Francisco B. T. Pessine

Bio: Francisco B. T. Pessine is an academic researcher from State University of Campinas. The author has contributed to research in topics: Excited state & Nuclear magnetic resonance spectroscopy. The author has an hindex of 14, co-authored 45 publications receiving 485 citations. Previous affiliations of Francisco B. T. Pessine include University of Southern California.

Review: Cyclodextrin Inclusion Complexes Probed by NMR Techniques

Abstract: Cyclodextrins (CDs) are cyclic oligomers of glucopyranose units that play an important role as a host in inclusion complexes, where non-covalent interactions are involved. They have been extensively studied in supramolecular chemistry. Because of its biocompatibility, relatively non-toxicity and relatively low price, CDs have been widely employed for encapsulation of several substances, being used in food, cosmetic and pharmaceutical industries. Nuclear Magnetic Resonance spectroscopy (NMR) is one of the most useful techniques to study interactions of cyclodextrins with guest compounds. It is relatively easy to apply, the experiments are fast and it is the only technique that provides information on the right orientation of the guest molecule inside the cavity and also on other important parameters related to the physico-chemical characteristics of the inclusion complexes. In this review, it will be discussed the study of inclusion complexes between drugs and cyclodextrins by different NMR techniques. Initially, a brief introduction of the properties of cyclodextrins, its importance as innovative drug carrier systems and its applicability is reviewed. Then different NMR techniques used for characterization of inclusion complexes are detailed, with examples studied in our group, which involves since simple measures of 1H-NMR spectrum to more sophisticated experiments, e.g. Diffusion Ordered SpectroscopY (DOSY), NOE methods (ROESY), T1 measure and solid NMR by 13C Cross-Polarization Magic Angle Spinning (CPMAS).

Tobacco Mosaic Virus Disassembly by High Hydrostatic Pressure in Combination with Urea and Low Temperature

Abstract: We investigated the effect of low temperature and urea combined with high pressure on tobacco mosaic virus (TMV). The evaluation of its aggregation state and denaturation process was studied using ...

Synthesis and characterization of inclusion complex of the vasodilator drug minoxidil with β-cyclodextrin

Abstract: The inclusion complex of β-cyclodextrin and minoxidil (2,4-diamino-6-piperidinopyrimidine 3-oxide) was synthesized using two methods—kneading and freeze-drying—and characterized by UV-Vis spectroscopy, infrared spectroscopy, powder X-ray diffractometry, differential scanning calorimetry, thermal gravimetric analysis, and nuclear magnetic resonance spectroscopy. These techniques have demonstrated the existence of inclusion compound formation between the host and guest with a molar ratio of 1:1. The studies of solubility and the data obtained by nuclear magnetic resonance spectroscopy showed a weak interaction between the guest and the cyclodextrin molecules in solution.

Theoretical studies of Nile Red by ab initio and semiempirical methods

Abstract: Ab initio and semiempirical calculations were carried out for the Nile Red (NR) molecule to study the possible occurrence of the twisted intramolecular charge transfer process The results showed that NR is planar in the ground state (using the CEP-31g basis set) with a high barrier to rotation of the diethylamine group by 90° (0334 and 0381 eV with AM1 and CEP-31g, respectively) CIS calculations showed that the charge transfer decreases after the twisting, in contrast to the TICT prediction The solvatochromic effect was justified through the dipole moments calculated for the first excited state

Formulation of functionalized PLGA nanoparticles with folic acid-conjugated chitosan for carboplatin encapsulation

Abstract: Poly( d , l -lactic-co-glycolic acid), or PLGA, is the most frequently used biodegradable and biocompatible polymer in preparation of nanoparticles for biomedical applications In this work nanoparticles composed of PLGA were prepared to produce nanocarriers for a platinum-based antitumoral drug: carboplatin The carboplatin-loaded PLGA nanoparticles were obtained by nanoprecipitation method, using TPGS (D-α-tocopheryl polyethylene glycol succinate) as stabilizer and acetone as organic phase In order to improve the delivery of carboplatin to cancer cells, folic acid-conjugated chitosan-coated (FA-CS) PLGA nanoparticles were also prepared, using 22 factorial design with center point for unmodified and surface modified nanoparticles For PLGA nanoparticles, the results showed that mean particle size is dependent of time, amplitude of sonication, volume and concentration of TPGS aqueous solution (according to a linear model), while PDI and zeta potential are constants The optimized formulation (1210 nm, PDI = 0120 and −340 mV) was stable over a period of 60 days when stored at 10 °C, with entrapment efficiency (EE) = 5%, drug loading = 037% and nanoparticle yield = 77% Also, it was possible to improve these parameters (EE = 395%, drug loading = 26% and yield = 91%) by reduction of dialysis (24–2 h) and acetone evaporation (24–1 h) time For surface modified PLGA nanoparticles, mean particle size and PDI are dependent of stirring time and concentration of FA-CS solution (according to a quadratic model), while zeta potential is also dependent of these factors but according to a linear model The optimal formulation showed particles with size of 1780 nm, PDI = 020, zeta potential = 460 mV, EE = 355%, drug loading = 18% and nanoparticle yield = 92% Encapsulation of carboplatin was confirmed by UV–Vis spectroscopy using a derivatization technique with orto-phenylenediamine In conclusion, the results obtained in this work demonstrated that formulation variables can be explored to obtain the optimal preparation conditions of PLGA nanoparticles

Drug Discovery Today

Abstract: In recent years, tools for the development of new drugs have been dramatically improved. These include genomic and proteomic research, numerous biophysical methods, combinatorial chemistry and screening technologies. In addition, early ADMET studies are employed in order to significantly reduce the failure rate in the development of drug candidates. As a consequence, the lead finding, lead optimization and development process has gained marked enhancement in speed and efficiency. In parallel to this development, major pharma companies are increasingly outsourcing many components of drug discovery research to biotech companies. All these measures are designed to address the need for a faster time to market. New screening methodologies have contributed significantly to the efficiency of the drug discovery process. The conventional screening of single compounds or compound libraries has been dramatically accelerated by high throughput screening methods. In addition, in silico screening methods allow the evaluation of virtual compounds. A wide range of new lead finding and lead optimization opportunities result from novel screening methods by NMR, which are the topic of this review article.

Laser-induced gas-surface interactions

Abstract: Chemical reactions in homogeneous systems activated by laser radiation have been extensively investigated for more than a decade. The applications of lasers to promote gas-surface interactions have just been realized in recent years. The purpose of this paper is to examine the fundamental processes involved in laser-induced gas-surface chemical interactions. Specifically, the photon-enhanced adsorption, adsorbate-adsorbate and adsorbate-solid reactions, product formation and desorption processes are discussed in detail. The dynamic processes involved in photoexcitation of the electronic and vibrational states, the energy transfer and relaxation in competition with chemical interactions are considered. These include both single and multiple photon adsorption, and fundamental and overtone transitions in the excitation process, and inter- and intra-molecular energy transfer, and coupling with phonons, electron-hole pairs and surface plasmons in the energy relaxation process. Many current experimental and theoretical studies on the subject are reviewed and discussed with the goal of clarifying the relative importance of the surface interaction steps and relating the resulting concepts to the experimentally observed phenomena. Among the many gas-solid systems that have been investigated, there has been more extensive use of CO adsorbed on metals, and SF6 and XeF2 interactions with silicon as examples to illustrate the many facets of the electronically and vibrationally activated surface processes. Results on IR laser stimulated desorption of C5H5N and C5D5N molecules from various solid surfaces are also presented. It is clearly shown that rapid intermolecular energy exchange and molecule to surface energy transfer can have important effects on photodesorption cross sections and isotope selectivities. It is concluded that utilization of lasers in gas-surface studies not only can provide fundamental insight into the mechanism and dynamics involved in heterogeneous interactions, but also offer the possibility for technical innovation for practical applications.

Transport of liposomal and albumin loaded curcumin to living cells: an absorption and fluorescence spectroscopic study.

Abstract: Curcumin, a lipid soluble antioxidant, exhibits solvent and medium sensitive absorption and fluorescence properties. Using such changes, the average binding constants of curcumin to phosphatidylcholine (PC) liposomes and human serum albumin (HSA) were estimated to be 2.5 x 10(4) M(-1) and 6.1 x 10(4) M(-1) respectively. From the studies on temperature dependent fluorescence anisotropy of liposomal curcumin and its fluorescence quenching by acrylamide and iodide, it was concluded that curcumin is located in the gel phase of the liposomes. Similarly from the studies on quenching of tryptophan fluorescence in HSA by curcumin, it was found to be in the same domain as that of tryptophan. Both liposomal and HSA vehicles were examined for the transfer of curcumin to spleen lymphocyte cells, EL4 lymphoma cell line and compared with aqueous DMSO vehicles. From these studies it was found that liposomal vehicle is capable of loading more curcumin in to cells than HSA or aqueous-DMSO, and lymphoma cells show preferential uptake of curcumin to lymphocytes. The fluorescence of curcumin in EL4 lymphoma cells was found to be significantly higher as compared to the lymphocytes. The present study demonstrates a simple and quantitative method of estimation of curcumin delivered to cells by different vehicles using absorption and fluorescence spectroscopy.