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Heinz C Schröder,1 Meik Neufurth,1 Huan Zhou,2 Shunfeng Wang,1 Xiaohong Wang,1 Werner E G Müller1 1ERC Advanced Investigator Group, Institute for Physiological Chemistry, University Medical Center of the Johannes Gutenberg University, Mainz, Germany; 2School of Health Sciences and Biomedical Engineering, Heibei University of Technology, Tianjin, People’s Republic of ChinaCorrespondence: Heinz C Schröder; Werner E G Müller, ERC Advanced Investigator Group, Institute for Physiological Chemistry, University Medical Center of the Johannes Gutenberg University, Duesbergweg 6, Mainz, 55128, Germany, Tel +49 6131 392 5791 ; +49 6131 392 5910, Email hschroed@uni-mainz.de; wmueller@uni-mainz.deAbstract: Inorganic polyphosphates (polyP) are long-chain polymers of orthophosphate residues, which, depending on the external conditions, can be present both physiologically and synthetically in either soluble, nanoparticulate or coacervate form. In recent years, these polymers have received increasing attention due to their unprecedented ability to exhibit both morphogenetic and metabolic energy delivering properties. There are no other physiological molecules that contain as many metabolically utilizable, high-energy bonds as polyP, making these polymers of particular medical interest as components of advanced hydrogel scaffold materials for potential applications in ATP-dependent tissue regeneration and repair. However, these polymers show physiological activity only in soluble form and in the coacervate phase, but not as stable metal-polyP nanoparticles. Therefore, understanding the mechanisms of formation of polyP coacervates and nanoparticles as well as their transformations is important for the design of novel materials for tissue implants, wound healing, and drug delivery and is discussed here.Keywords: polyphosphate nanoparticles, phase separation, biomaterial, metabolic energy, morphogenetic activity, tissue regeneration

[Display omitted] • Synechococcus PCC 7002 produced calcium-enriched polyphosphate nanoparticles (CaPNPs). • Calcium in CaPNPs was readily available to intestinal absorption via both ion channel-mediated and endocytic pathways. • CaPNPs had a calcium bioavailability approximately 100% relative to that of CaCl 2 and more than 1.6 times of that of CaCO 3. • CaPNPs possessed desirable resistance against phytate's antagonistic action on calcium absorption. Biogenic nanoparticles are promising carriers to deliver essential minerals. Here, calcium-enriched polyphosphate nanoparticles (CaPNPs) with a Ca/P molar ratio > 0.5 were produced by Synechococcus sp. PCC 7002 in the growth medium containing 1.08 g/L CaCl 2 , and had nearly spherical morphologies with a wide size distribution of 5–75 nm and strongly anionic surface properties with an average ζ-potential of –39 mV, according to dynamic light-scattering analysis, transmission and scanning electron microscopy, and energy-dispersive X-ray spectroscopy. The ex-vivo ligated mouse ileal loop assays found that calcium in CaPNPs was readily available to intestinal absorption via both ion channel-mediated and endocytic pathways, specifically invoking macropinocytic internalization, lysosomal degradation, and transcytosis. Rat oral pharmacokinetics revealed that CaPNPs had a calcium bioavailability approximately 100 % relative to that of CaCl 2 and more than 1.6 times of that of CaCO 3. CaPNPs corrected the retinoic acid-induced increase in serum calcium, phosphorus, and bone-specific alkaline phosphatase, and decrease in serum osteocalcin, bone mineral content/density, and femoral geometric parameters with an efficacy equivalent to CaCl 2 and markedly greater than CaCO 3. In contrast to CaCl 2 , CaPNPs possessed desirable resistance against phytate's antagonistic action on calcium absorption in these ex vivo and in vivo studies. Overall, CaPNPs are attractive as a candidate agent for calcium supplementation, especially to populations on high-phytate diets. [ABSTRACT FROM AUTHOR]

The development of an effective sensing platform is critical for the electrochemical detection of heavy metal ions (HMIs) in water. In this study, we fabricated a newly designed sensor through the in situ assembly of reduced graphene oxide (rGO) and polyphosphate nanoparticles (polyP NPs) on a carbon cloth electrode via microorganism-mediated green biochemical processes. The characterization results revealed that the rGO produced via microbial reduction had a three-dimensional porous structure, serving as an exceptional scaffold for hosting polyP NPs, and the polyP NPs were evenly distributed on the rGO network. In terms of detecting HMIs, the numerous functional groups of polyP NPs play a major role in the coordination with the cations. This electrochemical sensor, based on polyP NPs/rGO, enabled the individual and simultaneous determination of lead ion (Pb2+) and copper ion (Cu2+) with detection limits of 1.6 nM and 0.9 nM, respectively. Additionally, the electrode exhibited outstanding selectivity for the target analytes in the presence of multiple interfering metal ions. The fabricated sensor was successfully used to determine Pb2+/Cu2+ in water samples with satisfactory recovery rates ranging from 92.16% to 104.89%. This study establishes a facile, cost-effective, and environmentally friendly microbial approach for the synthesis of electrode materials and the detection of environmental pollutants. • A noval electrochemical sensor with high sensitivity for Pb2+ and Cu2+ was developed. • C. freundii was utilized to self-assemble polyP NPs/rGO as the electrode matrix. • The composite electrode features abundant active sites, high conductivity and porosity. • This sensor demonstrated low detection limits, excellent stability and robust interference resistance. [ABSTRACT FROM AUTHOR]

Probiotic-derived polyphosphates have attracted interest as potential therapeutic agents to improve intestinal health. The current study discovered the intracellular accumulation of polyphosphates in a marine cyanobacterium Synechococcus sp. PCC 7002 as nano-sized granules. The maximum accumulation of polyphosphates in Synechococcus sp. PCC 7002 was found at the late logarithmic growth phase when the medium contained 0.74 mM of KH2PO4, 11.76 mM of NaNO3, and 30.42 mM of Na2SO4. Biogenic polyphosphate nanoparticles (BPNPs) were obtained intact from the algae cells by hot water extraction, and were purified to remove the organic impurities by Sephadex G-100 gel filtration. By using 100 kDa ultrafiltration, BPNPs were fractionated into the larger and smaller populations with diameters ranging between 30–70 nm and 10–30 nm, respectively. 4′,6-diamidino-2-phenylindole fluorescence and orthophosphate production revealed that a minor portion of BPNPs (about 14–18%) were degraded during simulated gastrointestinal digestion. In vitro studies using lipopolysaccharide-activated RAW264.7 cells showed that BPNPs inhibited cyclooxygenase-2, inducible nitric oxide (NO) synthase expression, and the production of proinflammatory mediators, including NO, tumor necrosis factor-α, interleukin-6, and interleukin-1β through suppressing the Toll-like receptor 4/NF-κB signaling pathway. Overall, there is promise in the use of the marine cyanobacterium Synechococcus sp. PCC 7002 to produce BPNPs, an anti-inflammatory postbiotic.

Nanoscale delivery systems have gained a surge of interest in improving the stability, food compatibility, and bioavailability of essential minerals. Biogenic polyphosphate nanoparticles from microalgae have a great potential to enrich and deliver mineral nutrients. Here, zinc-enriched polyphosphate nanoparticles (ZnPNPs) with a zinc/calcium molar ratio of around 0.2 were obtained from Synechococcus sp. PCC 7002 supplemented with 3.75 mg/L zinc in the growth medium, and displayed small size and anionic nature with a monomer diameter of around 18 nm and a zeta potential of around −36 mV. Zinquin fluorescence measurements unveiled that ZnPNPs were well absorbed and readily incorporated into labile zinc pool by polarized Caco-2 cells in vitro. ZnPNPs showed good resistance to phytate's inhibition on zinc transportation across ligated mouse small intestine ex vivo at the phytate × calcium/zinc molar ratio as seen in baked whole wheat bread, and by treating with NaN3, amiloride, low temperature, chloroquine, and wortmanin, ZnPNPs transportation was found to invoke macropinocytic internalization, lysosomal degradation, and transcytosis. Oral pharmacokinetics and liver and skeletal muscle retention of zinc in rats revealed good in vivo zinc bioavailability of ZnPNPs under high dietary phytate conditions. Overall, ZnPNPs are attractive for zinc supplementation/fortification to populations on phytate-rich diets. [Display omitted] • ZnPNPs were obtained from Synechococcus sp. PCC 7002 by the enrichment of zinc. • ZnPNPs could be well absorbed and readily incorporated into labile cell zinc pool in vitro. • A good resistance to phytate's inhibition on zinc transportation was observed across ligated mouse small intestine ex vivo. • ZnPNPs transportation invoked macropinocytic internalization, lysosomal degradation, and transcytosis. • Oral pharmacokinetics revealed good zinc bioavailability of ZnPNPs against high dietary phytate in vivo. [ABSTRACT FROM AUTHOR]