A colorimetric assay for the determination of polyhexamethylene biguanide in pool and spa water using nickel-nioxime

A novel nickel-nioxime analytical method to measure polyhexamethylene biguanide (PHMB) in swimming pools and spas was developed. This method utilizes nickel(II) chloride and 1,2-cyclohexanedionedioxime (nioxime) chemistry. In the method, nickel ions bind and neutralize PHMB in the solution. Excess, un-reacted nickel ions react with nioxime and the resulting colored solution is measured at 550 nm using a colorimetric assay. Currently, the colorimetric method to measure PHMB uses bromophenol blue (BPB). However, high levels of quaternary ammonium based algaecides and surfactant based products interfere with this colorimetric method. A time-consuming and expensive high-performance liquid chromatographic (HPLC) analysis can be used for samples with high levels of quaternary ammonium based algaecides or surfactants. The proposed nickel-nioxime detection method achieves comparable PHMB results to HPLC in about 5 min and is a very economical and simple method to perform.     

Synthesis,physico-chemical characterization and bioevaluation of Ni(II), Pd(II), and Pt(II) complexes with 1-(o-tolyl)biguanide: Antimicrobial and antitumor studies

New complexes of type [M(tbg)₂]Cl₂ [tbg = 1-(o-tolyl)biguanide; M = Ni(II), Pd(II), and Pt(II)] were synthesized and characterized to develop new biologically active compounds. The features of the complexes were assigned from microanalytical and thermal data. The NMR, FT-IR, and UV-Vis spectra were established by comparison with HtbgCl. All complexes exhibit a square-planar geometry resulting from the chelating behavior of tbg. The HtbgCl and [Ni(tbg)₂]Cl₂ complexes were fully characterized by single-crystal X-ray diffraction. The HtbgCl species crystallize in the monoclinic C2/c spatial group, while the Ni(II) complex adopts an orthorhombic Pna2₁ spatial group. The structure is stabilized by a complex hydrogen bonds network. The in vitro antimicrobial assays revealed improved antimicrobial activity for complexes in comparison with the ligand against both planktonic and biofilm embedded microbial cells. The most efficient compound, showing the largest spectrum of antimicrobial activity, including Gram-positive and Gram-negative bacteria, as well as fungal strains, in both planktonic and biofilm growth states was the Pd(II) complex, followed by the Pt(II) complex. The Pt(II) compound exhibited the most significant antiproliferative activity on the human cervical cancer SiHa cell line, inducing a cell cycle arrest in the G2/M phase.     

A comparative study of EDTA-gel derived BSCCO and Pb-BSCCO systems by thermoanalytical and X-ray diffraction techniques

Summary This paper deals with the first investigation concerning the thermal behaviour of Ni(II) complexes with ligands having biguanide moieties. The new complex [NiL(1)](ClO₄)₂·2.5H₂O (1) with the Schiff base resulted in [2+1] condensation of N,N-dimethylbiguanide with pentane-2,4-dione (L(1)) and the complex [Ni₂L(2)](ClO₄)₄ (2), with the Schiff base, L(2), resulted through the oxidative condensation of L(1) have been synthesized and characterised. The bonding and stereochemistry of the complexes have been characterized by IR and electronic spectra. The cyclic voltammograms show the characteristic waves for mononuclear and respectively binuclear Ni(II) complexes and indicate that both complexes exhibit catalytic effects on the CO₂ electrochemical reduction. The thermal behaviour provided confirmation of the complexes composition as well as the number and the nature of water molecules and the intervals of thermal stability. The different nature of the ligands generates a different thermal behaviour for complexes.     

Ag(Ⅲ)-聚六亚甲基双胍配合物的合成及抗菌性能表征

采用水溶液反应法,以不同粘均相对分子质量的聚六亚甲基双胍(PHMB)作为配体,合成出一系列稳定的由400 nm左右的小颗粒团聚而来的微米级四配位Ag(Ⅲ)-PHMB配合物,并对其进行表征证明了物质的结构与价态。通过抗菌活性实验发现,Ag(Ⅲ)-PHMB配合物的抗菌活性随着配体PHMB的粘均相对分子质量的升高而增大,随着粒径增大而减小。在低浓度条件下,微米级Ag(Ⅲ)-PHMB配合物的抗菌性能高于同等质量浓度的AgO、AgNO_3与PHMB;随着质量浓度的升高,微米级Ag(Ⅲ)-PHMB配合物与细菌的实际接触面积、缓释出的抗菌活性物质增长趋缓,因而抗菌活性升高趋缓。     

Metformin and Moroxidine Determination With Cu (II)

Abstract

Conductometric titrations of metformin and moroxidine are reported. The procedure is based on the copper-biguanide reaction which gives a pink soluble complex. Studies at several pH values and presence of NH₃ are carried out. NaOH-NH₃ (1:15) are added to 5 ml of biguanide aqueous solution and diluted to 60 ml and titrated with copper sulphate. Concentrations of metformin in 205x10^?4-1,7x10^?3 M range are determined. Foreign species presence is studied too.     

Spectroscopic Study of the Molecular Structure of the New Hybrid with a Potential Two-Way Antibacterial Effect

Bacterial strains become resistant to almost all classes of antibiotics, which makes it necessary to look for new substitutes. The non-absorbable ciprofloxacin–biguanide bismuth complex, used locally, may be a good alternative to a conventional therapy. The purpose of this study was to study the structure of the proposed ciprofloxacin (CIP) -bismuth(III)—chlorhexidine (CHX) composite (CIP-Bi-CHX). The spectroscopic techniques such as UV-VIS (ultraviolet-visible) spectroscopy, FTIR (Fourier-transform infrared) spectroscopy and NMR (Nuclear Magnetic Resonance) spectroscopy were used for structure characterization of the hybrid compound. The performed analysis confirmed the presence of the two active components—CIP and CHX and revealed the possible coordination sites of the ligands with bismuth ion in the metallo-organic structure. Spectroscopic study showed that the complexation between Bi(III) and CIP occurs through the carboxylate and ketone groups of the quinolone ring, while CHX combines with the central ion via the biguanide moieties.     

Metformin and Biguanide Complexes of Isothiocyanatosilane

Abstract

The preparation of neutral and ionic silicon–nitrogen complexes has been achieved by a single-step room temperature reaction by using isothiocyanatosilanes and metformin/biguanide ligands. These bidentate ligands coordinate to the silicon atom in a neutral as well as a deprotonated form to yield two different types of complexes. The resulting complexes have been characterized by the physical and spectroscopic techniques.     

Analysis of polyhexamethylene biguanide in multipurpose contact lens solutions

The objective of this study was to establish a reasonably simple and reliable method to measure very low concentrations of polyhexamethylene biguanide (PHMB) in multipurpose contact lens solutions (MPSs). By using a weak cation exchange solid phase extraction cartridge to extract the PHMB from MPS, followed by HPLC analysis using an evaporative light scattering detector, low levels (0.1 ppm) of PHMB were detected. Application of this method to a series of off-the-shelf MPS with PHMB as the active ingredient demonstrated these solutions contain 1 ppm. The contact lens solution with hydrogen peroxide as the active ingredient gave no peak where the PHMB peak eluted. The Polyquad^® contact lens solution generated a peak close to the retention time of PHMB. Recovery of PHMB from fortified hydrogen peroxide contact lens solution was good at 0.25 ppm and above; 105% with a RSD of 17% or less. The repeatability of the HPLC system ranged from 4 to 11% RSD; the reproducibility of the entire method was less than 17.5% RSD. Storage and stability studies indicated that storage of MPS with PHMB for chemical analysis are not temperature dependent, but are affected by the composition of the container in which the contact lens solution is stored.     

基于介孔纳米碳球接枝聚胍类化合物协同光热抗菌策略的研究

细菌感染是严重威胁着人们生命健康的主要问题之一. 与传统抗生素疗法相比, 新型抗菌策略光热疗法(PTT)展现出可控、微创及不易使细菌产生耐药性的优良性能. 然而单模形式下PTT疗法并不理想, 且高温下通常伴随着炎性反应等副作用, 联合抗菌策略可有效解决这一问题. 本研究制备了富含羧基的氧化介孔纳米碳球(OMCN), 通过酰胺化反应, 共价接枝聚六亚甲基双胍(PHMB), 得到OMCN-PHMB纳米平台. 实验结果表明, OMCN的光热性能具有良好的浓度与近红外光照功率依赖性. 在808 nm激光照射下, OMCN-PHMB的体内外联合光热治疗效果显著优于单一模式下的其它治疗组, 且组织学分析结果表明, 该纳米平台对小鼠的主要器官没有产生明显的毒性, 具有较高的生物相容性.