Development of anti-scale poly(aspartic acid-citric acid) dual polymer systems for water treatment

Metal ion chelation of poly(aspartic acid): From scale inhibition to therapeutic potentials

Poly(aspartic acid) (PASP) is a biodegradable, biocompatible water-soluble synthetic anionic polypeptide. PASP has shown a strong affinity and thus robust complexation with heavy and alkaline earth metal ions, from which several applications are currently benefiting, and several more could also originate. This paper discusses different areas where the ion chelation ability of PASP has thus far been exploited. Due to its calcium chelation ability, PASP prevents precipitation of calcium salts and hence is widely used as an effective scale inhibitor in industry. Due to potassium chelation, PASP prevents precipitation of potassium tartrate and is employed as an efficient and edible stabilizer for wine preservation. Due to iron chelation, PASP inhibits corrosion of steel surfaces in harsh environments. Due to chelation, PASP can also enhance stability of various colloidal systems that contain metal ions. The chelation ability of PASP alleviated the toxicity of heavy metals in Zebrafish, inhibited the formation of kidney stones and dissolved calcium phosphate which is the main mineral of the calcified vasculature. These findings and beyond, along with the biocompatibility and biodegradability of the polymer could direct future investigations towards chelation therapy by PASP and other novel and undiscovered areas where metal ions play a key role.

Predicting tubular heat exchanger efficiency reduction caused by marine biofilm adhesion using CFD simulations

A novel efficiency reduction model to tubular heat exchanger based on heat transfer losses by biofilm adhesion is proposed, which included a modified equation based on the real data-dependent time, seawater, hydrodynamics and heat transfer resistance using computational fluid dynamics (CFD). The biofilm growth model based on Verhulst model and experimental data has been obtained and simulated in a CFD software tool to analyze the tubular heat exchanger performance prediction cooled by seawater. The biofilm CFD model with appropriate fit, and the correlation coefficient (R2) values are between 0.97 and 0.99, was validated by experimental data obtained at different flow velocity. The final results of in/outlet difference temperatures were from 3.9 °C to 2.2 °C for different flow velocity with R2 > 0.97. The simulation results demonstrate that the novel CFD model is capable of predicting the efficiency losses during the development period of biofilm growth in in open-loop cooling seawater systems.

Green inhibitors reduce unwanted calcium carbonate precipitation: Implications for technical settings

Mineral scale deposits in water drainage and supply systems are a common and challenging issue, especially by clogging the water flow. The removal of such unwanted deposits is cost intensive arguing for case-specific and sustainable prevention strategies. In the present study, a novel on-site approach to prevent calcium carbonate (CaCO₃) scale formation was assessed in two road tunnel drainages: Application of the eco-friendly green inhibitor polyaspartate (PASP) caused (i) a significant inhibition of CaCO₃ precipitation, (ii) a more porous or even unconsolidated consistence of the deposits, and (iii) a shift from calcite to the metastable aragonite and vaterite polymorphs. Even relatively low PASP concentrations (1-33 mg/l) can significantly decrease CaCO₃ scale deposition, removing up to ∼7 t CaCO₃/year at an efficiency up to 84%. Application of PASP for water conditioning should also consider case-specific microbial activity effects, where consumption of PASP, e.g. by Leptothrix ochracea, can limit inhibition effects.

Poly(aspartic acid) in Biomedical Applications: From Polymerization, Modification, Properties, Degradation, and Biocompatibility to Applications

Poly(aspartic acid) (PASP) is an anionic polypeptide that is a highly versatile, biocompatible, and biodegradable polymer that fulfils key requirements for use in a wide variety of biomedical applications. The derivatives of PASP can be readily tailored via the amine-reactive precursor, poly(succinimide) (PSI), which opens up a large window of opportunity for the design and development of novel biomaterials. PASP also has a strong affinity with calcium ions, resulting in complexation, which has been exploited for bone targeting and biomineralization. In addition, recent studies have further verified the biocompatibility and biodegradability of PASP-based polymers, which is attributed to their protein-like structure. In light of growing interest in PASP and its derivatives, this paper presents a comprehensive review on their synthesis, characterization, modification, biodegradation, biocompatibility, and applications in biomedical areas.

Hydrogels Based on Poly(aspartic acid): Synthesis and Applications

This review presents an overview on the recent progress in the synthesis, crosslinking, interpenetrating networks, and applications of poly(aspartic acid) (PASP)-based hydrogels. PASP is a synthetic acidic polypeptide that has drawn a great deal of attention in diverse applications due particularly to its biocompatibility and biodegradability. Facile modification of its precursor, poly(succinimide) (PSI), by primary amines has opened a wide window for the design of state-of-the-art hydrogels. Apart from pH-sensitivity, PASP hydrogels can be modified with suitable species in order to respond to the other desired stimuli such as temperature and reducing/oxidizing media as well. Strategies for fabrication of nanostructured PASP-based hydrogels in the form of particle and fiber are also discussed. Different cross-linking agents for PSI/PASP such as diamines, dopamine, cysteamine, and aminosilanes are also introduced. Finally, applications of PASP-based hydrogels in diverse areas particularly in biomedical are reviewed.

Matrix-Free and Highly Efficient Room-Temperature Phosphorescence of Nitrogen-Doped Carbon Dots

Efficient room-temperature phosphorescence (RTP) of carbon dots (CDs) usually is seriously limited to appropriate solid matrix or introduced heavy atoms responsible for promoting intersystem crossing and suppress vibrational dissipation between singlet and triplet states. So, facile preparation efficient RTP of CDs with nonmatrix is still a highly difficulty and challenging task. Here, we first reported a subtle strategy to induce highly efficient free-matrix RTP of nitrogen-doped CDs (NCDs). The NCDs are composed of a core and hydrophilic surface of polyaspartic acid chains arising from high-temperature polymerization by a one-pot heating treatment of l-aspartic acid and d-glucose. The obtained NCDs have an ultralong phosphorescence lifetime of 747 ms and a high phosphorescence quantum yield (PQY) of 35% under 320 nm excitation in air. To the best of our knowledge, the PQY is currently the highest values recorded for RTP of CDs. The facile preparation and unique optical features offer these NCDs potential application in numerous applications, such as anticounterfeiting and white light-emitting diodes.