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Urinary tract infections (UTIs) are among the most common bacterial infections. Despite a wide range of therapeutic options, treatment success is compromised by the efficient mechanism of tissue colonization of uropathogenic Escherichia coli. In advanced drug delivery systems, a similar, glycan-mediated targeting mechanism may be realized by conjugating the drug to a plant lectin, like wheat germ agglutinin (WGA). We introduce a drug delivery vehicle consisting of human serum albumin as nanoparticle shell, olive oil as core component, the active pharmaceutical ingredients (API) trimethoprim and rifampicin as well as WGA to facilitate cellular internalization. When WGA was embedded into the proteinaceous particle shell, cell binding studies revealed up to 60 % higher cell binding potential. Additionally, nanoparticles showed a good efficacy against gram-negative just as against gram-positive bacteria. The combination of the promising cell-associative properties and the proven antimicrobial potential might lead to an improved efficacy of advanced treatment of UTIs., Competing Interests: Declaration of competing interest This research did not receive any specific grant from funding agencies in the public, commercial, or not-for-profit sectors. We declare no conflict of interest., (Copyright © 2023 The Author(s). Published by Elsevier Inc. All rights reserved.)

Although therapeutically active proteins are highly efficacious, their content in protective nanoparticles is often too low to elicit adequate plasma levels. A strategy to increase protein loading is the in-situ generation of calcium phosphate as a protein adsorbent. To verify this approach, a highly sensitive and reliable fluorimetric method for quantification of incorporated fluorescein-labelled bovine serum albumin (FITC-BSA) as a model protein drug was developed. Dequenching the fluorescein label by pronase E, which digests the protein backbone, and dissolving the nanoparticle matrix in acetonitrile enabled FITC-BSA quantification in the nanogram per milliliter range. This test was confirmed by a second assay involving alkaline hydrolysis of FITC-BSA and the matrix. Nanoparticles prepared with calcium phosphate contained 40 µg FITC-BSA/mg and nanoparticles without calcium phosphate only 15 µg FITC-BSA/mg, representing a 2.7-fold increase in model protein loading. In this work the nanoparticle preparation procedure was optimized in terms of size for administration in the inner ear, but the range of applications is not limited., (Copyright © 2021 The Authors. Published by Elsevier B.V. All rights reserved.)

Recurring infections and increasing resistances continue to complicate treatment of urinary tract infections. To investigate alternative treatment options, trimethoprim loaded micro- (D[4;3] of 1-9 µm) and nanoparticles (Z-Avg of 200-400 nm) were prepared from two types of poly(d,l-lactic-co-glycolic acid) (PLGA) for instillative therapy. While PLGA 503H microparticles could not be loaded with more than 2.6% trimethoprim, PLGA 2300 entrapped 22%. When preparing nanoparticles, both types displayed an even higher drug load of up to 29% using PLGA 2300, while PLGA 503H drug load stagnated at 10%. After eight hours, drug release from microparticles amounted to 55% (503H) and 35% (2300) whereas total drug release occurred after 8 (503H) and 9 days (2300). In case of nanoparticles, trimethoprim was liberated much faster with 60% after 2 h and a complete release after 24 h from both polymers. PLGA 2300 seems to be the better choice for entrapment of trimethoprim in microparticles considering the drug load. Both polymers, however, seem to be viable options for nanoparticles. Due to the higher overall drug load, nanoparticles seem to be advantageous over microparticles for instillative therapy, especially when prepared with PLGA 2300., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2020 Elsevier B.V. All rights reserved.)

A variety of research reports have provided evidence that the interplay between nanoparticles and biological systems is strongly dependent on the composition as well as on the size of the particles. However, irrespective of that a fine tuning of the interaction characteristics can be attained by functionalisation of the particle surface. In order to be able to monitor such interactions, an analytically accessible model system for potentially target-specific therapeutically relevant nanoparticles (NP) was generated by encapsulation of the highly hydrophobic fluorophore BODIPY 493/503 into poly(D,L-lactide-co-glycolide) (PLGA) nanodroplets. Analyses of the mean particle size and zeta potential revealed that plain and human serum albumin (HSA) conjugated NP can be stored without agglomeration for at least 28 days at 4 degrees C as well as -80 degrees C. Although transfer of the particles into commonly used buffers and cell culture medium did not affect the system's stability, protein-containing dispersants should not be used for experiments demanding high sensitivity as distinct quenching effects were observed. Concerning liberation of the fluorescent marker, no release occurred when incubating the suspension for 7 days at 4 degrees C, while an onset of release was expectedly detected after 3 h at 37 degrees C. These experimental limitations were taken into account for the particle-cell interaction studies which, as a consequence of the more hydrophilic particle surface, showed an enhanced adhesion of HSA-conjugated colloids to Caco-2 cells by means of flow cytometry and fluorescence microscopy.

The size dependent features of colloids at the nanometer scale have been issues of increasingly intensive research. In order to be able to correctly relate characteristics to certain size-populations, accurate and reliable particle sizing by dynamic light scattering (DLS) is a main prerequisite. So far, the complexity of the systems due to the presence of surfactants, proteins, and so forth in the nanoparticle suspensions has not been accounted for. In this work, practically relevant quantities of the frequently used PEO-PPO triblock copolymer surfactant Pluronic F-68 were studied for their effect on the size determination of nanoparticles by DLS. Induced changes in the tenside-content of the nanosphere suspension were monitored using a photometric assay and were correlated to the respective variances in mean particle size. These measurements showed that alterations in the range from 0.005 to 2% of Pluronic content are associated with shifts in diameter of 200 nm-particles by as much as 65 nm. The considerable changes that were found have been attributed to the surfactant-concentration-dependent fluctuations in the viscosity of the nanoparticle suspension, which affect the dimensions of colloids calculated according to the Stokes-Einstein relation.

Background: Most frequently the functionalization of nanoparticles is hampered by time-consuming, sometimes harsh conjugation and purification procedures causing premature drug release and/or degradation. A strategy to circumvent multi-step protocols is to synthesize building blocks with different functionalities and to use mixtures thereof for nanoparticle preparation in one step. Methods: BrijS20 was converted into an amine derivative via a carbamate linkage. The Brij-amine readily reacts with pre-activated carboxyl-containing ligands such as folic acid. The structures of the building blocks were confirmed by different spectroscopic methods and their utility was assessed by one-step preparation and characterization of nanoparticles applying PLGA as a matrix polymer. Results: Nanoparticles were about 200 nm in diameter independent of the composition. Experiments with human folate expressing single cells and monolayer revealed that the nanoparticle building block Brij mediates a "stealth" effect and the Brij-amine-folate a "targeting" effect. As compared to plain nanoparticles, the stealth effect decreased the cell interaction by 13%, but the targeting effect increased the cell interaction by 45% in the monolayer. Moreover, the targeting ligand density and thus the cell association of the nanoparticles is easily fine-tuned by selection of the initial ratio of the building blocks. Conclusions: This strategy might be a first step towards the one-step preparation of nanoparticles with tailored functionalities. Relying on a non-ionic surfactant is a versatile approach as it might be extended to other hydrophobic matrix polymers and promising targeting ligands from the biotech pipeline. [ABSTRACT FROM AUTHOR]

Urinary tract infections (UTIs) are among the most common bacterial infections. Despite a wide range of therapeutic options, treatment success is compromised by the efficient mechanism of tissue colonization of uropathogenic Escherichia coli. In advanced drug delivery systems, a similar, glycan-mediated targeting mechanism may be realized by conjugating the drug to a plant lectin, like wheat germ agglutinin (WGA). We introduce a drug delivery vehicle consisting of human serum albumin as nanoparticle shell, olive oil as core component, the active pharmaceutical ingredients (API) trimethoprim and rifampicin as well as WGA to facilitate cellular internalization. When WGA was embedded into the proteinaceous particle shell, cell binding studies revealed up to 60 % higher cell binding potential. Additionally, nanoparticles showed a good efficacy against gram-negative just as against gram-positive bacteria. The combination of the promising cell-associative properties and the proven antimicrobial potential might lead to an improved efficacy of advanced treatment of UTIs. The aim of this study was the development of a versatile drug delivery vehicle for an improved intravesical treatment of urinary tract infections. The development of antibiotic loaded WGA-functionalized nanoparticles might help to ensure enhanced bioavailability levels to improve treatment efficacy. Taken together, the data suggest that the here produced particles could serve as valid delivery vehicles providing the opportunity to follow and eradicate uropathogenic E. coli in their intracellular bacterial reservoirs resulting in an innovative and advanced treatment of urinary tract infections. [Display omitted] • Urinary tract infections are among the most common bacterial infections. • Uropathogenic Escherichia coli (UPEC) trigger uptake via a FimH lectin domain. • Uptake mechanism can be mimicked by protein nanoparticles (NPs) via plant lectins. • NPs have promising cell-associative properties and antimicrobial activity. • Versatile NPs might lead to an improved therapy of urinary tract infections. [ABSTRACT FROM AUTHOR]

• Short plasma half-life and high hydrophilicity of gemcitabine require high dosage. • Acylation of amino group provides tuneable lipophilicity and solubility. • Encapsulation in PLGA-nanoparticles enables API protection and controlled release. • Grafting the surface with wheat germ agglutinin imparts bioadhesive characteristics. After surgical removal of the tumour tissue, bladder cancer is treated by intravesical instillation of cytotoxic drugs such as gemcitabine. Gemcitabine, however, is highly hydrophilic and possesses a short half-life due to fast enzymatic deamination. Additionally, continuous dilution by urine, a hardly permeable urothelial barrier and rapid excretion by urination make therapy difficult. To modify lipophilicity of the drug, N-acyl-gemcitabine derivatives with quite different solubility and logP were synthesized, purified and characterized. The loading of PLGA nanoparticles with the N-acyl-gemcitabine derivatives followed by release in artificial urine, revealed that the drug content increases but the subsequent release decreases with lipophilicity. Additionally, acylation increased cytotoxicity and opened passive diffusion as an additional pathway into cancer cells. To address physiological constraints, the surface of the monodisperse nanoparticles was grafted with bioadhesive wheat germ agglutinin. Cytoadhesion to artificial bladder cancer tissue and even uptake into the cells as indicated by microscopic imaging are expected to prolong the retention time in the bladder cavity as well as to promote uptake into the cells. By using N-caprylic-gemcitabine as most appropriate gemcitabine-derivative for drug loading and making use of the bioadhesive characteristics of wheat germ agglutinin for grafting the corona of PLGA-nanoparticles, an innovative strategy towards smart drug delivery for instillative therapy of bladder cancer is proposed. [Display omitted] [ABSTRACT FROM AUTHOR]

Abstract: The preparation of particulate contrast agents for magnetic resonance imaging (MRI) based on biodegradable poly(d,l-lactide-co-glycolide) (PLGA) nanocarriers is reported. By spacer-aided covalent surface-grafting of the prominent chelating ligands diethylenetriaminepentaacetic acid (DTPA) and 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid (DOTA), respectively, up to 236 μg gadolinium per mg PLGA can be immobilized in a stable manner. Due to the localisation at the particle surface, water protons may effectively interact with the gadolinium chelates and the modified particles exhibit high proton relaxivities as confirmed by T1 relaxivities of up to 17.5 mm −1s−1 (25 °C, 1.41 T) in case of Gd-DOTA-functionalized carriers and also supported by NMRD profiles. The obtained values compare favorably with marketed low-molecular weight contrast agents and thus suggest suitability for in vivo use. [ABSTRACT FROM AUTHOR]

Objective. The aim of this work was the development of appropriate analytical methods and assays for determining and monitoring composition and degradation of nanoparticles built from PLGA (poly D, L-lactid-co-glycolid), which can be reloaded with different drugs. A sensitive and precise method for monitoring of nanoparticle degradation in vitro was developed and optimized. Nanoparticles allow a selective enrichment of different drugs and knowledge of the nature and type of their degradation is essential for characterization and control of drug release and dosage. Materials and methods. The first method developed during this work to quantify the PLGA polymer matrix use advantage of the chemical reaction of aliphatic carboxylic acids with ferric chloride (FeCl3) thus quantifying both degradation products of PLGA, lactic and glycol acids, at the same time. A second assay method of choice was to react to the polymer hydrolysate with lactate dehydrogenase, thus assaying selectively the lactic acid part. Results. During development of both of described methods was possible to determine dynamic range for PLGA matrix and nanoparticles, as well as to characterize impact of Pluronic F-68 and glycolic acid on lactate dehydrogenase activity. Conclusion. During our work we were able to develop two sensitive methods for monitoring of biodegradation of polymers which are consecutively used as a nanoparticle matrix in drug targeting. [ABSTRACT FROM AUTHOR]

Silver nanoparticle enhanced fluorescence is introduced as an alternative method to surface plasmon resonance techniques for real time monitoring of biorecognitive interactions or immunoassays. This method relies on the phenomenon that an electromagnetic near field is generated upon illumination on the surface of silver nanoparticles. The interaction of this field with nearby fluorophores results in fluorescence enhancement. Thus, fluorophores in the bulk solution can be discriminated from surface bound fluorophores. Anti-insulin-antibodies were immobilized on the surface of silver colloids in the following order: A ready to use microplate was prepared by bottom up coating with layers of aminosilane, silver nanoparticles, Fc-recognizing F(ab)2-fragments and anti-insulin-antibodies. At equilibrium conditions fluorescein-labeled insulin could only be detected in the presence of the colloid; the detection limit was 250 nM, and a fourfold increase in fluorescence was observed upon real time monitoring. The competitive assay of labeled and unlabeled insulin revealed a working range of 10–200 nM insulin in serum. The rapid single step immunoassay is easy to perform even in microplate format, its sensitivity is comparable to ELISA techniques, and offers broad application for real time monitoring of molecular recognitive processes. [Copyright &y& Elsevier]

To approach in vivo conditions during real time monitoring of biorecognitive interactions, biomimetic surfaces were prepared by fusion of purified plasma membrane fractions from Caco-2 cells with self-assembled monolayers attached to silver colloid coated standard microplates. Proper orientation and integrity of the membrane coating was confirmed by binding of fluorescein-labelled wheat germ agglutinin (F-WGA) which interacts with certain carbohydrates of the glycocalyx. Additionally, the competition with the complementary carbohydrate decreased the F-WGA binding to 15%. The assay setup offers information about the real time binding kinetics and the affinity of the interaction with the cell membrane excluding interfering events such as internalization and metabolism. As exemplified by F-WGA-binding, the mean velocity of the interaction is 627.07 mFU/s and the working range is 40–240 nM with a detection limit of 1.6 pmol F-WGA. The storage stability of the ready-to-use plates exceeded at least 1 month. The real time monitoring of lectin-prodrug binding to the biomimetic membranes revealed that high conjugation numbers reduces the affinity.The assays are simple and fast one-step reactions without any washing steps as this new technique discriminates between membrane bound and bulk fluorescence. Thus, biomimetic membranes on silver colloid layers represent a versatile tool for high throughput screening at early stages of drug discovery and development. [Copyright &y& Elsevier]