisions (0.7%): two deep infections (requiring debridement and implant retention), one aseptic loosening, and one haemosiderosis. Results: Kaplan-Meier analysis demonstrated no difference in implant survival according to sex, age, or obesity status. Ten-year PROMs were available for 196/387 (50.6%) surviving patients and were excellent: mean Oxford Knee Score 34.4 (95% CI 32.7 to 36.1); mean Forgotten Joint Score (FJS) 51.2 (95% CI 16.1 to 86.3); mean EuroQol five-dimension five-level questionnaire score 69.9 (95% CI 46.8 to 93.0); 141/196 (71.9%) achieved the 22-point FJS patient-acceptable symptom state (PASS); and 156/196 (79.6%) were "very satisfied or satisfied". Conclusion: This is the only large study reporting ten-year implant survival and functional outcomes of TKA using a cemented single-radius design and with a CS tibial bearing construct. The findings of excellent implant survival, safety, and functional outcomes indicate that this combination is a safe and effective option in routine TKA. Further investigation of this single-radius design TKA with CS tibial bearings with well-matched patient study groups will allow further insight into the performance of these implants.

Tailor-Made Molecularly Imprinted Polymer for Selective Recognition of the Urinary Tumor Marker Pseudouridine.

Pseudouridine (Ψ) is an important urinary cancer biomarker, especially in human colorectal cancer (CRC). Disclosed herein is the first Ψ molecularly imprinted polymer (Ψ-MIP) material obtained from tailor-engineered functional monomers. The resulting MIP imprint exhibits a remarkable imprinting factor greater than 70. It is successfully used for the selective recognition of Ψ in spiked human urine. This selective functionalized material opens the route to the development of inexpensive disposable chemosensors for noninvasive CRC diagnosis and prognosis.

A phosphotyrosine-imprinted polymer receptor for the recognition of tyrosine phosphorylated peptides.

Hyperphosphorylation at tyrosine is commonly observed in tumor proteomes and, hence, specific phosphoproteins or phosphopeptides could serve as markers useful for cancer diagnostics and therapeutics. The analysis of such targets is, however, a challenging task, because of their commonly low abundance and the lack of robust and effective preconcentration techniques. As a robust alternative to the commonly used immunoaffinity techniques that rely on phosphotyrosine(pTyr)-specific antibodies, we have developed an epitope-imprinting strategy that leads to a synthetic pTyr-selective imprinted polymer receptor. The binding site incorporates two monourea ligands placed by preorganization around a pTyr dianion template. The tight binding site displayed good binding affinities for the pTyr template, in the range of that observed for corresponding antibodies, and a clear preference for pTyr over phosphoserine (pSer). In further analogy to the antibodies, the imprinted polymer was capable of capturing short tyrosine phosphorylated peptides in the presence of an excess of their non-phosphorylated counterparts or peptides phosphorylated at serine.

Molecularly imprinted polymers as antibody mimics in automated on-line fluorescent competitive assays.

An automated molecularly imprinted sorbent based assay (MIA) for the rapid and sensitive analysis of penicillin-type beta-lactam antibiotics (BLAs) has been developed and optimized. The polymers were prepared using penicillin G procaine salt as template (PENGp) and a stoichiometric quantity of a urea-based functional monomer to target the single oxyanionic species in the template molecule. Highly fluorescent competitors (emission quantum yields of 0.4-0.95), molecularly engineered to contain pyrene labels while keeping intact the 6-aminopenicillanic acid moiety for efficient recognition by the cross-linked polymers, have been tested as analyte analogues in the competitive assay. Pyrenemethylacetamido penicillanic acid (PAAP) was the tagged antibiotic providing for the highest selectivity when competing with PenG for the specific binding sites in the molecularly imprinted polymer (MIP). Upon desorption from the MIP, the emission signal generated by the PAAP was related to the antibiotic concentration in the sample. The 50% binding inhibition concentration of penicillin G standard curves was at 1.81 x 10(-6) M PENG, and the detection limit was 1.97 x 10(-7) M. The sensor showed a dynamic range (normalized signal in the 20 to 80% range) from 6.80 x 10(-7) to 7.21 x 10(-6) M (20-80% binding inhibition) PENG in acetonitrile:HEPES buffer 0.1 M at pH 7.5 (40:60, v/v) solutions. Competitive binding studies demonstrated various degrees of cross-reactivity with penicillin-type beta-lactam antibiotics such as ampicillin (71%), oxacillin (66%), penicillin V (56%), amoxicillin (13%), and nafcillin (46%) and a lower response to other isoxazolyl penicillins such as cloxacillin (27%) and dicloxacillin (16%). The total analysis time was 14 min per determination, and the MIP reactor could be reused for more than 150 cycles without significant loss of recognition. The automatic MIA has been successfully applied to the direct analysis of penicillin G in spiked urine samples with excellent recoveries (mean value 92%). Results displayed by comparative analysis of the optimized MIA with a chromatographic procedure for penicillin G showed excellent agreement between both methods.

Direct extraction of penicillin G and derivatives from aqueous samples using a stoichiometrically imprinted polymer.

A molecularly imprinted polymer (MIP) prepared using penicillin G procaine salt as the template (PENGp) and a stoichiometric quantity of urea-based functional monomer to target the single oxyanionic species in the template molecule has been applied to the development of a molecularly imprinted solid-phase extraction (MISPE) procedure for the selective preconcentration of beta-lactam antibiotics (BLAs) from environmental water samples. Various parameters affecting the extraction efficiency of the polymer have been evaluated to achieve the selective preconcentration of the antibiotics from aqueous samples and to reduce nonspecific interactions. This resulted in an MISPE-HPLC method allowing the direct extraction of the analytes from the sample matrix with a selective wash using just 10% (v/v) organic solvent. On the basis of UV detection only, the method showed good recoveries and precision, ranging between 93% and 100% (RSD 3.8-8.9%, n = 3) for tap water and between 90% and 100% (RSD 4.2-9.1%, n = 3) for river water fortified with 30 or 60 microg L-1 (50 mL samples) penicillin G, penicillin V, nafcillin, oxacillin, cloxacillin, and dicloxacillin, suggesting that this MIP can be successfully applied to the direct preconcentration of BLAs in environmental water samples.

Polymeric receptors for the recognition of folic acid and related compounds via substructure imprinting.

A range of 2-acrylamidopyridines, showing subtle differences in solution binding toward carboxylic acids, has been investigated as functional monomers in molecular imprinting. Imprinting of N-Z-L-glutamic acid with one such monomer is shown to be effective in the creation of a molecularly imprinted polymer (MIP) with recognition properties for its template and also for larger molecules containing glutamic acid residues. In comparison to a MIP prepared via a more "traditional" approach, the new polymeric receptors exhibit reduced nonspecific binding. The new receptors are compared with previously reported urea-based receptors targeting the glutamic acid residue and receptors targeting the pteridine substructure of folic acid.

A substructure approach toward polymeric receptors targeting dihydrofolate reductase inhibitors. 2. Molecularly imprinted polymers against Z-l-glutamic acid showing affinity for larger molecules.

The preparation of a molecularly imprinted polymer against N-Z-L-glutamic acid using a novel bis-urea functional monomer is described. The polymer exhibits affinity for the template over N-Z-protected aspartic acid and glycine and, further, is capable of binding larger molecules, e.g., the anti-cancer drug methotrexate, containing the glutamate substructure.