A highly efficient, multifunctional, bioderived white-emitting hydrogel (biophosphor) consisting of crosslinked bovine serum albumin and three fluorescent dyes, Coumarin 460, fluorescein, and 5(6)-carboxy-x-rhodamine, is reported here. White emission is obtained upon excitation of the biophosphor at 365 nm with appropriate mole ratios of the above dyes. The CIE 1931 chromaticity coordinates of white emission with 365 nm excitation are (0.36, 0.37), and the correlated color temperature is 5300 K. Multifunctional nature of the biophosphor is also demonstrated. A UV-light-emitting-diode (361 nm) coated with this biophosphor, for example, indicates white emission (CIE 0.28, 0.31) with a half-life of 106 (±5) h. The white emission is also highly sensitive to pH over a broad range (pH 1-11). Incorporation of glucose oxidase and peroxidase in the biophosphor allows for the detection of glucose over a physiologically relevant range of 1.8-288 mg dL −1 . This is a unique, advanced biophosphor with LED and sensing applications, and it is the first example of a multifunctional, proteinaceous white emitter. molar absorptivity and quantum efficiency of emissive components is a significant challenge for systems that combine direct emission and sensitized emission via Förster resonance energy transfer (FRET) to produce white light. [6,7] Hydrogels are hydrophilic polymer networks [8] and are emerging as versatile new matrices for high-efficiency generation of white light using intermolecular energy transfer processes. The gel matrix improves energy transfer efficiency by rigidifying the orientation of the donor (D)-acceptor (A) pairs [9] and preventing their aggregation, which can lead to quenching. [10] Despite the advantageous properties of white-emitting hydrogels, implementation in a functional device and photostability were not systematically studied, and biodegradability has not been demonstrated. Additionally, white-emitting proteinbased hydrogels are not known other than a report of a gelatin hydrogel with chromaticity coordinates [0.26, 0.33], far from being coordinates of pure white emission [0.33, 0.33]. [2] To the best of our knowledge, there are no reports of a multifunctional, nontoxic, biodegradable, white-emitting protein hydrogel.BSA is inexpensive and readily available as a waste product of the meat industry. BSA has a large number of primary amines (59 lysine) and carboxylic acids (99 aspartic acid/glutamic acid), [11] which can be crosslinked under controlled conditions by carbodiimide chemistry to form a network of amide bonds without disrupting the intricate secondary structure of the protein. [12,13] The protein's secondary structure plays an important role for dye binding at the intended site and for enzyme activity retention, when enzymes are incorporated in the matrix for sensing or catalytic applications. We envisioned that this molecular network of BSA would result in a water-rich hydrogel with discrete sites for dye binding which would be suitable for the construction of a white-emitting gel.Previou...
Preventing orthopedic implant-associated bacterial infections remains a critical challenge. Current practices of physically blending high-dose antibiotics with bone cements is known for cytotoxicity while covalently tethering antibiotics to implant surfaces is ineffective in eradicating bacteria from the periprosthetic tissue environment due to the short-range bactericidal actions, which are limited to the implant surface. Here, we covalently functionalize poly(ethylene glycol) dimethacrylate hydrogel coatings with vancomycin via an oligonucleotide linker sensitive to Staphylococcus aureus (S. aureus) micrococcal nuclease (MN) (PEGDMA-Oligo-Vanco). This design enables the timely release of vancomycin in the presence of S. aureus to kill the bacteria both on the implant surface and within the periprosthetic tissue environment. Ti6Al4V intramedullary (IM) pins surface-tethered with dopamine methacrylamide (DopaMA) and uniformly coated with PEGDMA-Oligo-Vanco effectively prevented periprosthetic infections in mouse femoral canals inoculated with bioluminescent S. aureus. Longitudinal bioluminescence monitoring, μCT quantification of femoral bone changes, end point quantification of implant surface bacteria, and histological detection of S. aureus in the periprosthetic tissue environment confirmed rapid and sustained bacterial clearance by the PEGDMA-Oligo-Vanco coating. The observed eradication of bacteria was in stark contrast with the significant bacterial colonization on implants and osteomyelitis development found in the absence of the MN-sensitive bactericidal coating. The effective vancomycin tethering dose presented in this on-demand release strategy was >200 times lower than the typical prophylactic antibiotic contents used in bone cements and may be applied to medical implants and bone/dental cements to prevent periprosthetic infections in high-risk clinical scenarios. This study also supports the timely bactericidal action by MN-triggered release of antibiotics as an effective prophylactic method to bypass the notoriously harder to treat periprosthetic biofilms and osteomyelitis.
Despite advanced implant sterilization and aseptic surgical techniques, periprosthetic bacterial infection remains a major challenge for orthopedic and dental implants. Bacterial colonization/biofilm formation around implants and their invasion into the dense skeletal tissue matrices are difficult to treat and could lead to implant failure and osteomyelitis. These complications require major revision surgeries and extended antibiotic therapies that are associated with high treatment cost, morbidity, and even mortality. Effective preventative measures mitigating risks for implant-related infections are thus in dire need. This review focuses on recent developments of anti-periprosthetic infection strategies aimed at either reducing bacterial adhesion, colonization, and biofilm formation or killing bacteria directly in contact with and/or in the vicinity of implants. These goals are accomplished through antifouling, quorum-sensing interfering, or bactericidal implant surface topographical engineering or surface coatings through chemical modifications. Surface topographical engineering of lotus leaf mimicking super-hydrophobic antifouling features and cicada wing-mimicking, bacterium-piercing nanopillars are both presented. Conventional physical coating/passive release of bactericidal agents is contrasted with their covalent tethering to implant surfaces through either stable linkages or linkages labile to bacterial enzyme cleavage or environmental perturbations. Pros and cons of these emerging anti-periprosthetic infection approaches are discussed in terms of their safety, efficacy, and translational potentials.
Rational design of protein-polymer composites and their use, under the influence of the stimulus, for numerous applications requires a clear understanding of protein-polymer interfaces. Here, using poly(acrylic acid) (PAA) and lysozyme as model systems, the binding interactions between these macromolecules were investigated by isothermal titration calorimetry. The binding is proposed to require and be governed by "charge neutralization of the protein/polymer interface" and predicted to depend on solution pH. Calorimetric data show strong exothermic binding of lysozyme to PAA with a molar ΔH and TΔS values of -107 and -95 kcal/mol, respectively, at pH 7 and room temperature. Both ΔH and TΔS decreased linearly with increasing pH from 3 to 8, and these plots had slopes of -17.7 and -17.5 kcal/mol per pH unit, respectively. The net result was that the binding propensity (ΔG) was nearly independent of pH but the binding stoichiometry, surprisingly, increased rapidly with increasing pH from 1 lysozyme binding per PAA molecule at pH 3 to 16 lysozyme molecules binding per PAA molecule at pH 8. A plot of stoichiometry vs pH was linear, and consistent with this result, a plot of ln(average size of the protein/polymer complex) vs pH was also linear. Thus, protonation-deprotonation plays a major role in the binding mechanism. "Charge neutralization" of the lysozyme/PAA interface controls the binding stoichiometry as well as the binding enthalpies/entropies in a predictable fashion, but it did not control the binding affinity (ΔG). The pH dependence of lysozyme binding to PAA, demonstrated here, provides a stimuli-responsive system for protein binding and release from the polymer surface.
Higher loading of enzymes on electrodes and efficient electron transfer from the enzyme to the electrode are urgently needed to enhance the current density of biofuel cells. The two-dimensional nature of the electrode surface limits the enzyme loading on the surface, and unfavorable interactions with electrode surfaces cause inactivation of the enzyme. Benign biohydrogels are designed here to address enzyme degradation, and the three-dimensional nature of the biohydrogel enhanced the enzyme density per unit area. A general strategy is demonstrated here using a redox active enzyme glucose oxidase embedded in a bovine serum albumin biohydrogel on flexible carbon cloth electrodes. In the presence of ferricyanide as a mediator, this bioelectrode generated a maximum current density (j) of 13.2 mA·cm at 0.45 V in the presence of glucose with a sensitivity of 67 μA·mol·cm and a half-life of >2 weeks at room temperature. A strong correlation of current density with water uptake by the biohydrogel was observed. Moreover, a soluble mediator (sodium ferricyanide) in the biohydrogel enhanced the current density by ∼1000-fold, and citrate-phosphate buffer has been found to be the best to achieve the maximum current density. A record 2.2% of the loaded enzyme was electroactive, which is greater than the highest value reported (2-fold). Stabilization of the enzyme in the biohydrogel resulted in retention of the enzymatic activity over a wide range of pH (4.0-8.0). We showed here that biohydrogels are excellent media for enzymatic electron transfer reactions required for bioelectronics and biofuel cell applications.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.