The covalent OH bonds of water vibrate and absorb radiation in the near infrared (NIR) region at wavelengths that vary according to the strength of the bonds which, at the same time, are sensitive to the number and/or strength of hydrogen bonds. By means of multivariate analytical tools, such spectral shift was exploited to study the effect of temperature, 25-hydroxycholesterol and progesterone on the H-bonded network of water in DMPA membranes. Temperature was found as the dominating factor altering the NIR spectra of water and then the H-bonds. Increasing temperatures disrupt the H-bonds network, strengthening the OH covalent bonds. The disruption of the H-bonds along the 13–58 °C range was noticeably greater than that caused by lipids or steroids at 500 μM. The H-bonded network of the interfacial water in DMPA membranes was disrupted by the presence of 25-hydroxycholesterol, but no significant disruption was observed in the presence of progesterone. The reduction of the H-bonds entails a reduction in the aggregation of the interfacial water by a reduction in the number of H-bonded molecules. It is proposed that the number of water molecules bonded with two H-bonds diminishes and the number of molecules with no H-bond increases roughly at similar proportions, with a constant population of molecules with one H-bond. The opposed effects of steroids are discussed in the context of their opposed effects on the phase state of membranes, the membrane water content and the steroid molecular structure.

水的共价O H键在近红外（NIR）区域中振动并吸收辐射，该波长根据键的强度而变化，同时对氢键的数量和/或强度敏感。通过多元分析工具，利用这种光谱位移来研究温度，25-羟基胆固醇和孕酮对DMPA膜中水的氢键网络的影响。发现温度是改变水的近红外光谱然后改变氢键的主要因素。温度升高会破坏氢键网络，从而增强OH共价键。氢键在13–58°C范围内的破坏明显大于500μM时由脂质或类固醇引起的破坏。DMPA膜中界面水的氢键网络由于25-羟基胆固醇的存在而被破坏，但是在孕酮的存在下没有观察到明显的破坏。H键的减少需要通过减少H键分子的数量来减少界面水的聚集。有人提出减少了带有两个氢键的水分子的数量，没有氢键的分子的数量以相似的比例大致增加，具有一个氢键的分子的数量恒定。在类固醇对膜相态的相反作用的背景下讨论了类固醇的相反作用，