# Green Approaches to Carbon Nanostructure-Based Biomaterials  
[PERSON]  
1 Chemical and Pharmaceutical Sciences Department, University of Trieste, 34127 Trieste, Italy; [EMAIL_ADDRESS] (S.A.); [EMAIL_ADDRESS] (M.C.C.); [EMAIL_ADDRESS] (P.F)  
[PERSON]  
1 Chemical and Pharmaceutical Sciences Department, University of Trieste, 34127 Trieste, Italy; [EMAIL_ADDRESS] (S.A.); [EMAIL_ADDRESS] (M.C.C.); [EMAIL_ADDRESS] (P.F)  
[PERSON]  
3 Dipartimento di Scienze Chimiche, Biologiche, Farmaceutiche e Ambientali, University of Messina, 98168 Messina, Italy; [EMAIL_ADDRESS] 3  
[PERSON]  
1225125  
Each of these components has its own unique properties related to the specific morphology, size, and reactivity. They generally feature very interesting electronic conductivity, high mechanical strength, low density, as well as the ability to undergo chemical functionalization to further tune their properties as needed for the intended application. It is thus not surprising that many reviews already exist on their clinical applications [14] in biomedicine [15; 16; 17] and, above all, on their potential use in oncology [18], such as innovative components in cancer theranostics [19] and cancer therapy [20], thanks to their ability to target the tumor micro-environment [21]. Indeed, the possibility to use them not only as vehicles for drug delivery [22], but also for innovative imaging [23] and biosensing [24], makes them ideal candidates for innovative theranostics [25; 26].  
Research is also very active on their applications to target diseases other than cancer, such as atherosclerosis [27], and infections [28], including the recent fight against coronaviruses [29]. Further areas of intense investigation include tissue engineering [30], in particular to reconstruct the heart [31] and to re-establish neural connections [32], due to their demonstrated ability to boost the electrical activity of conductive tissue [33] and stimulate nerve growth [34]. Finally, there has been increased interest in their electron-conductive abilities, to develop innovative wearable electronics [35].  
Interactions between carbon nanomaterials and biomolecules, especially DNA [36] and proteins [37], are the object of many investigations, due to their role in determining the dynamic structure of the biomolecular corona [38], which ultimately affects the response in vivo [39], e.g., the biodistribution [40], the immune response [41], for instance mediated by neutrophils [42], and, thus, the biodegradation [43].  
Despite decades of research efforts in these sectors, there are still many concerns regarding carbon nanostructure toxicity [44; 45] and immunogenicity [46], also due to the high heterogeneity of this class of materials, which present both unexploited opportunities and unresolved challenges [47] in nanomedicine. In particular, one of the latter regards the large-scale production for mainstream applications [48], considering the current emergency we are facing, in terms of preservation of the environment, especially the development and implementation of green routes for their sustainable production.  
Therefore, in light of the vastness and complexity of the topic of carbon nanomaterials for biomedical applications, this concise review aims to cover only the most recent advances in the nanomedicine area that describe green chemical routes for their preparation and chemical modifications, in the hope that it will inspire scientists that enter this area towards more environmentally conscious choices for their chemical procedures.