Giancarlo Fini

A comparative Raman and FTIR study of histamine (Hm), a small hormone present in a wide selection of living organisms, and its complexes with copper(II) at different pH values was carried out. Both the Raman and IR spectra present some marker bands useful for the identification of the structure of the species predominating in the Cu(II) aqueous and alcoholic systems. In particular, Raman spectroscopy appears to be a useful tool for analyzing the tautomeric equilibrium of the imidazole ring of Hm, because some bands (i.e., νC₄C₅) appear at different wavenumbers, depending on whether the imidazole moiety is in the N_τ‐H (tautomer I) or N_π‐H (tautomer II) protonated form. In aqueous solutions the manner in which Hm binds to Cu(II) depends on the pH. At basic pH the most relevant species formed are a dimer, [Cu₂L₂H₋₂]²⁺, and a monomeric complex, [CuL]²⁻ or [CuL₂]⁺. On the contrary, by decreasing the pH, Hm acts as a mono‐ or bidentate ligand, giving rise to two types of monomeric complexes, [CuLH]²⁻ and [CuL]²⁻ or [CuL₂]⁺. With respect to the Cu(II)–Hm alcoholic system, both the aminic group and the imidazole ring (tautomer I) take part in the Cu(II) coordination, leading to the formation of the [CuL]²⁻ or [CuL₂]⁺ monomeric complex. © 2003 Wiley Periodicals, Inc. Biopolymers (Biospectroscopy), 2003

Vibrational spectroscopy coupled with thermogravimetry (TG) and differential scanning calorimetry (DSC) was used to characterize racemic propanoic acid, 2-methyl-5,6,7,8-tetrahydro-6-(methylamino)-1,2-naphthalenediyl ester hydrochloride (CHF-1035), which is a new DA₂ dopaminergic receptor/α₂ agonist and β blocker under clinical investigation for the treatment of congestive heart failure. Raman spectroscopy disclosed at least two different CHF-1035 polymorphs; the marker bands characteristic of each form were identified. The modifications undergone by the CHF-1035 drug as a consequence of grinding and heating were investigated. Mechanical and gentle thermal treatments caused a polymorphic transformation of the drug crystal form. Raman spectroscopy proved suitable for investigating the possible presence of different polymorphic forms, their relative stability, and interconversion tendency in relation to industrial manufacturing processes undergone by the drug (i.e., grinding, compression, and heating). © 2002 Wiley Periodicals, Inc. Biopolymers (Biospectroscopy) 67: 289–293, 2002

This review highlights the potential of vibrational spectroscopy for investigating the molecular structure of some polymeric materials used in biomedical applications in relation to their biocompatibility. Many types of polymers are used for biomedical purposes; depending on the application, bioresorbable or non‐bioresorbable (semi‐crystalline or amorphous) polymers are used. Among bioresorbable polymers, we focused on homopolymers and copolymers based on poly(lactic acid), poly(glycolic acid) and poly(ε‐caprolactone). Being a nondestructive technique, Raman spectroscopy proved particularly suitable for evaluating the molecular structure and crystallinity of bioresorbable polymers and their degradation products. For various biomedical applications, non‐degradable semi‐crystalline polymers have been widely employed; in this class of polymers, we concentrated on ultra‐high molecular weight polyethylene (UHMWPE) used in orthopaedic implants (total hip and knee joints). Vibrational spectroscopy appeared particularly suitable in studying the oxidation and crystallinity of UHMWPE. Copyright © 2001 John Wiley & Sons, Ltd.