HUMAN IMMUNODEFICIENCY VIRUS (HIV)-BLOOD INTERACTIONS: SURFACE THERMODYNAMICS APPROACH

Sequel to the earlier works by Omenyi et al which established the role of surface thermodynamics in various biological processes from the electrostatic repulsion and van der Waals attraction mechanisms, HIV-blood interactions were modeled. This involved the use of the Hamaker coefficient approach as a thermodynamic tool in determining the interaction processes. It therefore became necessary to apply the Lifshitz derivation for van der Waals forces as an alternative to the contact angle approach which has been widely used in other biological systems. The methodology involved taking blood samples from twenty HIV-infected persons and from twenty uninfected persons for absorbance measurement using Ultraviolet Visible Spectrophotometer (Ultrospec3100pro). From the absorbance data various variables (e.g. dielectric constant, etc) required for computations with the Lifshitz formula were derived. CD4 counts using the digital CD4 counter were also obtained. Due to the very large body of data
involved, MATLAB software tools were employed in solving the ensuing mathematics. The Hamaker constants A11, A22, A33 and the combined Hamaker coefficients A132 were obtained using the values of the dielectric constant together with the Lifshitz equation. The harmonized Hamaker coefficients A132har and the absolute combined Hamaker coefficient, A132abs (an integral of all the values of the various Hamaker coefficients) for the infected blood samples were then calculated. The value of A132abs = 0.2587x10-21Joule (i.e. 0.2587x10-14erg) was obtained for HIVinfected blood. This value lies within the range of values derived by various researchers for other biological systems. Another significance of this result is the positive sense of the absolute combined Hamaker coefficient which implies net positive van der Waals forces indicating an attraction between the virus and the lymphocyte. This in effect suggests that infection has occurred thus confirming the role of this principle in HIV-blood interactions. A lower value of A131abs = 0.1026x10-21 Joule obtained for the uninfected blood samples is also an indicator that a
zero or negative absolute combined Hamaker coefficient is attainable. A mathematical model for the HIV-blood interaction mechanism was developed from the principle of particle-particle interaction mechanism. To propose a solution to HIV infection, it is necessary to find a way to render the absolute combined Hamaker coefficient A132abs negative. As a first step to this, a mathematical derivation for A33 ≥ 0.9763x10-21Joule which satisfies this condition for a negative A132abs was obtained. To achieve the condition of the stated A33 above with possible additive(s)
in form of drugs to the serum as the intervening medium will be the next step. This forms part of the suggested areas for further research.

BY ACHEBE, CHINONSO HUBERT, A DISSERTATION SUBMITTED TO THE DEPARTMENT OF MECHANICAL ENGINEERING, SCHOOL OF POST-GRADUATE STUDIES, FACULTY OF ENGINEERING NNAMDI AZIKIWE UNIVERSITY, AWKA IN PARTIAL FULFILMENT OF THE REQUIREMENTS FOR THE AWARD OF DOCTOR OF PHILOSOPHY (Ph.D.) IN MECHANICAL ENGINEERING