led to their commercial use as globular protein replacements for gene therapy,
immunodiagnostics [132, 133], and a variety of other biological applications [52].
6 Dendrimers: Window to a New Nano-periodic System
for Defining and Unifying Nanoscience
“Science will continue to advance regardless of disputes over priorities. However, confusion and disagreement over common scientific language and standards can plunge a
discipline into chaos. Such was the case for 19th century traditional chemistry before the
emergence of Mendeleyev’s Periodic Table of the Elements (1869).” From Mendeleyev’s
Dream – The Quest for the Elements by P. Strathern [134].
Clearly the need for a unifying system and framework that provides a central dogma
with predictive capabilities for a priori design assessment as well as for defining
risk/benefit boundaries remains an urgent challenge for nanotechnology [135]. Historically, a similar challenge existed for traditional chemistry in the early nineteenth
century. Prior to the emergence of a central dogma and a common scientific
language, traditional chemistry was viewed as an empirical discipline, which was
transformed into a precise, predictive science only after the advent of atomic/
molecular theory, established stoichiometries, and the emergence of well-defined
periodic property patterns as first described by Mendeleev in 1869 [134].
It is from this perspective that the National Science Foundation (NSF) sponsored
a workshop entitled “Periodic patterns, relationships and categories of well-defined
nanoscale building blocks” in 2007 [136]. This seminal workshop evolved an
embryonic consensus that subsequently led to a proposed concept for defining
and unifying nanoscience based on the integration of traditional chemistry “first
principles” with certain critical hierarchical design parameters (CHDPs)
[137, 138]. These CHDPs include size, shape, surface chemistry, flexibility/rigidity,
composition, and architecture and appear to be conserved and transferred as a
function of complexity (illustrated in Fig. 14).
These highly conserved CHDP transformations were first reported for a wide
range of divergent, structure-controlled dendrimer syntheses as early as 1990
[9]. These syntheses provided a remarkable window for observing CHDPdependent structure control related to divergent dendrimer synthesis. This structure
control and information transfer was observed from the atomic scale (critical atomic
design parameters, CADP), i.e., 10
À11 m ! molecular/subnanoscale (critical
molecular design parameters, CMDP), i.e., 10
À10 m ! nanoscale level (critical
nanoscale design parameters, CNDP), i.e., 10
À9 m, as shown in Fig. 15. Furthermore, it became readily apparent that these CHDPs defined discrete, reproducible
hierarchical periodic property patterns. These patterns were uniquely different at
each of these hierarchical levels. In essence, the predictions of Nobel Laureate
physicist, P.W. Anderson in 1972 were observed to be fulfilled [139]. Simply stated,
as one breaks hierarchical symmetry by advancement with well-defined building
blocks to higher structural complexity, the whole becomes not only more than, but
very different from the sum of its parts. As a consequence, one should expect to
350
D.A. Tomalia
immunodiagnostics [132, 133], and a variety of other biological applications [52].
6 Dendrimers: Window to a New Nano-periodic System
for Defining and Unifying Nanoscience
“Science will continue to advance regardless of disputes over priorities. However, confusion and disagreement over common scientific language and standards can plunge a
discipline into chaos. Such was the case for 19th century traditional chemistry before the
emergence of Mendeleyev’s Periodic Table of the Elements (1869).” From Mendeleyev’s
Dream – The Quest for the Elements by P. Strathern [134].
Clearly the need for a unifying system and framework that provides a central dogma
with predictive capabilities for a priori design assessment as well as for defining
risk/benefit boundaries remains an urgent challenge for nanotechnology [135]. Historically, a similar challenge existed for traditional chemistry in the early nineteenth
century. Prior to the emergence of a central dogma and a common scientific
language, traditional chemistry was viewed as an empirical discipline, which was
transformed into a precise, predictive science only after the advent of atomic/
molecular theory, established stoichiometries, and the emergence of well-defined
periodic property patterns as first described by Mendeleev in 1869 [134].
It is from this perspective that the National Science Foundation (NSF) sponsored
a workshop entitled “Periodic patterns, relationships and categories of well-defined
nanoscale building blocks” in 2007 [136]. This seminal workshop evolved an
embryonic consensus that subsequently led to a proposed concept for defining
and unifying nanoscience based on the integration of traditional chemistry “first
principles” with certain critical hierarchical design parameters (CHDPs)
[137, 138]. These CHDPs include size, shape, surface chemistry, flexibility/rigidity,
composition, and architecture and appear to be conserved and transferred as a
function of complexity (illustrated in Fig. 14).
These highly conserved CHDP transformations were first reported for a wide
range of divergent, structure-controlled dendrimer syntheses as early as 1990
[9]. These syntheses provided a remarkable window for observing CHDPdependent structure control related to divergent dendrimer synthesis. This structure
control and information transfer was observed from the atomic scale (critical atomic
design parameters, CADP), i.e., 10
À11 m ! molecular/subnanoscale (critical
molecular design parameters, CMDP), i.e., 10
À10 m ! nanoscale level (critical
nanoscale design parameters, CNDP), i.e., 10
À9 m, as shown in Fig. 15. Furthermore, it became readily apparent that these CHDPs defined discrete, reproducible
hierarchical periodic property patterns. These patterns were uniquely different at
each of these hierarchical levels. In essence, the predictions of Nobel Laureate
physicist, P.W. Anderson in 1972 were observed to be fulfilled [139]. Simply stated,
as one breaks hierarchical symmetry by advancement with well-defined building
blocks to higher structural complexity, the whole becomes not only more than, but
very different from the sum of its parts. As a consequence, one should expect to
350
D.A. Tomalia