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Garcia-Garcia L A, et al.

These papers were published by Nature Biotechnology, occurrence of each keyword. Only those keywords with
Biomaterials, and Advanced Materials and Science. five or more occurrences were selected, as this analysis
Next, a software program was specially developed sought to identify only the most relevant terms.
to text mine these articles and to determine the most 3. Results and Discussion
relevant words in each according to their frequency
of occurrence. Single words and pairs of words with Initially, 3,573 articles were identified for 2000 to 2017,
the highest frequencies were identified, and a cleaning of which 2,066 were from Scopus and 1,507 were from
task was performed to remove those not related to WoS. Their bibliographic information was retrieved for
bioprinting. An iterative process was developed to further analysis, and a cleaning process was applied to
validate the retrieved information and to design the narrow the results to 2,021 papers, whose bibliographic
search query, finally arriving at the following: data were used to create keyword co-occurrence maps.
( ( ( ( ( 3d OR 3-d OR three-dimensional ) W/1 ( VOSviewer was used to determine the keywords with
bioprint* OR engineer* OR print* OR tech* OR the highest frequency as well as the relevance scoring
fabricat* OR process* OR manufact* OR building of each keyword. This score was calculated to identify
OR built ) ) OR ( ( bio-engineer* OR bioengineer* terminology particularly related to the topic under study.
OR biofabricat* OR bioprint* OR biotech* OR A threshold of five or more occurrences was established,
biomanufact* ) ) OR ( bioadditive W/1 manufact* resulting in 2,956 keywords. Of these, 60% (1,773)
) OR ( 3d AND bioprint* ) ) ) W/5 ( scaffold* OR with the highest relevance score were included in the
construct* OR spheroid* OR channel* OR structure* analysis. A manual cleaning process was applied to these
OR matr* OR crosslinking OR block* OR keywords to strengthen the analysis and to eliminate
aggregate* OR sheet* OR biomim* OR bioactiv* general words such as ‘control’ or ‘patient’ that, although
OR biohybrid* OR bioresorbable OR bioscaffolds related to the topic, did not provide specific information
OR biosensors OR bioassembl* OR bioartificial related to the study’s focus (materials, applications, or
OR bioerodible OR biopatterning OR biopaper methods). This resulted in a final total of 1,759 keywords
OR microextrusion ) W/5 ( cell* OR tissue* OR from 2000 to 2017.
stem OR multicellular OR organ* OR biolog* OR All 1,759 keywords were plotted using Gephi software.
embryonic OR vascular OR vessels OR collagen This tool aids in the visualization of network maps over
OR bone* OR osseo* OR adipose OR vascular a wide range of areas to determine the interaction of their
OR cardiac OR heart OR cartilage* OR muscle ) components [25–28] . Figure 1 shows the keywords’ network
AND NOT ( “data storage” OR photonic OR pcl OR co-occurrence map. Each keyword is represented by a
“social capital” ) ) node, and all nodes are connected by 81,339 links. The
Here, W/# refers to the proximity of # words, and OR, node size is proportional to the occurrence frequency of
AND, and AND NOT are Boolean operators used to
combine or exclude terms. This study aimed to provide
the most complete landscape of scientific progress
worldwide, and therefore, information was collected
from the two largest scientific databases, Scopus, whose
coverage was mentioned previously, and Web of Science
(WoS), which contains information from more than
13,000 journals over an even wider range of areas from
social science to medical disciplines to engineering [23] .
The above query was used to search the titles, abstracts,
and keywords of published documents from both re-
sources. Considering that 3D bioprinting represents a
novel technology with major innovations starting in
the early 2000s, the research was limited to articles
published from 2000 to 2017. Bibliographic information
of Scopus and WoS documents was obtained, and a
further cleaning process was applied to homogenise
articles’ titles and keywords and to remove duplicate
articles. Subsequently, the data was imported into
VOSviewer, a software developed for the creation and
[24]
visualisation of network maps . This tool facilitated the
determination of the average publication year (APY) and Figure 1. Keyword network map of 1,759 nodes and their 81,339
links.

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