One of the most important aspects of chitosan' derivatization depends on the crosslinking of their polymeric chains. This chemical strategy may confer new properties to those derivatives, which can be used to enhance their biotechnological applications. So far, this work aims to discuss some strategies related to the crosslinking of chitosan focusing on reagents, reaction mechanisms and properties/applications of the crosslinked derivatives in several fields of science.

Resumo O presente estudo refere-se ao impacto do uso de agrotóxicos sobre a saúde humana no Submédio do Vale do São Francisco. Por meio de entrevistas objetivou-se analisar a influência dos condicionantes sociais, culturais e econômicos no processo saúde-doença dos trabalhadores expostos a agrotóxicos. Para a coleta de dados foram entrevistados 339 trabalhadores rurais de perímetros irrigados dos municípios de Juazeiro-BA e Petrolina-PE. Todos do sexo masculino, sendo 182 (53,7%) proprietários rurais e 157 (46,3%) empregados, predominando indivíduos entre 40 e 59 anos entre os proprietários e abaixo de 39 anos entre os trabalhadores. Mais de 50% apresentou baixo nível de escolaridade e 55,2% tinha rendimentos mensais menor ou igual a 2 salários mínimos. Muitos sabem da importância do uso de EPIs e da obrigatoriedade do receituário agronômico para a utilização e a compra de agrotóxicos, entretanto cerca de 40% não usam EPIs ou fazem uso de forma incompleta e 28,9% não apresentam receituário durante a compra. Mais de 9% dos participantes relataram casos de intoxicação, no entanto, menos de 7% procuraram atendimento especializado. Os trabalhadores sabem que o uso de agrotóxicos nas lavouras os expõem a situações de risco, mas essa informação não é suficiente para alterar a conduta no exercício laboral.

Theranostics combines therapeutic and imaging diagnostic techniques that are extremely dependent on the action of imaging agent, transporter of therapeutic molecules, and specific target ligand, in which fluorescent probes can act as diagnostic agents. In particular, naphthoimidazoles are potential bioactive heterocycle compounds to be used in several biomedical applications. With this aim, a group of seven naphth[1,2-d]imidazole compounds were synthesized from β-lapachone. Their optical properties and their cytotoxic activity against cancer cells and their compounds were evaluated and confirmed promising values for molar absorptivity coefficients (on the order of 10³ to 10⁴), intense fluorescence emissions in the blue region, and large Stokes shifts (20–103 nm). Furthermore, the probes were also selective for analyzed cancer cells (leukemic cells (HL-60). The naphth[1,2-d]imidazoles showed IC₅₀ between 8.71 and 29.92 μM against HL-60 cells. For HCT-116 cells, values for IC₅₀ between 21.12 and 62.11 μM were observed. The selective cytotoxicity towards cancer cells and the fluorescence of the synthesized naphth[1,2-d]imidazoles are promising responses that make possible the application of these components in antitumor theranostic systems.

Background: Natural naphthoquinones have shown diversified biological activities including antibacterial, antifungal, antimalarial, and cytotoxic activities. However, they are also compounds with acute cytotoxicity, immunotoxicity, carcinogenesis, and cardio- and hepatotoxicity, and the modification at their redox center is an interesting strategy to overcome such harmful activity. Objective: In this study, four novel semisynthetic hydrazones, derived from the isomers α- and β- lapachones (α and β, respectively) and coupled with the drugs hydralazine (HDZ) and isoniazid (ACIL), were prepared, evaluated by electrochemical methods and assayed for anticancer activity. Methods: The semisynthetic hydrazones were obtained and had their molecular structures established by NMR, IR, and MS. Anticancer activity was evaluated by cell viability determined by reduction of 3-(4,5-dimethyl-2-thiazol)-2,5-diphenyl-2H-tetrazolium bromide (MTT). The electrochemical studies, mainly cyclic voltammetry, were performed, in aprotic and protic media. Results: The study showed that the compounds 2, 3, and 4 were active against at least one of the cancer cell lines evaluated, compounds 3 and 4 being the most cytotoxic. Toward HL-60 cells, compound 3 was 20x more active than β-lapachone, and 3x more cytotoxic than doxorubicin. Furthermore, 3 showed an SI value of 39.62 for HL-60 cells. Compound 4 was active against all cancer cells tested, with IC₅₀ values in the range 2.90–12.40 μM. Electrochemical studies revealed a profile typical of self-protonation and reductive cleavage, dependent on the supporting electrolyte. Conclusion: These results therefore indicate that compounds 3 and 4 are strong candidates as prototypes of new antineoplastic drugs.